WorldWideScience

Sample records for satellite mass ejections

  1. Coronal Mass Ejections

    Science.gov (United States)

    Crooker, Nancy; Joselyn, Jo Ann; Feynman, Joan

    The early 1970's can be said to mark the beginning of The Enlightenment in the history of the Space Age, literally as well as by analogy to European history. Instruments blinded by Earth's atmosphere were lifted above and, for the first time, saw clearly and continuously the ethereal white light and sparkling x-rays from the solar corona. From these two bands of the light spectrum came images of coronal mass ejections and coronal holes, respectively. But whereas coronal holes were immediately identified as the source of high-speed solar wind streams, at first coronal mass ejections were greeted only by a sense of wonder. It took years of research to identify their signatures in the solar wind before the fastest ones could be identified with the well-known shock disturbances that cause the most violent space storms.

  2. Coronal Mass Ejections

    CERN Document Server

    Kunow, H; Linker, J. A; Schwenn, R; Steiger, R

    2006-01-01

    It is well known that the Sun gravitationally controls the orbits of planets and minor bodies. Much less known, however, is the domain of plasma fields and charged particles in which the Sun governs a heliosphere out to a distance of about 15 billion kilometers. What forces activates the Sun to maintain this power? Coronal Mass Ejections (CMEs) and their descendants are the troops serving the Sun during high solar activity periods. This volume offers a comprehensive and integrated overview of our present knowledge and understanding of Coronal Mass Ejections (CMEs) and their descendants, Interplanetary CMEs (ICMEs). It results from a series of workshops held between 2000 and 2004. An international team of about sixty experimenters involved e.g. in the SOHO, ULYSSES, VOYAGER, PIONEER, HELIOS, WIND, IMP, and ACE missions, ground observers, and theoreticians worked jointly on interpreting the observations and developing new models for CME initiations, development, and interplanetary propagation. The book provides...

  3. Computation and Prediction of plasma drag on Orbiting Satellites due to Space Environmental Perturbation by Coronal Mass Ejections (CMEs)

    Science.gov (United States)

    Nwankwo, Victor U. J.; Chakrabarti, Sandip Kumar

    2012-07-01

    Certain earth pointing Coronal Mass Ejections (CMEs) induce geomagnetic storms, which significantly affect human activities. Satellites orbiting earth are particularly vulnerable to blasts of solar energy resulting from this phenomenon. It is known that the huge amount of energetic ultraviolet radiation from this space environmental disturbance can heat up the outer atmosphere, causing it to expand. This can cause a significant drag on Earth-Orbiting satellites and even degrade the precision of Global Positioning Systems (GPS) measurements. However, CMEs are more damaging. They are more frequent during the active (solar maximum) Phase of the sun's approximately 11-year cycle. As we approach another maximum in 2012-2013, it is instructive to make an estimate of average daily production of energetic proton flux based on GOES data on earth-pointing CMEs in the past solar cycle. We also compute the drag on satellites due to atmospheric perturbations by CMEs and make predictions of how the existing satellite orbits could be affected near the peak of next solar cycle maximum.

  4. Effects of Plasma Drag on Low Earth Orbiting Satellites due to Heating of Earth's Atmosphere by Coronal Mass Ejections

    CERN Document Server

    Nwankwo, Victor U J

    2013-01-01

    Solar events, such as coronal mass ejections (CMEs) and solar flares, heat up the upper atmosphere and near-Earth space environment. Due to this heating and expansion of the outer atmosphere by the energetic ultraviolet, X-ray and particles expelled from the sun, the low Earth-Orbiting satellites (LEOS) become vulnerable to an enhanced drag force by the ions and molecules of the expanded atmosphere. Out of various types of perturbations, Earth directed CMEs play the most significant role. They are more frequent and intense during the active (solar maximum) phase of the sun's approximately 11-year cycle. As we are approaching another solar maximum later in 2013, it may be instructive to analyse the effects of the past solar cycles on the orbiting satellites using the archival data of space environment parameters as indicators. In this paper, we compute the plasma drag on a model LEOS due to the atmospheric heating by CMEs and other solar events as a function of the solar parameters. Using the current forecast ...

  5. Characteristics of Coronal Mass Ejections

    Science.gov (United States)

    Talukder, F.; Marchese, A. K.; Tulsee, T.

    2014-12-01

    A coronal mass ejection (CME) is a release of charged particles resulting from solar activity. These charged particles can affect electronics on spacecraft, airplanes, global positioning systems, and communication satellites. The purpose of this research was to study CME data from satellites and correlate these to other properties. Solar wind data collected by STEREO A/B and ACE satellites were analyzed. The data consisted of solar wind flux for various elements (helium through iron), as well as the components of the interplanetary magnetic field. CME events are known to cause a surge in the helium flux, as well as other particles. It is hypothesized that a CME event will cause an increase in the number of lighter elements relative to heavier particles. This is because for a given input of energy, lighter elements are expected to be accelerated to a greater extent than heavier elements. A significant increase was observed in the ratio between helium to oxygen (He/O) prior to intense CMEs. A CME event on November 4, 2003 caused an eleven-fold increase in the He/O ratio, while for another event on April 2, 2001 the He/O ratio increased from 80 to 700. A significant increase in He/O ratio is not observed during weaker CMEs. Furthermore, it was also observed that not all increases in the ratio were accompanied by CMEs. The increase in He/O ratio prior to the CME arrival might be used as a way to predict future events.

  6. Coronal Mass Ejections: Observations

    Directory of Open Access Journals (Sweden)

    David F. Webb

    2012-06-01

    Full Text Available Solar eruptive phenomena embrace a variety of eruptions, including flares, solar energetic particles, and radio bursts. Since the vast majority of these are associated with the eruption, development, and evolution of coronal mass ejections (CMEs, we focus on CME observations in this review. CMEs are a key aspect of coronal and interplanetary dynamics. They inject large quantities of mass and magnetic flux into the heliosphere, causing major transient disturbances. CMEs can drive interplanetary shocks, a key source of solar energetic particles and are known to be the major contributor to severe space weather at the Earth. Studies over the past decade using the data sets from (among others the SOHO, TRACE, Wind, ACE, STEREO, and SDO spacecraft, along with ground-based instruments, have improved our knowledge of the origins and development of CMEs at the Sun and how they contribute to space weather at Earth. SOHO, launched in 1995, has provided us with almost continuous coverage of the solar corona over more than a complete solar cycle, and the heliospheric imagers SMEI (2003 – 2011 and the HIs (operating since early 2007 have provided us with the capability to image and track CMEs continually across the inner heliosphere. We review some key coronal properties of CMEs, their source regions and their propagation through the solar wind. The LASCO coronagraphs routinely observe CMEs launched along the Sun-Earth line as halo-like brightenings. STEREO also permits observing Earth-directed CMEs from three different viewpoints of increasing azimuthal separation, thereby enabling the estimation of their three-dimensional properties. These are important not only for space weather prediction purposes, but also for understanding the development and internal structure of CMEs since we view their source regions on the solar disk and can measure their in-situ characteristics along their axes. Included in our discussion of the recent developments in CME

  7. Coronal Mass Ejections An Introduction

    CERN Document Server

    Howard, Timothy

    2011-01-01

    In times of growing technological sophistication and of our dependence on electronic technology, we are all affected by space weather. In its most extreme form, space weather can disrupt communications, damage and destroy spacecraft and power stations, and increase radiation exposure to astronauts and airline passengers. Major space weather events, called geomagnetic storms, are large disruptions in the Earth’s magnetic field brought about by the arrival of enormous magnetized plasma clouds from the Sun. Coronal mass ejections (CMEs) contain billions of tons of plasma and hurtle through space at speeds of several million miles per hour. Understanding coronal mass ejections and their impact on the Earth is of great interest to both the scientific and technological communities. This book provides an introduction to coronal mass ejections, including a history of their observation and scientific revelations, instruments and theory behind their detection and measurement, and the status quo of theories describing...

  8. Coronal Mass Ejections travel time

    Science.gov (United States)

    Braga, Carlos Roberto; Souza de Mendonça, Rafael Rodrigues; Dal Lago, Alisson; Echer, Ezequiel

    2017-10-01

    Coronal mass ejections (CMEs) are the main source of intense geomagnetic storms when they are earthward directed. Studying their travel time is a key-point to understand when the disturbance will be observed at Earth. In this work, we study the CME that originated the interplanetary disturbance observed on 2013/10/02. According to the observations, the CME that caused the interplanetary disturbance was ejected on 2013/09/29. We obtained the CME speed and estimate of the time of arrival at the Lagrangian Point L1 using the concept of expansion speed. We found that observed and estimated times of arrival of the shock differ between 2 and 23 hours depending on method used to estimate the radial speed.

  9. Periodicities in Solar Coronal Mass Ejections

    CERN Document Server

    Lou, Y Q; Fan, Z; Wang, S; Wang, J

    2003-01-01

    Mid-term quasi-periodicities in solar coronal mass ejections (CMEs) during the most recent solar maximum cycle 23 are reported here for the first time using the four-year data (February 5, 1999 to February 10, 2003) of the Large Angle Spectrometric Coronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO). In parallel, mid-term quasi-periodicities in solar X-ray flares (class >M5.0) from the Geosynchronous Operational Environment Satellites (GOES) and in daily averages of Ap index for geomagnetic disturbances from the World Data Center (WDC) at the International Association for Geomagnetism and Aeronomy (IAGA) are also examined for the same four-year time span. Several conceptual aspects of possible equatorially trapped Rossby-type waves at and beneath the solar photosphere are discussed.

  10. Space weather and coronal mass ejections

    CERN Document Server

    Howard, Tim

    2013-01-01

    Space weather has attracted a lot of attention in recent times. Severe space weather can disrupt spacecraft, and on Earth can be the cause of power outages and power station failure. It also presents a radiation hazard for airline passengers and astronauts. These ""magnetic storms"" are most commonly caused by coronal mass ejections, or CMES, which are large eruptions of plasma and magnetic field from the Sun that can reach speeds of several thousand km/s. In this SpringerBrief, Space Weather and Coronal Mass Ejections, author Timothy Howard briefly introduces the coronal mass ejection, its sc

  11. Forecasting Coronal Mass Ejections from Vector Magnetograms

    Science.gov (United States)

    Falconer, D. A.; Moore, R. L.; Gary, G. A.; Six, N. Frank (Technical Monitor)

    2002-01-01

    In a 17 vector magnetogram study of 12 bipolar active regions (Falconer, Moore, & Gary, 2002, ApJ in press), we correlated four quantitative global magnetic measures with the Coronal Mass Ejections (CME) productivity of the active region. The global measures included a measure of active region size, the total magnetic flux phi and three measures of an active region global nonpotentiality 1) the net current (I (sub N)), 2) the length of the strong-shear, strong-field main neutral line (L(sub SS)) and 3) and the normalized twist (alpha = muIN/PHI). The CME productivity was determined from YOHKOH/SXT observations, Geostationary Operational Environmental Satellite (GOES), and when possible Solar and Heliospheric Observatory/Large Angle and Spectrometric Coronagraph Experiment (SOHO/LASCO) observations within 12 days of the day of the magnetogram. We found that the three measures of global nonpotentiality (I(sub N), L(sub SS), alpha) were all well correlated (greater than 99% confidence level) with an active region's CME productivity. The sample size was to small to confirm if there was a statistical significant correlation of the globally nonscientist measures with future CME activity (i.e. from the date of the magnetogram forward). We are doubling our sample, and will report on the statistical significance of global nonpotentiality as a predictor of future CME productivity. The new active regions are all from the first year of the upgraded MSFC vector magnetograms. This work, is funded by NSF through the Space Weather Program, by NASA through the Living with the Star, Targeted Research and Technology, and by NASA Solar Physics Supporting Research and Technology Program. The upgrade to the MSFC vector magnetograph was supported by the High Energy Solar Spectroscopic Imager (HESSI) mission.

  12. Coronal Mass Ejections of Solar Cycle 23

    Indian Academy of Sciences (India)

    Nat Gopalswamy

    2006-06-01

    I summarize the statistical, physical, and morphological properties of coronal mass ejections (CMEs) of solar cycle 23, as observed by the Solar and Heliospheric Observatory (SOHO) mission. The SOHO data is by far the most extensive data, which made it possible to fully establish the properties of CMEs as a phenomenon of utmost importance to Sun–Earth connection as well as to the heliosphere. I also discuss various subsets of CMEs that are of primary importance for their impact on Earth.

  13. Potential Method of Predicting Coronal Mass Ejection

    Science.gov (United States)

    Imholt, Timothy

    2001-10-01

    Coronal Mass Ejections (CME) may be described as a blast of gas and highly charged solar mass fragments ejected into space. These ejections, when directed toward Earth, have many different effects on terrestrial systems ranging from the Aurora Borealis to changes in wireless communication. The early prediction of these solar events cannot be overlooked. There are several models currently accepted and utilized to predict these events, however, with earlier prediction of both the event and the location on the sun where the event occurs allows us to have earlier warnings as to when they will affect man-made systems. A better prediction could perhaps be achieved by utilizing low angular resolution radio telescope arrays to catalog data from the sun at different radio frequencies on a regular basis. Once this data is cataloged a better predictor for these CME’s could be found. We propose a model that allows a prediction to be made that appears to be longer than 24 hours.

  14. Energetics of Solar Coronal Mass Ejections

    CERN Document Server

    Subramanian, P; Subramanian, Prasad; Vourlidas, Angelos

    2007-01-01

    Aims: To investigate if solar coronal mass ejections are driven mainly by coupling to the ambient solar wind, or through the release of internal magnetic energy. Methods: We examine the energetics of 39 flux-rope like coronal mass ejections (CMEs) from the Sun using data in the distance range $\\sim$ 2--20 $R_{{\\o}dot}$ from the Large Angle Spectroscopic Coronograph (LASCO) aboard the Solar and Heliospheric Observatory (SOHO). This comprises a complete sample of the best examples of flux-rope CMEs observed by LASCO in 1996-2001. Results: We find that 69% of the CMEs in our sample experience a clearly identifiable driving power in the LASCO field of view. For these CMEs which are driven, we examine if they might be deriving most of their driving power by coupling to the solar wind. We do not find conclusive evidence in favor of this hypothesis. On the other hand, we find that their internal magnetic energy is a viable source of the required driving power. We have estimated upper and lower limits on the power th...

  15. Coronal Mass Ejections: From Sun to Earth

    Science.gov (United States)

    Patsourakos, S.

    2016-06-01

    Coronal Mass Ejections (CMEs) are gigantic expulsions of magnetized plasmas from the solar corona into the interplanetary (IP) space. CMEs spawn ~ 1015 gr of mass and reach speeds ranging between several hundred to a few thousand km/s (e.g., Gopalswamy et al. 2009; Vourlidas et al. 2010). It takes 1-5 days for a CME to reach Earth. CMEs are one of the most energetic eruptive manifestations in the solar system and are major drivers of space weather via their magnetic fields and energetic particles, which are accelerated by CME-driven shocks. In this review we give a short account of recent, mainly observational, results on CMEs from the STEREO and SDO missions which include the nature of their pre-eruptive and eruptive configurations and the CME propagation from Sun to Earth. We conclude with a discussion of the exciting capabilities in CME studies that will soon become available from new solar and heliospheric instrumentation.

  16. Kinematical properties of coronal mass ejections

    CERN Document Server

    Temmer, Manuela

    2016-01-01

    Coronal mass ejections (CMEs) are the most dynamic phenomena in our solar system. They abruptly disrupt the continuous outflow of solar wind by expelling huge clouds of magnetized plasma into interplanetary space with velocities enabling to cross the Sun-Earth distance within a few days. Earth-directed CMEs may cause severe geomagnetic storms when their embedded magnetic fields and the shocks ahead compress and reconnect with the Earth's magnetic field. The transit times and impacts in detail depend on the initial CME velocity, size, and mass, as well as on the conditions and coupling processes with the ambient solar wind flow in interplanetary space. The observed CME parameters may be severly affected by projection effects and the constant changing environmental conditions are hard to derive. This makes it difficult to fully understand the physics behind CME evolution, preventing to do a reliable forecast of Earth-directed events. This short review focusing on observational data, shows recent methods which w...

  17. Magnetic structure of Coronal Mass Ejections

    CERN Document Server

    Lyutikov, Maxim

    2012-01-01

    We present several models of the magnetic structure of solar coronal mass ejections (CMEs). First, we model CMEs as expanding force-free magnetic structures. While keeping the internal magnetic field structure of the stationary solutions, expansion leads to complicated internal velocities and rotation, while the field structures remain force-free. Second, expansion of a CME can drive resistive dissipation within the CME changing the ionization states of different ions. We fit in situ measurements of ion charge states to the resistive spheromak solutions. Finally, we consider magnetic field structures of fully confined stable magnetic clouds containing both toroidal and poloidal magnetic fields and having no surface current sheets. Expansion of such clouds may lead to sudden onset of reconnection events.

  18. Solar Eruptions: Coronal Mass Ejections and Flares

    Science.gov (United States)

    Gopalswamy, Nat

    2012-01-01

    This lecture introduces the topic of Coronal mass ejections (CMEs) and solar flares, collectively known as solar eruptions. During solar eruptions, the released energy flows out from the Sun in the form of magnetized plasma and electromagnetic radiation. The electromagnetic radiation suddenly increases the ionization content of the ionosphere, thus impacting communication and navigation systems. Flares can be eruptive or confined. Eruptive flares accompany CMEs, while confined flares hav only electromagnetic signature. CMEs can drive MHD shocks that accelerate charged particles to very high energies in the interplanetary space, which pose radiation hazard to astronauts and space systems. CMEs heading in the direction of Earth arrive in about two days and impact Earth's magnetosphere, producing geomagnetic storms. The magnetic storms result in a number of effects including induced currnts that can disrupt power grids, railroads, and underground pipelines

  19. Anisotropic mass ejection in binary mergers

    CERN Document Server

    Morris, T; Podsiadlowski, Ph.

    2006-01-01

    We investigate the mass loss from a rotationally distorted envelope following the early, rapid in-spiral of a companion star inside a common envelope. For initially wide, massive binaries (M_1+M_2=20M_{\\odot}, P\\sim 10 yr), the primary has a convective envelope at the onset of mass transfer and is able to store much of the available orbital angular momentum in its expanded envelope. Three-dimensional SPH calculations show that mass loss is enhanced at mid-latitudes due to shock reflection from a torus-shaped outer envelope. Mass ejection in the equatorial plane is completely suppressed if the shock wave is too weak to penetrate the outer envelope in the equatorial direction (typically when the energy deposited in the star is less than about 1/3 of the binding energy of the envelope). We present a parameter study to show how the geometry of the ejecta depends on the angular momentum and the energy deposited in the envelope during a merging event. Applications to the nearly axisymmetric, but very non-spherical ...

  20. Radio-quiet Fast Coronal Mass Ejections

    Science.gov (United States)

    Gopalswamy, N.; Aguilar-Rodriguez, E.; Kaiser, M. L.; Howard, R. A.

    2004-12-01

    Coronal mass ejections (CMEs) drive shocks in the interplanetary medium that produce type II radio emission. These CMEs are faster and wider on the average, than the general population of CMEs. However, when we start from fast (speed > 900 km/s) and wide (angular width > 60 degrees), more than half of them are not associated with radio bursts. In order to understand why these CMEs are radio quiet, we collected all the fast and wide (FW) CMEs detected by the Solar and Heliospheric Observatory (SOHO) mission's Large Angle and Spectrometric Coronagraph (LASCO) and isolated those without associated type II radio bursts. The radio bursts were identified in the dynamic spectra of the Radio and Plasma Wave (WAVES) Experiment on board the Wind spacecraft. We also checked the list against metric type II radio bursts reported in Solar Geophysical Data and isolated those without any radio emission. This exercise resulted in about 140 radio-quiet FW CMEs. We identified the source regions of these CMEs using the Solar Geophysical Data listings, cross-checked against the eruption regions in the SOHO/EIT movies. We explored a number of possibilities for the radio-quietness: (i) Source region being too far behind the limb, (ii) flare size, (iii) brightness of the CME, and (iv) the density of the ambient medium. We suggest that a combination of CME energy and the Alfven speed profile of the ambient medium is primarily responsible for the radio-quietness of these FW CMEs.

  1. Anatomy of Depleted Interplanetary Coronal Mass Ejections

    Science.gov (United States)

    Kocher, M.; Lepri, S. T.; Landi, E.; Zhao, L.; Manchester, W. B., IV

    2017-01-01

    We report a subset of interplanetary coronal mass ejections (ICMEs) containing distinct periods of anomalous heavy-ion charge state composition and peculiar ion thermal properties measured by ACE/SWICS from 1998 to 2011. We label them “depleted ICMEs,” identified by the presence of intervals where C6+/C5+ and O7+/O6+ depart from the direct correlation expected after their freeze-in heights. These anomalous intervals within the depleted ICMEs are referred to as “Depletion Regions.” We find that a depleted ICME would be indistinguishable from all other ICMEs in the absence of the Depletion Region, which has the defining property of significantly low abundances of fully charged species of helium, carbon, oxygen, and nitrogen. Similar anomalies in the slow solar wind were discussed by Zhao et al. We explore two possibilities for the source of the Depletion Region associated with magnetic reconnection in the tail of a CME, using CME simulations of the evolution of two Earth-bound CMEs described by Manchester et al.

  2. Why are halo coronal mass ejections faster?

    Institute of Scientific and Technical Information of China (English)

    Qing-Min Zhang; Yang Guo; Peng-Fei Chen; Ming-De Ding; Cheng Fang

    2010-01-01

    Halo coronal mass ejections(CMEs)have been to be significantly faster than normal CMEs,which is a long-standing puzzle.In order to solve the puzzle,we first investigate the observed properties of 31 limb CMEs that clearly display loopshaped frontal loops.The observational results show a strong tendency that slower CMEs are weaker in white-light intensity.Then,we perform a Monte Carlo simulation of 20000 artificial limb CMEs that have an average velocity of~523 km s-1.The Thomson scattering of these events is calculated when they are assumed to be observed as limb and halo events,respectively.It is found that the white-light intensity of many slow CMEs becomes remarkably reduced when they turn from being viewed as a limb event to being viewed as a halo event.When the intensity is below the background solar wind fluctuation,it is assumed that they would be missed by coronagraphs.The average velocity of"detectable"halo CMEs is~922 km s-1,very close to the observed value.This also indicates that wider events are more likely to be recorded.The results soundly suggest that the higher average velocity of halo CMEs is due to that a majority of slow events and some of narrow fast events carrying less material are so faint that they are blended with the solar wind fluctuations,and therefore are not observed.

  3. Active Longitude and Coronal Mass Ejection Occurrences

    Science.gov (United States)

    Gyenge, N.; Singh, T.; Kiss, T. S.; Srivastava, A. K.; Erdélyi, R.

    2017-03-01

    The spatial inhomogeneity of the distribution of coronal mass ejection (CME) occurrences in the solar atmosphere could provide a tool to estimate the longitudinal position of the most probable CME-capable active regions in the Sun. The anomaly in the longitudinal distribution of active regions themselves is often referred to as active longitude (AL). In order to reveal the connection between the AL and CME spatial occurrences, here we investigate the morphological properties of active regions. The first morphological property studied is the separateness parameter, which is able to characterize the probability of the occurrence of an energetic event, such as a solar flare or CME. The second morphological property is the sunspot tilt angle. The tilt angle of sunspot groups allows us to estimate the helicity of active regions. The increased helicity leads to a more complex buildup of the magnetic structure and also can cause CME eruption. We found that the most complex active regions appear near the AL and that the AL itself is associated with the most tilted active regions. Therefore, the number of CME occurrences is higher within the AL. The origin of the fast CMEs is also found to be associated with this region. We concluded that the source of the most probably CME-capable active regions is at the AL. By applying this method, we can potentially forecast a flare and/or CME source several Carrington rotations in advance. This finding also provides new information for solar dynamo modeling.

  4. Nanodust dynamics during a coronal mass ejection

    Science.gov (United States)

    Czechowski, Andrzej; Kleimann, Jens

    2017-09-01

    The dynamics of nanometer-sized grains (nanodust) is strongly affected by electromagnetic forces. High-velocity nanodust was proposed as an explanation for the voltage bursts observed by STEREO. A study of nanodust dynamics based on a simple time-stationary model has shown that in the vicinity of the Sun the nanodust is trapped or, outside the trapped region, accelerated to high velocities. We investigate the nanodust dynamics for a time-dependent solar wind and magnetic field configuration in order to find out what happens to nanodust during a coronal mass ejection (CME). The plasma flow and the magnetic field during a CME are obtained by numerical simulations using a 3-D magnetohydrodynamic (MHD) code. The equations of motion for the nanodust particles are solved numerically, assuming that the particles are produced from larger bodies moving in near-circular Keplerian orbits within the circumsolar dust cloud. The charge-to-mass ratios for the nanodust particles are taken to be constant in time. The simulation is restricted to the region within 0.14 AU from the Sun. We find that about 35 % of nanodust particles escape from the computational domain during the CME, reaching very high speeds (up to 1000 km s-1). After the end of the CME the escape continues, but the particle velocities do not exceed 300 km s-1. About 30 % of all particles are trapped in bound non-Keplerian orbits with time-dependent perihelium and aphelium distances. Trapped particles are affected by plasma ion drag, which causes contraction of their orbits.

  5. Predicting Coronal Mass Ejections Using Machine Learning Methods

    CERN Document Server

    Bobra, Monica G

    2016-01-01

    Of all the activity observed on the Sun, two of the most energetic events are flares and Coronal Mass Ejections (CMEs). Usually, solar active regions that produce large flares will also produce a CME, but this is not always true (Yashiro et al., 2005). Despite advances in numerical modeling, it is still unclear which circumstances will produce a CME (Webb & Howard, 2012). Therefore, it is worthwhile to empirically determine which features distinguish flares associated with CMEs from flares that are not. At this time, no extensive study has used physically meaningful features of active regions to distinguish between these two populations. As such, we attempt to do so by using features derived from [1] photospheric vector magnetic field data taken by the Solar Dynamics Observatory's Helioseismic and Magnetic Imager instrument and [2] X-ray flux data from the Geostationary Operational Environmental Satellite's X-ray Flux instrument. We build a catalog of active regions that either produced both a flare and a...

  6. Stealthy but Geoeffective Coronal Mass Ejections

    Science.gov (United States)

    Nitta, Nariaki; Mulligan, Tamitha

    2017-08-01

    We have long known about the existence of "problem" geomagnetic storms whose origins are elusive. In more general terms, not all the 1 AU disturbances can be clearly attributed to coronal mass ejections (CMEs), high speed streams (HSSs) or corotation interaction regions (CIRs.) When interplanetary CME (ICME) signatures are found in in situ data, there is not always a flare or filament eruption on the Sun or even an obvious CME observed close to the Sun that correlates with the ICME within a reasonable time range. These ICMEs sometimes result in intense storms. Furthermore, there is a possibility that some of the more severe storms could be partly contributed by such ICMEs of unclear origin. Therefore space weather prediction will remain incomplete without properly understanding these ICMEs. Even if the ICME is paired with a CME, it is sometimes difficult to find where the latter comes from. This is often called the “stealth CME” that apparently lacks low coronal signatures (LCSs). STEREO's second and third view points have tremendously helped us determine its front-side origin and find when and where it forms and accelerates, which is important for isolating possible LCSs. Although SDO/AIA has been continuously taking full-disk EUV images in a wide temperature range since 2010, there are still a number of stealthy CMEs whose LCSs are unclear or ambiguous. It is assumed that they start at high altitudes, leaving weak or negligible LCSs. Some of them seem to involve multiple magnetic domains, and weak or open field regions. We present AIA observations of several stealthy CMEs, including recent ones, that were responsible for geomagnetic storms, emphasizing the need to compare images with long time differences and to find the periods at which the CME forms and accelerates. We also discuss uncertainties in interpreting in situ data as to whether a CME is present when data are dominated by other solar wind features, such as HSS and CIR.

  7. The Search for Stellar Coronal Mass Ejections

    Science.gov (United States)

    Villadsen, Jacqueline Rose

    2017-05-01

    Coronal mass ejections (CMEs) may dramatically impact habitability and atmospheric composition of planets around magnetically active stars, including young solar analogs and many M dwarfs. Theoretical predictions of such effects are limited by the lack of observations of stellar CMEs. This thesis addresses this gap through a search for the spectral and spatial radio signatures of CMEs on active M dwarfs. Solar CMEs produce radio bursts with a distinctive spectral signature, narrow-band plasma emission that drifts to lower frequency as a CME expands outward. To search for analogous events on nearby stars, I worked on system design, software, and commissioning for the Starburst project, a wideband single-baseline radio interferometry backend dedicated to stellar observations. In addition, I led a survey of nearby active M dwarfs with the Karl G. Jansky Very Large Array (VLA), detecting coherent radio bursts in 13 out of 23 epochs, over a total of 58 hours. This survey's ultra-wide bandwidth (0.23-6.0 GHz) dynamic spectroscopy, unprecedented for stellar observations, revealed diverse behavior in the time-frequency plane. Flare star UV Ceti produced complex, luminous events reminiscent of brown dwarf aurorae; AD Leo sustained long-duration, intense, narrow-band "storms"; and YZ CMi emitted a burst with substructure with rapid frequency drift, resembling solar Type III bursts, which are attributed to electrons moving at speeds of order 10% of the speed of light. To search for the spatial signature of CMEs, I led 8.5-GHz observations with the Very Long Baseline Array simultaneous to 24 hours of the VLA survey. This program detected non-thermal continuum emission from the stars in all epochs, as well as continuum flares on AD Leo and coherent bursts on UV Ceti, enabling measurement of the spatial offset between flaring and quiescent emission. These observations demonstrate the diversity of stellar transients that can be expected in time-domain radio surveys, especially

  8. The Search for Stellar Coronal Mass Ejections

    Science.gov (United States)

    Villadsen, Jacqueline; Hallinan, Gregg; Monroe, Ryan; Bourke, Stephen; Starburst Program Team

    2017-01-01

    Coronal mass ejections (CMEs) may dramatically impact habitability and atmospheric composition of planets around magnetically active stars, including young solar analogs and many M dwarfs. Theoretical predictions of such effects are limited by the lack of observations of stellar CMEs. My thesis addresses this gap through a search for the spectral and spatial radio signatures of CMEs on active M dwarfs.Solar CMEs produce radio bursts with a distinctive spectral signature, narrow-band plasma emission that drifts to lower frequency as a CME expands outward. To search for analogous events on nearby stars, I worked on system design, software, and commissioning for the Starburst project, a wideband single-baseline radio interferometry backend dedicated to stellar observations. In addition, I led a survey of nearby active M dwarfs with the Karl G. Jansky Very Large Array (JVLA), detecting 12 bright (>10 mJy) radio bursts in 58 hours. This survey’s ultra-wide bandwidth (0.23-6.0 GHz) dynamic spectroscopy, unprecedented for stellar observations, revealed diverse behavior in the time-frequency plane. Flare star UV Ceti produced complex, luminous events reminiscent of brown dwarf aurorae; AD Leo sustained long-duration, intense, narrow-band "storms"; and YZ CMi emitted a burst with substructure with rapid frequency drift, resembling solar Type III bursts, which are attributed to electrons moving at speeds of order 10% of the speed of light.To search for the spatial signature of CMEs, I led 8.5-GHz observations with the Very Long Baseline Array simultaneous to 24 hours of the JVLA survey. This program detected non-thermal continuum emission from the stars in all epochs, as well as continuum flares on AD Leo and coherent bursts on UV Ceti, enabling measurement of the spatial offset between flaring and quiescent emission.These observations demonstrate the diversity of stellar transients that can be expected in time-domain radio surveys, especially with the advent of large low

  9. Anticipating the Geoeffectiveness of Coronal Mass Ejections Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Coronal Mass Ejections (CMEs) are responsible for some of the most severe space weather at Earth. Major geomagnetic storms arise when CMEs carry large amounts of...

  10. Observational Properties of Coronal Mass Ejections

    Science.gov (United States)

    2006-01-01

    2003. Peameis, D.V., Magntetic topology of imspumlsive assd gradutal solar energetic particle Xic. H., L. Ofmran, and G. Lawvrence, Cone model for...425, 1097, 2004. Yashiro, S., N. Gopalssvamy, G. Michalek, assd R.A. Hosvard, Properties of narrow coronal Sltatstnigara~jU, A., Y.-i. Mootn, M. Dryer...G.M.,’FTit relatiomtslip hetwseen prominence ermtptions assd coronal mnass ejections.. 107(A8), 1223, doi: 10. 1029/2001 JAOO9 143, 2002. .1. Atssnn.s

  11. The coronal mass ejection waiting-time distribution

    CERN Document Server

    Wheatland, M S

    2003-01-01

    The distribution of times $\\Delta t$ between coronal mass ejections (CMEs) in the Large Angle and Spectrometric Coronagraph (LASCO) CME catalog for the years 1996-2001 is examined. The distribution exhibits a power-law tail $\\propto (\\Delta t)^{\\gamma}$ with an index $\\gamma\\approx -2.36\\pm 0.11$ for large waiting times ($\\Delta t>10 {\\rm hours}$). The power-law index of the waiting-time distribution varies with the solar cycle: for the years 1996-1998 (a period of low activity), the power-law index is $\\gamma\\approx-1.86\\pm 0.14$, and for the years 1999-2001 (a period of higher activity), the index is $\\gamma\\approx-2.98\\pm 0.20$. The observed CME waiting-time distribution, and its variation with the cycle, may be understood in terms of CMEs occurring as a time-dependent Poisson process. The CME waiting-time distribution is compared with that for greater than C1 class solar flares in the Geostationary Operational Environmental Satellite (GOES) catalog for the same years. The flare and CME waiting-time distri...

  12. Reconnection in a slow Coronal Mass Ejection

    Directory of Open Access Journals (Sweden)

    G. Poletto

    2008-10-01

    Full Text Available This paper aims at studying reconnection occurring in the aftermath of the 28 May 2004, CME, first imaged by the LASCO (Large Angle and Spectrometric Coronagraph C2 at 11:06 UT. The CME was observed in White Light and UV radiation: images acquired by the LASCO C2 and C3 coronagraphs and spectra acquired by UVCS (Ultraviolet Coronagraph Spectrometer allowed us to identify the level at which field lines, stretched outwards by the CME ejection, reconnect below the CME bubble. As the CME propagates outwards, reconnection occurs at increasingly higher levels. The process goes on at a low pace for several hours: here we give the profile of the reconnection rate vs. heliocentric distance over a time interval of ≈14 h after the CME onset, extending estimates of the reconnection rate to larger distances than previously inferred by other authors. The reconnection rate appears to decrease with time/altitude. We also calculate upper and lower limits to the density in the diffusion region between 4 and 7 R and conclude by comparing estimates of the classical and anomalous resistivity in the diffusion region with the value inferred from the data. The latter turns out to be ≥5 order of magnitudes larger than predicted by classical or anomalous theories, pointing to the need of identifying the process responsible for the observed value.

  13. Space Weather Effects of Coronal Mass Ejection

    Indian Academy of Sciences (India)

    K. N. Iyer; R. M. Jadav; A. K. Jadeja; P. K. Manoharan; Som Sharma; Hari Om Vats

    2006-06-01

    This paper describes the space weather effects of a major CME which was accompanied by extremely violent events on the Sun. The signatures of the event in the interplanetary medium (IPM) sensed by Ooty Radio Telescope, the solar observations by LASCO coronagraph onboard SOHO, GOES X-ray measurements, satellite measurements of the interplanetary parameters, GPS based ionospheric measurements, the geomagnetic storm parameter Dst and ground based ionosonde data are used in the study to understand the space weather effects in the different regions of the solar-terrestrial environment. The effects of this event are compared and possible explanations attempted.

  14. The interplanetary mass ejections behaviour in the heliosphere

    CERN Document Server

    Dumitrache, Cristiana

    2014-01-01

    We present here an overview of an important solar phenomenon with major implication for space weather and planetary life. The coronal mass ejections (CMEs) come from the Sun and expand in the heliosphere, becoming interplanetary coronal mass ejections (ICMEs). They represent huge clouds of plasma and magnetic fields that travel with velocities reaching even 2000 km/s and perturbing the planetary and interplanetary field. The magnetic clouds (MC) are a special class of ICMEs. We summarize some aspects as the ICMEs identification, propagation and track back to the Sun, where the solar source could be found. We notice here few known catalogs of the ICMEs and magnetic clouds.

  15. A Filament-Associated Halo Coronal Mass Ejection

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    There are only a few observations published so far that show the initiation of a coronal mass ejection (CME) and illustrate the magnetic changes in the surface origin of a CME. Any attempt to connect a CME with its local solar activities is meaningful. In this paper we present a clear instance of a halo CME initiation. A careful analysis of magnetograms shows that the only obvious magnetic changes in the surface region of the CME is a magnetic flux cancellation underneath a quiescent filament. The early disturbance was seen as the slow upward motion in segments of the quiescent filament. Four hours later, the filament was accelerated to about 50 km s-1 and erupted. While a small part of the material in the filament was ejected into the upper corona, most of the mass was transported to a nearby region. About forty minutes later, the transported mass was also ejected partially to the upper corona. The eruption of the filament triggered a two-ribbon flare, with post-flare loops connecting the flare ribbons. A halo CME, which is inferred to be associated with the eruptive filament, was observed from LASCO/C2 and C3. The halo CME contained two CME events, each event corresponded to a partial mass ejection of the filament. We suggest that the magnetic reconnection at the lower atmosphere is responsible for the filament eruption and the halo CME.

  16. Mass ejection in neutron star mergers

    Science.gov (United States)

    Rosswog, S.; Liebendörfer, M.; Thielemann, F.-K.; Davies, M. B.; Benz, W.; Piran, T.

    1999-01-01

    We present the results of 3D Newtonian SPH simulations of the merger of a neutron star binary. The microscopic properties of matter are described by the physical equation of state of Lattimer and Swesty (LS-EOS). To check the model dependence of the results we vary the resolution ( ~ 21000 and ~ 50000 particles), the equation of state (stiff and soft polytropes), the artificial viscosity scheme, the stellar masses, we include neutrinos (free-streaming limit), switch off the gravitational backreaction force, and vary the initial stellar spins. In addition we test the influence of the initial configuration, i.e. spherical stars versus corotating equilibrium configurations. The final matter distribution consists of a rapidly spinning central object with 2.5 to 3.1 Msun of baryonic mass that probably collapses to a black hole, a thick disk of 0.1 to 0.3 Msun and an extended low density region. In the case of corotation this low density material forms spiral arms that expand explosively due to an increase of the adiabatic exponent and the release of nuclear binding energy in the case of the LS-EOS, but remain narrow and well defined for the stiff polytropic equation of state. The main and new result is that for the realistic LS-EOS, depending on the initial spin, between 4*10(-3) and 4*10(-2) Msun of material become unbound. If, as suggested, large parts of this matter consist of r-process nuclei, neutron star mergers could account for the whole observed r-process material in the Galaxy.

  17. Coronal Mass Ejections and Non-recurrent Forbush Decreases

    Science.gov (United States)

    Belov, A.; Abunin, A.; Abunina, M.; Eroshenko, E.; Oleneva, V.; Yanke, V.; Papaioannou, A.; Mavromichalaki, H.; Gopalswamy, N.; Yashiro, S.

    2014-10-01

    Coronal mass ejections (CMEs) and their interplanetary counterparts (interplanetary coronal mass ejections, ICMEs) are responsible for large solar energetic particle events and severe geomagnetic storms. They can modulate the intensity of Galactic cosmic rays, resulting in non-recurrent Forbush decreases (FDs). We investigate the connection between CME manifestations and FDs. We used specially processed data from the worldwide neutron monitor network to pinpoint the characteristics of the recorded FDs together with CME-related data from the detailed online catalog based upon the Solar and Heliospheric Observatory (SOHO)/ Large Angle and Spectrometric Coronagraph (LASCO) data. We report on the correlations of the FD magnitude to the CME initial speed, the ICME transit speed, and the maximum solar wind speed. Comparisons between the features of CMEs (mass, width, velocity) and the characteristics of FDs are also discussed. FD features for halo, partial halo, and non-halo CMEs are presented and discussed.

  18. On pulsar-driven mass ejection in low-mass X-ray binaries

    Institute of Scientific and Technical Information of China (English)

    Lei Fu; Xiang-Dong Li

    2011-01-01

    There is accumulating evidence for mass ejection in low-mass X-ray binaries (LMXBs) driven by radio pulsar activity during X-ray quiescence.We consider the condition for mass ejection by comparing the radiation pressure from a millisecond pulsar,and the gas pressure at the inner Lagrange point or at the surrounding accretion disk.We calculate the critical spin period of the pulsar below which mass ejection is allowed.Combining with the evolution of the mass transfer rate,we present constraints on the orbital periods of the systems.We show that mass ejection could happen in both wide and compact LMXBs.It may be caused by transient accretion due to thermal instability in the accretion disks in the former,and irradiation-driven mass-transfer cycles in the latter.

  19. Physical properties of erupting plasma associated with coronal mass ejections

    Science.gov (United States)

    Lee, J.; Raymond, J. C.; Reeves, K. K.; Moon, Y.; Kim, K.

    2013-12-01

    We investigate the physical properties (temperature, density, and mass) of erupting plasma observed in X-rays and EUV, which are all associated with coronal mass ejections observed by SOHO/LASCO. The erupting plasmas are observed as absorption or emission features in the low corona. The absorption feature provides a lower limit to the cold mass while the emission feature provides an upper limit to the mass of observed plasma in X-ray and EUV. We compare the mass constraints for each temperature response and find that the mass estimates in EUV and XRT are smaller than the total mass in the coronagraph. Several events were observed by a few passbands in the X-rays, which allows us to determine the temperature of the eruptive plasma using a filter ratio method. The temperature of one event is estimated at about 8.6 MK near the top of the erupting plasma. This measurement is possibly an average temperature for higher temperature plasma because the XRT is more sensitive at higher temperatures. In addition, a few events show that the absorption features of a prominence or a loop change to emission features with the beginning of their eruptions in all EUV wavelengths of SDO/AIA, which indicates the heating of the plasma. By estimating the physical properties of the erupting plasmas, we discuss the heating of the plasmas associated with coronal mass ejections in the low corona.

  20. EUV and Coronagraphic Observations of Coronal Mass Ejections

    Indian Academy of Sciences (India)

    Durgesh Tripathi

    2006-06-01

    The Large Angle Spectrometric Coronagraph (LASCO) and Extreme-ultraviolet Imaging Telescope (EIT) onboard Solar and Heliospheric Observatory (SOHO) provide us with unprecedented multi-wavelength observations helping us to understand different dynamic phenomena on the Sun and in the corona. In this paper we discuss the association between post-eruptive arcades (PEAs) detected by EIT and white-light coronal mass ejections (CMEs) detected by LASCO/C2 telescope.

  1. Predicting the magnetic vectors within coronal mass ejections arriving at Earth

    CERN Document Server

    Savani, N P; Szabo, A; Mays, M L; Thompson, B J; Richardson, I G; Evans, R; Pulkkinen, A; Nieves-Chinchilla, T

    2015-01-01

    The process by which the Sun affects the terrestrial environment on short timescales is predominately driven by the amount of magnetic reconnection between the solar wind and Earth's magnetosphere. Reconnection occurs most efficiently when the solar wind magnetic field has a southward component. The most severe impacts are during the arrival of a coronal mass ejection (CME) when the magnetosphere is both compressed and magnetically connected to the heliospheric environment, leading to disruptions to, for example, power grids and satellite navigation. Unfortunately, forecasting magnetic vectors within coronal mass ejections remains elusive. Here we report how, by combining a statistically robust helicity rule for a CME's solar origin with a simplified flux rope topology the magnetic vectors within the Earth-directed segment of a CME can be predicted. In order to test the validity of this proof-of-concept architecture for estimating the magnetic vectors within CMEs, a total of eight CME events (between 2010 and...

  2. Dynamical mass ejection from black hole-neutron star binaries

    CERN Document Server

    Kyutoku, Koutarou; Okawa, Hirotada; Shibata, Masaru; Taniguchi, Keisuke

    2015-01-01

    We investigate properties of material ejected dynamically in the merger of black hole-neutron star binaries by numerical-relativity simulations. We systematically study dependence of ejecta properties on the mass ratio of the binary, spin of the black hole, and equation of state of the neutron-star matter. Dynamical mass ejection is driven primarily by tidal torque, and the ejecta is much more anisotropic than that from binary neutron star mergers. In particular, the dynamical ejecta is concentrated around the orbital plane with a half opening angle of 10deg--20deg and often sweeps only a half of the plane. The ejecta mass can be as large as ~0.1M_sun, and the velocity is subrelativistic with ~0.2--0.3c for typical cases. The ratio of the ejecta mass to the bound mass (disk and fallback components) becomes high and the ejecta velocity is large when the binary mass ratio is large, i.e., the black hole is massive. The remnant black hole-disk system receives a kick velocity of O(100)km/s due to the ejecta linear...

  3. Episodic AGB Mass Ejection and the Creation of Fallback Shells

    CERN Document Server

    Chen, Zhuo; Blackman, Eric

    2015-01-01

    The short duration of mass ejection events during the Ascending Giant Branch (AGB) phase of stellar evolution can take different forms ranging thermal pulses to regular stellar pulsations. In most cases the shells ejected by the star are assumed to reach the escape velocity and expand into circumstellar space until they dissipate or merge with the surrounding gas. In this paper we investigate the case of an AGB star that emits a pulse of material below the escape velocity as may occur during a Common Envelope event. We explore the evolution of the shell created by this short mass loss event. We seek to determine when the shell falls back onto the star as opposed to being driven to escape velocity by the action of winds which occur after shell ejection. The problem is solved via 2.5D AMR AstroBEAR hydrodynamic simulations and a simplified one dimensional analytic model. We find that for given set of initial wind characteristics there is a critical shell velocity that distinguishes between shell fallback and sh...

  4. Geoeffectiveness of Coronal Mass Ejections in the SOHO Era

    DEFF Research Database (Denmark)

    Dumbovic, M.; Devos, A.; Vrsnak, B.;

    2014-01-01

    The main objective of the study is to determine the probability distributions of the geomagnetic Dst index as a function of the coronal mass ejection (CME) and solar flare parameters for the purpose of establishing a probabilistic forecast tool for the geomagnetic storm intensity. Several CME...... and flare parameters as well as the effect of successive-CME occurrence in changing the probability for a certain range of Dst index values, were examined. The results confirm some of already known relationships between remotely-observed properties of solar eruptive events and geomagnetic storms, namely...

  5. Photospheric magnetic field of an eroded-by-solar-wind coronal mass ejection

    Science.gov (United States)

    Palacios, J.; Cid, C.; Saiz, E.; Guerrero, A.

    2017-10-01

    We have investigated the case of a coronal mass ejection that was eroded by the fast wind of a coronal hole in the interplanetary medium. When a solar ejection takes place close to a coronal hole, the flux rope magnetic topology of the coronal mass ejection (CME) may become misshapen at 1 AU as a result of the interaction. Detailed analysis of this event reveals erosion of the interplanetary coronal mass ejection (ICME) magnetic field. In this communication, we study the photospheric magnetic roots of the coronal hole and the coronal mass ejection area with HMI/SDO magnetograms to define their magnetic characteristics.

  6. Full Halo Coronal Mass Ejections: Arrival at the Earth

    CERN Document Server

    Shen, Chenglong; Pan, Zonghao; Miao, Bin; Ye, Pinzhong; Wang, S

    2014-01-01

    A geomagnetic storm is mainly caused by a front-side coronal mass ejection (CME) hitting the Earth and then interacting with the magnetosphere. However, not all front-side CMEs can hit the Earth. Thus, which CMEs hit the Earth and when they do so are important issues in the study and forecasting of space weather. In our previous work (Shen et al., 2013), the de-projected parameters of the full-halo coronal mass ejections (FHCMEs) that occurred from 2007 March 1 to 2012 May 31 were estimated, and there are 39 front-side events could be fitted by the GCS model. In this work, we continue to study whether and when these front-side FHCMEs (FFHCMEs) hit the Earth. It is found that 59\\% of these FFHCMEs hit the Earth, and for central events, whose deviation angles $\\epsilon$, which are the angles between the propagation direction and the Sun-Earth line, are smaller than 45 degrees, the fraction increases to 75\\%. After checking the deprojected angular widths of the CMEs, we found that all of the Earth-encountered CM...

  7. A Solar Coronal Jet Event Triggers A Coronal Mass Ejection

    CERN Document Server

    Liu, Jiajia; Shen, Chenglong; Liu, Kai; Pan, Zonghao; Wang, S

    2015-01-01

    We present the multi-point and multi-wavelength observation and analysis on a solar coronal jet and coronal mass ejection (CME) event in this paper. Employing the GCS model, we obtained the real (three-dimensional) heliocentric distance and direction of the CME and found it propagate in a high speed over 1000 km/s . The jet erupted before and shared the same source region with the CME. The temporal and spacial relation- ship between them guide us the possibility that the jet triggered the CME and became its core. This scenario could promisingly enrich our understanding on the triggering mechanism of coronal mass ejections and their relations with coronal large-scale jets. On the other hand, the magnetic field configuration of the source region observed by the SDO/HMI instrument and the off- limb inverse Y-shaped configuration observed by SDO/AIA 171 A passband, together provide the first detailed observation on the three-dimensional reconnection process of large-scale jets as simulated in Pariat et al. 2009. ...

  8. Forbush decreases associated to Stealth Coronal Mass Ejections

    Science.gov (United States)

    Heber, B.; Wallmann, C.; Galsdorf, D.; Herbst K.; Kühl, P.; Dumbovic, M.; Vršnak, B.; Veronig, A.; Temmer, M.; Möstl, C.; Dalla, S.

    Interplanetary coronal mass ejections (ICMEs) are structures in the solar wind that are the counterparts of coronal mass ejections (CMEs) at the Sun. It is commonly believed that enhanced magnetic fields in interplanetary shocks and solar ejecta as well as the increased turbulence in the solar wind sheath region are the cause of Forbush decreases (FDs) representing decreases of galactic cosmic ray (GCR) intensities. Recently, stealth CMEs i.e.~CMEs with no apparent solar surface association have become a subject in recent studies of solar activity. Whether all of such stealth CMEs can drive a FD is difficult to investigate on the basis of neutron monitor NM measurements because these measurements not only reflect the GCR intensity variation in interplanetary space but also the variation of the geomagnetic field as well as the conditions in the Earth atmosphere. Single detector counter from spacecraft instrumentation, here SOHO and Chandra EPHIN, exceed counting statistic of NMs allowing to determine intensity variation of less than 1 permil in interplanetary space on the basis of 30 minute count rate averages. Here we present the ongoing analysis of eleven stealth CMEs.

  9. The initiation of coronal mass ejections by magnetic flux emergence

    Science.gov (United States)

    Dubey, G.; van der Holst, B.; Poedts, S.

    2006-12-01

    Aims.The initiation of solar Coronal Mass Ejections (CMEs) is studied in the framework of computational Magneto-Hydro-Dynamics (MHD). Methods: .The initial configuration includes a magnetic flux rope that is embedded in a gravitationally stratified solar atmosphere with a background dipole magnetic field in spherical, axi-symmetric geometry. The flux rope is in equilibrium due to an image current below the photosphere. An emerging magnetic flux triggering mechanism is used to make this equilibrium configuration unstable. Results: . When the magnetic flux emerges within the filament below the flux rope this results in a catastrophic behavior similar to earlier, more simple models. As a result, the flux rope rises and a current sheet forms below it. It is shown that the magnetic reconnection in the current sheet below the flux rope in combination with the outward curvature forces results in a fast ejection of the flux rope as observed for solar CMEs. We have done a parameter study of the effect of the flux emergence rate on the velocity and the acceleration of the resulting CMEs.

  10. Dynamical Mass Ejection from Binary Neutron Star Mergers

    CERN Document Server

    Radice, David; Lippuner, Jonas; Roberts, Luke F; Ott, Christian D; Rezzolla, Luciano

    2016-01-01

    We present fully general-relativistic simulations of binary neutron star mergers with a temperature and composition dependent nuclear equation of state. We study the dynamical mass ejection from both quasi-circular and dynamical-capture eccentric mergers. We systematically vary the level of our treatment of the microphysics to isolate the effects of neutrino cooling and heating and we compute the nucleosynthetic yields of the ejecta. We find that eccentric binaries can eject significantly more material than quasi-circular binaries and generate bright infrared and radio emission. In all our simulations the outflow is composed of a combination of tidally- and shock-driven ejecta, mostly distributed over a broad $\\sim 60^\\circ$ angle from the orbital plane, and, to a lesser extent, by thermally driven winds at high latitudes. Ejecta from eccentric mergers are typically more neutron rich than those of quasi-circular mergers. This is the effect of the strong tidal torques exerted on the neutron stars during their ...

  11. Episodic mass ejections from common-envelope objects

    Science.gov (United States)

    Clayton, Matthew; Podsiadlowski, Philipp; Ivanova, Natasha; Justham, Stephen

    2017-09-01

    After the initial fast spiral-in phase experienced by a common-envelope binary, the system may enter a slow, self-regulated phase, possibly lasting hundreds of years, in which all the energy released by orbital decay can be efficiently transported to the surface, where it is radiated away. If the remaining envelope is to be removed during this phase, this removal must occur through some as-yet-undetermined mechanism. We carried out 1D hydrodynamic simulations of a low-mass red giant undergoing a synthetic common-envelope event in such a slow spiral-in phase, using the stellar evolutionary code mesa. We simulated the heating of the envelope due to frictional dissipation from a binary companion's orbit in multiple configurations and investigated the response of the giant's envelope. We find that our model envelopes become dynamically unstable and develop large-amplitude pulsations, with periods in the range 3-20 yr and very short growth time-scales of similar order. The shocks and associated rebounds that emerge as these pulsations grow are in some cases strong enough to dynamically eject shells of matter of up to 0.1 M⊙, ∼10 per cent of the mass of the envelope, from the stellar surface at above escape velocity. These ejections are seen to repeat within a few decades, leading to a time-averaged mass-loss rate of the order of 10-3 M⊙ yr-1, which is sufficiently high to represent a candidate mechanism for removing the entire envelope over the duration of the slow spiral-in phase.

  12. On interplanetary coronal mass ejection identification at 1 AU

    Science.gov (United States)

    Mulligan, T.; Russell, C. T.; Gosling, J. T.

    1999-06-01

    Coronal mass ejections are believed to be produced in the corona from closed magnetic regions not previously participating in the solar wind expansion. At 1 AU their interplanetary counterparts (ICMEs) generally have a number of distinct plasma and field signatures that distinguish them from the ambient solar wind. These include heat flux dropouts, bi-directional streaming, enhanced alpha particle events, times of depressed proton temperatures, intervals of distorted or enhanced magnetic field, and times of large magnetic field rotations characteristic of magnetic clouds. The first three of these signatures are phenomena that occur at some point within the ICME, but do not necessarily persist throughout the entire ICME. The large scale magnetic field rotations, distortions and enhancements, and the proton temperature depressions tend to mark more accurately the beginning and end of the ICME proper. We examine herein the reliability with which each of these markers identifies ICMEs utilizing ISEE-3 data from 1978-1980.

  13. An ice-cream cone model for coronal mass ejections

    Science.gov (United States)

    Xue, X. H.; Wang, C. B.; Dou, X. K.

    2005-08-01

    In this study, we use an ice-cream cone model to analyze the geometrical and kinematical properties of the coronal mass ejections (CMEs). Assuming that in the early phase CMEs propagate with near-constant speed and angular width, some useful properties of CMEs, namely the radial speed (v), the angular width (α), and the location at the heliosphere, can be obtained considering the geometrical shapes of a CME as an ice-cream cone. This model is improved by (1) using an ice-cream cone to show the near real configuration of a CME, (2) determining the radial speed via fitting the projected speeds calculated from the height-time relation in different azimuthal angles, (3) not only applying to halo CMEs but also applying to nonhalo CMEs.

  14. On Sun-to-Earth Propagation of Coronal Mass Ejections

    CERN Document Server

    Liu, Ying D; Lugaz, Noé; Möstl, Christian; Davies, Jackie A; Bale, Stuart D; Lin, Robert P

    2013-01-01

    We investigate how coronal mass ejections (CMEs) propagate through, and interact with, the inner heliosphere between the Sun and Earth, a key question in CME research and space weather forecasting. CME Sun-to-Earth kinematics are constrained by combining wide-angle heliospheric imaging observations, interplanetary radio type II bursts and in situ measurements from multiple vantage points. We select three events for this study, the 2012 January 19, 23, and March 7 CMEs. Different from previous event studies, this work attempts to create a general picture for CME Sun-to-Earth propagation and compare different techniques for determining CME interplanetary kinematics. Key results are obtained concerning CME Sun-to-Earth propagation. Our comparison between different techniques (and data sets) also has important implications for CME observations and their interpretations. Future CME observations and space weather forecasting are discussed based on these results. See detail in the PDF.

  15. MHD Remote Numerical Simulations: Evolution of Coronal Mass Ejections

    CERN Document Server

    Hernandez-Cervantes, L; Gonzalez-Ponce, A R

    2008-01-01

    Coronal mass ejections (CMEs) are solar eruptions into interplanetary space of as much as a few billion tons of plasma, with embedded magnetic fields from the Sun's corona. These perturbations play a very important role in solar--terrestrial relations, in particular in the spaceweather. In this work we present some preliminary results of the software development at the Universidad Nacional Autonoma de Mexico to perform Remote MHD Numerical Simulations. This is done to study the evolution of the CMEs in the interplanetary medium through a Web-based interface and the results are store into a database. The new astrophysical computational tool is called the Mexican Virtual Solar Observatory (MVSO) and is aimed to create theoretical models that may be helpful in the interpretation of observational solar data.

  16. The Kinematics and Morphology of Solar Coronal Mass Ejections

    CERN Document Server

    Byrne, Jason P

    2012-01-01

    Solar coronal mass ejections (CMEs) are large-scale eruptions of plasma and magnetic field from the Sun into the corona and interplanetary space. They are the most significant drivers of adverse space weather at Earth and other locations in the heliosphere, so it is important to understand the physics governing their eruption and propagation. However the diffuse morphology and transient nature of CMEs makes them difficult to identify and track using traditional image processing techniques. In this thesis the implementation of multiscale image processing techniques to identify and track the CME front through coronagraph images is detailed. An ellipse characterisation of the CME front is used to determine the CME kinematics and morphology with increased precision as compared to techniques used in current CME catalogues, and efforts are underway to automate this procedure for applying to a large number of CME observations for future analysis. It was found that CMEs do not simply undergo constant acceleration, bu...

  17. Flux Rope Formation Preceding Coronal Mass Ejection Onset

    CERN Document Server

    Green, L M

    2009-01-01

    We analyse the evolution of a sigmoidal (S shaped) active region toward eruption, which includes a coronal mass ejection (CME) but leaves part of the filament in place. The X-ray sigmoid is found to trace out three different magnetic topologies in succession: a highly sheared arcade of coronal loops in its long-lived phase, a bald-patch separatrix surface (BPSS) in the hours before the CME, and the first flare loops in its major transient intensity enhancement. The coronal evolution is driven by photospheric changes which involve the convergence and cancellation of flux elements under the sigmoid and filament. The data yield unambiguous evidence for the existence of a BPSS, and hence a flux rope, in the corona prior to the onset of the CME.

  18. Plasma Heating Suring a Coronal Mass Ejection Observed by SOHO

    CERN Document Server

    Murphy, N A; Korreck, K E

    2011-01-01

    We perform a time-dependent ionization analysis to constrain plasma heating requirements during a fast partial halo coronal mass ejection (CME) observed on 2000 June 28 by the Ultraviolet Coronagraph Spectrometer (UVCS) aboard the Solar and Heliospheric Observatory (SOHO). We use two methods to derive densities from the UVCS measurements, including a density sensitive O V line ratio at 1213.85 and 1218.35 Angstroms, and radiative pumping of the O VI 1032,1038 doublet by chromospheric emission lines. The most strongly constrained feature shows cumulative plasma heating comparable to or greater than the kinetic energy, while features observed earlier during the event show cumulative plasma heating comparable to or less than the kinetic energy. SOHO Michelson Doppler Imager (MDI) observations are used to estimate the active region magnetic energy. We consider candidate plasma heating mechanisms and provide constraints when possible. Because this CME was associated with a relatively weak flare, the contribution b...

  19. Geoeffectiveness of Coronal Mass Ejections in the SOHO era

    CERN Document Server

    Dumbovic, Mateja; Vrsnak, Bojan; Sudar, Davor; Rodriguez, Luciano; Ruzdjak, Domagoj; Leer, Kristoffer; Vennerstrom, Susanne; Veronig, Astrid

    2014-01-01

    The main objective of the study is to determine the probability distributions of the geomagnetic Dst index as a function of the coronal mass ejection (CME) and solar flare parameters for the purpose of establishing a probabilistic forecast tool for the geomagnetic storm intensity. Several CME and flare parameters as well as the effect of successive-CME occurrence in changing the probability for a certain range of Dst index values, were examined. The results confirm some of already known relationships between remotely-observed properties of solar eruptive events and geomagnetic storms, namely the importance of initial CME speed, apparent width, source position, and the associated solar flare class. In this paper we quantify these relationships in a form to be used for space weather forecasting in future. The results of the statistical study are employed to construct an empirical statistical model for predicting the probability of the geomagnetic storm intensity based on remote solar observations of CMEs and fl...

  20. Interplanetary Coronal Mass Ejections observed by MESSENGER and Venus Express

    CERN Document Server

    Good, S W

    2015-01-01

    Interplanetary coronal mass ejections (ICMEs) observed by the MESSENGER (MES) and Venus Express (VEX) spacecraft have been catalogued and analysed. The ICMEs were identified by a relatively smooth rotation of the magnetic field direction consistent with a flux rope structure, coinciding with a relatively enhanced magnetic field strength. A total of 35 ICMEs were found in the surveyed MES data (primarily from March 2007 to April 2012), and 84 ICMEs in the surveyed VEX data (from May 2006 to December 2013). The ICME flux rope configurations have been determined. Ropes with northward leading edges were about four times more common than ropes with southward leading edges, in agreement with a previously established solar cycle dependence. Ropes with low inclinations to the solar equatorial plane were about four times more common than ropes with high inclinations, possibly an observational effect. Left and right-handed ropes were observed in almost equal numbers. In addition, data from MES, VEX, STEREO-A, STEREO-B ...

  1. Global Energetics in Solar Flares and Coronal Mass Ejections

    Science.gov (United States)

    Aschwanden, Markus J.

    2017-08-01

    We present a statistical study of the energetics of coronal mass ejections (CME) and compare it with the magnetic, thermal, and nonthermal energy dissipated in flares. The physical parameters of CME speeds, mass, and kinetic energies are determined with two different independent methods, i.e., the traditional white-light scattering method using LASCO/SOHO data, and the EUV dimming method using AIA/SDO data. We analyze all 860 GOES M- and X-class flare events observed during the first 7 years (2010-2016) of the SDO mission. The new ingredients of our CME modeling includes: (1) CME geometry in terms of a self-similar adiabatic expansion, (2) DEM analysis of CME mass over entire coronal temperature range, (3) deceleration of CME due to gravity force which controls the kinetic and potentail CME energy as a function of time, (4) the critical speed that controls eruptive and confined CMEs, (5) the relationship between the center-of-mass motion during EUV dimming and the leading edge motion observed in white-light coronagraphs. Novel results are: (1) Physical parameters obtained from both the EUV dimming and white-light method can be reconciled; (2) the equi-partition of CME kinetic and thermal flare energy; (3) the Rosner-Tucker-Vaiana scaling law. We find that the two methods in EUV and white-light wavelengths are highly complementary and yield more complete models than each method alone.

  2. Dynamical mass ejection from binary neutron star mergers

    Science.gov (United States)

    Radice, David; Galeazzi, Filippo; Lippuner, Jonas; Roberts, Luke F.; Ott, Christian D.; Rezzolla, Luciano

    2016-08-01

    We present fully general-relativistic simulations of binary neutron star mergers with a temperature and composition dependent nuclear equation of state. We study the dynamical mass ejection from both quasi-circular and dynamical-capture eccentric mergers. We systematically vary the level of our treatment of the microphysics to isolate the effects of neutrino cooling and heating and we compute the nucleosynthetic yields of the ejecta. We find that eccentric binaries can eject significantly more material than quasi-circular binaries and generate bright infrared and radio emission. In all our simulations the outflow is composed of a combination of tidally- and shock-driven ejecta, mostly distributed over a broad ˜60° angle from the orbital plane, and, to a lesser extent, by thermally driven winds at high latitudes. Ejecta from eccentric mergers are typically more neutron rich than those of quasi-circular mergers. We find neutrino cooling and heating to affect, quantitatively and qualitatively, composition, morphology, and total mass of the outflows. This is also reflected in the infrared and radio signatures of the binary. The final nucleosynthetic yields of the ejecta are robust and insensitive to input physics or merger type in the regions of the second and third r-process peaks. The yields for elements on the first peak vary between our simulations, but none of our models is able to explain the Solar abundances of first-peak elements without invoking additional first-peak contributions from either neutrino and viscously-driven winds operating on longer time-scales after the mergers, or from core-collapse supernovae.

  3. Type Ia supernova bolometric light curves and ejected mass estimates from the Nearby Supernova Factory

    CERN Document Server

    Scalzo, R; Antilogus, P; Aragon, C; Bailey, S; Baltay, C; Bongard, S; Buton, C; Cellier-Holzem, F; Childress, M; Chotard, N; Copin, Y; Fakhouri, H K; Gangler, E; Guy, J; Kim, A; Kowalski, M; Kromer, M; Nordin, J; Nugent, P; Paech, K; Pain, R; Pecontal, E; Pereira, R; Perlmutter, S; Rabinowitz, D; Rigault, M; Runge, K; Saunders, C; Sim, S A; Smadja, G; Tao, C; Taubenberger, S; Thomas, R C; Weaver, B A

    2014-01-01

    We present a sample of normal type Ia supernovae from the Nearby Supernova Factory dataset with spectrophotometry at sufficiently late phases to estimate the ejected mass using the bolometric light curve. We measure $^{56}$Ni masses from the peak bolometric luminosity, then compare the luminosity in the $^{56}$Co-decay tail to the expected rate of radioactive energy re- lease from ejecta of a given mass. We infer the ejected mass in a Bayesian context using a semi-analytic model of the ejecta, incorporating constraints from contemporary numerical models as priors on the density structure and distribution of $^{56}$Ni throughout the ejecta. We find a strong correlation between ejected mass and light curve decline rate, and consequently $^{56}$Ni mass, with ejected masses in our data ranging from 0.9-1.4 $M_\\odot$. Most fast-declining (SALT2 $x_1 < -1$) normal SNe Ia have significantly sub-Chandrasekhar ejected masses in our fiducial analysis.

  4. Global Energetics of Solar Flares: IV. Coronal Mass Ejection Energetics

    CERN Document Server

    Aschwanden, Markus J

    2016-01-01

    This study entails the fourth part of a global flare energetics project, in which the mass $m_{\\mathrm{cme}}$, kinetic energy $E_{\\mathrm{kin}}$, and the gravitational potential energy $E_{\\mathrm{grav}}$ of coronal mass ejections (CMEs) is measured in 399 M and X-class flare events observed during the first 3.5 yrs of the Solar Dynamics Observatory (SDO) mission, using a new method based on the EUV dimming effect. The EUV dimming is modeled in terms of a radial adiabatic expansion process, which is fitted to the observed evolution of the total emission measure of the CME source region. The model derives the evolution of the mean electron density, the emission measure, the bulk plasma expansion velocity, the mass, and the energy in the CME source region. The EUV dimming method is truly complementary to the Thomson scattering method in white light, which probes the CME evolution in the heliosphere at $r > 2 R_{\\odot}$, while the EUV dimming method tracks the CME launch in the corona. We compare the CME paramet...

  5. Anomalous-plasmoid-ejection-induced secondary magnetic reconnection: modeling solar flares and coronal mass ejections by laser–plasma experiments

    Institute of Scientific and Technical Information of China (English)

    Quanli; Dong; Dawei; Yuan; Shoujun; Wang; Xun; Liu; Yutong; Li; Xiaoxuan; Lin; Huigang; Wei; Jiayong; Zhong; Shaoen; Jiang; Yongkun; Ding; Bobin; Jiang; Kai; Du; Yongjian; Tang; Mingyang; Yu; Xiantu; He; Neng; Hua; Zhanfeng; Qiao; Kuixi; Huang; Ming; Chen; Jianqiang; Zhu; Gang; Zhao; Zhengming; Sheng; Jie; Zhang

    2013-01-01

    The driving mechanism of solar flares and coronal mass ejections is a topic of ongoing debate, apart from the consensus that magnetic reconnection plays a key role during the impulsive process. While present solar research mostly depends on observations and theoretical models, laboratory experiments based on high-energy density facilities provide the third method for quantitatively comparing astrophysical observations and models with data achieved in experimental settings.In this article, we show laboratory modeling of solar flares and coronal mass ejections by constructing the magnetic reconnection system with two mutually approaching laser-produced plasmas circumfused of self-generated megagauss magnetic fields. Due to the Euler similarity between the laboratory and solar plasma systems, the present experiments demonstrate the morphological reproduction of flares and coronal mass ejections in solar observations in a scaled sense,and confirm the theory and model predictions about the current-sheet-born anomalous plasmoid as the initial stage of coronal mass ejections, and the behavior of moving-away plasmoid stretching the primary reconnected field lines into a secondary current sheet conjoined with two bright ridges identified as solar flares.

  6. Automatic Determination of the Conic Coronal Mass Ejection Model Parameters

    Science.gov (United States)

    Pulkkinen, A.; Oates, T.; Taktakishvili, A.

    2009-01-01

    Characterization of the three-dimensional structure of solar transients using incomplete plane of sky data is a difficult problem whose solutions have potential for societal benefit in terms of space weather applications. In this paper transients are characterized in three dimensions by means of conic coronal mass ejection (CME) approximation. A novel method for the automatic determination of cone model parameters from observed halo CMEs is introduced. The method uses both standard image processing techniques to extract the CME mass from white-light coronagraph images and a novel inversion routine providing the final cone parameters. A bootstrap technique is used to provide model parameter distributions. When combined with heliospheric modeling, the cone model parameter distributions will provide direct means for ensemble predictions of transient propagation in the heliosphere. An initial validation of the automatic method is carried by comparison to manually determined cone model parameters. It is shown using 14 halo CME events that there is reasonable agreement, especially between the heliocentric locations of the cones derived with the two methods. It is argued that both the heliocentric locations and the opening half-angles of the automatically determined cones may be more realistic than those obtained from the manual analysis

  7. Losses of Energetic Electrons in Earth's Outer Radiation Belt During Unusual Coronal Mass Ejections

    Science.gov (United States)

    Lugaz, Noé; Huang, Chia-Lin; Schwadron, Nathan; Spence, Harlan; Farrugia, Charles; Winslow, Reka

    2016-07-01

    The most extreme changes in solar wind parameters important for the coupling between the solar wind and the magnetosphere (dynamic pressure, dawn-to-dusk electric field, Alfven Mach number, plasma beta, …) occur during the passage at Earth of coronal mass ejections (CMEs). While the response of Earth's radiation belts to CMEs and CME-driven shocks has been investigated in great details, few studies have focused on what makes some CMEs and their shocks especially effective in driving losses of energetic electrons in the outer radiation belt. Here, we present specific examples of losses during the passage at Earth of a coronal mass ejection. In particular, we discuss the conditions which may result in the magnetopause to retreat earthward up to geosynchronous orbit, resulting in significant losses of energetic electrons due to magnetopause shadowing. We also present the result of a low-density magnetic ejecta which impacted Earth in January 2013. Combining interplanetary, magnetosheath, outer magnetosphere and radiation belt measurements by more than ten satellites, including the Van Allen Probes, THEMIS and Cluster, we show how a period of extremely low Mach number and dynamic pressure during the passage of the magnetic cloud resulted in dramatic losses in the outer radiation belt and a large-scale reorganization of the entire day-side magnetosphere.

  8. Sizes and locations of coronal mass ejections - SMM observations from 1980 and 1984-1989

    Science.gov (United States)

    Hundhausen, A. J.

    1993-01-01

    A statistical description of the sizes and locations of 1209 mass ejections observed with the SMM coronagraph/polarimeter in 1980 and 1984-1989 is presented. The average width of the coronal mass ejections detected with this instrument was close to 40 deg in angle for the entire period of SMM observations. No evidence was found for a significant change in mass ejection widths as reported by Howard et al. (1986). There is clear evidence for changes in the latitude distribution of mass ejections over this epoch. Mass ejections occurred over a much wider range of latitudes at the times of high solar activity (1980 and 1989) than at times of low activity (1985-1986).

  9. Coronal ``Wave'': Magnetic Footprint of a Coronal Mass Ejection?

    Science.gov (United States)

    Attrill, Gemma D. R.; Harra, Louise K.; van Driel-Gesztelyi, Lidia; Démoulin, Pascal

    2007-02-01

    We investigate the properties of two ``classical'' EUV Imaging Telescope (EIT) coronal waves. The two source regions of the associated coronal mass ejections (CMEs) possess opposite helicities, and the coronal waves display rotations in opposite senses. We observe deep core dimmings near the flare site and also widespread diffuse dimming, accompanying the expansion of the EIT wave. We also report a new property of these EIT waves, namely, that they display dual brightenings: persistent ones at the outermost edge of the core dimming regions and simultaneously diffuse brightenings constituting the leading edge of the coronal wave, surrounding the expanding diffuse dimmings. We show that such behavior is consistent with a diffuse EIT wave being the magnetic footprint of a CME. We propose a new mechanism where driven magnetic reconnections between the skirt of the expanding CME magnetic field and quiet-Sun magnetic loops generate the observed bright diffuse front. The dual brightenings and the widespread diffuse dimming are identified as innate characteristics of this process.

  10. Coronal mass ejections and geomagnetic storms: Seasonal variations

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, J.L.; Gosling, J.T.; McComas, D.J.

    1992-07-01

    The well-established semiannual geomagnetic cycle, with peak activity near the equinoxes, has been attributed to the angle between the solar rotation axis and the geomagnetic dipole, which modulates the GSM Bz component in the interplanetary magnetic field (MF). This effect is predicted to be accentuated in the shocked plasma ahead of fast coronal mass ejections (CMESs); its relevance to the internal fields of the ejecta is unclear. CMEs, particularly fast events driving interplanetary shocks, are the cause of almost all large geomagnetic storms near solar maximum. We use a set of CMEs identified by ISEE-3 observations of bidirectional electron streaming, plus IMF and geomagnetic data, to investigate the semiannual geomagnetic variation and its relation to CMEs. We find that the geomagnetic effectiveness of CMEs and post-shock solar wind is well-ordered by speed and by the southward component of the IMF in GSM coordinates, as well as by preexisting geomagnetic conditions. The post-shock seasonal effect, with geomagnetic effectiveness maximizing near April 5 for negative GSEQ By and near October 5 for positive GSEQ By, is identifiable in shock and shock/CME events, but not for CME events without leading shocks. When used to complement the more fundamental causal parameter of CME speed, the seasonal effect appears to have value for prediction of geomagnetic storms.

  11. Coronal mass ejections and geomagnetic storms: Seasonal variations

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, J.L.; Gosling, J.T.; McComas, D.J.

    1992-01-01

    The well-established semiannual geomagnetic cycle, with peak activity near the equinoxes, has been attributed to the angle between the solar rotation axis and the geomagnetic dipole, which modulates the GSM Bz component in the interplanetary magnetic field (MF). This effect is predicted to be accentuated in the shocked plasma ahead of fast coronal mass ejections (CMESs); its relevance to the internal fields of the ejecta is unclear. CMEs, particularly fast events driving interplanetary shocks, are the cause of almost all large geomagnetic storms near solar maximum. We use a set of CMEs identified by ISEE-3 observations of bidirectional electron streaming, plus IMF and geomagnetic data, to investigate the semiannual geomagnetic variation and its relation to CMEs. We find that the geomagnetic effectiveness of CMEs and post-shock solar wind is well-ordered by speed and by the southward component of the IMF in GSM coordinates, as well as by preexisting geomagnetic conditions. The post-shock seasonal effect, with geomagnetic effectiveness maximizing near April 5 for negative GSEQ By and near October 5 for positive GSEQ By, is identifiable in shock and shock/CME events, but not for CME events without leading shocks. When used to complement the more fundamental causal parameter of CME speed, the seasonal effect appears to have value for prediction of geomagnetic storms.

  12. On interplanetary coronal mass ejection identification at 1 AU

    Energy Technology Data Exchange (ETDEWEB)

    Mulligan, T.; Russell, C.T. [Institute of Geophysics and Planetary Physics and the Department of Earth and Space Sciences University of California Los Angeles (United States); Gosling, J.T. [Los Alamos National Laboratory, Los Alamos, New Mexico (United States)

    1999-06-01

    Coronal mass ejections are believed to be produced in the corona from closed magnetic regions not previously participating in the solar wind expansion. At 1 AU their interplanetary counterparts (ICMEs) generally have a number of distinct plasma and field signatures that distinguish them from the ambient solar wind. These include heat flux dropouts, bi-directional streaming, enhanced alpha particle events, times of depressed proton temperatures, intervals of distorted or enhanced magnetic field, and times of large magnetic field rotations characteristic of magnetic clouds. The first three of these signatures are phenomena that occur at some point within the ICME, but do not necessarily persist throughout the entire ICME. The large scale magnetic field rotations, distortions and enhancements, and the proton temperature depressions tend to mark more accurately the beginning and end of the ICME proper. We examine herein the reliability with which each of these markers identifies ICMEs utilizing ISEE-3 data from 1978{endash}1980. {copyright} {ital 1999 American Institute of Physics.}

  13. Large Geomagnetic Storms Associated with Limb Halo Coronal Mass Ejections

    CERN Document Server

    Gopalswamy, Nat; Xie, Hong; Akiyama, Sachiko; Makela, Pertti

    2009-01-01

    Solar cycle 23 witnessed the observation of hundreds of halo coronal mass ejections (CMEs), thanks to the high dynamic range and extended field of view of the Large Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory (SOHO) mission. More than two thirds of halo CMEs originating on the front side of the Sun have been found to be geoeffective (Dst = 45deg) have a 20% shorter delay time on the average. It was suggested that the geomagnetic storms due to limb halos must be due to the sheath portion of the interplanetary CMEs (ICMEs) so that the shorter delay time can be accounted for. We confirm this suggestion by examining the sheath and ejecta portions of ICMEs from Wind and ACE data that correspond to the limb halos. Detailed examination showed that three pairs of limb halos were interacting events. Geomagnetic storms following five limb halos were actually produced by other disk halos. The storms followed by four isolated limb halos and the ones associated with interact...

  14. The Relationship of Coronal Mass Ejections to Streamers

    CERN Document Server

    Subramanian, P; Rich, N B; Howard, R A; Subramanian, Prasad

    1999-01-01

    We have examined images from the Large Angle Spectroscopic Coronagraph (LASCO) to study the relationship of Coronal Mass Ejections (CMEs) to coronal streamers. We wish to test the suggestion (Low 1996) that CMEs arise from flux ropes embedded in a streamer erupting, thus disrupting the streamer. The data span a period of two years near sunspot minimum through a period of increased activity as sunspot numbers increased. We have used LASCO data from the C2 coronagraph which records Thomson scattered white light from coronal electrons at heights between 1.5 and 6R_sun. Maps of the coronal streamers have been constructed from LASCO C2 observations at a height of 2.5R_sun at the east and west limbs. We have superposed the corresponding positions of CMEs observed with the C2 coronagraph onto the synoptic maps. We identified the different kinds of signatures CMEs leave on the streamer structure at this height (2.5R_sun). We find four types of CMEs with respect to their effect on streamers: 1. CMEs that disrupt the s...

  15. The 3D structure of Coronal Mass Ejections

    Science.gov (United States)

    Patsourakos, Spiros

    2016-07-01

    Coronal Mass Ejections (CMEs) represent one of the most powerful energy release phenomena in the entire solar system and are a major driver of space weather. Prior to 2006, our observational access to CMEs was limited to single viewpoint remote sensing observations in the inner/outer corona, and in-situ observations further away, e.g. at 1 AU. Taking all these factors together, turned out to be a major obstacle in our understanding and characterizing of the 3D structure and evolution of CMEs. The situation improved dramatically with the availability of multi-viewpoint imaging observations of CMEs, all way through from the Sun to 1 AU, from the STEREO mission since 2006, combined with observations from other missions (SOHO, Hinode, SDO, IRIS). With this talk we will discuss several key recent results in CME science resulting from the analysis of multi-viewpoint observations. This includes: (1) shape and structure; (2) kinematics and energetics; (3) trajectories, deflections and rotations; (4) arrival times and velocities at 1 AU; (5) magnetic field structure; (6) relationships with coronal and interplanetary shocks and solar energetic particles. The implications of these results in terms of CME theories and models will be also addressed. We will conclude with a discussion of important open issues in our understanding of CMEs and how these could be addressed with upcoming (Solar Orbiter, Solar Probe Plus) and under-study missions (e.g., L5).

  16. A numerical study of two interacting coronal mass ejections

    Directory of Open Access Journals (Sweden)

    J. M. Schmidt

    2004-06-01

    Full Text Available The interaction in the solar wind between two coronal mass ejections (CMEs is investigated using numerical simulations. We show that the nature of the interaction depends on whether the CME magnetic structures interact, but in all cases the result is an equilisation of the speed of the two CMEs. In the absence of magnetic interaction, the forward shock of the faster trailing CME interacts with the slow leading CME, and accelerates it. When the two CMEs have magnetic fields with the same sense of rotation, magnetic reconnection occurs between the two CMEs, leading to the formation of a single magnetic structure: in the most extreme cases, one CME "eats" the other. When the senses of rotation are opposite, reconnection does not occur, but the CMEs collide in a highly non-elastic manner, again forming a single structure. The possibility of enhanced particle acceleration in such processes is assessed. The presence of strong magnetic reconnection provides excellent opportunities for the acceleration of thermal particles, which then form a seed population for further acceleration at the CME shocks. The presence of a large population of seed particles will thus lead to an overall increase in energetic particle fluxes, as suggested by some observations.

  17. Regarding the detectability and measurement of coronal mass ejections

    Directory of Open Access Journals (Sweden)

    Howard Timothy A.

    2015-01-01

    Full Text Available In this review I discuss the problems associated with the detection and measurement of coronal mass ejections (CMEs. CMEs are important phenomena both scientifically, as they play a crucial role in the evolution of the solar corona, and technologically, as their impact with the Earth leads to severe space weather activity in the form of magnetic storms. I focus on the observation of CMEs using visible white light imagers (coronagraphs and heliospheric imagers, as they may be regarded as the binding agents between different datasets and different models that are used to reconstruct them. Our ability to accurately measure CMEs observed by these imagers is hampered by many factors, from instrumental to geometrical to physical. Following a brief review of the history of CME observation and measurement, I explore the impediments to our ability to measure them and describe possible means for which we may be able to mitigate those impediments. I conclude with a discussion of the claim that we have reached the limit of the information that we can extract from the current generation of white light imagers, and discuss possible ways forward regarding future instrument capabilities.

  18. Data Constrained Coronal Mass Ejections in A Global Magnetohydrodynamics Model

    CERN Document Server

    Jin, M; van der Holst, B; Sokolov, I; Toth, G; Mullinix, R E; Taktakishvili, A; Chulaki, A; Gombosi, T I

    2016-01-01

    We present a first-principles-based coronal mass ejection (CME) model suitable for both scientific and operational purposes by combining a global magnetohydrodynamics (MHD) solar wind model with a flux rope-driven CME model. Realistic CME events are simulated self-consistently with high fidelity and forecasting capability by constraining initial flux rope parameters with observational data from GONG, SOHO/LASCO, and STEREO/COR. We automate this process so that minimum manual intervention is required in specifying the CME initial state. With the newly developed data-driven Eruptive Event Generator Gibson-Low (EEGGL), we present a method to derive Gibson-Low (GL) flux rope parameters through a handful of observational quantities so that the modeled CMEs can propagate with the desired CME speeds near the Sun. A test result with CMEs launched with different Carrington rotation magnetograms are shown. Our study shows a promising result for using the first-principles-based MHD global model as a forecasting tool, wh...

  19. Ensemble Modeling of the 23 July 2012 Coronal Mass Ejection

    Science.gov (United States)

    Cash, M. D.; Biesecker, D. A.; Pizzo, V.; Koning, C. A.; Millward, G.; Arge, C. N.; Henney, C. J.; Odstrcil, D.

    2015-10-01

    On 23 July 2012 a significant and rapid coronal mass ejection (CME) was detected in situ by the Solar Terrestrial Relations Observatory (STEREO) A. This CME was unusual due to its extremely brief Sun-to-1 AU transit time of less than 21 h and its exceptionally high impact speed of 2246 km/s. If this CME had been Earth directed, it would have produced a significant geomagnetic storm with potentially serious consequences. To protect our ground- and space-based assets, there is a clear need to accurately forecast the arrival times of such events using realistic input parameters and models run in near real time. Using Wang-Sheely-Arge (WSA)-Enlil, the operational model currently employed at the NOAA Space Weather Prediction Center, we investigate the sensitivity of the 23 July CME event to model input parameters. Variations in the initial CME speed, angular width, and direction, as well as the ambient solar wind background, are investigated using an ensemble approach to study the effect on the predicted arrival time of the CME at STEREO A. Factors involved in the fast transit time of this large CME are discussed, and potential improvements to modeling such events with the WSA-Enlil model are presented.

  20. A Type II Radio Burst without a Coronal Mass Ejection

    CERN Document Server

    Su, W; Ding, M D; Chen, P F; Sun, J Q

    2015-01-01

    Type II radio bursts are thought to be a signature of coronal shocks. In this paper, we analyze a short-lived type II burst that started at 07:40 UT on 2011 February 28. By carefully checking white-light images, we find that the type II radio burst is not accompanied by a coronal mass ejection, only with a C2.4 class flare and narrow jet. However, in the extreme-ultraviolet (EUV) images provided by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO), we find a wave-like structure that propagated at a speed of $\\sim$ 600 km s$^{-1}$ during the burst. The relationship between the type II radio burst and the wave-like structure is in particular explored. For this purpose, we first derive the density distribution under the wave by the differential emission measure (DEM) method, which is used to restrict the empirical density model. We then use the restricted density model to invert the speed of the shock that produces the observed frequency drift rate in the dynamic spectrum. The ...

  1. A Study of Fast Flareless Coronal Mass Ejections

    CERN Document Server

    Song, H Q; Ye, D D; Han, G Q; Du, G H; Li, G; Zhang, J; Hu, Q

    2013-01-01

    Two major processes have been proposed to convert the coronal magnetic energy into the kinetic energy of a coronal mass ejection (CME): resistive magnetic reconnection and ideal macroscopic magnetohydrodynamic instability of magnetic flux rope. However, it remains elusive whether both processes play a comparable role or one of them prevails during a particular eruption. To shed light on this issue, we carefully studied energetic but flareless CMEs, \\textit{i.e.}, fast CMEs not accompanied by any flares. Through searching the Coordinated Data Analysis Workshops (CDAW) database of CMEs observed in Solar Cycle 23, we found 13 such events with speeds larger than 1000 km s$^{-1}$. Other common observational features of these events are: (1) none of them originated in active regions; they were associated with eruptions of well-developed long filaments in quiet-Sun regions, (2) no apparent enhancement of flare emissions was present in soft X-ray, EUV and microwave data. Further studies of two events reveal that (1) ...

  2. VLA Measurements of Faraday Rotation through Coronal Mass Ejections

    CERN Document Server

    Kooi, Jason E; Buffo, Jacob J; Spangler, Steven R

    2016-01-01

    Coronal mass ejections (CMEs) are large-scale eruptions of plasma from the Sun that play an important role in space weather. Faraday rotation (FR) is the rotation of the plane of polarization that results when a linearly polarized signal passes through a magnetized plasma such as a CME. FR observations of a source near the Sun can provide information on the plasma structure of a CME shortly after launch. We report on simultaneous white-light and radio observations made of three CMEs in August 2012. We made sensitive Very Large Array (VLA) full-polarization observations using 1 - 2 GHz frequencies of a "constellation" of radio sources through the solar corona at heliocentric distances that ranged from 6 - 15 solar radii. Of the nine sources observed, three were occulted by CMEs: two sources (0842+1835 and 0900+1832) were occulted by a single CME and one source (0843+1547) was occulted by two CMEs. In addition to our radioastronomical observations, which represent one of the first active hunts for CME Faraday r...

  3. Self-similar expansion of solar coronal mass ejections: Implications for Lorentz self-force driving

    Energy Technology Data Exchange (ETDEWEB)

    Subramanian, Prasad; Arunbabu, K. P.; Mauriya, Adwiteey [Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411008 (India); Vourlidas, Angelos, E-mail: p.subramanian@iiserpune.ac.in [Space Science Division, Naval Research Laboratory, 4555 Overlook Avenue, SW Washington, DC 20375 (United States)

    2014-08-01

    We examine the propagation of several coronal mass ejections (CMEs) with well-observed flux rope signatures in the field of view of the SECCHI coronagraphs on board the STEREO satellites using the graduated cylindrical shell fitting method of Thernisien et al. We find that the manner in which they propagate is approximately self-similar; i.e., the ratio (κ) of the flux rope minor radius to its major radius remains approximately constant with time. We use this observation of self-similarity to draw conclusions regarding the local pitch angle (γ) of the flux rope magnetic field and the misalignment angle (χ) between the current density J and the magnetic field B. Our results suggest that the magnetic field and current configurations inside flux ropes deviate substantially from a force-free state in typical coronagraph fields of view, validating the idea of CMEs being driven by Lorentz self-forces.

  4. Galaxy evolution near groups and clusters: ejected satellites and the spatial extent of environmental quenching

    CERN Document Server

    Wetzel, Andrew R; Conroy, Charlie; Bosch, Frank C van den

    2013-01-01

    While satellite galaxies within groups/clusters are more likely to exhibit quiescent star formation rates (SFR) than central (field) galaxies, an enhanced quiescent likelihood extends to galaxies that are several virial radii beyond groups/clusters. Using a galaxy group/cluster catalog from SDSS DR7, we show that this enhancement has two causes. First, massive halos are clustered, so neighboring halos that host their own satellite galaxies boost the observed quiescent fraction out to large distances. Second, and more interestingly, central galaxies exhibit a strongly enhanced quiescent fraction out to 2.5 virial radii (with some enhancement out to 5 virial radii) beyond groups/clusters. We show that this enhancement for central galaxies can be explained by 'ejected' satellite galaxies that orbit beyond their host halo's virial radius. Using a cosmological N-body simulation, we examine the orbital histories of ejected satellites, showing that they extend out to 2.5 virial radii beyond their host halo and compo...

  5. Magnetic reconnection in the interior of interplanetary coronal mass ejections.

    Science.gov (United States)

    Fermo, R L; Opher, M; Drake, J F

    2014-07-18

    Recent in situ observations of interplanetary coronal mass ejections (ICMEs) found signatures of reconnection exhausts in their interior or trailing edge. Whereas reconnection on the leading edge of an ICME would indicate an interaction with the coronal or interplanetary environment, this result suggests that the internal magnetic field reconnects with itself. In light of this data, we consider the stability properties of flux ropes first developed in the context of astrophysics, then further elaborated upon in the context of reversed field pinches (RFPs). It was shown that the lowest energy state of a flux rope corresponds to ∇ × B = λB with λ a constant, the so-called Taylor state. Variations from this state will result in the magnetic field trying to reorient itself into the Taylor state solution, subject to the constraints that the toroidal flux and magnetic helicity are invariant. In reversed field pinches, this relaxation is mediated by the reconnection of the magnetic field, resulting in a sawtooth crash. If we likewise treat the ICME as a flux rope, any deviation from the Taylor state will result in reconnection within the interior of the flux tube, in agreement with the observations by Gosling et al. Such a departure from the Taylor state takes place as the flux tube cross section expands in the latitudinal direction, as seen in magnetohydrodynamic (MHD) simulations of flux tubes propagating through the interplanetary medium. We show analytically that this elongation results in a state which is no longer in the minimum energy Taylor state. We then present magnetohydrodynamic simulations of an elongated flux tube which has evolved away from the Taylor state and show that reconnection at many surfaces produces a complex stochastic magnetic field as the system evolves back to a minimum energy state configuration.

  6. A SOLAR CORONAL JET EVENT TRIGGERS A CORONAL MASS EJECTION

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jiajia; Wang, Yuming; Shen, Chenglong; Liu, Kai; Pan, Zonghao; Wang, S. [CAS Key Laboratory of Geospace Environment, Earh and Space Science School, University of Science and Technology of China, No. 96, JinZhai Road, Hefei, Anhui 230026 (China)

    2015-11-10

    In this paper, we present multi-point, multi-wavelength observations and analysis of a solar coronal jet and coronal mass ejection (CME) event. Employing the GCS model, we obtained the real (three-dimensional) heliocentric distance and direction of the CME and found it to propagate at a high speed of over 1000 km s{sup −1}. The jet erupted before the CME and shared the same source region. The temporal and spacial relationship between these two events lead us to the possibility that the jet triggered the CME and became its core. This scenario hold the promise of enriching our understanding of the triggering mechanism of CMEs and their relations to coronal large-scale jets. On the other hand, the magnetic field configuration of the source region observed by the Solar Dynamics Observatory (SDO)/HMI instrument along with the off-limb inverse Y-shaped configuration observed by SDO/AIA in the 171 Å passband provide the first detailed observation of the three-dimensional reconnection process of a large-scale jet as simulated in Pariat et al. The eruption process of the jet highlights the importance of filament-like material during the eruption of not only small-scale X-ray jets, but likely also of large-scale EUV jets. Based on our observations and analysis, we propose the most probable mechanism for the whole event, with a blob structure overlaying the three-dimensional structure of the jet, to describe the interaction between the jet and the CME.

  7. Speeds of coronal mass ejections: SMM observations from 1980 and 1984-1989

    Science.gov (United States)

    Hundhausen, A. J.; Burkepile, J. T.; St. Cyr, O. C.

    1994-01-01

    The speeds of 936 features in 673 coronal mass ejections have been determined from trajectories observed with the Solar Maximum Mission (SMM) coronagraph in 1980 and 1984 to 1989. The distribution of observed speeds has a range (from 5th to 95th percentile) of 35 to 911 km/s; the average and median speeds are 349 and 285 km/s. The speed distributions of some selected classes of mass ejections are significantly different. For example, the speeds of 331 'outer loops' range from 80 to 1042 km/s; the average and median speeds for this class of ejections are 445 and 372 km/s. The speed distributions from each year of SMM observations show significant changes, with the annual average speeds varying from 157 (1984) to 458 km/s (1985). These variations are not simply related to the solar activity cycle; the annual averages from years near the sunspot maxima and minimum are not significantly different. The widths, latitudes, and speeds of mass ejections determined from the SMM observations are only weakly correlated. In particular, mass ejection speeds vary only slightly with the heliographic latitudes of the ejection. High-latitude ejections, which occur well poleward of the active latitudes, have speeds similar to active latitude ejections.

  8. ON SUN-TO-EARTH PROPAGATION OF CORONAL MASS EJECTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ying D. [State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing (China); Luhmann, Janet G.; Moestl, Christian; Bale, Stuart D.; Lin, Robert P. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Lugaz, Noe [Space Science Center, University of New Hampshire, Durham, NH 03824 (United States); Davies, Jackie A., E-mail: liuxying@ssl.berkeley.edu [Space Science and Technology Department, Rutherford Appleton Laboratory, Didcot (United Kingdom)

    2013-05-20

    We investigate how coronal mass ejections (CMEs) propagate through, and interact with, the inner heliosphere between the Sun and Earth, a key question in CME research and space weather forecasting. CME Sun-to-Earth kinematics are constrained by combining wide-angle heliospheric imaging observations, interplanetary radio type II bursts, and in situ measurements from multiple vantage points. We select three events for this study, the 2012 January 19, 23, and March 7 CMEs. Different from previous event studies, this work attempts to create a general picture for CME Sun-to-Earth propagation and compare different techniques for determining CME interplanetary kinematics. Key results are obtained concerning CME Sun-to-Earth propagation: (1) the Sun-to-Earth propagation of fast CMEs can be approximately formulated into three phases: an impulsive acceleration, then a rapid deceleration, and finally a nearly constant speed propagation (or gradual deceleration); (2) the CMEs studied here are still accelerating even after the flare maximum, so energy must be continuously fed into the CME even after the time of the maximum heating and radiation has elapsed in the corona; (3) the rapid deceleration, presumably due to interactions with the ambient medium, mainly occurs over a relatively short timescale following the acceleration phase; and (4) CME-CME interactions seem a common phenomenon close to solar maximum. Our comparison between different techniques (and data sets) has important implications for CME observations and their interpretations: (1) for the current cases, triangulation assuming a compact CME geometry is more reliable than triangulation assuming a spherical front attached to the Sun for distances below 50-70 solar radii from the Sun, but beyond about 100 solar radii we would trust the latter more; (2) a proper treatment of CME geometry must be performed in determining CME Sun-to-Earth kinematics, especially when the CME propagation direction is far away from the

  9. Thermosphere and geomagnetic response to interplanetary coronal mass ejections observed by ACE and GRACE: Statistical results

    CERN Document Server

    Krauss, S; Veronig, A M; Baur, O; Lammer, H

    2015-01-01

    For the period July 2003 to August 2010, the interplanetary coronal mass ejection (ICME) catalogue maintained by Richardson and Cane lists 106 Earth-directed events, which have been measured in-situ by plasma and field instruments onboard the ACE satellite. We present a statistical investigation of the Earth's thermospheric neutral density response by means of accelerometer measurements collected by the GRACE satellites, which are available for 104 ICMEs in the data set, and its relation to various geomagnetic indices and characteristic ICME parameters such as the impact speed, southward magnetic field strength (Bz). The majority of ICMEs causes a distinct density enhancement in the thermosphere, with up to a factor of eight compared to the pre-event level. We find high correlations between ICME Bz and thermospheric density enhancements (~0.9), while the correlation with the ICME impact speed is somewhat smaller (~0.7). The geomagnetic indices revealing the highest correlations are Dst and SYM-H (~0.9), the l...

  10. Why does the apparent mass of a coronal mass ejection increase?

    CERN Document Server

    Feng, Li; Shen, Fang; Shen, Chenglong; Inhester, Bernd; Lu, Lei; Gan, Weiqun

    2015-01-01

    Mass is one of the most fundamental parameters characterizing the dynamics of a coronal mass ejection (CME). It has been found that CME apparent mass measured from the brightness enhancement in coronagraph images shows an increasing trend during its evolution in the corona. However, the physics behind it is not clear. Does the apparent mass gain come from the mass outflow from the dimming regions in the low corona, or from the pileup of the solar wind plasma around the CME when it propagates outwards from the Sun? We analyzed the mass evolution of six CME events. Their mass can increase by a factor of 1.6 to 3.2 from 4 to 15 Rs in the field of view (FOV) of the coronagraph on board the Solar Terrestrial Relations Observatory (STEREO). Over the distance about 7 to 15 Rs, where the coronagraph occulting effect can be negligible, the mass can increase by a factor of 1.3 to 1.7. We adopted the `snow-plough' model to calculate the mass contribution of the piled-up solar wind in the height range from about 7 to 15 ...

  11. Coronal Mass Ejections, Interplanetary Shocks In Relation With Forbush Decreases Associated With Intense Geomagnetic Storms

    Science.gov (United States)

    Verma, P. L.; Patel, Nand Kumar; Prajapati, Mateswari

    2014-05-01

    Coronal mass ejections (CMEs} are the most energetic solar events in which large amount of solar plasma materials are ejected from the sun into heliosphere, causing major disturbances in solar wind plasma, Interplanetary shocks, Forbush decrease(Fds) in cosmic ray intensity and geomagnetic storms. We have studied Forbush decreases associated with intense geomagnetic storms observed at Oulu super neutron monitor, during the period of May 1998-Dec 2006 with coronal mass ejections (CMEs), X-ray solar flares and interplanetary shocks. We have found that all the (100%) Forbush decreases associated with intense geomagnetic storms are associated with halo and partial halo coronal mass ejections (CMEs). The association rate between halo and partial halo coronal mass ejections are found 96.00%and 04.00% respectively. Most of the Forbush decreases associated with intense geomagnetic storms (96.29%) are associated with X-ray solar flares of different categories . The association rates for X-Class, M-Class, and C- Class X -ray solar flares are found 34.62%, 50.00% and 15.38% respectively .Further we have concluded that majority of the Forbush decrease associated with intense geomagnetic storms are related to interplanetary shocks (92.30 %) and the related shocks are forward shocks. We have found positive co-relation with co-relation co-efficient .7025 between magnitudes of Forbush decreases associated with intense geomagnetic storms and speed of associated coronal mass ejections. Positive co-relation with co-relation co-efficient 0.48 has also been found between magnitudes of intense geomagnetic storms and speed of associated coronal mass ejections.

  12. Activity associated with coronal mass ejections at solar minimum - SMM observations from 1984-1986

    Science.gov (United States)

    St. Cyr, O. C.; Webb, D. F.

    1991-01-01

    Seventy-three coronal mass ejections (CMEs) observed by the coronagraph aboard SMM between 1984 and 1986 were examined in order to determine the distribution of various forms of solar activity that were spatially and temporally associated with mass ejections during solar minimum phase. For each coronal mass ejection a speed was measured, and the departure time of the transient from the lower corona estimated. Other forms of solar activity that appeared within 45 deg longitude and 30 deg latitude of the mass ejection and within +/-90 min of its extrapolated departure time were explored. The statistical results of the analysis of these 73 CMEs are presented, and it is found that slightly less than half of them were infrequently associated with other forms of solar activity. It is suggested that the distribution of the various forms of activity related to CMEs does not change at different phases of the solar cycle. For those CMEs with associations, it is found that eruptive prominences and soft X-rays were the most likely forms of activity to accompany the appearance of mass ejections.

  13. The role of aerodynamic drag in propagation of interplanetary coronal mass ejections

    DEFF Research Database (Denmark)

    Vršnak, B.; Žic, T.; Falkenberg, Thea Vilstrup;

    2010-01-01

    Context. The propagation of interplanetary coronal mass ejections (ICMEs) and the forecast of their arrival on Earth is one of the central issues of space weather studies. Aims. We investigate to which degree various ICME parameters (mass, size, take-off speed) and the ambient solar-wind paramete...

  14. The Interaction of Two Coronal Mass Ejections: Influence of Relative Orientation

    CERN Document Server

    Lugaz, N; Manchester, W B; Schwadron, N

    2013-01-01

    We report on a numerical investigation of two coronal mass ejections (CMEs) which interact as they propagate in the inner heliosphere. We focus on the effect of the orientation of the CMEs relative to each other by performing four different simulations with the axis of the second CME rotated by 90 degrees from one simulation to the next. Each magneto-hydrodynamic (MHD) simulation is performed in three dimensions (3-D) with the Space Weather Modeling Framework (SWMF) in an idealized setting reminiscent of solar minimum conditions. We extract synthetic satellite measurements during and after the interaction and compare the different cases. We also analyze the kinematics of the two CMEs, including the evolution of their widths and aspect ratios. We find that the first CME contracts radially as a result of the interaction in all cases, but the amount of subsequent radial expansion depends on the relative orientation of the two CMEs. Reconnection between the two ejecta and between the ejecta and the interplanetary...

  15. Enhancement of Terrestrial Diffuse X-ray Emission Associated With Coronal Mass Ejection and Geomagnetic Storm

    CERN Document Server

    Ezoe, Yuichiro; Yoshitake, Hiroshi; Mitsuda, Kazuhisa; Terada, Naoki; Oishi, Shihoko; Ohashi, Takaya

    2011-01-01

    We present an analysis of a Suzaku observation taken during the geomagnetic storm of 2005 August 23-24. We found time variation of diffuse soft X-ray emission when a coronal mass ejection hit Earth and caused a geomagnetic storm. The diffuse emission consists of fluorescent scattering of solar X-rays and exospheric solarwind charge exchange. The former is characterized by a neutral oxygen emission line due to strong heating of the upper atmosphere during the storm time, while the latter is dominated by a sum of C V, C VI, N VI, N VII, O VII, and O VIII emission lines due to the enhanced solar wind flux in the vicinity of the exosphere. Using the solar wind data taken with the ACE and WIND satellites,a time correlation between the solar wind and the strong O VII line flux were investigated. We estimated necessary column densities for the solar X-ray scattering and exospheric SWCX. From these results, we argue that a part of the solar wind ions enter inside the magnetosphere and cause the SWCX reaction.

  16. Detection of Coronal Mass Ejections Using Multiple Features and Space-Time Continuity

    Science.gov (United States)

    Zhang, Ling; Yin, Jian-qin; Lin, Jia-ben; Feng, Zhi-quan; Zhou, Jin

    2017-07-01

    Coronal Mass Ejections (CMEs) release tremendous amounts of energy in the solar system, which has an impact on satellites, power facilities and wireless transmission. To effectively detect a CME in Large Angle Spectrometric Coronagraph (LASCO) C2 images, we propose a novel algorithm to locate the suspected CME regions, using the Extreme Learning Machine (ELM) method and taking into account the features of the grayscale and the texture. Furthermore, space-time continuity is used in the detection algorithm to exclude the false CME regions. The algorithm includes three steps: i) define the feature vector which contains textural and grayscale features of a running difference image; ii) design the detection algorithm based on the ELM method according to the feature vector; iii) improve the detection accuracy rate by using the decision rule of the space-time continuum. Experimental results show the efficiency and the superiority of the proposed algorithm in the detection of CMEs compared with other traditional methods. In addition, our algorithm is insensitive to most noise.

  17. A spectacular coronal mass ejection event and associated phenomena

    Science.gov (United States)

    Ma, Yuan; Li, Chun-Sheng; Song, Qian

    Based on the data taken from S. G. D. and relevant simultaneous observations of solar radio bursts, gamma-ray emission and geophysical effects on June 15, 1991 the relationships among these phenomena are discussed in this paper. Through the analyses it is considered that proton events and GLE events occurred on June 15 in 1991, which were the geophysic responses caused by CME (V>=750 km/s). Simultaneous observation of the bursts at the centimetric and decimetric wavelengths can obtain the U-shape spectrum of speak fluxes, which is still one of the effective tools for predicting proton events and its production mechanism can be explained by using the acceleration of the direct current field parallel to the magnetic field in the electric current sheet formed in the process of the production of spray prominences. However, the process in which electrons are accelerated up to the high energy state remains to be explained. The whole event of June 15 1991, from the coronal matter ejection (or the spray prominences in active regions) to the production of various geophysic effects, has explained and verified.

  18. Implications of mass and energy loss due to coronal mass ejections on magnetically-active stars

    CERN Document Server

    Drake, Jeremy J; Yashiro, Seiji; Gopalswamy, Nat

    2013-01-01

    Analysis of a database of solar coronal mass ejections (CMEs) and associated flares over the period 1996-2007 finds well-behaved power law relationships between the 1-8 AA flare X-ray fluence and CME mass and kinetic energy. We extrapolate these relationships to lower and higher flare energies to estimate the mass and energy loss due to CMEs from stellar coronae, assuming that the observed X-ray emission of the latter is dominated by flares with a frequency as a function of energy dn/dE=kE^-alpha. For solar-like stars at saturated levels of X-ray activity, the implied losses depend fairly weakly on the assumed value of alpha and are very large: M_dot ~ 5x10^-10 M_sun/yr and E_dot ~ 0.1L_sun. In order to avoid such large energy requirements, either the relationships between CME mass and speed and flare energy must flatten for X-ray fluence >~ 10^31 erg, or the flare-CME association must drop significantly below 1 for more energetic events. If active coronae are dominated by flares, then the total coronal energ...

  19. Model for estimating the effects of surface roughness on mass ejection from shocked materials

    Energy Technology Data Exchange (ETDEWEB)

    Asay, J R; Bertholf, L D

    1978-10-01

    A statistical model is presented for estimating the effects of surface roughness on mass ejection from shocked surfaces. In the model, roughness is characterized by the total volume of defects, such as pits, scratches and machine marks, on a surface. The amount of material ejected from these defects during shock loading can be estimated by assuming that jetting from surface depressions is the primary mode of ejection and by making simplifying assumptions about jetting processes. Techniques are discussed for estimating the effects of distribution in defect size and shape, and results are presented for several different geometries of defects. The model is used to compare predicted and measured ejecta masses from six different materials. Surface defects in these materials range from pits and scratches on polished surfaces to prepared defects such as machined or porous surfaces. Good agreement is achieved between predicted and measured results which suggests general applicability of the model.

  20. The formation of Pluto's low-mass satellites

    Energy Technology Data Exchange (ETDEWEB)

    Kenyon, Scott J. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Bromley, Benjamin C., E-mail: skenyon@cfa.harvard.edu, E-mail: bromley@physics.utah.edu [Department of Physics, University of Utah, 201 JFB, Salt Lake City, UT 84112 (United States)

    2014-01-01

    Motivated by the New Horizons mission, we consider how Pluto's small satellites—currently Styx, Nix, Kerberos, and Hydra—grow in debris from the giant impact that forms the Pluto-Charon binary. After the impact, Pluto and Charon accrete some of the debris and eject the rest from the binary orbit. During the ejection, high-velocity collisions among debris particles produce a collisional cascade, leading to the ejection of some debris from the system and enabling the remaining debris particles to find stable orbits around the binary. Our numerical simulations of coagulation and migration show that collisional evolution within a ring or a disk of debris leads to a few small satellites orbiting Pluto-Charon. These simulations are the first to demonstrate migration-induced mergers within a particle disk. The final satellite masses correlate with the initial disk mass. More massive disks tend to produce fewer satellites. For the current properties of the satellites, our results strongly favor initial debris masses of 3-10 × 10{sup 19} g and current satellite albedos A ≈ 0.4-1. We also predict an ensemble of smaller satellites, R ≲ 1-3 km, and very small particles, R ≈ 1-100 cm and optical depth τ ≲ 10{sup –10}. These objects should have semimajor axes outside the current orbit of Hydra.

  1. IMPLICATIONS OF MASS AND ENERGY LOSS DUE TO CORONAL MASS EJECTIONS ON MAGNETICALLY ACTIVE STARS

    Energy Technology Data Exchange (ETDEWEB)

    Drake, Jeremy J.; Cohen, Ofer [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Yashiro, Seiji [Interferometrics Inc., Herndon, VA 20171 (United States); Gopalswamy, Nat, E-mail: jdrake@cfa.harvard.edu [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2013-02-20

    Analysis of a database of solar coronal mass ejections (CMEs) and associated flares over the period 1996-2007 finds well-behaved power-law relationships between the 1-8 A flare X-ray fluence and CME mass and kinetic energy. We extrapolate these relationships to lower and higher flare energies to estimate the mass and energy loss due to CMEs from stellar coronae, assuming that the observed X-ray emission of the latter is dominated by flares with a frequency as a function of energy dn/dE = kE {sup -{alpha}}. For solar-like stars at saturated levels of X-ray activity, the implied losses depend fairly weakly on the assumed value of {alpha} and are very large: M-dot {approx}5 Multiplication-Sign 10{sup -10} M{sub sun} yr{sup -1} and E-dot {approx}0.1 L{sub sun}. In order to avoid such large energy requirements, either the relationships between CME mass and speed and flare energy must flatten for X-ray fluence {approx}> 10{sup 31} erg, or the flare-CME association must drop significantly below 1 for more energetic events. If active coronae are dominated by flares, then the total coronal energy budget is likely to be up to an order of magnitude larger than the canonical 10{sup -3} L {sub bol} X-ray saturation threshold. This raises the question of what is the maximum energy a magnetic dynamo can extract from a star? For an energy budget of 1% of L {sub bol}, the CME mass loss rate is about 5 Multiplication-Sign 10{sup -11} M {sub Sun} yr{sup -1}.

  2. The Solar Atmosphere at Three Temperatures During a Coronal Mass Ejection

    Science.gov (United States)

    Zhitnik, I.; Pertzov, A.; Oparin, S.; Oraevsky, V.; Slemzin, V.; Sobelman, I.; Feynman, J.; Goldstein, B.

    1998-01-01

    On April 14, 1994 a major coronal mass ejection (CME) occured while the solar atmosphere was being observed in XUV by the Terek C instrument aboard the CORONAS spacecraft. We here compare the TEREK data before and after the CME with the Yohkoh soft x-ray data and the National Solar Observatory He I 10830 data from April 13 and 14.

  3. The classification of ambiguity in polarimetric reconstruction of coronal mass ejection

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Xinghua; Wang, Huaning; Huang, Xin; Du, Zhanle; He, Han, E-mail: xhdai@nao.cas.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2014-01-10

    The Thomson scattering theory indicates that there exist explicit and implicit ambiguities in polarimetric analyses of coronal mass ejection (CME) observations. We suggest a classification for these ambiguities in CME reconstruction. Three samples, including double explicit, mixed, and double implicit ambiguity, are shown with the polarimetric analyses of STEREO CME observations. These samples demonstrate that this classification is helpful for improving polarimetric reconstruction.

  4. Observation of two coronal mass ejections on April 7, 2011 by radio telescope URAN-2

    Science.gov (United States)

    Brazhenko, A.; Melnik, V.; Konovalenko, A.; Dorovskyy, V.; Vashchishin, V.; Franzusenko, A.; Rucker, H.

    2012-09-01

    Two CME's (coronal mass ejection) were registered by SOHO and STEREO on April 7, 2011. The results of observations obtained by radio telescope URAN-2 of different CME manifestations in radio emission at decameter wavelengths are discussed in this paper. Particularly we report about registration of new type of fine structure of type II bursts.

  5. Mass Ejection from Old and Young Stars and the Sun

    Science.gov (United States)

    Jatenco-Pereira, V.; Opher, R.

    1990-11-01

    RESUMEN. Para poder explicar: 1) la enorme cantidad de perdida de masa y la baja velocidad asint5tica de las estrellas gigantes de o, y 2) los flujos de masa observados en protoestrellas, se sugiere un modelo para Ia perdida de masa, en donde se usa un flujo de ondas de Alfvencomo un mecanismo de aceleraci6n para los vientos de estrellas de tipo y vientos en protoestrellas. Se estudian los mecanismos de disipaci5n de las ondas de Alfven: los amortiguamientos no lineal, de superficie reso- nante y turbulento. En nuestro modelo se usa una divergente A(r) = A(R0) (r/r0)5 (donde A(r) es el area a una distancia radial r, y (A(r)/r2)max/(A(ro)/r02 - 10). Tambien se sugiere un modelo para una de hoyo coronal en el Sol. Se muestra que para satisfacer los datos observacionales en el Sol, tomando en cuenta la deposici6n del momento de las ondas de Alfven sobre el viento, se necesita: (a) una divergencia lenta en un hoyo coronal hasta una altura de 0.01 - 0.1 R seguido de (b) una divergencia rap ida de hasta una altura aproximada de 1 R . ABSTRACT: In order to explain (1) a large mass-loss rate and a small asymptotic flow speed of late-type giant stars and (2) the observed protostellar mass outflows, we suggest a model for mass loss, where we use a flux of Alfven waves as a mechanism of acceleration for late-type giant star winds and protostellar winds. We study the Alfven wave dissipation mechanisms: nonlinear damping, resonant surface damping, and turbulent damping. In our model we use a diverging geometry A(r) = A(r0) (r I r )S (where A(r) is the cross sectional area of the geometry at a radial distance r, and(A(r) I r2)max/(A(r0)/r02) = 10). We also suggest a model for a coronal hole geometry in the sun. We show that in order to satisfy the observational data of the sun, taking into account Alfven wave momentum deposition in the wind, we need: (a) a slow divergence in a coronal hole up t6 a height of 0.01 - 0.1 followed by (b) a rapid divergence up to a height of

  6. Mass ejection by pulsational pair-instability in very massive stars and implications for luminous supernovae

    CERN Document Server

    Yoshida, Takashi; Maeda, Keiichi; Ishii, Tatsuo

    2015-01-01

    Massive stars having a CO core of $\\sim 40 - 60$ M$_\\odot$ experience pulsational pair-instability (PPI) after carbon-burning. This instability induces strong pulsations of the whole star and a part of outer envelope is ejected. We investigate the evolution and mass ejection of metal-poor very massive stars which experience PPI. We use stellar models with initial masses of 140, 200, and 250 M$_\\odot$ and the metallicity Z=0.004. Their masses decrease to 54.09, 58.65, and 61.03 M$_\\odot$ before the neon-burning owing to mass loss and He mass fraction at the surface becomes about 20%. During the PPI period of $\\sim 1 - 2000$ years, they experience six, four, and three pulsations, respectively. The larger CO-core model has the longer PPI period and ejects the larger amount of mass. Since almost all surface He has been lost by the pulsations, these stars become type Ic supernovae if they explode. Light curves during the PPI stage and supernovae are investigated and are implicated in luminous supernovae. The lumin...

  7. Relationship of EUV Irradiance Coronal Dimming Slope and Depth to Coronal Mass Ejection Speed and Mass

    Science.gov (United States)

    Mason, James Paul; Woods, Thomas N.; Webb, David F.; Thompson, Barbara J.; Colaninno, Robin C.; Vourlidas, Angelos

    2016-10-01

    Extreme ultraviolet (EUV) coronal dimmings are often observed in response to solar eruptive events. These phenomena can be generated via several different physical processes. For space weather, the most important of these is the temporary void left behind by a coronal mass ejection (CME). Massive, fast CMEs tend to leave behind a darker void that also usually corresponds to minimum irradiance for the cooler coronal emissions. If the dimming is associated with a solar flare, as is often the case, the flare component of the irradiance light curve in the cooler coronal emission can be isolated and removed using simultaneous measurements of warmer coronal lines. We apply this technique to 37 dimming events identified during two separate two-week periods in 2011 plus an event on 2010 August 7, analyzed in a previous paper to parameterize dimming in terms of depth and slope. We provide statistics on which combination of wavelengths worked best for the flare-removal method, describe the fitting methods applied to the dimming light curves, and compare the dimming parameters with corresponding CME parameters of mass and speed. The best linear relationships found are \\begin{eqnarray*}{v}{CME} ≤ft[\\displaystyle \\frac{{km}}{{{s}}}\\right] & ≈ & 2.36× {10}6 ≤ft[\\displaystyle \\frac{{km}}{ % }\\right]× {s}\\dim ≤ft[\\displaystyle \\frac{ % }{{{s}}}\\right]\\ {m}{CME} [{{g}}] & ≈ & 2.59× {10}15≤ft[\\displaystyle \\frac{g}{ % }\\right]× \\sqrt{{d}\\dim } [ % ].\\end{eqnarray*} These relationships could be used for space weather operations of estimating CME mass and speed using near-real-time irradiance dimming measurements.

  8. Relationship of EUV Irradiance Coronal Dimming Slope and Depth to Coronal Mass Ejection Speed and Mass

    CERN Document Server

    Mason, James Paul; Webb, David F; Thompson, Barbara J; Colaninno, Robin C; Vourlidas, Angelos

    2016-01-01

    Extreme ultraviolet (EUV) coronal dimmings are often observed in response to solar eruptive events. These phenomena can be generated via several different physical processes. For space weather, the most important of these is the temporary void left behind by a coronal mass ejection (CME). Massive, fast CMEs tend to leave behind a darker void that also usually corresponds to minimum irradiance for the cooler coronal emissions. If the dimming is associated with a solar flare, as is often the case, the flare component of the irradiance light curve in the cooler coronal emission can be isolated and removed using simultaneous measurements of warmer coronal lines. We apply this technique to 37 dimming events identified during two separate two-week periods in 2011, plus an event on 2010 August 7 analyzed in a previous paper, to parameterize dimming in terms of depth and slope. We provide statistics on which combination of wavelengths worked best for the flare-removal method, describe the fitting methods applied to t...

  9. Ejection of Hyper-Velocity Stars from the Galactic Centre by Intermediate-Mass Black Holes

    CERN Document Server

    Baumgardt, H; Zwart, S P; Baumgardt, Holger; Gualandris, Alessia; Zwart, Simon Portegies

    2006-01-01

    We have performed N-body simulations of the formation of hyper-velocity stars (HVS) in the centre of the Milky Way due to inspiralling intermediate-mass black holes (IMBHs). We considered IMBHs of different masses, all starting from circular orbits at an initial distance of 0.1 pc. We find that the IMBHs sink to the centre of the Galaxy due to dynamical friction, where they deplete the central cusp of stars. Some of these stars become HVS and are ejected with velocities sufficiently high to escape the Galaxy. Since the HVS carry with them information about their origin, in particular in the moment of ejection, the velocity distribution and the direction in which they escape the Galaxy, detecting a population of HVS will provide insight in the ejection processes and could therefore provide indirect evidence for the existence of IMBHs. Our simulations show that HVS are generated in short bursts which last only a few Myrs until the IMBH is swallowed by the supermassive black hole (SMBH). HVS are ejected almost i...

  10. ERNE observations of energetic particles associated with Earth-directed coronal mass ejections in April and May, 1997

    Directory of Open Access Journals (Sweden)

    A. Anttila

    Full Text Available Two Earth-directed coronal mass ejections (CMEs, which were most effective in energetic (~1–50 MeV particle acceleration during the first 18 months since the Solar and Heliospheric Observatory (SOHO launch, occurred on April 7 and May 12, 1997. In the analysis of these events we have deconvoluted the injection spectrum of energetic protons by using the method described by Anttila et al. In order to apply the method developed earlier for data of a rotating satellite (Geostationary Operational Environmental Satellites, GOES, we first had to develop a method to calculate the omnidirectional energetic particle intensities from the observations of Energetic and Relativistic Nuclei and Electrons (ERNE, which is an energetic particle detector onboard the three-axis stabilized SOHO spacecraft. The omnidirectional intensities are calculated by fitting an exponential pitch angle distribution from directional information of energetic protons observed by ERNE. The results of the analysis show that, compared to a much faster and more intensive CMEs observed during the previous solar maximum, the acceleration efficiency decreases fast when the shock propagates outward from the Sun. The particles injected at distances <0.5 AU from the Sun dominate the particle flux during the whole period, when the shock propagates to the site of the spacecraft. The main portion of particles injected by the shock during its propagation further outward from the Sun are trapped around the shock, and are seen as an intensity increase at the time of the shock passage.

    Key words: Interplanetary physics (interplanetary shocks – Solar physics, astrophysics and astronomy (energetic particles; flares and mass ejections

  11. IS SOLAR CYCLE 24 PRODUCING MORE CORONAL MASS EJECTIONS THAN CYCLE 23?

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.-M.; Colaninno, R., E-mail: yi.wang@nrl.navy.mil, E-mail: robin.colaninno@nrl.navy.mil [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)

    2014-04-01

    Although sunspot numbers are roughly a factor of two lower in the current cycle than in cycle 23, the rate of coronal mass ejections (CMEs) appears to be at least as high in 2011-2013 as during the corresponding phase of the previous cycle, according to three catalogs that list events observed with the Large Angle and Spectrometric Coronagraph (LASCO). However, the number of CMEs detected is sensitive to such factors as the image cadence and the tendency (especially by human observers) to under-/overcount small or faint ejections during periods of high/low activity. In contrast to the total number, the total mass of CMEs is determined mainly by larger events. Using the mass measurements of 11,000 CMEs given in the manual CDAW catalog, we find that the mass loss rate remains well correlated with the sunspot number during cycle 24. In the case of the automated CACTus and SEEDS catalogs, the large increase in the number of CMEs during cycle 24 is almost certainly an artifact caused by the near-doubling of the LASCO image cadence after mid-2010. We confirm that fast CMEs undergo a much stronger solar-cycle variation than slow ones, and that the relative frequency of slow and less massive CMEs increases with decreasing sunspot number. We conclude that cycle 24 is not only producing fewer CMEs than cycle 23, but that these ejections also tend to be slower and less massive than those observed one cycle earlier.

  12. Redefining the boundaries of interplanetary coronal mass ejections from observations at the ecliptic plane

    CERN Document Server

    Cid, C; Saiz, E; Guerrero, A

    2016-01-01

    On 2015 January 6-7, an interplanetary coronal mass ejection (ICME) was observed at L1. This event, which can be associated with a weak and slow coronal mass ejection, allows us to discuss on the differences between the boundaries of the magnetic cloud and the compositional boundaries. A fast stream from a solar coronal hole surrounding this ICME offers a unique opportunity to check the boundaries' process definition and to explain differences between them. Using Wind and ACE data, we perform a complementary analysis involving compositional, magnetic, and kinematic observations providing relevant information regarding the evolution of the ICME as travelling away from the Sun. We propose erosion, at least at the front boundary of the ICME, as the main reason for the difference between the boundaries, and compositional signatures as the most precise diagnostic tool for the boundaries of ICMEs.

  13. Understanding the Global Structure and Evolution of Coronal Mass Ejections in the Solar Wind

    Science.gov (United States)

    Riley, Pete

    2004-01-01

    This report summarizes the technical progress made during the first six months of the second year of the NASA Living with a Star program contract Understanding the global structure and evolution of coronal mass ejections in the solar wind, between NASA and Science Applications International Corporation, and covers the period November 18, 2003 - May 17,2004. Under this contract SAIC has conducted numerical and data analysis related to fundamental issues concerning the origin, intrinsic properties, global structure, and evolution of coronal mass ejections in the solar wind. During this working period we have focused on a quantitative assessment of 5 flux rope fitting techniques. In the following sections we summarize the main aspects of this work and our proposed investigation plan for the next reporting period. Thus far, our investigation has resulted in 6 refereed scientific publications and we have presented the results at a number of scientific meetings and workshops.

  14. Low Frequency (30-110 MHz) Radio Imaging Observations Of Solar Coronal Mass Ejections

    Science.gov (United States)

    Ramesh, R.

    Ground based radio imaging observations play an useful role in the study of mass ejections from the solar corona since they do not have the limitation of an occulter and both the disk/limb events can be detected early in their development, particularly via the thermal bremmstrahlung emission from the frontal loop of the CME. I present here some of the recent results on the above topic using data obtained with the Gauribidanur radioheliograph, near Bangalore in India.

  15. Direct observations of magnetic flux rope formation during a solar coronal mass ejection

    OpenAIRE

    Song, Hongqiang; Zhang, Jie; Chen, Yao; Cheng, Xin

    2014-01-01

    Coronal mass ejections (CMEs) are the most spectacular eruptive phenomena in the solar atmosphere. It is generally accepted that CMEs are results of eruptions of magnetic flux ropes (MFRs). However, a heated debate is on whether MFRs pre-exist before the eruptions or they are formed during the eruptions. Several coronal signatures, \\textit{e.g.}, filaments, coronal cavities, sigmoid structures and hot channels (or hot blobs), are proposed as MFRs and observed before the eruption, which suppor...

  16. Real-Time Analysis of Global Waves Accompanying Coronal Mass Ejections

    Science.gov (United States)

    2016-06-30

    tions and modelling to conclude that a solar eruption must have sufficient energy and downward pressure on the chromosphere before it can produce a...intensity of the wave relative to the background chromosphere. Upon completion of the code, it was applied to a series of solar flares observed by both...wave-like features seen in H observations of the solar chromosphere. They are strongly associated with coronal mass ejections (CMEs) and can cover a

  17. Systematics of dynamical mass ejection, nucleosynthesis, and radioactively powered electromagnetic signals from neutron-star mergers

    CERN Document Server

    Bauswein, A; Janka, H -T

    2013-01-01

    Neutron star (NS) mergers can eject considerable amounts of neutron-rich matter, allowing for r-processing. The radioactive decay of the products heats the ejecta and makes them potentially observable as a source of thermal electromagnetic radiation. We investigate systematically the dynamical mass ejection during the NS collision in dependence on uncertain properties of the nuclear equation of state (EoS) by using 40 representative, microphysical EoSs in relativistic merger simulations. The NS compactness, characterized by the radius R_1.35 of nonrotating NSs of 1.35 Msun, is the crucial parameter that determines the ejecta mass. NSs with smaller radii R_1.35 ("soft"' EoS) collide more violently and eject systematically higher masses. These range from ~10^-3 Msun to ~10^-2 Msun for symmetric 1.35-1.35 Msun binaries with R_1.35 between 16 km and 11 km, and from ~5*10^-3 Msun to ~2*10^-2 Msun for asymmetric 1.2-1.5 Msun binaries. Correspondingly, the bolometric peak luminosities of the optical transients vary ...

  18. Genesis Solar Wind Interstream, Coronal Hole and Coronal Mass Ejection Samples: Update on Availability and Condition

    Science.gov (United States)

    Allton, J. H.; Gonzalez, C. P.; Allums, K. K.

    2017-01-01

    Recent refinement of analysis of ACE/SWICS data (Advanced Composition Explorer/Solar Wind Ion Composition Spectrometer) and of onboard data for Genesis Discovery Mission of 3 regimes of solar wind at Earth-Sun L1 make it an appropriate time to update the availability and condition of Genesis samples specifically collected in these three regimes and currently curated at Johnson Space Center. ACE/SWICS spacecraft data indicate that solar wind flow types emanating from the interstream regions, from coronal holes and from coronal mass ejections are elementally and isotopically fractionated in different ways from the solar photosphere, and that correction of solar wind values to photosphere values is non-trivial. Returned Genesis solar wind samples captured very different kinds of information about these three regimes than spacecraft data. Samples were collected from 11/30/2001 to 4/1/2004 on the declining phase of solar cycle 23. Meshik, et al is an example of precision attainable. Earlier high precision laboratory analyses of noble gases collected in the interstream, coronal hole and coronal mass ejection regimes speak to degree of fractionation in solar wind formation and models that laboratory data support. The current availability and condition of samples captured on collector plates during interstream slow solar wind, coronal hole high speed solar wind and coronal mass ejections are de-scribed here for potential users of these samples.

  19. Microwave radio emissions as a proxy for coronal mass ejection speed in arrival predictions of interplanetary coronal mass ejections at 1 AU

    Science.gov (United States)

    Matamoros, Carolina Salas; Klein, Karl Ludwig; Trottet, Gerard

    2017-01-01

    The propagation of a coronal mass ejection (CME) to the Earth takes between about 15 h and several days. We explore whether observations of non-thermal microwave bursts, produced by near-relativistic electons via the gyrosynchrotron process, can be used to predict travel times of interplanetary coronal mass ejections (ICMEs) from the Sun to the Earth. In a first step, a relationship is established between the CME speed measured by the Solar and Heliospheric Observatory/Large Angle and Spectrometric Coronagraph (SoHO/LASCO) near the solar limb and the fluence of the microwave burst. This relationship is then employed to estimate speeds in the corona of earthward-propagating CMEs. These speeds are fed into a simple empirical interplanetary acceleration model to predict the speed and arrival time of the ICMEs at Earth. The predictions are compared with observed arrival times and with the predictions based on other proxies, including soft X-rays (SXR) and coronographic measurements. We found that CME speeds estimated from microwaves and SXR predict the ICME arrival at the Earth with absolute errors of 11 ± 7 and 9 ± 7 h, respectively. A trend to underestimate the interplanetary travel times of ICMEs was noted for both techniques. This is consistent with the fact that in most cases of our test sample, ICMEs are detected on their flanks. Although this preliminary validation was carried out on a rather small sample of events (11), we conclude that microwave proxies can provide early estimates of ICME arrivals and ICME speeds in the interplanetary space. This method is limited by the fact that not all CMEs are accompanied by non-thermal microwave bursts. But its usefulness is enhanced by the relatively simple observational setup and the observation from ground, which makes the instrumentation less vulnerable to space weather hazards.

  20. Filaments disappearance in relation to coronal mass ejections during the solar cycle 23

    Science.gov (United States)

    Mawad, R.; Shaltout, Mosalam; Yousef, M.; Yousef, S.; Ewaida, M.

    2015-01-01

    We have studied the relationship between filament disappearances with CMEs during solar period 1996-2010. We used the observed disappearing filaments in Hα data from Meudon given in NOAA, and coronal mass ejections data (CMEs) from SOHO/LASCO. We obtained 278 CME events (14%) contemporary filament disappearances and CME ejections (from a total of 2018 filament disappearance events and 15,874 CME events during 1996-2010). We found that the number of associated CME-filament disappearance events increased with the increase of the solar activity and significantly decreased with quiet sun. The longer filament disappearances have activity and ability to contemporary association with CMEs more than shorter filament disappearances. The filament disappearance powers the associated CMEs. CMEs which are associated with filament disappearance are ejected with higher speeds, massive, more energetic, and smaller angular width compared to non-associated CME events. In addition, the associated filament disappearance CMEs have two types depending on their duration; short-lived (9 h).

  1. Comparison of a Global Magnetic Evolution Model with Observations of Coronal Mass Ejections

    CERN Document Server

    Yeates, A R; Nandy, Dibyendu; Mackay, D H; Martens, P C H; van Ballegooijen, A A

    2009-01-01

    The relative importance of different initiation mechanisms for coronal mass ejections (CMEs) on the Sun is uncertain. One possible mechanism is the loss of equilibrium of coronal magnetic flux ropes formed gradually by large-scale surface motions. In this paper, the locations of flux rope ejections in a recently-developed quasi-static global evolution model are compared with observed CME source locations over a 4.5-month period in 1999. Using EUV data, the low-coronal source locations are determined unambiguously for 98 out of 330 CMEs. Despite the incomplete observations, positive correlation (with coefficient up to 0.49) is found between the distributions of observed and simulated ejections, but only when binned into periods of one month or longer. This binning timescale corresponds to the time interval at which magnetogram data are assimilated into the coronal simulations, and the correlation arises primarily from the large-scale surface magnetic field distribution; only a weak dependence is found on the m...

  2. Investigation of the Large Scale Evolution and Topology of Coronal Mass Ejections in the Solar Wind

    Science.gov (United States)

    Riley, Peter

    1999-12-01

    This investigation is concerned with the large-scale evolution and topology of Coronal Mass Ejections (CMEs) in the solar wind. During this reporting period we have analyzed a series of low density intervals in the ACE (Advanced Composition Explorer) plasma data set that bear many similarities to CMEs. We have begun a series of 3D, MHD (Magnetohydrodynamics) coronal models to probe potential causes of these events. We also edited two manuscripts concerning the properties of CMEs in the solar wind. One was re-submitted to the Journal of Geophysical Research.

  3. Energy of coronal mass ejections and large-scale structure of solar magnetic fields

    Science.gov (United States)

    Ivanov, E. V.

    2016-12-01

    The relationship between variations of the energy and linear velocity of coronal mass ejections (CME) and the typical dimensions of structural elements of the large-scale solar magnetic field structure (LSMFS) is investigated for the period of 1996-2014. It is shown that the maximum linear velocity and maximum energy of CME correspond to the values of the effective solar multipole index n 4.0-4.4. These values determine the maximum size of the complexes of active regions, which, together with the observed maximum values of magnetic field intensity in the complexes, limit the possible maximum CME energy.

  4. Latitudinal Distribution of Solar Flares and Their Association with Coronal Mass Ejections

    Institute of Scientific and Technical Information of China (English)

    Pankaj K. Shrivastava; Neelam Singh

    2005-01-01

    Major solar flare events have been utilised to study the latitudinal frequency distribution of solar flares in northern and southern hemispheres for the period of 1986 to 2003. A statistical analysis has been performed to obtain the correlation between Coronal Mass Ejections (CMEs) and Forbush decrease (Fds)of cosmic ray intensity. Almost the same flares distribution in both hemispheres is found in association with CMEs. In a further analysis, it is noted that a larger number of CME-associated solar flares located in the northern hemisphere are found to be more effective in producing Forbush decreases.

  5. Solar Coronal Mass Ejection as a Result of Magnetic Helicity Accumulation in the Corona

    Institute of Scientific and Technical Information of China (English)

    ZHANG Mei

    2011-01-01

    Coronal mass ejections (CMEs) are a major form of solar activities. A CME takes away 10^15-16 g of plasma from solar low corona, to disturb the near-Earth space if the CME direction is favorable. Here we summarize our understandings and reasoning that lead us to conclude that CMEs are the unavoidable products of magnetic helicity accumulation in the corona. Our study puts the formation of magnetic flux ropes and CME eruptions as natural and unavoidable results of coronal evolution.

  6. The role of aerodynamic drag in propagation of interplanetary coronal mass ejections

    DEFF Research Database (Denmark)

    Vršnak, B.; Žic, T.; Falkenberg, Thea Vilstrup;

    2010-01-01

    Context. The propagation of interplanetary coronal mass ejections (ICMEs) and the forecast of their arrival on Earth is one of the central issues of space weather studies. Aims. We investigate to which degree various ICME parameters (mass, size, take-off speed) and the ambient solar-wind paramete...... streams. We apply the model to the Sun-Earth event associated with the CME of 25 July 2004 and compare the results with the outcome of the numerical MHD modeling....... (density and velocity) affect the ICME Sun-Earth transit time. Methods. We study solutions of a drag-based equation of motion by systematically varying the input parameters. The analysis is focused on ICME transit times and 1 AU velocities. Results. The model results reveal that wide ICMEs of low masses...

  7. COMPOSITION STRUCTURE OF INTERPLANETARY CORONAL MASS EJECTIONS FROM MULTISPACECRAFT OBSERVATIONS, MODELING, AND COMPARISON WITH NUMERICAL SIMULATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Reinard, Alysha A. [University of Colorado/Cooperative Institute for Research in Environmental Sciences and National Oceanic and Atmospheric Administration/Space Weather Prediction Center, Boulder, CO 80505 (United States); Lynch, Benjamin J. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Mulligan, Tamitha, E-mail: alysha.reinard@noaa.gov, E-mail: blynch@ssl.berkeley.edu, E-mail: tamitha.mulligan@aero.org [Space Sciences Department, Aerospace Corporation, Los Angeles, CA 90009 (United States)

    2012-12-20

    We present an analysis of the ionic composition of iron for two interplanetary coronal mass ejections (ICMEs) observed on 2007 May 21-23 by the ACE and STEREO spacecraft in the context of the magnetic structure of the ejecta flux rope, sheath region, and surrounding solar wind flow. This analysis is made possible due to recent advances in multispacecraft data interpolation, reconstruction, and visualization as well as results from recent modeling of ionic charge states in MHD simulations of magnetic breakout and flux cancellation coronal mass ejection (CME) initiation. We use these advances to interpret specific features of the ICME plasma composition resulting from the magnetic topology and evolution of the CME. We find that, in both the data and our MHD simulations, the flux ropes centers are relatively cool, while charge state enhancements surround and trail the flux ropes. The magnetic orientations of the ICMEs are suggestive of magnetic breakout-like reconnection during the eruption process, which could explain the spatial location of the observed iron enhancements just outside the traditional flux rope magnetic signatures and between the two ICMEs. Detailed comparisons between the simulations and data were more complicated, but a sharp increase in high iron charge states in the ACE and STEREO-A data during the second flux rope corresponds well to similar features in the flux cancellation results. We discuss the prospects of this integrated in situ data analysis and modeling approach to advancing our understanding of the unified CME-to-ICME evolution.

  8. Alfvenic Fluctuations in an Interplanetary Coronal Mass Ejection Observed Near 1 AU

    Institute of Scientific and Technical Information of China (English)

    梁浩明; 肖池阶; 周桂萍; 濮祖荫; 王红刚; 王晓钢

    2012-01-01

    As for the present situation of coronal mass ejection (CME) triggering models, the distributions of Alfv@n waves in flux ropes are different from model to model, and thus examining those distributions in interplanetary coronal mass ejection (ICME) is an effective way to connect ICME observations with these theoretical models of CME triggering. However, previous observations of Alfv@nic fluctuations in ICMEs were rare with locations ranging from 0.3 AU to 0.68 AU only, which is usually explained as rapid dissipation of those remnant waves. Here we present an observation of Alfv@n waves in a magnetic cloud (MC) near 1 AU, in situ detected by WIND in February 17,-~20, 2011. The MC was generated by a CME accompanied with the first X-class flare in the 24th solar cycle. The slope of the power spectral densities of magnetic fluctuation in the MC, are similar to those modes in ambient solar wind, but more anisotropic. The results will also be helpful for studies of CME theories and ICME thermodynamics.

  9. Solar Radio Emission as a Prediction Technique for Coronal Mass Ejections' registration

    Science.gov (United States)

    Sheiner, Olga; Fridman, Vladimir

    2016-07-01

    The concept of solar Coronal Mass Ejections (CMEs) as global phenomenon of solar activity caused by the global magnetohydrodynamic processes is considered commonly accepted. These processes occur in different ranges of emission, primarily in the optical and the microwave emission being generated near the surface of the sun from a total of several thousand kilometers. The usage of radio-astronomical data for CMEs prediction is convenient and promising. Actually, spectral measurements of solar radio emission cover all heights of solar atmosphere, sensitivity and accuracy of measurements make it possible to record even small energy changes. Registration of the radio emission is provided by virtually all-weather ground-based observations, and there is the relative cheapness to obtain the corresponding information due to a developed system of monitoring observations. On the large statistical material there are established regularities of the existence of sporadic radio emission at the initial stage of CMEs' formation and propagation in the lower layers of the solar atmosphere during the time interval from 2-3 days to 2 hours before registration of CMEs on coronagraph. In this report we present the prediction algorithm and scheme of short-term forecasting developed on the base of statistical analysis regularities of solar radio emission data prior to "isolated" solar Coronal Mass Ejections registered in 1998, 2003, 2009-2013.

  10. On the autonomous detection of coronal mass ejections in heliospheric imager data

    Science.gov (United States)

    Tappin, S. J.; Howard, T. A.; Hampson, M. M.; Thompson, R. N.; Burns, C. E.

    2012-05-01

    We report on the development of an Automatic Coronal Mass Ejection (CME) Detection tool (AICMED) for the Solar Mass Ejection Imager (SMEI). CMEs observed with heliospheric imagers are much more difficult to detect than those observed by coronagraphs as they have a lower contrast compared with the background light, have a larger range of intensity variation and are easily confused with other transient activity. CMEs appear in SMEI images as very faint often-fragmented arcs amongst a much brighter and often variable background. AICMED operates along the same lines as Computer Aided CME Tracking (CACTus), using the Hough Transform on elongation-time J-maps to extract straight lines from the data set. We compare AICMED results with manually measured CMEs on almost three years of data from early in SMEI operations. AICMED identified 83 verifiable events. Of these 46 could be matched with manually identified events, the majority of the non-detections can be explained. The remaining 37 AICMED events were newly discovered CMEs. The proportion of false identification was high, at 71% of the autonomously detected events. We find that AICMED is very effective as a region of interest highlighter, and is a promising first step in autonomous heliospheric imager CME detection, but the SMEI data are too noisy for the tool to be completely automated.

  11. RADIAL AND AZIMUTHAL OSCILLATIONS OF HALO CORONAL MASS EJECTIONS IN THE SUN

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Harim; Moon, Y.-J.; Nakariakov, V. M., E-mail: harim@khu.ac.kr, E-mail: moonyj@khu.ac.kr, E-mail: V.Nakariakov@warwick.ac.uk [School of Space Research, Kyung Hee University, Yongin 446-701 (Korea, Republic of)

    2015-04-10

    We present the first observational detection of radial and azimuthal oscillations in full halo coronal mass ejections (HCMEs). We analyze nine HCMEs well-observed by the Large Angle and Spectrometric Coronagraph (LASCO) from 2011 February to June. Using the LASCO C3 running difference images, we estimated the instantaneous apparent speeds of the HCMEs in different radial directions from the solar disk center. We find that the development of all these HCMEs is accompanied by quasi-periodic variations of the instantaneous radial velocity with the periods ranging from 24 to 48 minutes. The amplitudes of the instant speed variations reach about a half of the projected speeds. The amplitudes are found to anti-correlate with the periods and correlate with the HCME speed, indicating the nonlinear nature of the process. The oscillations have a clear azimuthal structure in the heliocentric polar coordinate system. The oscillations in seven events are found to be associated with distinct azimuthal wave modes with the azimuthal wave number m = 1 for six events and m = 2 for one event. The polarization of the oscillations in these seven HCMEs is broadly consistent with those of their position angles with the mean difference of 43°. The oscillations may be connected with natural oscillations of the plasmoids around a dynamical equilibrium, or self-oscillatory processes, e.g., the periodic shedding of Alfvénic vortices. Our results indicate the need for an advanced theory of oscillatory processes in coronal mass ejections.

  12. Interplanetary Coronal Mass Ejection (ICME) and Cosmic rays transmission during Forbush decreases

    Science.gov (United States)

    Okpala, K. C.

    2015-12-01

    Forbush decrease (FD) is an observed reduction in galactic cosmic ray (GCR) intensity as measured by ground neutron monitors often associated energetic events on the Sun such as coronal mass ejections (CME). FD is associated with increased activity of the sun as reflected in the size of the interplanetary coronal mass ejections passing around the Earth and the corotating regions in the Heliosphere. Since the interplanetary anisotropy evolves itself during a geomagnetic storm in addition to the reconfiguration of external magnetospheric currents, it is expected that changes in transmissivity of cosmic rays of galactic origin will occur during Geomagnetic storms. In this study we examine sixty-three (63) FD events and associated geomagnetic storms over the last three solar cycles from 1970 to 2013. The negative peaks of the FDs and the Dst coincided for most of the events (~70%). There was good correlation (>0.67) between the FDs and Dst. Signatures of influence of external magnetospheric currents on the count rates of the neutron monitors stations during periods of Forbush decreases (FDs) is provided. This evidence is observed as sudden increases in the count rates during the main phase of simultaneous FD. The magnitude of the sudden rise in the count rates of Neutron monitors and peak dst correlated well (>0.50) both for high latitude and mid latitude stations.

  13. Are We Observing Coronal Mass Ejections in OH/IR AGB Stars?

    Science.gov (United States)

    Heiles, Carl

    2017-05-01

    Solar Coronal Mass Ejections (CMEs) are magnetic electron clouds that are violently ejected by the same magnetic reconnection events that produce Solar flares. CMEs are the major driving source of the hazardous space weather environments near the Earth. In exoplanet systems, the equivalent of Solar wind and CMEs can affect a planet's atmosphere, and in extreme cases can erode it, as probably happened with Mars, or disrupt the cosmic-ray shielding aspect of the planet's magnetic field.We (Jensen et al. 2013SoPh..285...83J, 2016SoPh..291..465J) have developed a new way to observe the electron column density and magnetic field of CMEs, namely to measure the frequency change and Faraday rotation of a spacecraft downlink carrier produced by propagation effects in the plasma. Surprisingly, this can work on other stars if they have the equivalent of the spacecraft carrier, as do OH/IR stars.OH/IR stars are Asymptotic Giant Branch (AGB) stars, which are red giant stars burning He in their final stages of stellar evolution. They have highly convective surfaces and large mass-ejection rates in the form of expanding dense shells of molecular gas and obscuring dust, which were ejected from the star by chaotic turbulent motions and then accelerated by radiation pressure. OH masers reside in these shells, pumped by the IR emission from the dust. The OH masers on the far side of the star (i.e., the positive-velocity masers) are the surrogate for the Solar-case spacecraft signal.The big question: Can we see CMEs in OH/IR stars? We have observed six OH/IR stars with the Arecibo Observatory for a total of about 150 hours over the past 1.5 years. We see changes in OH maser frequency and in the position angle of linear polarization. Both can be produced by electron clouds moving across the line of sight. We will present statistical summaries of the variability and interpret them in terms of CME models.

  14. Mass-radius relationships in icy satellites

    Science.gov (United States)

    Lupo, M. J.; Lewis, J. S.

    1979-01-01

    Using published laboratory data for H2O ice, a modeling technique was developed by which the bulk density, density and temperature profile, rotational moment of inertia, central pressure, and location of the rock-ice interface can all be obtained as a function of the radius, the heliocentric distance, and the silicate composition. Models of the interiors of Callisto, Ganymede, Europa, Rhea, and Titan are given, consistent with present mass and radius data. The radius and mass of spheres of ice under self-gravitation for two different temperature classes are given (103 and 77 deg K). Measurements of mass, radius and I/MR2 by spacecraft can be interpreted by this model to yield substantial information about the internal structure and the ice/rock ratio of the icy satellites of Jupiter and Saturn.

  15. On Understanding the Nature of Collision of Coronal Mass Ejections Observed by \\textit{STEREO}

    CERN Document Server

    Mishra, Wageesh; Srivastava, Nandita

    2016-01-01

    Our study attempts to understand the collision characteristics of two coronal mass ejections (CMEs) launched successively from the Sun on 2013 October 25. The estimated kinematics, from three-dimensional (3D) reconstruction techniques applied to observations of CMEs by SECCHI/Coronagraphic (COR) and Heliospheric Imagers (HIs), reveal their collision around 37 $R_\\sun$ from the Sun. In the analysis, we take into account the propagation and expansion speeds, impact direction, angular size as well as the masses of the CMEs. These parameters are derived from imaging observations, but may suffer from large uncertainties. Therefore, by adopting head-on as well as oblique collision scenarios, we have quantified the range of uncertainties involved in the calculation of the coefficient of restitution for expanding magnetized plasmoids. Our study shows that the comparatively large expansion speed of the following CME than that of the preceding CME, results in a higher probability of super-elastic collision. We also inf...

  16. Deflections of Fast Coronal Mass Ejections and the Properties of Associated Solar Energetic Particle Events

    Science.gov (United States)

    Kahler, S. W.; Akiyama, S.; Gopalswamy, N.

    2012-01-01

    The onset times and peak intensities of solar energetic particle (SEP) events at Earth have long been thought to be influenced by the open magnetic fields of coronal holes (CHs). The original idea was that a CH lying between the solar SEP source region and the magnetic footpoint of the 1 AU observer would result in a delay in onset and/or a decrease in the peak intensity of that SEP event. Recently, Gopalswamy et al. showed that CHs near coronal mass ejection (CME) source regions can deflect fast CMEs from their expected trajectories in space, explaining the appearance of driverless shocks at 1 AU from CMEs ejected near solar central meridian (CM). This suggests that SEP events originating in CME-driven shocks may show variations attributable to CH deflections of the CME trajectories. Here, we use a CH magnetic force parameter to examine possible effects of CHs on the timing and intensities of 41 observed gradual E approx 20 MeV SEP events with CME source regions within 20 deg. of CM. We find no systematic CH effects on SEP event intensity profiles. Furthermore, we find no correlation between the CME leading-edge measured position angles and SEP event properties, suggesting that the widths of CME-driven shock sources of the SEPs are much larger than the CMEs. Independently of the SEP event properties, we do find evidence for significant CME deflections by CH fields in these events

  17. OBSERVATION OF HEATING BY FLARE-ACCELERATED ELECTRONS IN A SOLAR CORONAL MASS EJECTION

    Energy Technology Data Exchange (ETDEWEB)

    Glesener, Lindsay; Bain, Hazel M. [Space Sciences Laboratory, University of California at Berkeley, 7 Gauss Way, Berkeley, CA 94720 (United States); Krucker, Säm [Also at Institute of 4-D Technologies, School of Engineering, University of Applied Sciences Northwestern Switzerland, 5210 Windisch, Switzerland. (Switzerland); Lin, Robert P., E-mail: glesener@ssl.berkeley.edu [Also at Physics Department, University of California at Berkeley, Berkeley, CA 94720, USA. (United States)

    2013-12-20

    We report a Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) observation of flare-accelerated electrons in the core of a coronal mass ejection (CME) and examine their role in heating the CME. Previous CME observations have revealed remarkably high thermal energies that can far surpass the CME's kinetic energy. A joint observation by RHESSI and the Atmospheric Imaging Assembly of a partly occulted flare on 2010 November 3 allows us to test the hypothesis that this excess energy is collisionally deposited by flare-accelerated electrons. Extreme ultraviolet (EUV) images show an ejection forming the CME core and sheath, with isothermal multifilter analysis revealing temperatures of ∼11 MK in the core. RHESSI images reveal a large (∼100 × 50 arcsec{sup 2}) hard X-ray (HXR) source matching the location, shape, and evolution of the EUV plasma, indicating that the emerging CME is filled with flare-accelerated electrons. The time derivative of the EUV emission matches the HXR light curve (similar to the Neupert effect observed in soft and HXR time profiles), directly linking the CME temperature increase with the nonthermal electron energy loss, while HXR spectroscopy demonstrates that the nonthermal electrons contain enough energy to heat the CME. This is the most direct observation to date of flare-accelerated electrons heating a CME, emphasizing the close relationship of the two in solar eruptive events.

  18. The spectroscopic imprint of the pre-eruptive configuration resulting into two major coronal mass ejections

    CERN Document Server

    Syntelis, Petros; Patsourakos, Spiros; Tsinganos, Kanaris

    2016-01-01

    We present a spectroscopic analysis of the pre-eruptive configuration of active region NOAA 11429, prior to two very fast coronal mass ejections (CMEs) on March 7, 2012 that are associated with this active region. We study the thermal components and the dynamics associated with the ejected flux ropes. Using differential emission measure (DEM) analysis of Hinode/EIS and SDO/AIA observations, we identify the emission components of both the flux rope and the host active region. We then follow the time evolution of the flux rope emission components by using AIA observations. The plasma density and the Doppler and non-thermal velocities associated with the flux ropes are also calculated from the EIS data. The eastern and western parts of the active region, in which the two different fast CMEs originated during two X-class flares, were studied separately. In both regions we identified an emission component in the temperature range of $\\log T=6.8 - 7.1$ associated with the presence of flux ropes. The time evolution ...

  19. Statistical study of coronal mass ejection source locations: Understanding CMEs viewed in coronagraphs

    Science.gov (United States)

    Wang, Yuming; Chen, Caixia; Gui, Bin; Shen, Chenglong; Ye, Pinzhong; Wang, S.

    2011-04-01

    How to properly understand coronal mass ejections (CMEs) viewed in white light coronagraphs is crucial to many relative researches in solar and space physics. The issue is now particularly addressed in this paper through studying the source locations of all the 1078 Large Angle and Spectrometric Coronagraph (LASCO) CMEs listed in Coordinated Data Analysis Workshop (CDAW) CME catalog during 1997-1998 and their correlation with CMEs' apparent parameters. By manually checking LASCO and Extreme Ultraviolet Imaging Telescope (EIT) movies of these CMEs, we find that, except 231 CMEs whose source locations cannot be identified due to poor data, there are 288 CMEs with location identified on the frontside solar disk, 234 CMEs appearing above solar limb, and 325 CMEs without evident eruptive signatures in the field of view of EIT. On the basis of the statistical results of CMEs' source locations, there are four physical issues: (1) the missing rate of CMEs by SOHO LASCO and EIT, (2) the mass of CMEs, (3) the causes of halo CMEs, and (4) the deflections of CMEs in the corona, are exhaustively analyzed. It is found that (1) about 32% frontside CMEs cannot be recognized by SOHO, (2) the brightness of a CME at any heliocentric distance is roughly positively correlated with its speed, and the CME mass derived from the brightness is probably overestimated, (3) both projection effect and violent eruption are the major causes of halo CMEs, and especially for limb halo CMEs the latter is the primary one, and (4) most CMEs deflected toward equator near the solar minimum; these deflections can be classified into three types: the asymmetrical expansion, the nonradial ejection, and the deflected propagation.

  20. Composition Structure of Interplanetary Coronal Mass Ejections From Multispacecraft Observations, Modeling, and Comparison with Numerical Simulations

    CERN Document Server

    Reinard, Alysha; Mulligan, Tamitha

    2012-01-01

    We present an analysis of the ionic composition of iron for two interplanetary coronal mass ejections observed in May 21-23 2007 by the ACE and STEREO spacecraft in the context of the magnetic structure of the ejecta flux rope, sheath region, and surrounding solar wind flow. This analysis is made possible due to recent advances in multispacecraft data interpolation, reconstruction, and visualization as well as results from recent modeling of ionic charge states in MHD simulations of magnetic breakout and flux cancellation CME initiation. We use these advances to interpret specific features of the ICME plasma composition resulting from the magnetic topology and evolution of the CME. We find that in both the data and our MHD simulations, the flux ropes centers are relatively cool, while charge state enhancements surround and trail the flux ropes. The magnetic orientation of the ICMEs are suggestive of magnetic breakout-like reconnection during the eruption process which could explain the spatial location of the...

  1. Observing the Unobservable: identification and Characterization of Stealth Coronal Mass Ejections

    Science.gov (United States)

    D'Huys, Elke

    2016-01-01

    In this doctoral thesis we study stealth CMEs: solar coronal mass ejections that are clearly observed in coronagraph data but do not show significant low-coronal or on-disk signatures of eruption. This lack of coronal signatures makes it challenging to determine their source region and predict their trajectory throughout interplanetary space. Combining PROBA2/SWAP data with that of other instruments, we identify 40 such events and investigate their properties both observationally and statistically. We find that our sample size is insufficient to determine the scaling law for the CME angular width reliably. We therefore analyze in general what the effect is of a limited sample size on the estimation of a power law parameter. Armed with this knowledge, we return to our sample of stealth CMEs, re-analyze the power law for their angular widths and compare the results to the power law found for normal CMEs.

  2. Observing the Unobservable: Identification and Characterisation of Stealth Coronal Mass Ejections

    Science.gov (United States)

    D'Huys, Elke; Seaton, Daniel B.; Poedts, Stefaan; Berghmans, David

    2016-05-01

    I will present my doctoral thesis research on stealth CMEs: solar coronal mass ejections that are clearly observed in coronagraph data but do not show significant low-coronal or on-disk signatures of eruption. This lack of coronal signatures makes it challenging to determine their source region and predict their trajectory throughout interplanetary space. We identified 40 such events and investigated their properties both observationally and statistically. We found that our sample size was insufficient to determine the scaling law for the CME angular width reliably. We therefore analyzed in general what the effect is of a limited sample size on the estimation of a power law parameter. Armed with this knowledge, we returned to our sample of stealth CMEs, re-analyzed the power law for their angular widths and compared the results to the power law found for normal CMEs.

  3. Anomalous Expansion of Coronal Mass Ejections During Solar Cycle 24 and Its Space Weather Implications

    Science.gov (United States)

    Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji; Xie, Hong; Makela, Pertti; Michalek, Grzegorz

    2014-01-01

    The familiar correlation between the speed and angular width of coronal mass ejections (CMEs) is also found in solar cycle 24, but the regression line has a larger slope: for a given CME speed, cycle 24 CMEs are significantly wider than those in cycle 23. The slope change indicates a significant change in the physical state of the heliosphere, due to the weak solar activity. The total pressure in the heliosphere (magnetic + plasma) is reduced by approximately 40%, which leads to the anomalous expansion of CMEs explaining the increased slope. The excess CME expansion contributes to the diminished effectiveness of CMEs in producing magnetic storms during cycle 24, both because the magnetic content of the CMEs is diluted and also because of the weaker ambient fields. The reduced magnetic field in the heliosphere may contribute to the lack of solar energetic particles accelerated to very high energies during this cycle.

  4. Evolution of Magnetic Helicity During Eruptive Flares and Coronal Mass Ejections

    CERN Document Server

    Priest, Eric; Janvier, Miho

    2016-01-01

    During eruptive solar flares and coronal mass ejections, a non-pot{\\-}ential magnetic arcade with much excess magnetic energy goes unstable and reconnects. It produces a twisted erupting flux rope and leaves behind a sheared arcade of hot coronal loops. We suggest that: the twist of the erupting flux rope can be determined from conservation of magnetic flux and magnetic helicity and equipartition of magnetic helicity. It depends on the geometry of the initial pre-eruptive structure. Two cases are considered, in the first of which a flux rope is not present initially but is created during the eruption by the reconnection. In the second case, a flux rope is present under the arcade in the pre-eruptive state, and the effect of the eruption and reconnection is to add an amount of magnetic helicity that depends on the fluxes of the rope and arcade and the geometry.

  5. Coronal Mass Ejections Observed at the Total Solar Eclipse on 13 November 2012

    CERN Document Server

    Hanaoka, Yoichiro; Ohgoe, Osamu; Sakai, Yoshiaki; Shiota, Kazuo

    2013-01-01

    We carried out white-light observations of the total solar eclipse on 13 November 2012 at two sites, where the totality occurred 35 minutes apart. We caught an ongoing coronal mass ejection (CME) and a pre-CME loop structure just before the eruption in the height range between 1-2 R_sun. The source region of CMEs was revealed to be in this height range, where the material and the magnetic field of CMEs were located before the eruption. This height range includes the gap between the extreme ultraviolet observations of the low corona and the spaceborne white-light observations of the high corona, but the eclipse observation shows that this height range is essentially important to study the CME initiation. The eclipse observation is basically just a snapshot of CMEs, but it indicates that future continuous observations of CMEs within this height range are promising.

  6. First Simultaneous Views of the Axial and Lateral Perspectives of a Coronal Mass Ejection

    CERN Document Server

    Cabello, I; Balmaceda, L; Dohmen, I

    2016-01-01

    The different appearances exhibited by coronal mass ejections (CMEs) are believed to be in part the result of different orientations of their main axis of symmetry, consistent with a flux-rope configuration. There are observational reports of CMEs seen along their main axis (axial perspective) and perpendicular to it (lateral perspective), but no simultaneous observations of both perspectives from the same CME have been reported to date. The stereoscopic views of the telescopes onboard the $Solar$-$Terrestrial$ $Relations$ $Observatory$ (STEREO) twin spacecraft, in combination with the views from the $Solar$ $and$ $Heliospheric$ $Observatory$ (SOHO) and the $Solar$ $Dynamics$ $Observatory$ (SDO), allow us to study the axial and lateral perspectives of a CME simultaneously for the first time. In addition, this study shows that the lateral angular extent ($L$) increases linearly with time, while the angular extent of the axial perspective ($D$) presents this behavior only from the low corona to $\\approx\\,$5 $R_...

  7. Statistical Evidence for Contributions of Flares and Coronal Mass Ejections to Major Solar Energetic Particle Events

    CERN Document Server

    Trottet, G; Klein, K -L; de Wit, T Dudok; Miteva, R

    2014-01-01

    Solar energetic particle (SEP) events are related to flares and coronal mass ejections (CMEs). This work is a new investigation of statistical relationships between SEP peak intensities - deka-MeV protons and near-relativistic electrons - and characteristic quantities of the associated solar activity. We consider the speed of the CME and quantities describing the flare-related energy release: peak flux and fluence of soft X-ray (SXR) emission, fluence of microwave emission. The sample comprises 38 SEP events associated with strong SXR bursts (classes M and X) in the western solar hemisphere between 1997 and 2006, and where the flare-related particle acceleration is accompanied by radio bursts indicating electron escape to the interplanetary space. The main distinction of the present statistical analysis from earlier work is that besides the classical Pearson correlation coefficient the partial correlation coefficients are calculated in order to disentangle the effects of correlations between the solar paramet...

  8. On the enhanced coronal mass ejection detection rate since the solar cycle 23 polar field reversal

    CERN Document Server

    Petrie, Gordon

    2015-01-01

    Coronal mass ejections (CMEs) with angular width $> 30^{\\circ}$ have been observed to occur at a higher rate during solar cycle 24 compared to cycle 23, per sunspot number. This result is supported by data from three independent databases constructed using Large Angle and Spectrometric Coronagraph Experiment (LASCO) coronagraph images, two employing automated detection techniques and one compiled manually by human observers. According to the two databases that cover a larger field of view, the enhanced CME rate actually began shortly after the cycle 23 polar field reversal, in 2004, when the polar fields returned with a 40\\% reduction in strength and interplanetary radial magnetic field became $\\approx 30\\%$ weaker. This result is consistent with the link between anomalous CME expansion and heliospheric total pressure decrease recently reported by Gopalswamy et al.

  9. MAVEN observations of the response of Mars to an interplanetary coronal mass ejection.

    Science.gov (United States)

    Jakosky, B M; Grebowsky, J M; Luhmann, J G; Connerney, J; Eparvier, F; Ergun, R; Halekas, J; Larson, D; Mahaffy, P; McFadden, J; Mitchell, D F; Schneider, N; Zurek, R; Bougher, S; Brain, D; Ma, Y J; Mazelle, C; Andersson, L; Andrews, D; Baird, D; Baker, D; Bell, J M; Benna, M; Chaffin, M; Chamberlin, P; Chaufray, Y-Y; Clarke, J; Collinson, G; Combi, M; Crary, F; Cravens, T; Crismani, M; Curry, S; Curtis, D; Deighan, J; Delory, G; Dewey, R; DiBraccio, G; Dong, C; Dong, Y; Dunn, P; Elrod, M; England, S; Eriksson, A; Espley, J; Evans, S; Fang, X; Fillingim, M; Fortier, K; Fowler, C M; Fox, J; Gröller, H; Guzewich, S; Hara, T; Harada, Y; Holsclaw, G; Jain, S K; Jolitz, R; Leblanc, F; Lee, C O; Lee, Y; Lefevre, F; Lillis, R; Livi, R; Lo, D; Mayyasi, M; McClintock, W; McEnulty, T; Modolo, R; Montmessin, F; Morooka, M; Nagy, A; Olsen, K; Peterson, W; Rahmati, A; Ruhunusiri, S; Russell, C T; Sakai, S; Sauvaud, J-A; Seki, K; Steckiewicz, M; Stevens, M; Stewart, A I F; Stiepen, A; Stone, S; Tenishev, V; Thiemann, E; Tolson, R; Toublanc, D; Vogt, M; Weber, T; Withers, P; Woods, T; Yelle, R

    2015-11-01

    Coupling between the lower and upper atmosphere, combined with loss of gas from the upper atmosphere to space, likely contributed to the thin, cold, dry atmosphere of modern Mars. To help understand ongoing ion loss to space, the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft made comprehensive measurements of the Mars upper atmosphere, ionosphere, and interactions with the Sun and solar wind during an interplanetary coronal mass ejection impact in March 2015. Responses include changes in the bow shock and magnetosheath, formation of widespread diffuse aurora, and enhancement of pick-up ions. Observations and models both show an enhancement in escape rate of ions to space during the event. Ion loss during solar events early in Mars history may have been a major contributor to the long-term evolution of the Mars atmosphere.

  10. Automated Detection of Coronal Mass Ejections in STEREO Heliospheric Imager data

    CERN Document Server

    Pant, V; Rodriguez, L; Mierla, M; Banerjee, D; Davies, J A

    2016-01-01

    We have performed, for the first time, the successful automated detection of Coronal Mass Ejections (CMEs) in data from the inner heliospheric imager (HI-1) cameras on the STEREO A spacecraft. Detection of CMEs is done in time-height maps based on the application of the Hough transform, using a modified version of the CACTus software package, conventionally applied to coronagraph data. In this paper we describe the method of detection. We present the result of the application of the technique to a few CMEs that are well detected in the HI-1 imagery, and compare these results with those based on manual cataloging methodologies. We discuss in detail the advantages and disadvantages of this method.

  11. Evidence for shock generation in the solar corona in the absence of coronal mass ejections

    Science.gov (United States)

    Eselevich, V. G.; Eselevich, M. V.; Zimovets, I. V.; Sharykin, I. N.

    2017-09-01

    The solar event SOL2012-10-23T03:13, which was associated with a X1.8 flare without an accompanying coronal mass ejection (CME) and with a Type II radio burst, is analyzed. A method for constructing the spatial and temporal profiles of the difference brightness detected in the AIA/SDOUVand EUV channels is used together with the analysis of the Type II radio burst. The formation and propagation of a region of compression preceded by a collisional shock detected at distances R shock could be due to a transient (impulsive) action exerted on the surrounding plasma by an eruptive, high-temperature magnetic rope. The initial instability and eruption of this rope could be initiated by emerging magnetic flux, and its heating from magnetic reconnection. The cessation of the eruption of the rope could result from its interaction with surrounding magnetic structures (coronal loops).

  12. An analysis of interplanetary solar radio emissions associated with a coronal mass ejection

    CERN Document Server

    Krupar, Vratislav; Kruparova, Oksana; Santolik, Ondrej; Soucek, Jan; Magdalenic, Jasmina; Vourlidas, Angelos; Maksimovic, Milan; Bothmer, Volker; Mrotzek, Niclas; Pluta, Adam; Barnes, David; Davies, Jackie; Oliveros, Juan Carlos Martinez; Bale, Stuart

    2016-01-01

    Coronal mass ejections (CMEs) are large-scale eruptions of magnetized plasma that may cause severe geomagnetic storms if Earth-directed. Here we report a rare instance with comprehensive in situ and remote sensing observa- tions of a CME combining white-light, radio, and plasma measurements from four different vantage points. For the first time, we have successfully applied a radio direction-finding technique to an interplanetary type II burst detected by two identical widely separated radio receivers. The derived locations of the type II and type III bursts are in general agreement with the white light CME recon- struction. We find that the radio emission arises from the flanks of the CME, and are most likely associated with the CME-driven shock. Our work demon- strates the complementarity between radio triangulation and 3D reconstruction techniques for space weather applications.

  13. Investigations of the sensitivity of a coronal mass ejection model (ENLIL) to solar input parameters

    DEFF Research Database (Denmark)

    Falkenberg, Thea Vilstrup; Vršnak, B.; Taktakishvili, A.;

    2010-01-01

    investigate the parameter space of the ENLILv2.5b model using the CME event of 25 July 2004. ENLIL is a time‐dependent 3‐D MHD model that can simulate the propagation of cone‐shaped interplanetary coronal mass ejections (ICMEs) through the solar system. Excepting the cone parameters (radius, position...... (CMEs), but in order to predict the caused effects, we need to be able to model their propagation from their origin in the solar corona to the point of interest, e.g., Earth. Many such models exist, but to understand the models in detail we must understand the primary input parameters. Here we......, and initial velocity), all remaining parameters are varied, resulting in more than 20 runs investigated here. The output parameters considered are velocity, density, magnetic field strength, and temperature. We find that the largest effects on the model output are the input parameters of upper limit...

  14. Modeling Coronal Mass Ejections with the Multi-Scale Fluid-Kinetic Simulation Suite

    Science.gov (United States)

    Pogorelov, N. V.; Borovikov, S. N.; Kryukov, I. A.; Wu, S. T.; Yalim, M. S.; Colella, P. C.; Van Straalen, B.

    2017-05-01

    The solar eruptions and interacting solar wind streams are key drivers of geomagnetic storms and various related space weather disturbances that may have hazardous effects on the space-borne and ground-based technological systems as well as on human health. Coronal mass ejections (CMEs) and their interplanetary counterparts, interplanetary CMEs (ICMEs), belong to the strongest disturbances and therefore are of great importance for the space weather predictions. In this paper we show a few examples of how adaptive mesh refinement makes it possible to resolve the complex CME structure and its evolution in time while a CME propagates from the inner boundary to Earth. Simulations are performed with the Multi-Scale Fluid-Kinetic Simulation Suite (MS-FLUKSS).

  15. Associations of decimetric type Ⅲ bursts with coronal mass ejections and Hα flares

    Institute of Scientific and Technical Information of China (English)

    Yuan Ma; De-Yu Wang; Jun Lin; Shuo Dai; Xue-Fei Zhang

    2010-01-01

    We present a statistical study of decimetric type Ⅲ radio bursts,coronal mass ejections(CMEs),and Hα flares observed in the period from July 2000 to March2005.In total,we investigated 395 decimetric type Ⅲ radio burst events,21% of which showed apparent correlation to CMEs that were associated with Hα flares.We noticed that the Hα flares which were strongly associated with CMEs were gradual events,and82% of them took place before CMEs appeared in the field of view of LASCO C2;that most of the CME-associated radio bursts started in the frequency range around750 MHz with a frequency drifting rate of several hundred MHz s-1,of which both positive and negative ones were recognized; and that the correlation of type Ⅲ radio bursts to CMEs without associated flares is fairly vague,less than 9%.

  16. Coronal Mass Ejections propagating towards Mars and the consequent Forbush decreases

    Science.gov (United States)

    Guo, Jingnan; Banerjee, Dipankar; Wimmer-Schweingruber, Robert; Pant, Vaibhav

    2016-07-01

    In order to study the impact of interplanetary coronal mass ejections (ICMEs) on planet Mars, we explore the CME lists observed by coronagraphic images at Earth location heading towards Mars, i.e., the separation of the two planets are about 90 degrees. This is realized by the application of CACTus which detects CMEs in image sequences from LASCO/SOHO at Earth's L1 location. The properties of these ICMEs and their propagation towards Mars are modeled and compared with in-situ observations of Forbush decreases at the surface of Mars by the Radiation Assessment Detector (RAD) onboard of Mars Science Laboratory (MSL). This helps us to understand the contributions of ICMEs towards the onset of Forbush decreases at Mars as well as the evolution and propagation ICMEs in the inter-planetary space.

  17. Investigating the Kinematics of Coronal Mass Ejections with the Automated CORIMP Catalog

    CERN Document Server

    Byrne, Jason P

    2015-01-01

    Studying coronal mass ejections (CMEs) in coronagraph data can be challenging due to their diffuse structure and transient nature, compounded by the variations in their dynamics, morphology, and frequency of occurrence. The large amounts of data available from missions like the Solar and Heliospheric Observatory (SOHO) make manual cataloging of CMEs tedious and prone to human error, and so a robust method of detection and analysis is required and often preferred. A new coronal image processing catalog called CORIMP has been developed in an effort to achieve this, through the implementation of a dynamic background separation technique and multiscale edge detection. These algorithms together isolate and characterise CME structure in the field-of-view of the Large Angle Spectrometric Coronagraph (LASCO) onboard SOHO. CORIMP also applies a Savitzky-Golay filter, along with quadratic and linear fits, to the height-time measurements for better revealing the true CME speed and acceleration profiles across the plane-...

  18. Automated Detection of Coronal Mass Ejections in STEREO Heliospheric Imager Data

    Science.gov (United States)

    Pant, V.; Willems, S.; Rodriguez, L.; Mierla, M.; Banerjee, D.; Davies, J. A.

    2016-12-01

    We have performed, for the first time, the successful automated detection of coronal mass ejections (CMEs) in data from the inner heliospheric imager (HI-1) cameras on the STEREO-A spacecraft. Detection of CMEs is done in time-height maps based on the application of the Hough transform, using a modified version of the CACTus software package, conventionally applied to coronagraph data. In this paper, we describe the method of detection. We present the results of the application of the technique to a few CMEs, which are well detected in the HI-1 imagery, and compare these results with those based on manual-cataloging methodologies. We discuss, in detail, the advantages and disadvantages of this method.

  19. Coronal Mass Ejections Near the Sun and in the Interplanetary Medium

    Science.gov (United States)

    Gopalswamy, Nat

    2012-01-01

    Coronal mass ejections (CMEs) are the most energetic phenomenon in the heliosphere. During solar eruptions, the released energy flows out from the Sun in the form of magnetized plasma and electromagnetic radiation. The electromagnetic radiation suddenly increases the ionization content of the ionosphere, thus impacting communication and navigation systems. The plasma clouds can drive shocks that accelerate charged particles to very high energies in the interplanetary space, which pose radiation hazard to astronauts and space systems. The plasma clouds also arrive at Earth in about two days and impact Earth's magnetosphere, producing geomagnetic storms. The magnetic storms result in a number of effects including induced currents that can disrupt power grids, railroads, and underground pipelines. This lecture presents an overview of the origin, propagation, and geospace consequences of CMEs and their interplanetary counterparts.

  20. Coronal Mass Ejections and their Implications for the Corona and Heliosphere

    Science.gov (United States)

    Antiochos, Spiro K.

    2008-01-01

    Coronal mass ejections (CMEs) are the largest and most energetic form of transients that connect the Sun to the heliosphere. They are critically important both for understanding the physical mechanisms of explosive solar activity and for predicting space weather. Furthermore they are an extreme example of how cross-scale coupling can play a critical role in determining the properties of a large-scale dynamical system. In this presentation CME theories are reviewed and the latest results from 3D numerical modeling of CME initiation propagation to the heliosphere are presented. In particular the focus is on the breakout model, but many of the results hold for the flux rope models as well. The implications of these results for understanding heliospheric structure and dynamics and for upcoming space missions will be discussed.

  1. Kinematic and Energetic Properties of the 2012 March 12 Polar Coronal Mass Ejection

    CERN Document Server

    Gopalswamy, N; Akiyama, S

    2015-01-01

    We report on the energetics of the 2012 March 12 polar coronal mass ejection (CME) originating from a southern latitude of ~60o. The polar CME is similar to low-latitude CMEs in almost all respects: three-part morphology, post eruption arcade (PEA), CME and filament kinematics, CME mass and kinetic energy, and the relative thermal energy content of the PEA. From polarized brightness images, we estimate the CME mass, which is close to the average mass of low-latitude CMEs. The CME kinetic energy (3.3x1030 erg) is also typical of the general population of CMEs. From photospheric magnetograms, we estimate the free energy (1.8x1031 erg) in the polar crown source region, which we find is sufficient to power the CME and the PEA. About 19% of the free energy went into the CME kinetic energy. We compute the thermal energy content of the PEA (2.3x1029 erg) and find it to be a small fraction (6.8%) of the CME kinetic energy. This fraction is remarkably similar to that in active region CMEs associated with major flares....

  2. Coronal Mass Ejections and Dimmings: A Comparative Study using MHD Simulations and SDO Observations

    Science.gov (United States)

    Jin, Meng; Cheung, Mark; DeRosa, Marc L.; Nitta, Nariaki; Schrijver, Karel

    2017-08-01

    Solar coronal dimmings have been observed extensively in the past two decades. Due to their close association with coronal mass ejections (CMEs), there is a critical need to improve our understanding of the physical processes that cause dimmings and determine their relationship with CMEs. In this study, we investigate coronal dimmings by combining simulation and observational efforts. By utilizing a data-driven global magnetohydrodynamics model (AWSoM: Alfven-wave Solar Model), we simulate coronal dimmings resulting from different CME energetics and flux rope configurations. We synthesize the emissions of different EUV spectral bands/lines and compare with SDO/AIA and EVE observations. A detailed analysis of simulation and observation data suggests that the “core” dimming is mainly caused by the mass loss from the CME, while the “remote” dimming could have a different origin (e.g., plasma heating). Moreover, the interaction between the erupting flux rope with different orientations and the global solar corona could significantly influence the coronal dimming patterns. Using metrics such as dimming depth, dimming slope, and recovery time, we investigate the relationship between dimmings and CME properties (e.g., CME mass, CME speed) in the simulation. Our result suggests that coronal dimmings encode important information about CMEs. We also discuss how our knowledge about solar coronal dimmings could be extended to the study of stellar CMEs.

  3. Mass and power modeling of communication satellites

    Science.gov (United States)

    Price, Kent M.; Pidgeon, David; Tsao, Alex

    1991-01-01

    Analytic estimating relationships for the mass and power requirements for major satellite subsystems are described. The model for each subsystem is keyed to the performance drivers and system requirements that influence their selection and use. Guidelines are also given for choosing among alternative technologies which accounts for other significant variables such as cost, risk, schedule, operations, heritage, and life requirements. These models are intended for application to first order systems analyses, where resources do not warrant detailed development of a communications system scenario. Given this ground rule, the models are simplified to 'smoothed' representation of reality. Therefore, the user is cautioned that cost, schedule, and risk may be significantly impacted where interpolations are sufficiently different from existing hardware as to warrant development of new devices.

  4. The Heliocentric Distance Where the Deflections and Rotations of Solar Coronal Mass Ejections Occur

    CERN Document Server

    Kay, C

    2015-01-01

    Understanding the trajectory of a coronal mass ejection (CME), including any deflection from a radial path, and the orientation of its magnetic field is essential for space weather predictions. Kay et al. (2015b) developed a model, Forecasting a CME's Altered Trajectory (ForeCAT), of CME deflections and rotation due to magnetic forces, not including the effects of reconnection. ForeCAT is able to reproduce the deflection of observed CMEs (Kay et al. 2015a). The deflecting CMEs tend to show a rapid increase of their angular momentum close to the Sun, followed by little to no increase at farther distances. Here we quantify the distance at which the CME deflection is "determined," which we define as the distance after which the background solar wind has negligible influence on the total deflection. We consider a wide range in CME masses and radial speeds and determine that the deflection and rotation of these CMEs can be well-described by assuming they propagate with constant angular momentum beyond 10 Rs. The a...

  5. Binary orbits as the driver of gamma-ray emission and mass ejection in classical novae

    CERN Document Server

    Chomiuk, Laura; Yang, Jun; O'Brien, T J; Paragi, Zsolt; Mioduszewski, Amy J; Beswick, R J; Cheung, C C; Mukai, Koji; Nelson, Thomas; Ribeiro, Valerio A R M; Rupen, Michael P; Sokoloski, J L; Weston, Jennifer; Zheng, Yong; Bode, Michael F; Eyres, Stewart; Roy, Nirupam; Taylor, Gregory B

    2014-01-01

    Classical novae are the most common astrophysical thermonuclear explosions, occurring on the surfaces of white dwarf stars accreting gas from companions in binary star systems. Novae typically expel ~10^(-4) solar masses of material at velocities exceeding 1,000 kilometres per second. However, the mechanism of mass ejection in novae is poorly understood, and could be dominated by the impulsive flash of thermonuclear energy, prolonged optically thick winds, or binary interaction with the nova envelope. Classical novae are now routinely detected in gigaelectronvolt gamma-ray wavelengths, suggesting that relativistic particles are accelerated by strong shocks in the ejecta. Here we report high-resolution radio imaging of the gamma-ray-emitting nova V959 Mon. We find that its ejecta were shaped by the motion of the binary system: some gas was expelled rapidly along the poles as a wind from the white dwarf, while denser material drifted out along the equatorial plane, propelled by orbital motion. At the interface ...

  6. The Effect on the Lunar Exosphere of a Coroual Mass Ejection Passage

    Science.gov (United States)

    Killen, R. M.; Hurley, D. M.; Farrell, W. M.

    2011-01-01

    Solar wind bombardment onto exposed surfaces in the solar system produces an energetic component to the exospheres about those bodies. The solar wind energy and composition are highly dependent on the origin of the plasma. Using the measured composition of the slow wind, fast wind, solar energetic particle (SEP) population, and coronal mass ejection (CME), broken down into their various components, we have estimated the total sputter yield for each type of solar wind. We show that the heavy ion component, especially the He++ and 0+7 can greatly enhance the total sputter yield during times when the heavy ion population is enhanced. Folding in the flux, we compute the source rate for several species during different types of solar wind. Finally, we use a Monte Carlo model developed to simulate the time-dependent evolution of the lunar exosphere to study the sputtering component of the exosphere under the influence of a CME passage. We simulate the background exosphere of Na, K, Ca, and Mg. Simulations indicate that sputtering increases the mass of those constituents in the exosphere a few to a few tens times the background values. The escalation of atmospheric density occurs within an hour of onset The decrease in atmospheric density after the CME passage is also rapid, although takes longer than the increase, Sputtered neutral particles have a high probability of escaping the moon,by both Jeans escape and photo ionization. Density and spatial distribution of the exosphere can be tested with the LADEE mission.

  7. Automated detection of coronal mass ejections in three-dimensions using multi-viewpoint observations

    Science.gov (United States)

    Hutton, J.; Morgan, H.

    2017-03-01

    A new, automated method of detecting coronal mass ejections (CMEs) in three dimensions for the LASCO C2 and STEREO COR2 coronagraphs is presented. By triangulating isolated CME signal from the three coronagraphs over a sliding window of five hours, the most likely region through which CMEs pass at 5 R⊙ is identified. The centre and size of the region gives the most likely direction of propagation and approximate angular extent. The Automated CME Triangulation (ACT) method is tested extensively using a series of synthetic CME images created using a wireframe flux rope density model, and on a sample of real coronagraph data; including halo CMEs. The accuracy of the angular difference (σ) between the detection and true input of the synthetic CMEs is σ = 7.14°, and remains acceptable for a broad range of CME positions relative to the observer, the relative separation of the three observers and even through the loss of one coronagraph. For real data, the method gives results that compare well with the distribution of low coronal sources and results from another instrument and technique made further from the Sun. The true three dimension (3D)-corrected kinematics and mass/density are discussed. The results of the new method will be incorporated into the CORIMP database in the near future, enabling improved space weather diagnostics and forecasting.

  8. THE HELIOCENTRIC DISTANCE WHERE THE DEFLECTIONS AND ROTATIONS OF SOLAR CORONAL MASS EJECTIONS OCCUR

    Energy Technology Data Exchange (ETDEWEB)

    Kay, C.; Opher, M., E-mail: ckay@bu.edu [Astronomy Department, Boston University, Boston, MA 02215 (United States)

    2015-10-01

    Understanding the trajectory of a coronal mass ejection (CME), including any deflection from a radial path, and the orientation of its magnetic field is essential for space weather predictions. Kay et al. developed a model, Forecasting a CME’s Altered Trajectory (ForeCAT), of CME deflections and rotation due to magnetic forces, not including the effects of reconnection. ForeCAT is able to reproduce the deflection of observed CMEs. The deflecting CMEs tend to show a rapid increase of their angular momentum close to the Sun, followed by little to no increase at farther distances. Here we quantify the distance at which the CME deflection is “determined,” which we define as the distance after which the background solar wind has negligible influence on the total deflection. We consider a wide range in CME masses and radial speeds and determine that the deflection and rotation of these CMEs can be well-described by assuming they propagate with constant angular momentum beyond 10 R{sub ⊙}. The assumption of constant angular momentum beyond 10 R{sub ⊙} yields underestimates of the total deflection at 1 AU of only 1%–5% and underestimates of the rotation of 10%. Since the deflection from magnetic forces is determined by 10 R{sub ⊙}, non-magnetic forces must be responsible for any observed interplanetary deflections or rotations where the CME has increasing angular momentum.

  9. Automated Detection of coronal mass ejections in three-dimensions using multi-viewpoint observations

    Science.gov (United States)

    Hutton, Joseph; Morgan, Huw

    2016-10-01

    A new, automated method of detecting Solar Wind transients such as Coronal Mass Ejections (CMEs) in three dimensions for the LASCO C2 and STEREO COR2 coronagraphs is presented. By triangulating isolated CME signal from the three coronagraphs over a sliding window of five hours, the most likely region through which CMEs pass at 5 solar radii is identified. The centre and size of the region gives the most likely direction of propagation and angular extent. The Automated CME Triangulation (ACT) method is tested extensively using a series of synthetic CME images created using a flux rope density model, and on a sample of real coronagraph data; including Halo CMEs. The accuracy of the detection remains acceptable regardless of CME position relative to the observer, the relative separation of the three observers, and even through the loss of one coronagraph. By comparing the detection results with the input parameters of the synthetic CMEs, and the low coronal sources of the real CMEs, it is found that the detection is on average accurate to within 7.14 degrees. All current CME catalogues (CDAW, CACTus, SEEDS, ARTEMIS and CORIMP) rely on plane-of-sky measurements for key parameters such as height and velocity. Estimating the true geometry using the new method gains considerable accuracy for kinematics and mass/density. The results of the new method will be incorporated into the CORIMP database in the near future, enabling improved space weather diagnostics and forecasting.

  10. Binary Orbits as the Driver of Gamma-Ray Emission and Mass Ejection in Classical Novae

    Science.gov (United States)

    Chomiuk, Laura; Linford, Justin D.; Yang, Jun; O'Brien, T. J.; Paragi, Zsolt; Mioduszewski, Amy J.; Beswick, R. J.; Cheung, C. C.; Mukai, Koji; Nelson, Thomas

    2014-01-01

    Classical novae are the most common astrophysical thermonuclear explosions, occurring on the surfaces of white dwarf stars accreting gas from companions in binary star systems. Novae typically expel about 10 (sup -4) solar masses of material at velocities exceeding 1,000 kilometers per second.However, the mechanism of mass ejection in novae is poorly understood, and could be dominated by the impulsive flash of thermonuclear energy, prolonged optically thick winds or binary interaction with the nova envelope. Classical novae are now routinely detected at giga-electronvolt gamma-ray wavelengths, suggesting that relativistic particles are accelerated by strong shocks in the ejecta. Here we report high-resolution radio imaging of the gamma-ray-emitting nova V959 Mon. We find that its ejecta were shaped by the motion of the binary system: some gas was expelled rapidly along the poles as a wind from the white dwarf, while denser material drifted out along the equatorial plane, propelled by orbital motion..At the interface between the equatorial and polar regions, we observe synchrotron emission indicative of shocks and relativistic particle acceleration, thereby pinpointing the location of gamma-ray production. Binary shaping of the nova ejecta and associated internal shocks are expected to be widespread among novae, explaining why many novae are gamma-ray emitters.

  11. Natal kicks of stellar mass black holes by asymmetric mass ejection in fallback supernovae

    Science.gov (United States)

    Janka, Hans-Thomas

    2013-09-01

    Integrating trajectories of low-mass X-ray binaries containing black holes within the Galactic potential, Repetto, Davies & Sigurdsson recently showed that the large distances of some systems above the Galactic plane can only be explained if black holes receive appreciable natal kicks. Surprisingly, they found that the distribution of black hole kick velocities (rather than that of the momenta) should be similar to that of neutron stars. Here I argue that this result can be understood if neutron star and black hole kicks are a consequence of large-scale asymmetries created in the supernova ejecta by the explosion mechanism. The corresponding anisotropic gravitational attraction of the asymmetrically expelled matter does not only accelerate new-born neutron stars by the `gravitational tug-boat mechanism', but can also lead to delayed black hole formation by asymmetric fallback of the slowest parts of the initial ejecta on to the transiently existing neutron star, in course of which the momentum of the black hole can grow with the fallback mass. Black hole kick velocities will therefore not be reduced by the ratio of neutron star to black hole mass as would be expected for kicks caused by anisotropic neutrino emission of the nascent neutron star.

  12. Physics of erupting solar flux ropes: Coronal mass ejections (CMEs)—Recent advances in theory and observation

    Science.gov (United States)

    Chen, James

    2017-09-01

    Solar eruptions, observed as flares and coronal mass ejections (CMEs), are the most energetic visible plasma phenomena in the solar system. CMEs are the central component of solar eruptions and are detected as coherent magnetized plasma structures expanding in the solar wind (SW). If they reach the Earth, their magnetic fields can drive strong disturbances in the ionosphere, causing deleterious effects on terrestrial technological systems. The scientific and practical importance of CMEs has led to numerous satellite missions observing the Sun and SW. This has culminated in the ability to continuously observe CMEs expanding from the Sun to 1 AU, where the magnetic fields and plasma parameters of the evolved structures ("ejecta") can be measured in situ. Until recently, the physical mechanisms responsible for eruptions were major unanswered questions in solar and by extension stellar physics. New observations of CME dynamics and associated eruptive phenomena are now providing more stringent constraints on models, and quantitative theory-data comparisons are helping to establish the correct mechanism of solar eruptions, particularly the driving force of CMEs and the evolution of their magnetic fields in three dimensions. Recent work has demonstrated that theoretical results can simultaneously replicate the observed CME position-time data, temporal profiles of associated solar flare soft X-ray emissions, and the magnetic field and plasma parameters of CME ejecta measured at 1 AU. Thus, a new theoretical framework with testable predictions is emerging to model eruptions and the coupling of CME ejecta to geomagnetic disturbances. The key physics in CME dynamics is the Lorentz hoop force acting on toroidal "flux ropes," scalable from tokamaks and similar laboratory plasma structures. The present paper reviews the latest advances in observational and theoretical understanding of CMEs with the emphasis on quantitative comparisons of theory and observation.

  13. The Eruption of a Small-scale Emerging Flux Rope as the Driver of an M-class Flare and of a Coronal Mass Ejection

    Science.gov (United States)

    Yan, X. L.; Jiang, C. W.; Xue, Z. K.; Wang, J. C.; Priest, E. R.; Yang, L. H.; Kong, D. F.; Cao, W. D.; Ji, H. S.

    2017-08-01

    Solar flares and coronal mass ejections are the most powerful explosions in the Sun. They are major sources of potentially destructive space weather conditions. However, the possible causes of their initiation remain controversial. Using high-resolution data observed by the New Solar Telescope of Big Bear Solar Observaotry, supplemented by Solar Dynamics Observatory observations, we present unusual observations of a small-scale emerging flux rope near a large sunspot, whose eruption produced an M-class flare and a coronal mass ejection. The presence of the small-scale flux rope was indicated by static nonlinear force-free field extrapolation as well as data-driven magnetohydrodynamics modeling of the dynamic evolution of the coronal three-dimensional magnetic field. During the emergence of the flux rope, rotation of satellite sunspots at the footpoints of the flux rope was observed. Meanwhile, the Lorentz force, magnetic energy, vertical current, and transverse fields were increasing during this phase. The free energy from the magnetic flux emergence and twisting magnetic fields is sufficient to power the M-class flare. These observations present, for the first time, the complete process, from the emergence of the small-scale flux rope, to the production of solar eruptions.

  14. Quantitative analysis of bidirectional electron fluxes within coronal mass ejections at 1 AU

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, J.L.; Gosling, J.T.; McComas, D.J.; Bame, S.J.; Feldman, W.C.

    1991-01-01

    The solar wind electron heat flux is carried primarily by suprathermal halo'' electrons beamed antisunward along the interplanetary magnetic field (IMF), indicating magnetic connection to the Sun only in one direction. However, electron observations at 1 AU show that counterstreaming halo beams, suggesting closed magnetic structures, prevail within coronal mass ejections (CMEs). These structures might be magnetic tongues'', tied to the Sun at both ends, magnetically detached plasmoids, or complex flux rope structures. Here we present first results of analysis of ISEE-3 observations within 39 CMEs, including the asymmetry between the counterstreaming beams and its control by the IMF orientation, and the variation of the electron distributions as CMEs convect past the spacecraft. We find that some CMEs contain nearly symmetric electron beams, while others are strongly asymmetric, and that the antisunward beam is generally dominant. The more nearly radial the IMF, the greater is the asymmetry between outward and inward beams. We present an example of a distinctive strahl-on-strahl'' distribution, suggesting continued magnetic connection to the corona, in which a narrow antisunward beam is superimposed on a broader beam. Taken as a whole, our results appear to favor a tongue or flux rope scenario rather than a fully detached plasmoid. 4 refs., 6 figs.

  15. Magnetic Properties of Metric Noise Storms Associated with Coronal Mass Ejections

    Institute of Scientific and Technical Information of China (English)

    Ya-Yuan Wen; Jing-Xiu Wang; Yu-Zong Zhang

    2007-01-01

    Using Nan(c)ay Radioheliograph (NRH) imaging observations, combined with SOHO/Michelson Doppler Imager (MDI) magnetogram observations and coronal magnetic field extrapolation, we studied the magnetic nature of metric noise storms that are associated with coronal mass ejections (CMEs). Four events are selected: the events of 2000 July 14,2001 April 26, 2002 August 16 and 2001 March 28. The identified noise storm sources cover or partially cover the active regions (ARs), but the centers of storm sources are offset from the ARs. Using extrapolated magnetic field lines, we find that the noise storm sources trace the boundary between the open and closed field lines. We demonstrate that the disappearance of noise storm source is followed by the appearance of the burst source. The burst sources spread on the solar disk and their distributions correspond to the extent of the CME in LASCO C2 field of view. All the SOHO/Extreme Ultraviolet Imaging Telescope (EIT) dimmings associated with noise storm sources are located at the periphery of noise storms where the magnetic lines of force were previously closed and low-lying. When the closed field becomes partially or fully open, the basic configurations of noise storm sources are changed, then the noise storm sources are no longer observed. These observations provide the information that the variations of noise storms manifest the restructuring or reconfiguring of the coronal magnetic field.

  16. Maximum Coronal Mass Ejection Speed as an Indicator of Solar and Geomagnetic Activities

    CERN Document Server

    Kilcik, A; Abramenko, V; Goode, P R; Gopalswamy, N; Ozguc, A; Rozelot, J P; 10.1088/0004-637X/727/1/44

    2011-01-01

    We investigate the relationship between the monthly averaged maximal speeds of coronal mass ejections (CMEs), international sunspot number (ISSN), and the geomagnetic Dst and Ap indices covering the 1996-2008 time interval (solar cycle 23). Our new findings are as follows. (1) There is a noteworthy relationship between monthly averaged maximum CME speeds and sunspot numbers, Ap and Dst indices. Various peculiarities in the monthly Dst index are correlated better with the fine structures in the CME speed profile than that in the ISSN data. (2) Unlike the sunspot numbers, the CME speed index does not exhibit a double peak maximum. Instead, the CME speed profile peaks during the declining phase of solar cycle 23. Similar to the Ap index, both CME speed and the Dst indices lag behind the sunspot numbers by several months. (3) The CME number shows a double peak similar to that seen in the sunspot numbers. The CME occurrence rate remained very high even near the minimum of the solar cycle 23, when both the sunspot ...

  17. Comparison of Asymmetric and Ice-cream Cone Models for Halo Coronal Mass Ejections

    Science.gov (United States)

    Na, H.; Moon, Y.

    2011-12-01

    Halo coronal mass ejections (HCMEs) are major cause of the geomagnetic storms. To minimize the projection effect by coronagraph observation, several cone models have been suggested: an ice-cream cone model, an asymmetric cone model etc. These models allow us to determine the three dimensional parameters of HCMEs such as radial speed, angular width, and the angle between sky plane and central axis of the cone. In this study, we compare these parameters obtained from different models using 48 well-observed HCMEs from 2001 to 2002. And we obtain the root mean square error (RMS error) between measured projection speeds and calculated projection speeds for both cone models. As a result, we find that the radial speeds obtained from the models are well correlated with each other (R = 0.86), and the correlation coefficient of angular width is 0.6. The correlation coefficient of the angle between sky plane and central axis of the cone is 0.31, which is much smaller than expected. The reason may be due to the fact that the source locations of the asymmetric cone model are distributed near the center, while those of the ice-cream cone model are located in a wide range. The average RMS error of the asymmetric cone model (85.6km/s) is slightly smaller than that of the ice-cream cone model (87.8km/s).

  18. SIMULATIONS OF THE KELVIN–HELMHOLTZ INSTABILITY DRIVEN BY CORONAL MASS EJECTIONS IN THE TURBULENT CORONA

    Energy Technology Data Exchange (ETDEWEB)

    Gómez, Daniel O.; DeLuca, Edward E. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St, Cambridge, MA 02138 (United States); Mininni, Pablo D. [Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Física de Buenos Aires, Ciudad Universitaria, 1428 Buenos Aires (Argentina)

    2016-02-20

    Recent high-resolution Atmospheric Imaging Assembly/Solar Dynamics Observatory images show evidence of the development of the Kelvin–Helmholtz (KH) instability, as coronal mass ejections (CMEs) expand in the ambient corona. A large-scale magnetic field mostly tangential to the interface is inferred, both on the CME and on the background sides. However, the magnetic field component along the shear flow is not strong enough to quench the instability. There is also observational evidence that the ambient corona is in a turbulent regime, and therefore the criteria for the development of the instability are a priori expected to differ from the laminar case. To study the evolution of the KH instability with a turbulent background, we perform three-dimensional simulations of the incompressible magnetohydrodynamic equations. The instability is driven by a velocity profile tangential to the CME–corona interface, which we simulate through a hyperbolic tangent profile. The turbulent background is generated by the application of a stationary stirring force. We compute the instability growth rate for different values of the turbulence intensity, and find that the role of turbulence is to attenuate the growth. The fact that KH instability is observed sets an upper limit on the correlation length of the coronal background turbulence.

  19. Geometric Triangulation of Imaging Observations to Track Coronal Mass Ejections Continuously Out to 1 AU

    CERN Document Server

    Liu, Ying; Luhmann, Janet G; Vourlidas, Angelos; Bale, Stuart D; Lin, Robert P

    2010-01-01

    We describe a geometric triangulation technique, based on time-elongation maps constructed from imaging observations, to track coronal mass ejections (CMEs) continuously in the heliosphere and predict their impact on the Earth. Taking advantage of stereoscopic imaging observations from STEREO, this technique can determine the propagation direction and radial distance of CMEs from their birth in the corona all the way to 1 AU. The efficacy of the method is demonstrated by its application to the 2008 December 12 CME, which manifests as a magnetic cloud (MC) from in situ measurements at the Earth. The predicted arrival time and radial velocity at the Earth are well confirmed by the in situ observations around the MC. Our method reveals non-radial motions and velocity changes of the CME over large distances in the heliosphere. It also associates the flux-rope structure measured in situ with the dark cavity of the CME in imaging observations. Implementation of the technique, which is expected to be a routine possi...

  20. Constraining the Kinematics of Coronal Mass Ejections in the Inner Heliosphere with In Situ Signatures

    CERN Document Server

    Rollett, T; Temmer, M; Veronig, A M; Farrugia, C J; Biernat, H K

    2011-01-01

    We present a new approach to combine remote observations and in situ data by STEREO/HI and Wind, respectively, to derive the kinematics and propagation directions of interplanetary coronal mass ejections (ICMEs). We used two methods, Fixed-{\\phi} (F{\\phi}) and Harmonic Mean (HM), to convert ICME elongations into distance, and constrained the ICME direction such that the ICME time-distance and time-velocity profiles are most consistent with in situ measurements of the arrival time and velocity. The derived time-velocity functions from the Sun to 1 AU for the three events under study (1-6 June 2008, 13-18 February 2009, 3-5 April 2010) do not show strong differences for the two extreme geometrical assumptions of a wide ICME with a circular front (HM) or an ICME of small spatial extent in the ecliptic (F{\\phi}). Due to the geometrical assumptions, HM delivers the propagation direction further away from the observing spacecraft with a mean difference of ~25\\circ.

  1. Propagation of the 2012 March Coronal Mass Ejections from the Sun to Heliopause

    CERN Document Server

    Liu, Ying D; Wang, Chi; Luhmann, Janet G

    2014-01-01

    In 2012 March the Sun exhibited extraordinary activities. In particular, the active region NOAA AR 11429 emitted a series of large coronal mass ejections (CMEs) which were imaged by STEREO as it rotated with the Sun from the east to west. These sustained eruptions are expected to generate a global shell of disturbed material sweeping through the heliosphere. A cluster of shocks and interplanetary CMEs (ICMEs) were observed near the Earth, and are propagated outward from 1 AU using an MHD model. The transient streams interact with each other, which erases memory of the source and results in a large merged interaction region (MIR) with a preceding shock. The MHD model predicts that the shock and MIR would reach 120 AU around 2013 April 22, which agrees well with the period of radio emissions and the time of a transient disturbance in galactic cosmic rays detected by Voyager 1. These results are important for understanding the "fate" of CMEs in the outer heliosphere and provide confidence that the heliopause is ...

  2. Predicting Coronal Mass Ejections transit times to Earth with neural network

    CERN Document Server

    Sudar, D; Dumbović, M

    2015-01-01

    Predicting transit times of Coronal Mass Ejections (CMEs) from their initial parameters is a very important subject, not only from the scientific perspective, but also because CMEs represent a hazard for human technology. We used a neural network to analyse transit times for 153 events with only two input parameters: initial velocity of the CME, $v$, and Central Meridian Distance, CMD, of its associated flare. We found that transit time dependence on $v$ is showing a typical drag-like pattern in the solar wind. The results show that the speed at which acceleration by drag changes to deceleration is $v\\approx$500 km s$^{-1}$. Transit times are also found to be shorter for CMEs associated with flares on the western hemisphere than those originating on the eastern side of the Sun. We attribute this difference to the eastward deflection of CMEs on their path to 1 AU. The average error of the NN prediction in comparison to observations is $\\approx$12 hours which is comparable to other studies on the same subject.

  3. Observations of an extreme storm in interplanetary space caused by successive coronal mass ejections

    CERN Document Server

    Liu, Ying D; Kajdič, Primož; Kilpua, Emilia K J; Lugaz, Noé; Nitta, Nariaki V; Möstl, Christian; Lavraud, Benoit; Bale, Stuart D; Farrugia, Charles J; Galvin, Antoinette B

    2014-01-01

    Space weather refers to dynamic conditions on the Sun and in the space environment of the Earth, which are often driven by solar eruptions and their subsequent interplanetary disturbances. It has been unclear how an extreme space weather storm forms and how severe it can be. Here we report and investigate an extreme event with multi-point remote-sensing and in-situ observations. The formation of the extreme storm showed striking novel features. We suggest that the in-transit interaction between two closely launched coronal mass ejections resulted in the extreme enhancement of the ejecta magnetic field observed near 1 AU at STEREO A. The fast transit to STEREO A (in only 18.6 hours), or the unusually weak deceleration of the event, was caused by the preconditioning of the upstream solar wind by an earlier solar eruption. These results provide a new view crucial to solar physics and space weather as to how an extreme space weather event can arise from a combination of solar eruptions.

  4. UVCS/SoHO Catalog of Coronal Mass Ejections from 1996 to 2005: Spectroscopic Proprieties

    CERN Document Server

    Giordano, Silvio; Raymond, John; Ko, Yuan-Kuen; Suleiman, Raid

    2013-01-01

    Ultraviolet spectra of the extended solar corona have been routinely obtained by SoHO/UVCS since 1996. Sudden variations of spectral parameters are mainly due to the detection of Coronal Mass Ejections (CMEs) crossing the instrumental slit. We present a catalog of CME ultraviolet spectra based upon a systematic search of events in the LASCO CME catalog, and we discuss their statistical properties. Our catalog includes 1059 events through the end of 2005, covering nearly a full solar cycle. It is online available at the URL $\\rm http://solarweb.oato.inaf.it/UVCS\\_CME$ and embedded in the online LASCO CME catalog ($\\rm http://cdaw.gsfc.nasa.gov/CME\\_list$). The emission lines observed provide diagnostics of CME plasma parameters, such as the light-of-sight velocity, density and temperature and allow to link the CME onset data to the extended corona white-light images. The catalog indicates whether there are clear signatures of features such as shock waves, current sheets, O VI flares, helical motions and which ...

  5. History and Development of Coronal Mass Ejections as a Key Player in Solar Terrestrial Relationship

    CERN Document Server

    Gopalswamy, Nat

    2016-01-01

    Coronal mass ejections (CMEs) are relatively a recently-discovered phenomenon, in 1971, some fifteen years into the Space Era. It took another two decades to realize that CMEs are the most important players in solar terrestrial relationship as the root cause of severe weather in Earth's space environment. CMEs are now counted among the major natural hazards because they cause large solar energetic particle (SEP) events and major geomagnetic storms, both of which pose danger to humans and their technology in space and ground. Geomagnetic storms discovered in the 1700s, solar flares discovered in the 1800s, and SEP events discovered in the1900s are all now found to be closely related to CMEs via various physical processes occurring at various locations in and around CMEs, when they interact with the ambient medium. This article identifies a number of key developments that preceded the discovery of white-light CMEs suggesting that CMEs were waiting to be discovered. The last two decades witnessed an explosion of...

  6. Stationarity and periodicities of linear speed of coronal mass ejection: a statistical signal processing approach

    Science.gov (United States)

    Chattopadhyay, Anirban; Khondekar, Mofazzal Hossain; Bhattacharjee, Anup Kumar

    2017-09-01

    In this paper initiative has been taken to search the periodicities of linear speed of Coronal Mass Ejection in solar cycle 23. Double exponential smoothing and Discrete Wavelet Transform are being used for detrending and filtering of the CME linear speed time series. To choose the appropriate statistical methodology for the said purpose, Smoothed Pseudo Wigner-Ville distribution (SPWVD) has been used beforehand to confirm the non-stationarity of the time series. The Time-Frequency representation tool like Hilbert Huang Transform and Empirical Mode decomposition has been implemented to unearth the underneath periodicities in the non-stationary time series of the linear speed of CME. Of all the periodicities having more than 95% Confidence Level, the relevant periodicities have been segregated out using Integral peak detection algorithm. The periodicities observed are of low scale ranging from 2-159 days with some relevant periods like 4 days, 10 days, 11 days, 12 days, 13.7 days, 14.5 and 21.6 days. These short range periodicities indicate the probable origin of the CME is the active longitude and the magnetic flux network of the sun. The results also insinuate about the probable mutual influence and causality with other solar activities (like solar radio emission, Ap index, solar wind speed, etc.) owing to the similitude between their periods and CME linear speed periods. The periodicities of 4 days and 10 days indicate the possible existence of the Rossby-type waves or planetary waves in Sun.

  7. Heliospheric Propagation of Coronal Mass Ejections: Drag-Based Model Fitting

    CERN Document Server

    Žic, T; Temmer, M

    2015-01-01

    The so-called drag-based model (DBM) simulates analytically the propagation of coronal mass ejections (CMEs) in interplanetary space and allows the prediction of their arrival times and impact speeds at any point in the heliosphere ("target"). The DBM is based on the assumption that beyond a distance of about 20 solar radii from the Sun, the dominant force acting on CMEs is the "aerodynamic" drag force. In the standard form of DBM, the user provisionally chooses values for the model input parameters, by which the kinematics of the CME over the entire Sun--"target" distance range is defined. The choice of model input parameters is usually based on several previously undertaken statistical studies. In other words, the model is used by ad hoc implementation of statistics-based values of the input parameters, which are not necessarily appropriate for the CME under study. Furthermore, such a procedure lacks quantitative information on how well the simulation reproduces the coronagraphically observed kinematics of ...

  8. On the 3-D reconstruction of Coronal Mass Ejections using coronagraph data

    Directory of Open Access Journals (Sweden)

    M. Mierla

    2010-01-01

    Full Text Available Coronal Mass ejections (CMEs are enormous eruptions of magnetized plasma expelled from the Sun into the interplanetary space, over the course of hours to days. They can create major disturbances in the interplanetary medium and trigger severe magnetic storms when they collide with the Earth's magnetosphere. It is important to know their real speed, propagation direction and 3-D configuration in order to accurately predict their arrival time at the Earth. Using data from the SECCHI coronagraphs onboard the STEREO mission, which was launched in October 2006, we can infer the propagation direction and the 3-D structure of such events. In this review, we first describe different techniques that were used to model the 3-D configuration of CMEs in the coronagraph field of view (up to 15 R⊙. Then, we apply these techniques to different CMEs observed by various coronagraphs. A comparison of results obtained from the application of different reconstruction algorithms is presented and discussed.

  9. Coronal mass ejection initiation: On the nature of the Flux Cancellation Model

    CERN Document Server

    Amari, Tahar; Mikic, Zoran; Linker, Jon A

    2010-01-01

    We consider a three-dimensional bipolar force-free magnetic field with non zero magnetic helicity, occupying a half-space, and study the problem of its evolution driven by an imposed photospheric flux decrease. For this specific setting of the Flux Cancellation Model describing coronal mass ejections occuring in active regions, we address the issues of the physical meaning of flux decrease, of the influence on field evolution of the size of the domain over which this decrease is imposed, and of the existence of an energetic criterion characterizing the possible onset of disruption of the configuration. We show that: (1) The imposed flux disappearance can be interpreted in terms of transport of positive and negative fluxes towards the inversion line, where they get annihilated. (2) For the particular case actually computed, in which the initial state is quite sheared, the formation of a twisted flux rope and the subsequent global disruption of the configuration are obtained when the flux has decreased by only ...

  10. High Energy Solar Particle Events and their Associated Coronal Mass Ejections

    CERN Document Server

    Manoharan, P K

    2010-01-01

    Intense solar energetic particle (SEP) events data, associated with ground level enhancements (GLEs), occurred during 1989 to 2006 have been obtained from the spectrometers on board GOES spacecraft in the energy range 10-100 MeV. The interplanetary effects of these events and their associated coronal mass ejections (CMEs) have been provided by the LASCO/SOHO coronagraph images in the field of view of 2-30 {\\rsun} and the interplanetary scintillation images from the Ooty Radio Telescope in the heliocentric distance range of $\\sim$40-250 R$_\\odot$. The comparison between the radial evolution of the CME and its associated particle spectrum shows that the spectrum is soft at the onset of the particle event. A flat spectrum is observed at the peak of the particle event and the spectrum becomes steeper as the CME moves farther out into the inner heliosphere. However, the magnitude of change in spectral slopes differs from one CME to the other, suggesting the difference in energy available within the CME to drive th...

  11. On the Propagation of a Geoeffective Coronal Mass Ejection during March 15 -- 17, 2015

    CERN Document Server

    Wang, Yuming; Liu, Jiajia; Shen, Chenglong; Shen, Fang; Yang, Zicai; Zic, T; Vrsnak, B; Webb, D F; Liu, Rui; Wang, S; Zhang, Jie; Hu, Qiang; Zhuang, Bin

    2016-01-01

    The largest geomagnetic storm so far in the solar cycle 24 was produced by a fast coronal mass ejection (CME) originating on 2015 March 15. It was an initially west-oriented CME and expected to only cause a weak geomagnetic disturbance. Why did this CME finally cause such a large geomagnetic storm? We try to find some clues by investigating its propagation from the Sun to 1 AU. First, we reconstruct the CME's kinematic properties in the corona from the SOHO and SDO imaging data with the aid of the graduated cylindrical shell (GCS) model. It is suggested that the CME propagated to the west $\\sim$$33^\\circ$$\\pm$$10^\\circ$ away from the Sun-Earth line with a speed of about 817 km s$^{-1}$ before leaving the field of view of the SOHO/LASCO C3 camera. A magnetic cloud (MC) corresponding to this CME was measured in-situ by the Wind spacecraft two days later. By applying two MC reconstruction methods, we infer the configuration of the MC as well as some kinematic information, which implies that the CME possibly expe...

  12. Interplanetary Propagation Behavior of the Fast Coronal Mass Ejection from 23 July 2012

    CERN Document Server

    Temmer, Manuela

    2014-01-01

    The fast coronal mass ejection (CME) from 23 July 2012 raised attention due to its extremely short transit time from Sun to 1 AU of less than 21 h. In-situ data from STEREO-A revealed the arrival of a fast forward shock with a speed of more than 2200 km s$^{-1}$ followed by a magnetic structure moving with almost 1900 km s$^{-1}$. We investigate the propagation behavior of the CME shock and magnetic structure with the aim to reproduce the short transit time and high impact speed as derived from in-situ data. We carefully measure the 3D kinematics of the CME using the graduated cylindrical shell model, and obtain a maximum speed of 2580$\\pm$280 km s$^{-1}$ for the CME shock and of 2270$\\pm$420 km s$^{-1}$ for its magnetic structure. Based on the 3D kinematics, the drag-based model (DBM) reproduces the observational data reasonably well. To successfully simulate the CME shock, we find that the ambient flow speed should be of average value close to the slow solar wind speed (450 km s$^{-1}$), and the initial sho...

  13. Earth-Affecting Coronal Mass Ejections Without Obvious Low Coronal Signatures

    Science.gov (United States)

    Nitta, Nariaki V.; Mulligan, Tamitha

    2017-09-01

    We present a study of the origin of coronal mass ejections (CMEs) that were not accompanied by obvious low coronal signatures (LCSs) and yet were responsible for appreciable disturbances at 1 AU. These CMEs characteristically start slowly. In several examples, extreme ultraviolet (EUV) images taken by the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory reveal coronal dimming and a post-eruption arcade when we make difference images with long enough temporal separations, which are commensurate with the slow initial development of the CME. Data from the EUV imager and COR coronagraphs of the Sun Earth Connection Coronal and Heliospheric Investigation onboard the Solar Terrestrial Relations Observatory, which provide limb views of Earth-bound CMEs, greatly help us limit the time interval in which the CME forms and undergoes initial acceleration. For other CMEs, we find similar dimming, although only with lower confidence as to its link to the CME. It is noted that even these unclear events result in unambiguous flux rope signatures in in situ data at 1 AU. There is a tendency that the CME source regions are located near coronal holes or open field regions. This may have implications for both the initiation of the stealthy CME in the corona and its outcome in the heliosphere.

  14. Properties of the Fast Forward Shock Driven by the July 23 2012 Extreme Coronal Mass Ejection

    CERN Document Server

    Riley, Pete; Giacalone, Joe; Lario, David; Liu, Ying

    2015-01-01

    Late on July 23, 2012, the STEREO-A spacecraft encountered a fast forward shock driven by a coronal mass ejection launched from the Sun earlier that same day. The estimated travel time of the disturbance ($\\sim 20$ hrs), together with the massive magnetic field strengths measured within the ejecta ($> 100$nT), made it one of the most extreme events observed during the space era. In this study, we examine the properties of the shock wave. Because of an instrument malfunction, plasma measurements during the interval surrounding the CME were limited, and our approach has been modified to capitalize on the available measurements and suitable proxies, where possible. We were able to infer the following properties. First, the shock normal was pointing predominantly in the radial direction (${\\bf n} = 0.97 {\\bf e}_r -0.09 {\\bf e}_t -0.23 {\\bf e}_n$). Second, the angle between ${\\bf n}$ and the upstream magnetic field, $\\theta_{Bn}$, was estimated to be $\\approx 34^{\\circ}$, making the shock "quasi-parallel," and sup...

  15. Data-constrained Coronal Mass Ejections in a Global Magnetohydrodynamics Model

    Science.gov (United States)

    Jin, M.; Manchester, W. B.; van der Holst, B.; Sokolov, I.; Tóth, G.; Mullinix, R. E.; Taktakishvili, A.; Chulaki, A.; Gombosi, T. I.

    2017-01-01

    We present a first-principles-based coronal mass ejection (CME) model suitable for both scientific and operational purposes by combining a global magnetohydrodynamics (MHD) solar wind model with a flux-rope-driven CME model. Realistic CME events are simulated self-consistently with high fidelity and forecasting capability by constraining initial flux rope parameters with observational data from GONG, SOHO/LASCO, and STEREO/COR. We automate this process so that minimum manual intervention is required in specifying the CME initial state. With the newly developed data-driven Eruptive Event Generator using Gibson–Low configuration, we present a method to derive Gibson–Low flux rope parameters through a handful of observational quantities so that the modeled CMEs can propagate with the desired CME speeds near the Sun. A test result with CMEs launched with different Carrington rotation magnetograms is shown. Our study shows a promising result for using the first-principles-based MHD global model as a forecasting tool, which is capable of predicting the CME direction of propagation, arrival time, and ICME magnetic field at 1 au (see the companion paper by Jin et al. 2016a).

  16. A Numerical Study of Long-Range Magnetic Impacts during Coronal Mass Ejections

    CERN Document Server

    Jin, M; Cheung, M C M; DeRosa, M L; Nitta, N V; Title, A M

    2016-01-01

    With the global view and high-cadence observations from SDO/AIA and STEREO, many spatially separated solar eruptive events appear to be coupled. However, the mechanisms for "sympathetic" events are still largely unknown. In this study, we investigate the impact of an erupting flux rope on surrounding solar structures through large-scale magnetic coupling. We build a realistic environment of the solar corona on 2011 February 15 using a global magnetohydrodynamics (MHD) model and initiate coronal mass ejections (CMEs) in active region (AR) 11158 by inserting Gibson-Low analytical flux ropes. We show that a CME's impact on the surrounding structures depends not only on the magnetic strength of these structures and their distance to the source region, but also on the interaction between the CME with the large-scale magnetic field. Within the CME expansion domain where the flux rope field directly interacts with the solar structures, expansion-induced reconnection often modifies the overlying field, thereby increa...

  17. Periodicity in the most violent solar eruptions: recent observations of coronal mass ejections and flares revisited

    Institute of Scientific and Technical Information of China (English)

    Peng-Xin Gao; Jing-Lan Xie; Hong-Fei Liang

    2012-01-01

    Using the Hilbert-Huang Transform method,we investigate the periodicity in the monthly occurrence numbers and monthly mean energy of coronal mass ejections (CMEs) observed by the Large Angle and Spectrometric Coronagraph Experiment on board the Solar and Heliographic Observatory from 1999 March to 2009 December.We also investigate the periodicity in the monthly occurrence numbers of Hα flares and monthly mean flare indices from 1996 January to 2008 December.The results show the following.(1) The period of 5.66 yr is found to be statistically significant in the monthly occurrence numbers of CMEs; the period of 10.5 yr is found to be statistically significant in the monthly mean energy of CMEs.(2) The periods of 3.05 and 8.70 yr are found to be statistically significant in the monthly occurrence numbers of Hα flares; the period of 9.14yr is found to be statistically significant in the monthly mean flare indices.

  18. FLARE-GENERATED TYPE II BURST WITHOUT ASSOCIATED CORONAL MASS EJECTION

    Energy Technology Data Exchange (ETDEWEB)

    Magdalenic, J.; Marque, C.; Zhukov, A. N. [Solar-Terrestrial Center of Excellence, SIDC, Royal Observatory of Belgium, Avenue Circulaire 3, B-1180 Brussels (Belgium); Vrsnak, B. [Hvar Observatory, Faculty of Geodesy, Kaciceva 26, HR-10000 Zagreb (Croatia); Veronig, A., E-mail: Jasmina.Magdalenic@oma.be [IGAM/Kanzelhoehe Observatory, Institut of Physics, Universitaet Graz, Universitaetsplatz 5, A-8010 Graz (Austria)

    2012-02-20

    We present a study of the solar coronal shock wave on 2005 November 14 associated with the GOES M3.9 flare that occurred close to the east limb (S06 Degree-Sign E60 Degree-Sign ). The shock signature, a type II radio burst, had an unusually high starting frequency of about 800 MHz, indicating that the shock was formed at a rather low height. The position of the radio source, the direction of the shock wave propagation, and the coronal electron density were estimated using Nancay Radioheliograph observations and the dynamic spectrum of the Green Bank Solar Radio Burst Spectrometer. The soft X-ray, H{alpha}, and Reuven Ramaty High Energy Solar Spectroscopic Imager observations show that the flare was compact, very impulsive, and of a rather high density and temperature, indicating a strong and impulsive increase of pressure in a small flare loop. The close association of the shock wave initiation with the impulsive energy release suggests that the impulsive increase of the pressure in the flare was the source of the shock wave. This is supported by the fact that, contrary to the majority of events studied previously, no coronal mass ejection was detected in association with the shock wave, although the corresponding flare occurred close to the limb.

  19. Interplanetary coronal mass ejections at Mercury: Database and effects on the magnetosphere

    Science.gov (United States)

    Winslow, Reka; Anderson, Brian J.; Schwadron, Nathan; Lugaz, Noé; Farrugia, Charles; Philpott, Lydia; Paty, Carol

    2016-07-01

    We use observations from the MESSENGER spacecraft, in orbit around Mercury, to investigate interplanetary coronal mass ejections (ICMEs) near 0.3 AU. MESSENGER is the first spacecraft since Helios 1 and 2 in the 1980s to make in situ measurements of the interplanetary medium at heliocentric distances < 0.5 AU. Because extensive observations, both remote sensing and in-situ, are available throughout the MESSENGER mission, these data present a unique opportunity for observing the innermost heliosphere and the development of the solar wind and interplanetary transients. We catalog ICME events observed by the MESSENGER Magnetometer between 2011 and 2015 and present statistical analyses of ICME properties at Mercury. In addition, using existing data sets of ICMEs at 1 AU, we investigate key ICME property changes from Mercury to 1 AU. Using our database of nearly 70 ICMEs, we also statistically characterize Mercury's magnetosphere during times of ICMEs, when Mercury's magnetosphere becomes significantly altered. We conduct a systematic investigation of the large-scale processes in Mercury's magnetosphere during extreme solar wind conditions, by studying the motion of the bow shock and magnetopause boundaries, erosion of the dayside magnetosphere, the size, extent, and plasma pressure of the cusp region, and the plasma precipitation to the surface.

  20. Solar jet-coronal hole collision and a related coronal mass ejection

    CERN Document Server

    Zheng, Ruisheng; Du, Guohui; Li, Chuanyang

    2016-01-01

    Jets are defined as impulsive, well-collimated upflows, occurring in different layers of the solar atmosphere with different scales. Their relationship with coronal mass ejections (CMEs), another type of solar impulsive events, remains elusive. Using the high-quality imaging data of AIA/SDO, here we show a well-observed coronal jet event, in which part of the jets, with the embedding coronal loops, runs into a nearby coronal hole (CH) and gets bounced towards the opposite direction. This is evidenced by the flat-shape of the jet front during its interaction with the CH and the V-shaped feature in the time-slice plot of the interaction region. About a half-hour later, a CME initially with a narrow and jet-like front is observed by the LASCO C2 coronagraph, propagating along the direction of the post-collision jet. We also observe some 304 A dark material flowing from the jet-CH interaction region towards the CME. We thus suggest that the jet and the CME are physically connected, with the jet-CH collision and t...

  1. Multi-viewpoint Coronal Mass Ejection Catalog Based on STEREO COR2 Observations

    Science.gov (United States)

    Vourlidas, Angelos; Balmaceda, Laura A.; Stenborg, Guillermo; Dal Lago, Alisson

    2017-04-01

    We present the first multi-viewpoint coronal mass ejection (CME) catalog. The events are identified visually in simultaneous total brightness observations from the twin SECCHI/COR2 coronagraphs on board the Solar Terrestrial Relations Observatory mission. The Multi-View CME Catalog differs from past catalogs in three key aspects: (1) all events between the two viewpoints are cross-linked, (2) each event is assigned a physics-motivated morphological classification (e.g., jet, wave, and flux rope), and (3) kinematic and geometric information is extracted semi-automatically via a supervised image segmentation algorithm. The database extends from the beginning of the COR2 synoptic program (2007 March) to the end of dual-viewpoint observations (2014 September). It contains 4473 unique events with 3358 events identified in both COR2s. Kinematic properties exist currently for 1747 events (26% of COR2-A events and 17% of COR2-B events). We examine several issues, made possible by this cross-linked CME database, including the role of projection on the perceived morphology of events, the missing CME rate, the existence of cool material in CMEs, the solar cycle dependence on CME rate, speeds and width, and the existence of flux rope within CMEs. We discuss the implications for past single-viewpoint studies and for Space Weather research. The database is publicly available on the web including all available measurements. We hope that it will become a useful resource for the community.

  2. Direct observations of magnetic flux rope formation during a solar coronal mass ejection

    CERN Document Server

    Song, Hongqiang; Chen, Yao; Cheng, Xin

    2014-01-01

    Coronal mass ejections (CMEs) are the most spectacular eruptive phenomena in the solar atmosphere. It is generally accepted that CMEs are results of eruptions of magnetic flux ropes (MFRs). However, a heated debate is on whether MFRs pre-exist before the eruptions or they are formed during the eruptions. Several coronal signatures, \\textit{e.g.}, filaments, coronal cavities, sigmoid structures and hot channels (or hot blobs), are proposed as MFRs and observed before the eruption, which support the pre-existing MFR scenario. There is almost no reported observation about MFR formation during the eruption. In this letter, we present an intriguing observation of a solar eruptive event occurred on 2013 November 21 with the Atmospheric Imaging Assembly on board the \\textit{Solar Dynamic Observatory}, which shows a detailed formation process of the MFR during the eruption. The process started with the expansion of a low-lying coronal arcade, possibly caused by the flare magnetic reconnection underneath. The newly-fo...

  3. Radial Speed Evolution of Interplanetary Coronal Mass Ejections during Solar Cycle 23

    CERN Document Server

    Iju, Tomoya; Fujiki, Ken'ichi

    2013-01-01

    We report radial speed evolution of interplanetary coronal mass ejections (ICMEs) detected by the SOHO/LASCO coronagraph, interplanetary scintillation (IPS) at 327 MHz, and in-situ observations. In this study, we analyze solar wind disturbance factor (g-value) data derived from IPS observations during 1997-2009 covering nearly whole period of Solar Cycle 23. By comparing observations from the SOHO/LASCO, IPS, and in-situ, we then identify 39 ICMEs that could be analyzed carefully. Here, we define two speeds VSOHO and Vbg that are initial speed of ICME and the speed of background solar wind, respectively. Examinations for them yield the following results; 1) Fast ICMEs (with VSOHO - Vbg > 500 km/s) rapidly decelerate, moderate ICMEs (with 0 km/s < VSOHO - Vbg < 500 km/s) show either gradually decelerating or uniform motion, and slow ICMEs (with VSOHO - Vbg < 0 km/s) accelerate. The radial speeds converge on the speed of background solar wind during their outward propagation. We subsequently find; 2) b...

  4. Propagation of Solar Energetic Particles during Multiple Coronal Mass Ejection Events

    CERN Document Server

    Pohjolainen, Silja; Valtonen, Eino

    2015-01-01

    We study solar energetic particle (SEP) events during multiple solar eruptions. The analysed sequences, on 24-26 November 2000, 9-13 April 2001, and 22-25 August 2005, consisted of halo-type coronal mass ejections (CMEs) that originated from the same active region and were associated with intense flares, EUV waves, and interplanetary (IP) radio type II and type III bursts. The first two solar events in each of these sequences showed SEP enhancements near Earth, but the third in the row did not. We observed that in these latter events the type III radio bursts were stopped at much higher frequencies than in the earlier events, indicating that the bursts did not reach the typical plasma density levels near Earth. To explain the missing third SEP event in each sequence, we suggest that the earlier-launched CMEs and the CME-driven shocks either reduced the seed particle population and thus led to inefficient particle acceleration, or that the earlier-launched CMEs and shocks changed the propagation paths or preve...

  5. Statistical Analysis of Periodic Oscillations in LASCO Coronal Mass Ejection Speeds

    Science.gov (United States)

    Michalek, G.; Shanmugaraju, A.; Gopalswamy, N.; Yashiro, S.; Akiyama, S.

    2016-12-01

    A large set of coronal mass ejections (CMEs, 3463) has been selected to study their periodic oscillations in speed in the Solar and Heliospheric Observatory (SOHO) mission's Large Angle and Spectrometric Coronagraph (LASCO) field of view. These events, reported in the SOHO/LASCO catalog in the period of time 1996 - 2004, were selected based on having at least 11 height-time measurements. This selection criterion allows us to construct at least ten-point speed-distance profiles and evaluate kinematic properties of CMEs with a reasonable accuracy. To identify quasi-periodic oscillations in the speed of the CMEs a sinusoidal function was fitted to speed-distance profiles and the speed-time profiles. Of the considered events 22 % revealed periodic velocity fluctuations. These speed oscillations have on average amplitude equal to 87 km s^{-1} and period 7.8 R _{⊙}/241 min (in distance/time). The study shows that speed oscillations are a common phenomenon associated with CME propagation implying that all the CMEs have a similar magnetic flux-rope structure. The nature of oscillations can be explained in terms of magnetohydrodynamic (MHD) waves excited during the eruption process. More accurate detection of these modes could, in the future, enable us to characterize magnetic structures in space (space seismology).

  6. Is flux rope a necessary condition for the progenitor of coronal mass ejections?

    CERN Document Server

    Ouyang, Y; Chen, P F

    2015-01-01

    A magnetic flux rope structure is believed to exist in most coronal mass ejections (CMEs). However, it has been long debated whether the flux rope exists before eruption or is formed during eruption via magnetic reconnection. The controversy has been continuing because of our lack of routine measurements of the magnetic field in the pre-eruption structure, such as solar filaments. However, recently an indirect method was proposed to infer the magnetic field configuration based on the sign of helicity and the bearing direction of the filament barbs. In this paper, we apply this method to two erupting filament events, one on 2014 September 2 and the other on 2011 March 7, and find that the first filament is supported by a magnetic flux rope and the second filament is supported by a sheared arcade, i.e., the first one is an inverse-polarity filament and the second one is a normal-polarity filament. With the identification of the magnetic configurations in these two filaments, we stress that a flux rope is not a ...

  7. Ensemble prediction model of solar proton events associated with solar flares and coronal mass ejections

    Institute of Scientific and Technical Information of China (English)

    Xin Huang; Hua-Ning Wang; Le-Ping Li

    2012-01-01

    An ensemble prediction model of solar proton events (SPEs),combining the information of solar flares and coronal mass ejections (CMEs),is built.In this model,solar flares are parameterized by the peak flux,the duration and the longitude.In addition,CMEs are parameterized by the width,the speed and the measurement position angle.The importance of each parameter for the occurrence of SPEs is estimated by the information gain ratio.We find that the CME width and speed are more informative than the flare's peak flux and duration.As the physical mechanism of SPEs is not very clear,a hidden naive Bayes approach,which is a probability-based calculation method from the field of machine learning,is used to build the prediction model from the observational data.As is known,SPEs originate from solar flares and/or shock waves associated with CMEs.Hence,we first build two base prediction models using the properties of solar flares and CMEs,respectively.Then the outputs of these models are combined to generate the ensemble prediction model of SPEs.The ensemble prediction model incorporating the complementary information of solar flares and CMEs achieves better performance than each base prediction model taken separately.

  8. Solar flare associated coronal mass ejections causing geo-effectiveness and Forbush decreases

    Science.gov (United States)

    Bhatt, Beena; Chandra, Harish

    2017-02-01

    In the present study, we have selected 35 halo Coronal Mass Ejections (CMEs) associated with solar flares, Geomagnetic Storms (GSs) and Forbush decrease (Fd) chosen from 1st January 2000 to 31st December 2007 (i.e., the descending phase of solar cycle 23) observed by the Large Angle Spectrometric Coronagraph (LASCO) on board the SOHO spacecraft. Statistical analyses are performed to look at the distribution of solar flares associated with halo CMEs causing GSs and Fd and investigated the relationship between solar flare and halo CME parameters with GSs and Fd. Forbush decrease is the phenomenon of rapid decrease in cosmic ray intensity following the CME. Our analysis indicates that during 2000 to 2007 the northern region produced 44 % of solar flares associated with halo CMEs, GSs, and Fd, whereas 56 % solar flares associated with halo CMEs, GSs, and Fd were produced in the southern region. The northern and the southern hemispheres between 10° to 20° latitudinal belts are found to be more effective in producing events leading to Fd. From our selected events, we found that about 60 % of super-intense storms (Dst ≤ -200 nT) caused by halo CMEs are associated with X-class flares. Fast halo CMEs associated with X-class flares originating from 0° to 25° latitudes are better potential candidates in producing super-intense GSs than the slow halo CMEs associated with other classes of flares.

  9. Numerical research on the interaction between coronal mass ejection and streamer

    Institute of Scientific and Technical Information of China (English)

    叶占银; 魏奉思; 冯学尚; 石勇; 姚久胜

    2002-01-01

    By proposing a two-dimensional triggering model with concentrically circular closed magnetic field line structure,numerical research is made on the asymmetric propagation feature of coronal mass ejection (CME) in two cases emerging at the solar northern latitudes 10° and 45° respectively.The numerical results can qualitatively explain some features of CME event observed by the spacecraft SOHO and show that:(i) In these two cases,the triggering model can initiate CME with an asymmetric closed magnetic field structure.(ii) Closed magnetic structure of CME event will keep deflecting to the current sheet when it propagates away from the sun and this deflecting effect mostly happens within tens of solar radii before CME travels finally along the current sheet.(iii) The triggering model emerging at different locations can introduce CME events with different magnetic shapes.This shape happens to be circular and crescent when the triggering model emerges at the northern latitudes 10° and 45°,respectively.``

  10. ON THE RELATIONSHIP BETWEEN THE CORONAL MAGNETIC DECAY INDEX AND CORONAL MASS EJECTION SPEED

    Energy Technology Data Exchange (ETDEWEB)

    Xu Yan; Liu Chang; Jing Ju; Wang Haimin, E-mail: yx2@njit.edu [Space Weather Research Lab, Center for Solar-Terrestrial Research, New Jersey Institute of Technology, 323 Martin Luther King Boulevard, Newark, NJ 07102-1982 (United States)

    2012-12-10

    Numerical simulations suggest that kink and torus instabilities are two potential contributors to the initiation and prorogation of eruptive events. A magnetic parameter called the decay index (i.e., the coronal magnetic gradient of the overlying fields above the eruptive flux ropes) could play an important role in controlling the kinematics of eruptions. Previous studies have identified a threshold range of the decay index that distinguishes between eruptive and confined configurations. Here we advance the study by investigating if there is a clear correlation between the decay index and coronal mass ejection (CME) speed. Thirty-eight CMEs associated with filament eruptions and/or two-ribbon flares are selected using the H{alpha} data from the Global H{alpha} Network. The filaments and flare ribbons observed in H{alpha} associated with the CMEs help to locate the magnetic polarity inversion line, along which the decay index is calculated based on the potential field extrapolation using Michelson Doppler Imager magnetograms as boundary conditions. The speeds of CMEs are obtained from the LASCO C2 CME catalog available online. We find that the mean decay index increases with CME speed for those CMEs with a speed below 1000 km s{sup -1} and stays flat around 2.2 for the CMEs with higher speeds. In addition, we present a case study of a partial filament eruption, in which the decay indices show different values above the erupted/non-erupted part.

  11. Linking remote imagery of a coronal mass ejection to its in situ signatures at 1 AU

    CERN Document Server

    Möstl, Christian; Temmer, Manuela; Miklenic, Christiane; Veronig, Astrid M; Galvin, Antoinette B; Leitner, Martin; Biernat, Helfried K

    2009-01-01

    In a case study (June 6-7, 2008) we report on how the internal structure of a coronal mass ejection (CME) at 1 AU can be anticipated from remote observations of white-light images of the heliosphere. Favorable circumstances are the absence of fast equatorial solar wind streams and a low CME velocity which allow us to relate the imaging and in-situ data in a straightforward way. The STEREO-B spacecraft encountered typical signatures of a magnetic flux rope inside an interplanetary CME (ICME) whose axis was inclined at 45 degree to the solar equatorial plane. Various CME direction-finding techniques yield consistent results to within 15 degree. Further, remote images from STEREO-A show that (1) the CME is unambiguously connected to the ICME and can be tracked all the way to 1 AU, (2) the particular arc-like morphology of the CME points to an inclined axis, and (3) the three-part structure of the CME may be plausibly related to the in situ data. This is a first step in predicting both the direction of travel and...

  12. Interactions between Coronal Mass Ejections Viewed in Coordinated Imaging and In Situ Observations

    CERN Document Server

    Liu, Ying D; Mostl, Christian; Martinez-Oliveros, Juan C; Bale, Stuart D; Lin, Robert P; Harrison, Richard A; Temmer, Manuela; Webb, David F; Odstrcil, Dusan

    2012-01-01

    The successive coronal mass ejections (CMEs) from 2010 July 30 - August 1 present us the first opportunity to study CME-CME interactions with unprecedented heliospheric imaging and in situ observations from multiple vantage points. We describe two cases of CME interactions: merging of two CMEs launched close in time and overtaking of a preceding CME by a shock wave. The first two CMEs on August 1 interact close to the Sun and form a merged front, which then overtakes the July 30 CME near 1 AU, as revealed by wide-angle imaging observations. Connections between imaging observations and in situ signatures at 1 AU suggest that the merged front is a shock wave, followed by two ejecta observed at Wind which seem to have already merged. In situ measurements show that the CME from July 30 is being overtaken by the shock at 1 AU and is significantly compressed, accelerated and heated. The interaction between the preceding ejecta and shock also results in variations in the shock strength and structure on a global scal...

  13. Near-Sun and 1 AU magnetic field of coronal mass ejections: A parametric study

    CERN Document Server

    Patsourakos, S

    2016-01-01

    Aims. The magnetic field of coronal mass ejections (CMEs) determines their structure, evolution, and energetics, as well as their geoeffectiveness. However, we currently lack routine diagnostics of the near-Sun CME magnetic field, which is crucial for determining the subsequent evolution of CMEs. Methods. We recently presented a method to infer the near-Sun magnetic field magnitude of CMEs and then extrapolate it to 1 AU. This method uses relatively easy to deduce observational estimates of the magnetic helicity in CME-source regions along with geometrical CME fits enabled by coronagraph observations. We hereby perform a parametric study of this method aiming to assess its robustness. We use statistics of active region (AR) helicities and CME geometrical parameters to determine a matrix of plausible near-Sun CME magnetic field magnitudes. In addition, we extrapolate this matrix to 1 AU and determine the anticipated range of CME magnetic fields at 1 AU representing the radial falloff of the magnetic field in t...

  14. SOLAR JET–CORONAL HOLE COLLISION AND A CLOSELY RELATED CORONAL MASS EJECTION

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Ruisheng; Chen, Yao; Du, Guohui; Li, Chuanyang, E-mail: ruishengzheng@sdu.edu.cn [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, and Institute of Space Sciences, Shandong University, 264209, Weihai (China)

    2016-03-10

    Jets are defined as impulsive, well-collimated upflows, occurring in different layers of the solar atmosphere with different scales. Their relationship with coronal mass ejections (CMEs), another type of solar impulsive events, remains elusive. Using high-quality imaging data from the Atmospheric Imaging Assembly/Solar Dynamics Observatory, we show a well-observed coronal jet event, in which the part of the jet with embedding coronal loops runs into a nearby coronal hole (CH) and gets bounced in the opposite direction. This is evidenced by the flat shape of the jet front during its interaction with the CH and the V-shaped feature in the time-slice plot of the interaction region. About a half-hour later, a CME with an initially narrow and jet-like front is observed by the LASCO C2 coronagraph propagating along the direction of the post-collision jet. We also observe some 304 Å dark material flowing from the jet–CH interaction region toward the CME. We thus suggest that the jet and the CME are physically connected, with the jet–CH collision and the large-scale magnetic topology of the CH being important in defining the eventual propagating direction of this particular jet–CME eruption.

  15. Solar signatures and eruption mechanism of the August 14, 2010 coronal mass ejection (CME)

    Science.gov (United States)

    D'Huys, Elke; Seaton, Daniel B.; De Groof, Anik; Berghmans, David; Poedts, Stefaan

    2017-03-01

    On August 14, 2010 a wide-angled coronal mass ejection (CME) was observed. This solar eruption originated from a destabilized filament that connected two active regions and the unwinding of this filament gave the eruption an untwisting motion that drew the attention of many observers. In addition to the erupting filament and the associated CME, several other low-coronal signatures that typically indicate the occurrence of a solar eruption were associated with this event. However, contrary to what was expected, the fast CME (v > 900 km s-1) was accompanied by only a weak C4.4 flare. We investigate the various eruption signatures that were observed for this event and focus on the kinematic evolution of the filament in order to determine its eruption mechanism. Had this solar eruption occurred just a few days earlier, it could have been a significant event for space weather. The risk of underestimating the strength of this eruption based solely on the C4.4 flare illustrates the need to include all eruption signatures in event analyses in order to obtain a complete picture of a solar eruption and assess its possible space weather impact.

  16. Tether-cutting Reconnection between Two Solar Filaments Triggering Outflows and a Coronal Mass Ejection

    CERN Document Server

    Chen, Huadong; Li, Leping; Ma, Suli

    2016-01-01

    Triggering mechanisms of solar eruptions have long been a challenge. A few previous case studies have indicated that preceding gentle filament merging via magnetic reconnection may launch following intense eruption, according with the tether-cutting (TC) model. However, detailed process of TC reconnection between filaments has not been exhibited yet. In this work, we report the high resolution observations from the Interface Region Imaging Spectrometer (IRIS) of TC reconnection between two sheared filaments in NOAA active region 12146. The TC reconnection commenced since 15:35 UT on 2014 August 29 and triggered an eruptive GOES C4.3-class flare 8 minutes later. An associated coronal mass ejection appeared in the field of view of SOHO/LASCO C2 about 40 minutes later. Thanks to the high spatial resolution of IRIS data, bright plasma outflows generated by the TC reconnection are clearly observed, which moved along the subarcsecond fine-scale flux tube structures in the erupting filament. Based on the imaging and...

  17. INTERACTIONS BETWEEN CORONAL MASS EJECTIONS VIEWED IN COORDINATED IMAGING AND IN SITU OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ying D.; Luhmann, Janet G.; Moestl, Christian; Martinez-Oliveros, Juan C.; Bale, Stuart D.; Lin, Robert P. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Harrison, Richard A. [Space Science and Technology Department, Rutherford Appleton Laboratory, Didcot (United Kingdom); Temmer, Manuela [Institute of Physics, University of Graz (Austria); Webb, David F. [Institute for Scientific Research, Boston College, Newton, MA 02459 (United States); Odstrcil, Dusan, E-mail: liuxying@ssl.berkeley.edu [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2012-02-20

    The successive coronal mass ejections (CMEs) from 2010 July 30 to August 1 present us the first opportunity to study CME-CME interactions with unprecedented heliospheric imaging and in situ observations from multiple vantage points. We describe two cases of CME interactions: merging of two CMEs launched close in time and overtaking of a preceding CME by a shock wave. The first two CMEs on August 1 interact close to the Sun and form a merged front, which then overtakes the July 30 CME near 1 AU, as revealed by wide-angle imaging observations. Connections between imaging observations and in situ signatures at 1 AU suggest that the merged front is a shock wave, followed by two ejecta observed at Wind which seem to have already merged. In situ measurements show that the CME from July 30 is being overtaken by the shock at 1 AU and is significantly compressed, accelerated, and heated. The interaction between the preceding ejecta and shock also results in variations in the shock strength and structure on a global scale, as shown by widely separated in situ measurements from Wind and STEREO B. These results indicate important implications of CME-CME interactions for shock propagation, particle acceleration, and space weather forecasting.

  18. Interactions between Coronal Mass Ejections Viewed in Coordinated Imaging and In Situ Observations

    Science.gov (United States)

    Liu, Ying D.; Luhmann, Janet G.; Moestl, Christian; Martinez-Oliveros, Juan C.; Bale, Stewart D.; Lin, Robert P.; Harrison, Richard A.; Temmer, Manuela; Webb, David F.; Odstrcil, Dusan

    2013-01-01

    The successive coronal mass ejections (CMEs) from 2010 July 30 - August 1 present us the first opportunity to study CME-CME interactions with unprecedented heliospheric imaging and in situ observations from multiple vantage points. We describe two cases of CME interactions: merging of two CMEs launched close in time and overtaking of a preceding CME by a shock wave. The first two CMEs on August 1 interact close to the Sun and form a merged front, which then overtakes the July 30 CME near 1 AU, as revealed by wide-angle imaging observations. Connections between imaging observations and in situ signatures at 1 AU suggest that the merged front is a shock wave, followed by two ejecta observed at Wind which seem to have already merged. In situ measurements show that the CME from July 30 is being overtaken by the shock at 1 AU and is significantly compressed, accelerated and heated. The interaction between the preceding ejecta and shock also results in variations in the shock strength and structure on a global scale, as shown by widely separated in situ measurements from Wind and STEREO B. These results indicate important implications of CME-CME interactions for shock propagation, particle acceleration and space weather forecasting.

  19. PROPAGATION OF THE 2012 MARCH CORONAL MASS EJECTIONS FROM THE SUN TO HELIOPAUSE

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ying D.; Wang, Chi [State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190 (China); Richardson, John D. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Luhmann, Janet G., E-mail: liuxying@spaceweather.ac.cn [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)

    2014-06-20

    In 2012 March the Sun exhibited extraordinary activities. In particular, the active region NOAA AR 11429 emitted a series of large coronal mass ejections (CMEs) which were imaged by the Solar Terrestrial Relations Observatory as it rotated with the Sun from the east to west. These sustained eruptions are expected to generate a global shell of disturbed material sweeping through the heliosphere. A cluster of shocks and interplanetary CMEs were observed near the Earth, and are propagated outward from 1 AU using an MHD model. The transient streams interact with each other, which erases memory of the source and results in a large merged interaction region (MIR) with a preceding shock. The MHD model predicts that the shock and MIR would reach 120 AU around 2013 April 22, which agrees well with the period of radio emissions and the time of a transient disturbance in galactic cosmic rays detected by Voyager 1. These results are important for understanding the ''fate'' of CMEs in the outer heliosphere and provide confidence that the heliopause is located around 120 AU from the Sun.

  20. Challenging Some Contemporary Views of Coronal Mass Ejections. II. The Case for Absent Filaments

    Science.gov (United States)

    Howard, T. A.; DeForest, C. E.; Schneck, U. G.; Alden, C. R.

    2017-01-01

    When a coronal mass ejection (CME) appears in a coronagraph it often exhibits three parts. This “classic” three-part configuration consists of a bright leading edge, a dark circular- or teardrop-shaped cavity, and a bright core within the cavity. It is generally accepted that these are manifestations of coronal plasma pileup, the driving magnetic flux rope, and the associated eruptive filament, respectively. The latter has become accepted by the community since coronagraph CMEs have been commonly associated with eruptive filaments for over 40 years. In this second part of our series challenging views on CMEs, we present the case that the inner core of the three-part coronagraph CME may not be, and in the most common cases is not, a filament. We present our case in the form of four exhibits showing that most of the CMEs in a broad survey are not associated with an eruptive filament at the Sun, and that the cores of those CMEs that are filament-associated do not geometrically resemble or consist of material from the associated filament. We conclude with a discussion on the possible causes of the bright CME core and what happens to the filament material postlaunch. We discuss how the CME core could arise spontaneously from the eruption of a flux rope from the Sun, or could be the result of a mathematical caustic produced by the geometric projection of a twisted flux rope.

  1. Solar filament eruptions and their physical role in triggering Coronal Mass Ejections

    CERN Document Server

    Schmieder, B; Aulanier, G

    2012-01-01

    Solar filament eruptions play a crucial role in triggering coronal mass ejections (CMEs). More than 80 % of eruptions lead to a CME. This correlation has been studied extensively during the past solar cycles and the last long solar minimum. The statistics made on events occurring during the rising phase of the new solar cycle 24 is in agreement with this finding. Both filaments and CMEs have been related to twisted magnetic fields. Therefore, nearly all the MHD CME models include a twisted flux tube, called a flux rope. Either the flux rope is present long before the eruption, or it is built up by reconnection of a sheared arcade from the beginning of the eruption. In order to initiate eruptions, different mechanisms have been proposed: new emergence of flux, and/or dispersion of the external magnetic field, and/or reconnection of field lines below or above the flux rope. These mechanisms reduce the downward magnetic tension and favor the rise of the flux rope. Another mechanism is the kink instability when t...

  2. Constraining the Mass and the Non-Radial Drag Coefficient of a Solar Coronal Mass Ejection

    CERN Document Server

    Kay, C; Opher, M

    2015-01-01

    Decades of observations show that CMEs can deflect from a purely radial trajectory yet no consensus exists as to the cause of these deflections. Many of theories attribute the CME deflection to magnetic forces. We developed ForeCAT (Kay et al. 2013, Kay et al. 2015), a model for CME deflections based solely on magnetic forces, neglecting any reconnection effects. Here we compare ForeCAT predictions to the observed deflection of the 2008 December 12 CME and find that ForeCAT can accurately reproduce the observations. Multiple observations show that this CME deflected nearly 30{\\deg} in latitude (Byrne et al. 2010, Gui et al. 2011) and 4.4{\\deg} in longitude (Gui et al. 2011). From the observations, we are able to constrain all of the ForeCAT input parameters (initial position, radial propagation speed, and expansion) except the CME mass and the drag coefficient that affects the CME motion. By minimizing the reduced chi-squared, $\\chi^2_{\

  3. Natal Kicks of Stellar-Mass Black Holes by Asymmetric Mass Ejection in Fallback Supernovae

    CERN Document Server

    Janka, H -Thomas

    2013-01-01

    Integrating trajectories of low-mass X-ray binaries containing black holes within the Galactic potential, Repetto, Davies & Sigurdsson recently showed that the large distances of some systems above the Galactic plane can only be explained if black holes receive appreciable natal kicks. Surprisingly, they found that the distribution of black hole kick velocities (rather than that of the momenta) should be similar to that of neutron stars. Here I argue that this result can be understood if neutron star and black hole kicks are a consequence of large-scale asymmetries created in the supernova ejecta by the explosion mechanism. The corresponding anisotropic gravitational attraction of the asymmetrically expelled matter does not only accelerate new-born neutron stars by the "gravitational tug-boat mechanism". It can also lead to delayed black-hole formation by asymmetric fallback of the slowest parts of the initial ejecta onto the transiently existing neutron star, in course of which the momentum of the black ...

  4. Dynamics and distribution of Jovian dust ejected from the Galilean satellites

    Science.gov (United States)

    Liu, Xiaodong; Sachse, Manuel; Spahn, Frank; Schmidt, Jürgen

    2016-07-01

    In this paper, the dynamical analysis of the Jovian dust originating from the four Galilean moons is presented. High-accuracy orbital integrations of dust particles are used to determine their dynamical evolution. A variety of forces are taken into account, including the Lorentz force, solar radiation pressure, Poynting-Robertson drag, solar gravity, the satellites' gravity, plasma drag, and gravitational effects due to nonsphericity of Jupiter. More than 20,000 dust particles from each source moon in the size range from 0.05 μm to 1 cm are simulated over 8000 (Earth) years until each dust grain hits a sink (moons, Jupiter, or escape from the system). Configurations of dust number density in the Jovicentric equatorial inertial frame are calculated and shown. In a Jovicentric frame rotating with the Sun the dust distributions are found to be asymmetric. For certain small particle sizes, the dust population is displaced towards the Sun, while for certain larger sizes, the dust population is displaced away from the Sun. The average lifetime as a function of particle size for ejecta from each source moon is derived, and two sharp jumps in the average lifetime are analyzed. Transport of dust between the Galilean moons and to Jupiter is investigated. Most of the orbits for dust particles from Galilean moons are prograde, while, surprisingly, a small fraction of orbits are found to become retrograde mainly due to solar radiation pressure and Lorentz force. The distribution of orbital elements is also analyzed.

  5. Exploring a Threat to Foreign Worlds: Detecting Coronal Mass Ejections on Nearby Stars

    Science.gov (United States)

    Villadsen, Jackie; Hallinan, Gregg; Bourke, Stephen

    2015-01-01

    Coronal mass ejections (CMEs) likely play a significant role in the mass loss and angular momentum evolution of active stars, and may significantly affect exoplanetary magnetospheres and atmospheres. It is difficult to quantitatively predict the magnitude of these effects because there have been no definitive detections of CMEs outside our own solar system. Dynamic radio spectroscopy of stellar flares offers the potential to make such detections. Broadband dynamic spectroscopy has long been used to study coherent radio emission associated with solar CMEs (known as Type II bursts), but such emission has not yet been detected from other stars. Type II bursts sweep downwards in frequency on timescales of tens of minutes, tracing the motion of a CME outwards through the stellar atmosphere into progressively lower plasma densities. I will present JVLA active M dwarf observations showing coherent stellar radio bursts that are extremely bright, comparable in luminosity to the brightest solar Type II bursts ever recorded. These stellar radio bursts are morphologically similar to solar Type II bursts except that the stellar bursts sweep upwards in frequency over time. We interpret these bursts as either bulk plasma motion downwards into the stellar atmosphere or polar auroral radiation modulated by rotation. I will also present progress on the Starburst program, a 3-year nightly observing program using two 27-meter telescopes at the Owens Valley Radio Observatory (the equivalent of a JVLA baseline). The Starburst program will survey stellar coherent radio bursts in order to characterize the rate and energetics of CMEs on nearby stars, combined with complementary observations to image and characterize the detected CMEs.

  6. Propagation of Coronal Mass Ejections Observed During the Rising Phase of Solar Cycle 24

    Science.gov (United States)

    Syed Ibrahim, M.; Manoharan, P. K.; Shanmugaraju, A.

    2017-09-01

    In this study, we investigate the interplanetary consequences and travel time details of 58 coronal mass ejections (CMEs) in the Sun-Earth distance. The CMEs considered are halo and partial halo events of width {>} 120°. These CMEs occurred during 2009 - 2013, in the ascending phase of the Solar Cycle 24. Moreover, they are Earth-directed events that originated close to the centre of the solar disk (within about ±30° from the Sun's centre) and propagated approximately along the Sun-Earth line. For each CME, the onset time and the initial speed have been estimated from the white-light images observed by the LASCO coronagraphs onboard the SOHO space mission. These CMEs cover an initial speed range of {˜} 260 - 2700 km s^{-1}. For these CMEs, the associated interplanetary shocks (IP shocks) and interplanetary CMEs (ICMEs) at the near-Earth environment have been identified from in-situ solar wind measurements available at the OMNI data base. Most of these events have been associated with moderate to intense IP shocks. However, these events have caused only weak to moderate geomagnetic storms in the Earth's magnetosphere. The relationship of the travel time with the initial speed of the CME has been compared with the observations made in the previous Cycle 23, during 1996 - 2004. In the present study, for a given initial speed of the CME, the travel time and the speed at 1 AU suggest that the CME was most likely not much affected by the drag caused by the slow-speed dominated heliosphere. Additionally, the weak geomagnetic storms and moderate IP shocks associated with the current set of Earth-directed CMEs indicate magnetically weak CME events of Cycle 24. The magnetic energy that is available to propagate CME and cause geomagnetic storm could be significantly low.

  7. Coronal mass ejections and other extreme characteristics of the 2003 October-November solar eruptions

    Science.gov (United States)

    Gopalswamy, N.; Yashiro, S.; Liu, Y.; Michalek, G.; Vourlidas, A.; Kaiser, M. L.; Howard, R. A.

    2005-09-01

    Fast coronal mass ejections (CMEs), X-class flares, solar energetic particle (SEP) events, and interplanetary shocks were abundantly observed during the episode of intense solar activity in late October and early November 2003. Most of the 80 CMEs originated from three active regions (NOAA ARs 484, 486, and 488). We compare the statistical properties of these CMEs with those of the general population of CMEs observed during cycle 23. We find that (1) the 2003 October-November CMEs were fast and wide on the average and hence were very energetic, (2) nearly 20 percent of the ultrafast CMEs (speed ≥2000 km s-1) of cycle 23 occurred during the October-November interval, including the fastest CME of the study period (˜2700 km s-1 on 4 November 2003 at 1954 UT), (3) the rate of full-halo CMEs was nearly four times the average rate during cycle 23, (4) at least sixteen shocks were observed near the Sun, while eight of them were intercepted by spacecraft along the Sun-Earth line, (5) the CMEs were highly geoeffective: the resulting geomagnetic storms were among the most intense of cycle 23, (6) the CMEs were associated with very large SEP events, including the largest event of cycle 23. These extreme properties were commensurate with the size and energy of the associated active regions. This study suggests that the speed of CMEs may not be much higher than ˜3000 km s-1, consistent with the free energy available in active regions. An important practical implication of such a speed limit is that the Sun-Earth travel times of CME-driven shocks may not be less than ˜0.5 day. Two of the shocks arrived at Earth in documented cases of such events since 1859.

  8. TETHER-CUTTING RECONNECTION BETWEEN TWO SOLAR FILAMENTS TRIGGERING OUTFLOWS AND A CORONAL MASS EJECTION

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Huadong; Zhang, Jun; Li, Leping [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Ma, Suli, E-mail: hdchen@nao.cas.cn [College of Science, China University of Petroleum, Qingdao 266580 (China)

    2016-02-20

    Triggering mechanisms of solar eruptions have long been a challenge. A few previous case studies have indicated that preceding gentle filament merging via magnetic reconnection may launch following intense eruption, according to the tether-cutting (TC) model. However, the detailed process of TC reconnection between filaments has not been exhibited yet. In this work, we report the high-resolution observations from the Interface Region Imaging Spectrometer (IRIS) of TC reconnection between two sheared filaments in NOAA active region 12146. The TC reconnection commenced on ∼15:35 UT on 2014 August 29 and triggered an eruptive GOES C4.3-class flare ∼8 minutes later. An associated coronal mass ejection appeared in the field of view of the Solar and Heliospheric Observatory/LASCO C2 about 40 minutes later. Thanks to the high spatial resolution of IRIS data, bright plasma outflows generated by the TC reconnection are clearly observed, which moved along the subarcsecond fine-scale flux tube structures in the erupting filament. Based on the imaging and spectral observations, the mean plane-of-sky and line-of-sight velocities of the TC reconnection outflows are separately measured to be ∼79 and 86 km s{sup −1}, which derives an average real speed of ∼120 km s{sup −1}. In addition, it is found that spectral features, such as peak intensities, Doppler shifts, and line widths in the TC reconnection region are evidently enhanced compared to those in the nearby region just before the flare.

  9. ARE HALO-LIKE SOLAR CORONAL MASS EJECTIONS MERELY A MATTER OF GEOMETRIC PROJECTION EFFECTS?

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Ryun-Young; Zhang, Jie [School of Physics, Astronomy and Computational Sciences, George Mason University, 4400 University Drive, MSN 6A2, Fairfax, VA 22030, USA. (United States); Vourlidas, Angelos, E-mail: ryunyoung.kwon@gmail.com [The Johns Hopkins University, Applied Physics Laboratory, Laurel, MD 20723, USA. (United States)

    2015-02-01

    We investigated the physical nature of halo coronal mass ejections (CMEs) based on the stereoscopic observations from the two STEREO spacecraft, Ahead and Behind (hereafter A and B), and the SOHO spacecraft. Sixty-two halo CMEs occurred as observed by SOHO LASCO C2 for the three-year period from 2010 to 2012 during which the separation angles between SOHO and STEREO were nearly 90°. In such quadrature configuration, the coronagraphs of STEREO, COR2-A and -B, showed the side view of those halo CMEs seen by C2. It has been widely believed that the halo appearance of a CME is caused by the geometric projection effect, i.e., a CME moves along the Sun-observer line. In other words, it would appear as a non-halo CME if viewed from the side. However, to our surprise, we found that 41 out of 62 events (66%) were observed as halo CMEs by all coronagraphs. This result suggests that a halo CME is not just a matter of the propagating direction. In addition, we show that a CME propagating normal to the line of sight can be observed as a halo CME due to the associated fast magnetosonic wave or shock front. We conclude that the apparent width of CMEs, especially halos or partial halos is driven by the existence and the extent of the associated waves or shocks and does not represent an accurate measure of the CME ejecta size. This effect needs to be taken into careful consideration in space weather predictions and modeling efforts.

  10. Three-dimensional stereoscopic analysis of a coronal mass ejection and comparison with UV spectroscopic data

    Energy Technology Data Exchange (ETDEWEB)

    Susino, Roberto; Bemporad, Alessandro [INAF-Osservatorio Astrofisico di Torino, via Osservatorio 20, I-10025 Pino Torinese (Italy); Dolei, Sergio, E-mail: susino@oato.inaf.it, E-mail: sdo@oact.inaf.it [INAF-Osservatorio Astrofisico di Catania, via S. Sofia 78, I-95123 Catania (Italy)

    2014-07-20

    A three-dimensional (3D) reconstruction of the 2007 May 20 partial-halo coronal mass ejection (CME) has been made using STEREO/EUVI and STEREO/COR1 coronagraphic images. The trajectory and kinematics of the erupting filament have been derived from Extreme Ultraviolet Imager (EUVI) image pairs with the 'tie-pointing' triangulation technique, while the polarization ratio technique has been applied to COR1 data to determine the average position and depth of the CME front along the line of sight. This 3D geometrical information has been combined for the first time with spectroscopic measurements of the O VI λλ1031.91, 1037.61 line profiles made with the Ultraviolet Coronagraph Spectrometer (UVCS) on board the Solar and Heliospheric Observatory. Comparison between the prominence trajectory extrapolated at the altitude of UVCS observations and the core transit time measured from UVCS data made possible a firm identification of the CME core observed in white light and UV with the prominence plasma expelled during the CME. Results on the 3D structure of the CME front have been used to calculate synthetic spectral profiles of the O VI λ1031.91 line expected along the UVCS slit, in an attempt to reproduce the measured line widths. Observed line widths can be reproduced within the uncertainties only in the peripheral part of the CME front; at the front center, where the distance of the emitting plasma from the plane of the sky is greater, synthetic widths turn out to be ∼25% lower than the measured ones. This provides strong evidence of line broadening due to plasma heating mechanisms in addition to bulk expansion of the emitting volume.

  11. Hemodynamic responses to small muscle mass exercise in heart failure patients with reduced ejection fraction

    Science.gov (United States)

    Barrett-O'Keefe, Zachary; Lee, Joshua F.; Berbert, Amanda; Witman, Melissa A. H.; Nativi-Nicolau, Jose; Stehlik, Josef; Richardson, Russell S.

    2014-01-01

    To better understand the mechanisms responsible for exercise intolerance in heart failure with reduced ejection fraction (HFrEF), the present study sought to evaluate the hemodynamic responses to small muscle mass exercise in this cohort. In 25 HFrEF patients (64 ± 2 yr) and 17 healthy, age-matched control subjects (64 ± 2 yr), mean arterial pressure (MAP), cardiac output (CO), and limb blood flow were examined during graded static-intermittent handgrip (HG) and dynamic single-leg knee-extensor (KE) exercise. During HG exercise, MAP increased similarly between groups. CO increased significantly (+1.3 ± 0.3 l/min) in the control group, but it remained unchanged across workloads in HFrEF patients. At 15% maximum voluntary contraction (MVC), forearm blood flow was similar between groups, while HFrEF patients exhibited an attenuated increase at the two highest intensities compared with controls, with the greatest difference at the highest workload (352 ± 22 vs. 492 ± 48 ml/min, HFrEF vs. control, 45% MVC). During KE exercise, MAP and CO increased similarly across work rates between groups. However, HFrEF patients exhibited a diminished leg hyperemic response across all work rates, with the most substantial decrement at the highest intensity (1,842 ± 64 vs. 2,675 ± 81 ml/min; HFrEF vs. control, 15 W). Together, these findings indicate a marked attenuation in exercising limb perfusion attributable to impairments in peripheral vasodilatory capacity during both arm and leg exercise in patients with HFrEF, which likely plays a role in limiting exercise capacity in this patient population. PMID:25260608

  12. The formation and launch of a coronal mass ejection flux rope: a narrative based on observations

    Energy Technology Data Exchange (ETDEWEB)

    Howard, T. A.; DeForest, C. E., E-mail: howard@boulder.swri.edu [Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302 (United States)

    2014-11-20

    We present a data-driven narrative of the launch and early evolution of the magnetic structure that gave rise to the coronal mass ejection (CME) on 2008 December 12. The structure formed on December 7 and launched early on December 12. We interpret this structure as a flux rope based on prelaunch morphology, postlaunch magnetic measurements, and the lack of large-scale magnetic reconnection signatures at launch. We ascribe three separate onset mechanisms to the complete disconnection of the flux rope from the Sun. It took 19 hr for the flux rope to be fully removed from the Sun, by which time the segment that first disconnected was around 40 R {sub ☉} away. This implies that the original flux rope was stretched or broken; we provide evidence for a possible bisection. A transient dark arcade was observed on the Sun that was later obscured by a bright arcade, which we interpret as the strapping field stretching and magnetically reconnecting as it disconnected from the coronal field. We identify three separate structures in coronagraph images to be manifestations of the same original flux rope, and we describe the implications for CME interpretation. We cite the rotation in the central flux rope vector of the magnetic clouds observed in situ by ACE/Wind and STEREO-B as evidence of the kink instability of the eastern segment of the flux rope. Finally, we discuss possible alternative narratives, including multiple prelaunch magnetic structures and the nonflux rope scenario. Our results support the view that, in at least some CMEs, flux rope formation occurs before launch.

  13. The Role of Overlying Magnetic Field in Modeling Coronal Mass Ejections

    Science.gov (United States)

    Olmedo, Oscar; Zhang, J.

    2009-05-01

    Recent models and observations have revealed that the magnetic fields overlying active regions play an important role in the eruption or confinement of flux ropes due to the torus instability. Flux ropes are now generally accepted to be the magnetic configuration of coronal mass ejections (CMEs) but their initiation is still not clear. In this study the external magnetic field profile of the well-developed flux rope model as proposed by James Chen (see J.Chen 1989, 1996) is examined. This external magnetic field represents overlying coronal loops, that may be of bipolar or complex topology with footpoints assumed to originate from an active region, and it is assumed that the only magnetic field component that affects the flux rope evolution is the one that is perpendicular to the flux ropes major axis. In this type of flux rope model, it has been suggested that the flux ropes initiation is driven by poloidal flux injection either of photospheric or coronal origin. Several test profiles are investigated, such as a power law profile, and a polynomial profile that could be thought of as a summation of magnetic multipoles. The gradient index for the prescribed magnetic field profile is studied and it is found that above a critical value the flux rope is eruptive and below this value it is confined, in agreement with observations and simulations. Implications of the results are that the torus instability is the most likely candidate in driving the eruption of flux rope CMEs, and that the distribution of magnetic field has a significant effect on the initiation and acceleration of CMEs.

  14. Two-step forecast of geomagnetic storm using coronal mass ejection and solar wind condition

    Science.gov (United States)

    Kim, R-S; Moon, Y-J; Gopalswamy, N; Park, Y-D; Kim, Y-H

    2014-01-01

    To forecast geomagnetic storms, we had examined initially observed parameters of coronal mass ejections (CMEs) and introduced an empirical storm forecast model in a previous study. Now we suggest a two-step forecast considering not only CME parameters observed in the solar vicinity but also solar wind conditions near Earth to improve the forecast capability. We consider the empirical solar wind criteria derived in this study (Bz ≤ −5 nT or Ey ≥ 3 mV/m for t≥ 2 h for moderate storms with minimum Dst less than −50 nT) and a Dst model developed by Temerin and Li (2002, 2006) (TL model). Using 55 CME-Dst pairs during 1997 to 2003, our solar wind criteria produce slightly better forecasts for 31 storm events (90%) than the forecasts based on the TL model (87%). However, the latter produces better forecasts for 24 nonstorm events (88%), while the former correctly forecasts only 71% of them. We then performed the two-step forecast. The results are as follows: (i) for 15 events that are incorrectly forecasted using CME parameters, 12 cases (80%) can be properly predicted based on solar wind conditions; (ii) if we forecast a storm when both CME and solar wind conditions are satisfied (∩), the critical success index becomes higher than that from the forecast using CME parameters alone, however, only 25 storm events (81%) are correctly forecasted; and (iii) if we forecast a storm when either set of these conditions is satisfied (∪), all geomagnetic storms are correctly forecasted. PMID:26213515

  15. Ensemble Forecasting of Coronal Mass Ejections Using the WSA-ENLIL with CONED Model

    Science.gov (United States)

    Emmons, D.; Acebal, A.; Pulkkinen, A.; Taktakishvili, A.; MacNeice, P.; Odstricil, D.

    2013-01-01

    The combination of the Wang-Sheeley-Arge (WSA) coronal model, ENLIL heliospherical model version 2.7, and CONED Model version 1.3 (WSA-ENLIL with CONED Model) was employed to form ensemble forecasts for 15 halo coronal mass ejections (halo CMEs). The input parameter distributions were formed from 100 sets of CME cone parameters derived from the CONED Model. The CONED Model used image processing along with the bootstrap approach to automatically calculate cone parameter distributions from SOHO/LASCO imagery based on techniques described by Pulkkinen et al. (2010). The input parameter distributions were used as input to WSA-ENLIL to calculate the temporal evolution of the CMEs, which were analyzed to determine the propagation times to the L1 Lagrangian point and the maximum Kp indices due to the impact of the CMEs on the Earth's magnetosphere. The Newell et al. (2007) Kp index formula was employed to calculate the maximum Kp indices based on the predicted solar wind parameters near Earth assuming two magnetic field orientations: a completely southward magnetic field and a uniformly distributed clock-angle in the Newell et al. (2007) Kp index formula. The forecasts for 5 of the 15 events had accuracy such that the actual propagation time was within the ensemble average plus or minus one standard deviation. Using the completely southward magnetic field assumption, 10 of the 15 events contained the actual maximum Kp index within the range of the ensemble forecast, compared to 9 of the 15 events when using a uniformly distributed clock angle.

  16. Statistical Study of the Interplanetary Coronal Mass Ejections from 1995 to 2015

    Science.gov (United States)

    Chi, Yutian; Shen, Chenglong; Wang, Yuming; Xu, Mengjiao; Ye, Pinzhong; Wang, Shui

    2016-10-01

    We establish a catalog of interplanetary coronal mass ejections (ICMEs) during the period from 1995 to 2015 using the in-situ observations from the Wind and ACE spacecraft. Based on this catalog, we extend the statistical properties of ICMEs to the maximum phase of Solar Cycle 24. We confirm previous results that the yearly occurrence frequencies of ICMEs and shocks, the ratios of ICMEs driving shocks are correlated with the sunspot numbers. For the magnetic cloud (MC), we confirm that the yearly occurrence frequencies of MCs do not show any correlation with sunspot numbers. The highest MC ratio of ICME occurred near the solar minimum. In addition, we analyzed the yearly variation of the ICME parameters. We found that the ICME velocities, the magnetic-field strength, and their related parameters are varied in pace with solar-cycle variation. At the solar maximum, ICMEs move faster and carry a stronger magnetic field. By comparing the parameters between MCs and non-MC ejecta, we confirm the result that the magnetic-field intensities of MC are higher than those in non-MC ejecta. Furthermore, we also discuss the forward shocks driven by ICMEs. We find that one half of the ICMEs have upstream shocks and ICMEs with shocks have faster speed and higher magnetic-field strength than the ICMEs without shocks. The magnetic-field parameters and solar-wind plasma parameters in the shock sheath regions are higher than those in the ejecta regions of ICMEs from a statistical point of view.

  17. Do interacting coronal mass ejections play a role in solar energetic particle events?

    Energy Technology Data Exchange (ETDEWEB)

    Kahler, S. W. [Air Force Research Laboratory, Space Vehicles Directorate, 3550 Aberdeen Avenue, Kirtland AFB, NM 87117 (United States); Vourlidas, A., E-mail: stephen.kahler@kirtland.af.mil [Space Sciences Division, Naval Research Laboratory, Washington, DC 20375 (United States)

    2014-03-20

    Gradual solar energetic (E > 10 MeV) particle (SEP) events are produced in shocks driven by fast and wide coronal mass ejections (CMEs). With a set of western hemisphere 20 MeV SEP events, we test the possibility that SEP peak intensities, Ip, are enhanced by interactions of their associated CMEs with preceding CMEs (preCMEs) launched during the previous 12 hr. Among SEP events with no, 1, or 2 or more (2+) preCMEs, we find enhanced Ip for the groups with preCMEs, but no differences in TO+TR, the time from CME launch to SEP onset and the time from onset to SEP half-peak Ip. Neither the timings of the preCMEs relative to their associated CMEs nor the preCME widths W {sub pre}, speeds V {sub pre}, or numbers correlate with the SEP Ip values. The 20 MeV Ip of all the preCME groups correlate with the 2 MeV proton background intensities, consistent with a general correlation with possible seed particle populations. Furthermore, the fraction of CMEs with preCMEs also increases with the 2 MeV proton background intensities. This implies that the higher SEP Ip values with preCMEs may not be due primarily to CME interactions, such as the 'twin-CME' scenario, but are explained by a general increase of both background seed particles and more frequent CMEs during times of higher solar activity. This explanation is not supported by our analysis of 2 MeV proton backgrounds in two earlier preCME studies of SEP events, so the relevance of CME interactions for larger SEP event intensities remains unclear.

  18. DIRECT OBSERVATIONS OF MAGNETIC FLUX ROPE FORMATION DURING A SOLAR CORONAL MASS EJECTION

    Energy Technology Data Exchange (ETDEWEB)

    Song, H. Q.; Chen, Y. [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment and Institute of Space Sciences, Shandong University, Weihai, Shandong 264209 (China); Zhang, J. [School of Physics, Astronomy and Computational Sciences, George Mason University, Fairfax, VA 22030 (United States); Cheng, X., E-mail: hqsong@sdu.edu.cn [School of Astronomy and Space Science, Nanjing University, Nanjing, Jiangsu 210093 (China)

    2014-09-10

    Coronal mass ejections (CMEs) are the most spectacular eruptive phenomena in the solar atmosphere. It is generally accepted that CMEs are the results of eruptions of magnetic flux ropes (MFRs). However, there is heated debate on whether MFRs exist prior to the eruptions or if they are formed during the eruptions. Several coronal signatures, e.g., filaments, coronal cavities, sigmoid structures, and hot channels (or hot blobs), are proposed as MFRs and observed before the eruption, which support the pre-existing MFR scenario. There is almost no reported observation of MFR formation during the eruption. In this Letter, we present an intriguing observation of a solar eruptive event that occurred on 2013 November 21 with the Atmospheric Imaging Assembly on board the Solar Dynamic Observatory, which shows the formation process of the MFR during the eruption in detail. The process began with the expansion of a low-lying coronal arcade, possibly caused by the flare magnetic reconnection underneath. The newly formed ascending loops from below further pushed the arcade upward, stretching the surrounding magnetic field. The arcade and stretched magnetic field lines then curved in just below the arcade vertex, forming an X-point. The field lines near the X-point continued to approach each other and a second magnetic reconnection was induced. It is this high-lying magnetic reconnection that led to the formation and eruption of a hot blob (∼10 MK), presumably an MFR, producing a CME. We suggest that two spatially separated magnetic reconnections occurred in this event, which were responsible for producing the flare and the hot blob (CME)

  19. Investigating the kinematics of coronal mass ejections with the automated CORIMP catalog

    Directory of Open Access Journals (Sweden)

    Byrne Jason P.

    2015-01-01

    Full Text Available Studying coronal mass ejections (CMEs in coronagraph data can be challenging due to their diffuse structure and transient nature, compounded by the variations in their dynamics, morphology and frequency of occurrence. The large amounts of data available from missions like the Solar and Heliospheric Observatory (SOHO make manual cataloging of CMEs tedious and prone to human error, and so a robust method of detection and analysis is required and often preferred. A new coronal image processing catalog called CORIMP has been developed in an effort to achieve this, through the implementation of a dynamic background separation technique and multiscale edge detection. These algorithms together isolate and characterise CME structure in the field-of-view of the Large Angle Spectrometric Coronagraph (LASCO onboard SOHO. CORIMP also applies a Savitzky-Golay filter, along with quadratic and linear fits, to the height-time measurements for better revealing the true CME speed and acceleration profiles across the plane-of-sky. Here we present a sample of new results from the CORIMP CME catalog, and directly compare them with the other automated catalogs of Computer Aided CME Tracking (CACTus and Solar Eruptive Events Detection System (SEEDS, as well as the manual CME catalog at the Coordinated Data Analysis Workshop (CDAW Data Center and a previously published study of the sample events. We further investigate a form of unsupervised machine learning by using a k-means clustering algorithm to distinguish detections of multiple CMEs that occur close together in space and time. While challenges still exist, this investigation and comparison of results demonstrate the reliability and robustness of the CORIMP catalog, proving its effectiveness at detecting and tracking CMEs throughout the LASCO dataset.

  20. Planar magnetic structures in coronal mass ejection-driven sheath regions

    Energy Technology Data Exchange (ETDEWEB)

    Palmerio, Erika; Kilpua, Emilia K.J. [Helsinki Univ. (Finland). Dept. of Physics; Savani, Neel P. [Maryland Univ., Baltimore County, MD (United States). Goddard Planetary Heliophysics Inst. (GPHI); NASA Goddard Space Flight Center, Greenbelt, MD (United States)

    2016-05-01

    Planar magnetic structures (PMSs) are periods in the solar wind during which interplanetary magnetic field vectors are nearly parallel to a single plane. One of the specific regions where PMSs have been reported are coronal mass ejection (CME)-driven sheaths. We use here an automated method to identify PMSs in 95 CME sheath regions observed in situ by the Wind and ACE spacecraft between 1997 and 2015. The occurrence and location of the PMSs are related to various shock, sheath, and CME properties. We find that PMSs are ubiquitous in CME sheaths; 85% of the studied sheath regions had PMSs with the mean duration of 6 h. In about one-third of the cases the magnetic field vectors followed a single PMS plane that covered a significant part (at least 67 %) of the sheath region. Our analysis gives strong support for two suggested PMS formation mechanisms: the amplification and alignment of solar wind discontinuities near the CME-driven shock and the draping of the magnetic field lines around the CME ejecta. For example, we found that the shock and PMS plane normals generally coincided for the events where the PMSs occurred near the shock (68% of the PMS plane normals near the shock were separated by less than 20 from the shock normal), while deviations were clearly larger when PMSs occurred close to the ejecta leading edge. In addition, PMSs near the shock were generally associated with lower upstream plasma beta than the cases where PMSs occurred near the leading edge of the CME. We also demonstrate that the planar parts of the sheath contain a higher amount of strong southward magnetic field than the non-planar parts, suggesting that planar sheaths are more likely to drive magnetospheric activity.

  1. Development of a Full Ice-cream Cone Model for Halo Coronal Mass Ejections

    Science.gov (United States)

    Na, Hyeonock; Moon, Y.-J.; Lee, Harim

    2017-04-01

    It is essential to determine three-dimensional parameters (e.g., radial speed, angular width, and source location) of coronal mass ejections (CMEs) for the space weather forecast. In this study, we investigate which cone type represents a halo CME morphology using 29 CMEs (12 Solar and Heliospheric Observatory (SOHO)/Large Angle and Spectrometric Coronagraph (LASCO) halo CMEs and 17 Solar Terrestrial Relations Observatory (STEREO)/Sun-Earth Connection Coronal and Heliospheric Investigation COR2 halo CMEs) from 2010 December to 2011 June. These CMEs are identified as halo CMEs by one spacecraft (SOHO or one of STEREO A and B) and limb ones by the other spacecraft (One of STEREO A and B or SOHO). From cone shape parameters of these CMEs, such as their front curvature, we find that the CME observational structures are much closer to a full ice-cream cone type than a shallow ice-cream cone type. Thus, we develop a full ice-cream cone model based on a new methodology that the full ice-cream cone consists of many flat cones with different heights and angular widths to estimate the three-dimensional parameters of the halo CMEs. This model is constructed by carrying out the following steps: (1) construct a cone for a given height and angular width, (2) project the cone onto the sky plane, (3) select points comprising the outer boundary, and (4) minimize the difference between the estimated projection speeds with the observed ones. By applying this model to 12 SOHO/LASCO halo CMEs, we find that 3D parameters from our method are similar to those from other stereoscopic methods (i.e., a triangulation method and a Graduated Cylindrical Shell model).

  2. Statistical properties of solar flares and coronal mass ejections through the solar cycle

    Energy Technology Data Exchange (ETDEWEB)

    Telloni, Daniele; Antonucci, Ester [INAF-Astrophysical Observatory of Torino, Via Osservatorio 20, 10025 Pino Torinese (Italy); Carbone, Vincenzo [University of Calabria, Department of Physics, Ponte P. Bucci Cubo 31C, 87036 Rende (Italy); CNR-Institute for Chemical-Physical Processes, Ponte P. Bucci Cubo 33B, 87036 Rende (Italy); Lepreti, Fabio [University of Calabria, Department of Physics, Ponte P. Bucci Cubo 31C, 87036 Rende (Italy)

    2016-03-25

    Waiting Time Distributions (WTDs) of solar flares are investigated all through the solar cycle. The same approach applied to Coronal Mass Ejections (CMEs) in a previous work is considered here for flare occurrence. Our analysis reveals that flares and CMEs share some common statistical properties, which result dependent on the level of solar activity. Both flares and CMEs seem to independently occur during minimum solar activity phases, whilst their WTDs significantly deviate from a Poisson function at solar maximum, thus suggesting that these events are correlated. The characteristics of WTDs are constrained by the physical processes generating those eruptions associated with flares and CMEs. A scenario may be drawn in which different mechanisms are actively at work during different phases of the solar cycle. Stochastic processes, most likely related to random magnetic reconnections of the field lines, seem to play a key role during solar minimum periods. On the other hand, persistent processes, like sympathetic eruptions associated to the variability of the photospheric magnetism, are suggested to dominate during periods of high solar activity. Moreover, despite the similar statistical properties shown by flares and CMEs, as it was mentioned above, their WTDs appear different in some aspects. During solar minimum periods, the flare occurrence randomness seems to be more evident than for CMEs. Those persistent mechanisms generating interdependent events during maximum periods of solar activity can be suggested to play a more important role for CMEs than for flares, thus mitigating the competitive action of the random processes, which seem instead strong enough to weaken the correlations among flare event occurrence during solar minimum periods. However, it cannot be excluded that the physical processes at the basis of the origin of the temporal correlation between solar events are different for flares and CMEs, or that, more likely, more sophisticated effects are

  3. A Numerical Study of Long-range Magnetic Impacts during Coronal Mass Ejections

    Science.gov (United States)

    Jin, M.; Schrijver, C. J.; Cheung, M. C. M.; DeRosa, M. L.; Nitta, N. V.; Title, A. M.

    2016-03-01

    With the global view and high-cadence observations from Solar Dynamics Observatory/Atmospheric Imaging Assembly and Solar TErrestrial RElations Observatory, many spatially separated solar eruptive events appear to be coupled. However, the mechanisms for “sympathetic” events are still largely unknown. In this study, we investigate the impact of an erupting flux rope on surrounding solar structures through large-scale magnetic coupling. We build a realistic environment of the solar corona on 2011 February 15 using a global magnetohydrodynamics model and initiate coronal mass ejections (CMEs) in active region 11158 by inserting Gibson-Low analytical flux ropes. We show that a CME’s impact on the surrounding structures depends not only on the magnetic strength of these structures and their distance to the source region, but also on the interaction between the CME and the large-scale magnetic field. Within the CME expansion domain where the flux rope field directly interacts with the solar structures, expansion-induced reconnection often modifies the overlying field, thereby increasing the decay index. This effect may provide a primary coupling mechanism underlying the sympathetic eruptions. The magnitude of the impact is found to depend on the orientation of the erupting flux rope, with the largest impacts occurring when the flux rope is favorably oriented for reconnecting with the surrounding regions. Outside the CME expansion domain, the influence of the CME is mainly through field line compression or post-eruption relaxation. Based on our numerical experiments, we discuss a way to quantify the eruption impact, which could be useful for forecasting purposes.

  4. A NUMERICAL STUDY OF LONG-RANGE MAGNETIC IMPACTS DURING CORONAL MASS EJECTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Jin, M.; Schrijver, C. J.; Cheung, M. C. M.; DeRosa, M. L.; Nitta, N. V.; Title, A. M., E-mail: jinmeng@lmsal.com [Lockheed Martin Solar and Astrophysics Lab, Palo Alto, CA 94304 (United States)

    2016-03-20

    With the global view and high-cadence observations from Solar Dynamics Observatory/Atmospheric Imaging Assembly and Solar TErrestrial RElations Observatory, many spatially separated solar eruptive events appear to be coupled. However, the mechanisms for “sympathetic” events are still largely unknown. In this study, we investigate the impact of an erupting flux rope on surrounding solar structures through large-scale magnetic coupling. We build a realistic environment of the solar corona on 2011 February 15 using a global magnetohydrodynamics model and initiate coronal mass ejections (CMEs) in active region 11158 by inserting Gibson–Low analytical flux ropes. We show that a CME’s impact on the surrounding structures depends not only on the magnetic strength of these structures and their distance to the source region, but also on the interaction between the CME and the large-scale magnetic field. Within the CME expansion domain where the flux rope field directly interacts with the solar structures, expansion-induced reconnection often modifies the overlying field, thereby increasing the decay index. This effect may provide a primary coupling mechanism underlying the sympathetic eruptions. The magnitude of the impact is found to depend on the orientation of the erupting flux rope, with the largest impacts occurring when the flux rope is favorably oriented for reconnecting with the surrounding regions. Outside the CME expansion domain, the influence of the CME is mainly through field line compression or post-eruption relaxation. Based on our numerical experiments, we discuss a way to quantify the eruption impact, which could be useful for forecasting purposes.

  5. Two-Step Forecast of Geomagnetic Storm Using Coronal Mass Ejection and Solar Wind Condition

    Science.gov (United States)

    Kim, R.-S.; Moon, Y.-J.; Gopalswamy, N.; Park, Y.-D.; Kim, Y.-H.

    2014-01-01

    To forecast geomagnetic storms, we had examined initially observed parameters of coronal mass ejections (CMEs) and introduced an empirical storm forecast model in a previous study. Now we suggest a two-step forecast considering not only CME parameters observed in the solar vicinity but also solar wind conditions near Earth to improve the forecast capability. We consider the empirical solar wind criteria derived in this study (Bz = -5 nT or Ey = 3 mV/m for t = 2 h for moderate storms with minimum Dst less than -50 nT) (i.e. Magnetic Field Magnitude, B (sub z) less than or equal to -5 nanoTeslas or duskward Electrical Field, E (sub y) greater than or equal to 3 millivolts per meter for time greater than or equal to 2 hours for moderate storms with Minimum Disturbance Storm Time, Dst less than -50 nanoTeslas) and a Dst model developed by Temerin and Li (2002, 2006) (TL [i.e. Temerin Li] model). Using 55 CME-Dst pairs during 1997 to 2003, our solar wind criteria produce slightly better forecasts for 31 storm events (90 percent) than the forecasts based on the TL model (87 percent). However, the latter produces better forecasts for 24 nonstorm events (88 percent), while the former correctly forecasts only 71 percent of them. We then performed the two-step forecast. The results are as follows: (i) for 15 events that are incorrectly forecasted using CME parameters, 12 cases (80 percent) can be properly predicted based on solar wind conditions; (ii) if we forecast a storm when both CME and solar wind conditions are satisfied (n, i.e. cap operator - the intersection set that is comprised of all the elements that are common to both), the critical success index becomes higher than that from the forecast using CME parameters alone, however, only 25 storm events (81 percent) are correctly forecasted; and (iii) if we forecast a storm when either set of these conditions is satisfied (?, i.e. cup operator - the union set that is comprised of all the elements of either or both

  6. Coronal mass ejection-related particle acceleration regions during a simple eruptive event

    Science.gov (United States)

    Salas-Matamoros, Carolina; Klein, Karl-Ludwig; Rouillard, Alexis P.

    2016-05-01

    An intriguing feature of many solar energetic particle (SEP) events is the detection of particles over a very extended range of longitudes in the heliosphere. This may be due to peculiarities of the magnetic field in the corona, to a broad accelerator, to cross-field transport of the particles, or to a combination of these processes. The eruptive flare on 26 April 2008 provided an opportunity to study relevant processes under particularly favourable conditions since it occurred in a very quiet solar and interplanetary environment. This enabled us to investigate the physical link between a single well-identified coronal mass ejection (CME), electron acceleration as traced by radio emission, and the production of SEPs. We conduct a detailed analysis, which combines radio observations (Nançay Radio Heliograph and Nançay Decametre Array, Wind/Waves spectrograph) with remote-sensing observations of the corona in extreme ultraviolet (EUV) and white light, as well as in situ measurements of energetic particles near 1AU (SoHO and STEREO spacecraft). By combining images taken from multiple vantage points, we were able to derive the time-dependent evolution of the 3D pressure front that was developing around the erupting CME. Magnetic reconnection in the post-CME current sheet accelerated electrons, which remained confined in closed magnetic fields in the corona, while the acceleration of escaping particles can be attributed to the pressure front ahead of the expanding CME. The CME accelerated electrons remotely from the parent active region, owing to the interaction of its laterally expanding flank, which was traced by an EUV wave, with the ambient corona. SEPs detected at one STEREO spacecraft and SoHO were accelerated later, when the frontal shock of the CME intercepted the spacecraft-connected interplanetary magnetic field line. The injection regions into the heliosphere inferred from the radio and SEP observations are separated in longitude by about 140°. The

  7. Global Energetics of Solar Flares. V. Energy Closure in Flares and Coronal Mass Ejections

    Science.gov (United States)

    Aschwanden, Markus J.; Caspi, Amir; Cohen, Christina M. S.; Holman, Gordon; Jing, Ju; Kretzschmar, Matthieu; Kontar, Eduard P.; McTiernan, James M.; Mewaldt, Richard A.; O’Flannagain, Aidan; Richardson, Ian G.; Ryan, Daniel; Warren, Harry P.; Xu, Yan

    2017-02-01

    In this study we synthesize the results of four previous studies on the global energetics of solar flares and associated coronal mass ejections (CMEs), which include magnetic, thermal, nonthermal, and CME energies in 399 solar M- and X-class flare events observed during the first 3.5 yr of the Solar Dynamics Observatory (SDO) mission. Our findings are as follows. (1) The sum of the mean nonthermal energy of flare-accelerated particles ({E}{nt}), the energy of direct heating ({E}{dir}), and the energy in CMEs ({E}{CME}), which are the primary energy dissipation processes in a flare, is found to have a ratio of ({E}{nt}+{E}{dir}+{E}{CME})/{E}{mag}=0.87+/- 0.18, compared with the dissipated magnetic free energy {E}{mag}, which confirms energy closure within the measurement uncertainties and corroborates the magnetic origin of flares and CMEs. (2) The energy partition of the dissipated magnetic free energy is: 0.51 ± 0.17 in nonthermal energy of ≥slant 6 {keV} electrons, 0.17 ± 0.17 in nonthermal ≥slant 1 {MeV} ions, 0.07 ± 0.14 in CMEs, and 0.07 ± 0.17 in direct heating. (3) The thermal energy is almost always less than the nonthermal energy, which is consistent with the thick-target model. (4) The bolometric luminosity in white-light flares is comparable to the thermal energy in soft X-rays (SXR). (5) Solar energetic particle events carry a fraction ≈ 0.03 of the CME energy, which is consistent with CME-driven shock acceleration. (6) The warm-target model predicts a lower limit of the low-energy cutoff at {e}c≈ 6 {keV}, based on the mean peak temperature of the differential emission measure of T e = 8.6 MK during flares. This work represents the first statistical study that establishes energy closure in solar flare/CME events.

  8. Solar flares, coronal mass ejections and solar energetic particle event characteristics

    Directory of Open Access Journals (Sweden)

    Papaioannou Athanasios

    2016-01-01

    Full Text Available A new catalogue of 314 solar energetic particle (SEP events extending over a large time span from 1984 to 2013 has been compiled. The properties as well as the associations of these SEP events with their parent solar sources have been thoroughly examined. The properties of the events include the proton peak integral flux and the fluence for energies above 10, 30, 60 and 100 MeV. The associated solar events were parametrized by solar flare (SF and coronal mass ejection (CME characteristics, as well as related radio emissions. In particular, for SFs: the soft X-ray (SXR peak flux, the SXR fluence, the heliographic location, the rise time and the duration were exploited; for CMEs the plane-of-sky velocity as well as the angular width were utilized. For radio emissions, type III, II and IV radio bursts were identified. Furthermore, we utilized element abundances of Fe and O. We found evidence that most of the SEP events in our catalogue do not conform to a simple two-class paradigm, with the 73% of them exhibiting both type III and type II radio bursts, and that a continuum of event properties is present. Although, the so-called hybrid or mixed events are found to be present in our catalogue, it was not possible to attribute each SEP event to a mixed/hybrid sub-category. Moreover, it appears that the start of the type III burst most often precedes the maximum of the SF and thus falls within the impulsive phase of the associated SF. At the same time, type III bursts take place within ≈5.22 min, on average, in advance from the time of maximum of the derivative of the SXR flux (Neupert effect. We further performed a statistical analysis and a mapping of the logarithm of the proton peak flux at E > 10 MeV, on different pairs of the parent solar source characteristics. This revealed correlations in 3-D space and demonstrated that the gradual SEP events that stem from the central part of the visible solar disk constitute a significant radiation

  9. Solar and interplanetary activities of isolated and non-isolated coronal mass ejections

    Science.gov (United States)

    Bendict Lawrance, M.; Shanmugaraju, A.; Moon, Y.-J.; Umapathy, S.

    2017-07-01

    We report our results on comparison of two halo Coronal Mass Ejections (CME) associated with X-class flares of similar strength (X1.4) but quite different in CME speed and acceleration, similar geo-effectiveness but quite different in Solar Energetic Particle (SEP) intensity. CME1 (non-isolated) was associated with a double event in X-ray flare and it was preceded by another fast halo CME of speed = 2684 km/s (pre-CME) associated with X-ray flare class X5.4 by 1 h from the same location. Since this pre-CME was more eastern, interaction with CME1 and hitting the earth were not possible. This event (CME1) has not suffered the cannibalism since pre-CME has faster speed than post-CME. Pre-CME plays a very important role in increasing the intensity of SEP and Forbush Decrease (FD) by providing energetic seed particles. So, the seed population is the major difference between these two selected events. CME2 (isolated) was a single event. We would like to address on the kinds of physical conditions related to such CMEs and their associated activities. Their associated activities such as, type II bursts, SEP, geomagnetic storm and FD are compared. The following results are obtained from the analysis. (1) The CME leading edge height at the start of metric/DH type II bursts are 2 R⊙/ 4 R⊙ for CME1, but 2 R⊙/ 2.75 R⊙ for CME2. (2) Peak intensity of SEP event associated with the two CMEs are quite different: 6530 pfu for CME1, but 96 pfu for CME2. (3) The Forbush decrease occurred with a minimum decrease of 9.98% in magnitude for CME1, but 6.90% for CME2. (4) These two events produced similar intense geomagnetic storms of intensity of Dst index -130 nT. (5) The maximum southward magnetic fields corresponding to Interplanetary CME (ICME) of these two events are nearly the same, but there is difference in Sheath Bz maximum (-14.2, -6.9 nT). (6) The time-line chart of the associated activities of two CMEs show some difference in the time delay between the onsets of

  10. Solar flares, coronal mass ejections and solar energetic particle event characteristics

    Science.gov (United States)

    Papaioannou, Athanasios; Sandberg, Ingmar; Anastasiadis, Anastasios; Kouloumvakos, Athanasios; Georgoulis, Manolis K.; Tziotziou, Kostas; Tsiropoula, Georgia; Jiggens, Piers; Hilgers, Alain

    2016-12-01

    A new catalogue of 314 solar energetic particle (SEP) events extending over a large time span from 1984 to 2013 has been compiled. The properties as well as the associations of these SEP events with their parent solar sources have been thoroughly examined. The properties of the events include the proton peak integral flux and the fluence for energies above 10, 30, 60 and 100 MeV. The associated solar events were parametrized by solar flare (SF) and coronal mass ejection (CME) characteristics, as well as related radio emissions. In particular, for SFs: the soft X-ray (SXR) peak flux, the SXR fluence, the heliographic location, the rise time and the duration were exploited; for CMEs the plane-of-sky velocity as well as the angular width were utilized. For radio emissions, type III, II and IV radio bursts were identified. Furthermore, we utilized element abundances of Fe and O. We found evidence that most of the SEP events in our catalogue do not conform to a simple two-class paradigm, with the 73% of them exhibiting both type III and type II radio bursts, and that a continuum of event properties is present. Although, the so-called hybrid or mixed events are found to be present in our catalogue, it was not possible to attribute each SEP event to a mixed/hybrid sub-category. Moreover, it appears that the start of the type III burst most often precedes the maximum of the SF and thus falls within the impulsive phase of the associated SF. At the same time, type III bursts take place within ≈5.22 min, on average, in advance from the time of maximum of the derivative of the SXR flux (Neupert effect). We further performed a statistical analysis and a mapping of the logarithm of the proton peak flux at E > 10 MeV, on different pairs of the parent solar source characteristics. This revealed correlations in 3-D space and demonstrated that the gradual SEP events that stem from the central part of the visible solar disk constitute a significant radiation risk. The velocity of

  11. Testing ElEvoHI on a multi-point in situ detected Coronal Mass Ejection

    Science.gov (United States)

    Amerstorfer, Tanja; Möstl, Christian; Hess, Phillip; Mays, M. Leila; Temmer, Manuela

    2017-04-01

    The Solar TErrestrial RElations Observatory (STEREO) has provided us a deep insight into the interplanetary propagation of coronal mass ejections (CMEs). Especially the wide-angle heliospheric imagers (HI) enabled the development of a multitude of methods for analyzing the evolution of CMEs through interplanetary (IP) space. Methods able to forecast arrival times and speeds at Earth (or other targets) use the advantage of following a CME's path of propagation up to 1 AU. However, these methods were not able to reduce today's errors in arrival time forecasts to less than ±6 hours, arrival speeds are mostly overestimated by some 100 km s-1. One reason for that is the assumption of constant propagation speed, which is clearly incorrect for most CMEs—especially for those being faster than the ambient solar wind. ElEvoHI, the Ellipse Evolution model (ElEvo) based on HI observations, is a new prediction tool, which uses the benefits of different methods and observations. It provides the possibility to adjust the CME frontal shape (angular width, ellipse aspect ratio) and the direction of motion for each CME event individually. This information can be gained from Graduated Cylindrical Shell (GCS) flux-rope fitting within coronagraph images. Using the Ellipse Conversion (ElCon) method, the observed HI elongation angle is converted into a unit of distance, which reveals the kinematics of the event. After fitting the time-distance profile of the CME using the drag-based equation of motion, where real-time in situ solar wind speed from 1 AU is used as additional input, we receive all input parameters needed to run a forecast using the ElEvo model and to predict arrival times and speeds at any target of interest in IP space. Here, we present a test on a slow CME event of 3 November 2010, in situ detected by the lined-up spacecraft MESSENGER and STEREO Behind. We gain the shape of the CME front from a cut of the 3D GCS CME shape with the ecliptic plane, resulting in an

  12. ARE DECAYING MAGNETIC FIELDS ABOVE ACTIVE REGIONS RELATED TO CORONAL MASS EJECTION ONSET?

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, J. [Department of Astronomy, University of California, Berkeley, CA 94720-7450 (United States); Welsch, B. T.; Li, Y. [Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450 (United States)

    2012-10-10

    Coronal mass ejections (CMEs) are powered by magnetic energy stored in non-potential (current-carrying) coronal magnetic fields, with the pre-CME field in balance between outward magnetic pressure of the proto-ejecta and inward magnetic tension from overlying fields that confine the proto-ejecta. In studies of global potential (current-free) models of coronal magnetic fields-Potential Field Source Surface (PFSS) models-it has been reported that model field strengths above flare sites tend to be weaker when CMEs occur than when eruptions fail to occur. This suggests that potential field models might be useful to quantify magnetic confinement. One straightforward implication of this idea is that a decrease in model field strength overlying a possible eruption site should correspond to diminished confinement, implying an eruption is more likely. We have searched for such an effect by post facto investigation of the time evolution of model field strengths above a sample of 10 eruption sites. To check if the strengths of overlying fields were relevant only in relatively slow CMEs, we included both slow and fast CMEs in our sample. In most events we study, we find no statistically significant evolution in either (1) the rate of magnetic field decay with height, (2) the strength of overlying magnetic fields near 50 Mm, or (3) the ratio of fluxes at low and high altitudes (below 1.1 R{sub Sun }, and between 1.1 and 1.5 R{sub Sun }, respectively). We did observe a tendency for overlying field strengths and overlying flux to increase slightly, and their rates of decay with height to become slightly more gradual, consistent with increased confinement. The fact that CMEs occur regardless of whether the parameters we use to quantify confinement are increasing or decreasing suggests that either (1) the parameters that we derive from PFSS models do not accurately characterize the actual large-scale field in CME source regions, (2) systematic evolution in the large-scale magnetic

  13. Near Real-Time Photometric Data Processing for the Solar Mass Ejection Imager (SMEI)

    Science.gov (United States)

    Hick, P. P.; Buffington, A.; Jackson, B. V.

    2004-12-01

    The Solar Mass Ejection Imager (SMEI) records a photometric white-light response of the interplanetary medium from Earth over most of the sky in near real time. In the first two years of operation the instrument has recorded the inner heliospheric response to several hundred CMEs, including the May 28, 2003 and the October 28, 2003 halo CMEs. In this preliminary work we present the techniques required to process the SMEI data from the time the raw CCD images become available to their final assembly in photometrically accurate maps of the sky brightness relative to a long-term time base. Processing of the SMEI data includes integration of new data into the SMEI data base; a conditioning program that removes from the raw CCD images an electronic offset ("pedestal") and a temperature-dependent dark current pattern; an "indexing" program that places these CCD images onto a high-resolution sidereal grid using known spacecraft pointing information. At this "indexing" stage further conditioning removes the bulk of the the effects of high-energy-particle hits ("cosmic rays"), space debris inside the field of view, and pixels with a sudden state change ("flipper pixels"). Once the high-resolution grid is produced, it is reformatted to a lower-resolution set of sidereal maps of sky brightness. From these sidereal maps we remove bright stars, background stars, and a zodiacal cloud model (their brightnesses are retained as additional data products). The final maps can be represented in any convenient sky coordinate system. Common formats are Sun-centered Hammer-Aitoff or "fisheye" maps. Time series at selected locations on these maps are extracted and processed further to remove aurorae, variable stars and other unwanted signals. These time series (with a long-term base removed) are used in 3D tomographic reconstructions. The data processing is distributed over multiple PCs running Linux, and, runs as much as possible automatically using recurring batch jobs ('cronjobs'). The

  14. Could Jupiter or Saturn Have Ejected a Fifth Giant Planet?

    CERN Document Server

    Cloutier, Ryan; Valencia, Diana

    2015-01-01

    Models of the dynamical evolution of the early solar system following the dispersal of the gaseous protoplanetary disk have been widely successful in reconstructing the current orbital configuration of the giant planets. Statistically, some of the most successful dynamical evolution simulations have initially included a hypothetical fifth giant planet, of ice giant mass, which gets ejected by a gas giant during the early solar system's proposed instability phase. We investigate the likelihood of an ice giant ejection event by either Jupiter or Saturn through constraints imposed by the current orbits of their wide-separation regular satellites Callisto and Iapetus respectively. We show that planetary encounters that are sufficient to eject an ice giant, often provide excessive perturbations to the orbits of Callisto and Iapetus making it difficult to reconcile a planet ejection event with the current orbit of either satellite. Quantitatively, we compute the likelihood of reconciling a regular Jovian satellite ...

  15. Real-time Analysis of Global Waves Accompanying Coronal Mass Ejections

    Science.gov (United States)

    2016-09-01

    Ejections FA9550-14-1-0213 Long, David M., Rae , I. Jonathan, Pérez-Suárez, D. University College London (UCL) Gower Street London WC1 E6BT European...significant portion of the Sun in under an hour. However, their origin and relationship to CMEs remains a mystery due to the manual techniques...1-0213 Principle Investigator; David M. Long Period of Performance; 1 October 2014 – 30 June 2016 Additional Staff; Jonathan Rae (Co–Investigator

  16. Exceptions to the rule: the X-flares of AR 2192 Lacking Coronal Mass Ejections

    Science.gov (United States)

    Thalmann, J. K.; Su, Y.; Temmer, M.; Veronig, A. M.

    2016-04-01

    NOAA Active region (AR) 2192, that was present on the Sun in October 2014, was the largest region which occurred since November 1990 (see Figure 1). The huge size accompanied by a very high activity level, was quite unexpected as it appeared during the unusually weak solar cycle 24. Nevertheless, the AR turned out to be one of the most prolific flaring ARs of cycle 24. It produced in total 6 X, 29 M, 79 C flares during its disk passage from October 18-29, 2014 (see Figure 2). Surprisingly, all flares greater than GOES class M5 and X were confined, i.e. had no coronal mass ejections (CME) associated. All the flare events had some obvious similarity in morphology, as they were located in the core of the AR and revealed only minor separation motion away from the neutral line but a large initial separation of the conjugate flare ribbons. In the paper by Thalmann et al. (2015) we describe the series of flares and give details about the confined X1.6 flare event from October 22, 2014 as well as the single eruptive M4.0 flare event from October 24, 2014. The study of the X1.6 flare revealed a large initial separation of flare ribbons together with recurrent flare brightenings, which were related to two episodes of enhanced hard X-ray emission as derived from RHESSI observations. This suggests that magnetic field structures connected to specific regions were repeatedly involved in the process of reconnection and energy release. Opposite to the central location of the sequence of confined events within the AR, a single eruptive (M4.0) event occurred on the outskirt of the AR in the vicinity of open magnetic fields. Our investigations revealed a predominantly north-south oriented magnetic system of arcade fields overlying the AR that could have preserved the magnetic arcade to erupt, and consequently kept the energy release trapped in a localized volume of magnetic field high up in the corona (as supported by the absence of a lateral motion of the flare ribbons and the

  17. Heights of Coronal Mass Ejections and Shocks Inferred from Metric and DH Type II Radio Bursts

    Science.gov (United States)

    Shanmugaraju, A.; Bendict Lawrance, M.; Moon, Y. J.; Lee, Jae-Ok; Suresh, K.

    2017-09-01

    A set of 27 continuous events that showed extension of metric Type-II radio bursts (m-Type IIs) into the deca-hectometric (DH) domain is considered. The coronal mass ejections (CMEs) associated with this type of continuous event supply more energy to produce space-weather effects than the CMEs that produce Type-II bursts in any one region. Since the heights of shock formation at the start of m-Type IIs were not available from observations, they were estimated using kinematic modeling in previous studies. In the present study, the heights of shock formation during metric and DH Type-II bursts are determined using two methods: i) the CME leading-edge method and ii) a method employing known electron-density models and start/end frequencies. In the first method, assuming that the shocks are generated by the associated CMEs at the leading edge, the height of the CME leading edge (LE) is calculated at the onset and end of m-Type IIs using the kinematic equation with constant acceleration or constant speed. The LE heights of CMEs that are assumed to be the heights of shock formation/end of nearly 79% of m-Type IIs are found to be within the acceptable range of 1 - 3 R_{⊙}. For other events, the heights are beyond this range, for which the shocks might either have been generated at the CME flanks/flare-blast waves, or the initial CME height might have been different. The CME/shock height at the onset and end of 17 DH Type IIs are found to be in the range of 2 - 6 R_{⊙} and within 30 R_{⊙}, respectively. In addition, the CME LE heights from observations at the onset and end of metric/DH Type IIs are compared with the heights corresponding to the observed frequency that is determined using the known electron-density models, and they are in agreement with the model results. The heights are also estimated using the space speed available for 15 halo CMEs, and it is found that the difference is smaller at the m-Type II start/end (0.02 to 0.66 R_{⊙}) and slightly greater

  18. Evidence for a current sheet forming in the wake of a Coronal Mass Ejection from multi-viewpoint coronagraph observations

    OpenAIRE

    Patsourakos, S.; Vourlidas, A.

    2010-01-01

    Ray-like features observed by coronagraphs in the wake of Coronal Mass Ejections (CMEs) are sometimes interpreted as the white light counterparts of current sheets (CSs) produced by the eruption. The 3D geometry of these ray-like features is largely unknown and its knowledge should clarify their association to the CS and place constraints on CME physics and coronal conditions. With this study we test these important implications for the first time. An example of such a post-CME ray was observ...

  19. An estimate of the magnetic field strength associated with a solar coronal mass ejection from low frequency radio observations

    CERN Document Server

    Raja, K Sasikumar; Hariharan, K; Kathiravan, C; Wang, T J

    2016-01-01

    We report ground based, low frequency heliograph (80 MHz), spectral (85-35 MHz) and polarimeter (80 and 40 MHz) observations of drifting, non-thermal radio continuum associated with the `halo' coronal mass ejection (CME) that occurred in the solar atmosphere on 2013 March 15. The magnetic field strengths ($B$) near the radio source were estimated to be $B \\approx 2.2 \\pm 0.4$ G at 80 MHz and $B \\approx 1.4 \\pm 0.2$ G at 40 MHz. The corresponding radial distances ($r$) are $r \\approx 1.9~R_{\\odot}$ (80 MHz) and $r \\approx 2.2~R_{\\odot}$ (40 MHz).

  20. The Mass Dependence of Dwarf Satellite Galaxy Quenching

    CERN Document Server

    Slater, Colin T

    2014-01-01

    We combine observations of the Local Group with data from the NASA-Sloan Atlas to show the variation in the quenched fraction of satellite galaxies from low mass dwarf spheroidals and dwarf irregulars to more massive dwarfs similar to the Magellanic clouds. While almost all of the low mass ($M_\\star \\lesssim 10^7$ $M_\\odot$) dwarfs are quenched, at higher masses the quenched fraction decreases to approximately 40-50%. This change in the quenched fraction is large, and suggests a sudden change in the effectiveness of quenching that correlates with satellite mass. We combine this observation with models of satellite infall and ram pressure stripping to show that the low mass satellites must quench within 1-2 Gyr of pericenter passage to maintain a high quenched fraction, but that many more massive dwarfs must continue to form stars today even though they likely fell in to their host >5 Gyr ago. We also characterize how the susceptibility of dwarfs to ram pressure must vary as a function of mass if it is to acco...

  1. Predictions of the arrival time of Coronal Mass Ejections at 1AU: an analysis of the causes of errors

    Directory of Open Access Journals (Sweden)

    M. Owens

    2004-01-01

    Full Text Available Three existing models of Interplanetary Coronal Mass Ejection (ICME transit between the Sun and the Earth are compared to coronagraph and in situ observations: all three models are found to perform with a similar level of accuracy (i.e. an average error between observed and predicted 1AU transit times of approximately 11h. To improve long-term space weather prediction, factors influencing CME transit are investigated. Both the removal of the plane of sky projection (as suffered by coronagraph derived speeds of Earth directed CMEs and the use of observed values of solar wind speed, fail to significantly improve transit time prediction. However, a correlation is found to exist between the late/early arrival of an ICME and the width of the preceding sheath region, suggesting that the error is a geometrical effect that can only be removed by a more accurate determination of a CME trajectory and expansion. The correlation between magnetic field intensity and speed of ejecta at 1AU is also investigated. It is found to be weak in the body of the ICME, but strong in the sheath, if the upstream solar wind conditions are taken into account.

    Key words. Solar physics, astronomy and astrophysics (flares and mass ejections – Interplanetary physics (interplanetary magnetic fields; sources of the solar wind

  2. Connecting speeds, directions and arrival times of 22 coronal mass ejections from the Sun to 1 AU

    CERN Document Server

    Möstl, C; Hall, J R; Liewer, P C; De Jong, E M; Colaninno, R C; Veronig, A M; Rollett, T; Temmer, M; Peinhart, V; Davies, J A; Lugaz, N; Liu, Y D; Farrugia, C J; Luhmann, J G; Vršnak, B; Harrison, R A; Galvin, A B

    2014-01-01

    Forecasting the in situ properties of coronal mass ejections (CMEs) from remote images is expected to strongly enhance predictions of space weather, and is of general interest for studying the interaction of CMEs with planetary environments. We study the feasibility of using a single heliospheric imager (HI) instrument, imaging the solar wind density from the Sun to 1 AU, for connecting remote images to in situ observations of CMEs. We compare the predictions of speed and arrival time for 22 CMEs (in 2008-2012) to the corresponding interplanetary coronal mass ejection (ICME) parameters at in situ observatories (STEREO PLASTIC/IMPACT, Wind SWE/MFI). The list consists of front- and backsided, slow and fast CMEs (up to $2700 \\: km \\: s^{-1}$). We track the CMEs to $34.9 \\pm 7.1$ degrees elongation from the Sun with J-maps constructed using the SATPLOT tool, resulting in prediction lead times of $-26.4 \\pm 15.3$ hours. The geometrical models we use assume different CME front shapes (Fixed-$\\Phi$, Harmonic Mean, S...

  3. Baryons Matter: Why Luminous Satellite Galaxies Have Reduced Central Masses

    CERN Document Server

    Zolotov, Adi; Willman, Beth; Governato, Fabio; Pontzen, Andrew; Christensen, Charlotte; Dekel, Avishai; Quinn, Tom; Shen, Sijing; Wadsley, James

    2012-01-01

    Using high resolution cosmological hydrodynamical simulations of Milky Way-massed disk galaxies, we demonstrate that supernovae feedback and tidal stripping lower the central masses of bright (-14 10^9 Msun, Mstar > 10^7 Msun) compared to DM-only simulations. The progenitors of the lower mass satellites are unable to maintain bursty star formation histories, due to both heating at reionization and gas loss from initial star forming events, preserving the steep inner density profile predicted by DM-only simulations. After infall, tidal stripping acts to further reduce the central densities of the luminous satellites, particularly those that enter with cored dark matter halos, increasing the discrepancy in the central masses predicted by baryon+DM and DM-only simulations. We show that DM-only simulations, which neglect the baryonic effects described in this work, produce denser satellites with larger central velocities. We provide a simple correction to the central DM mass predicted for satellites by DM-only s...

  4. Kinematic and morphological evolution and dynamics of coronal mass ejections in interplanetary space

    Science.gov (United States)

    Poomvises, Watanachak

    2010-12-01

    Studies of Coronal mass ejections (CMEs) are scientifically intriguing and practically important. CMEs are the main driver of space weather that specifies plasma, magnetic and particle conditions in near-Earth space. When CMEs pass through and interact with the Earth's magnetosphere, they can cause significant disruption in space and produce a variety of harmful effects on human's technological systems from space to the ground. Many studies have been carried out to understand their evolution. However, their kinematic and morphological evolution as they pass from Sun to Earth is still poorly understood, largely due to the lack of direct observations. Since the launch of the twin-STEREO spacecraft in 2006, tracking of CMEs in interplanetary space was made available for the first time. Further, one could make unprecedented 3-D measurement of CMEs, thanks to the simultaneous observations from two vantage points in space. In this dissertation, I make use of STEREO observations to study the kinematic and morphological evolution of CMEs in interplanetary space. The Raytrace model is utilized as a powerful tool to measure CMEs evolution in 3D. I find that CME leading edge (LE) velocity converges from an initial range between 400 km/s and 1500 km/s at 5 to 10 RS to a narrow range between 500 km/s and 750 km/s at 50 RS. The expansion velocity is also found to converge into a narrow range between 75 km/s and 175 km/s. Both LE and expansion velocities are nearly constant after 50 RS. I further find that the acceleration of CMEs in the inner heliosphere from ˜ 10 to 90 RS can be described by an exponential function, with an initial value as large as ˜ 80 m/s2 but exponentially decreasing to almost zero (more precisely, less than +/- 5 m/s2 considering the uncertainty of measurements). These results are important for constructing accurate space weather prediction models. In addition to the observational study, I have used the theoretical flux rope model to explain the

  5. Milky Way mass constraints from the Galactic satellite gap

    NARCIS (Netherlands)

    Cautun, Marius; Frenk, Carlos S.; van de Weygaert, Rien; Hellwing, Wojciech A.; Jones, Bernard J. T.

    2014-01-01

    We use the distribution of maximum circular velocities, Vmax, of satellites in the Milky Way (MW) to constrain the virial mass, M200, of the Galactic halo under an assumed prior of a Λ cold dark matter universe. This is done by analysing the subhalo populations of a large sample of haloes found in t

  6. Satellite-retrieval and modeling of glacier mass balance

    NARCIS (Netherlands)

    Ruyter de Wildt, Martijn Sybren de

    2002-01-01

    In this research project we use satellite measurements to infer the mean specific mass balance (Bm) of glaciers. Vatnajökull, the largest ice cap in Europe, is being used as a test-case because this ice cap has often been studied. Only one aspect of Vatnajökull has not been investigated so far, and

  7. Combined Multipoint Remote and In Situ Observations of the Asymmetric Evolution of a Fast Solar Coronal Mass Ejection

    CERN Document Server

    Rollett, T; Temmer, M; Frahm, R A; Davies, J A; Veronig, A M; Vrsnak, B; Amerstorfer, U V; Farrugia, C J; Zic, T; Zhang, T L

    2014-01-01

    We present an analysis of the fast coronal mass ejection (CME) of 2012 March 7, which was imaged by both STEREO spacecraft and observed in situ by MESSENGER, Venus Express, Wind and Mars Express. Based on detected arrivals at four different positions in interplanetary space, it was possible to strongly constrain the kinematics and the shape of the ejection. Using the white-light heliospheric imagery from STEREO-A and B, we derived two different kinematical profiles for the CME by applying the novel constrained self-similar expansion method. In addition, we used a drag-based model to investigate the influence of the ambient solar wind on the CME's propagation. We found that two preceding CMEs heading in different directions disturbed the overall shape of the CME and influenced its propagation behavior. While the Venus-directed segment underwent a gradual deceleration (from ~2700 km/s at 15 R_sun to ~1500 km/s at 154 R_sun), the Earth-directed part showed an abrupt retardation below 35 R_sun (from ~1700 to ~900...

  8. BRIGHT RAY-LIKE FEATURES IN THE AFTERMATH OF CORONAL MASS EJECTIONS: WHITE LIGHT VERSUS ULTRAVIOLET SPECTRA

    Energy Technology Data Exchange (ETDEWEB)

    Ciaravella, A. [INAF-Osservatorio Astronomico di Palermo, P.za Parlamento 1, I-90134 Palermo (Italy); Webb, D. F. [Institute for Scientific Research, Boston College, Newton, MA 02459 (United States); Giordano, S. [INAF-Osservatorio Astrofisico di Torino, via Osservatorio 20, I-10025 Pino Torinese (Italy); Raymond, J. C. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2013-03-20

    Current sheets (CSs) are important signatures of magnetic reconnection in the eruption of confined solar magnetic structures. Models of coronal mass ejections (CMEs) involve formation of a CS connecting the ejected flux rope with the post-eruption magnetic loops. CSs have been identified in white light (WL) images of CMEs as narrow rays trailing the outward moving CME core, and in ultraviolet spectra as narrow bright features emitting the [Fe XVIII] line. In this work, samples of rays detected in WL images or in ultraviolet spectra have been analyzed. Temperatures, widths, and line intensities of the rays have been measured, and their correlation to the CME properties has been studied. The samples show a wide range of temperatures with hot, coronal, and cool rays. In some cases, the UV spectra support the identification of rays as CSs, but they show that some WL rays are cool material from the CME core. In many cases, both hot and cool material are present, but offset from each other along the Ultraviolet Coronagraph Spectrometer slit. We find that about 18% of the WL rays show very hot gas consistent with the CS interpretation, while about 23% show cold gas that we attribute to cool prominence material draining back from the CME core. The remaining events have ordinary coronal temperatures, perhaps because they have relaxed back to a quiescent state.

  9. Height of Shock Formation in the Solar Corona Inferred from Observations of Type II Radio Bursts and Coronal Mass Ejections

    Science.gov (United States)

    Gopalswamy, N.; Xie, H.; Makela, P.; Yashiro, S.; Akiyama, S.; Uddin, W.; Srivastava, A. K.; Joshi, N. C.; Chandra, R.; Manoharan, P. K.

    2013-01-01

    Employing coronagraphic and EUV observations close to the solar surface made by the Solar Terrestrial Relations Observatory (STEREO) mission, we determined the heliocentric distance of coronal mass ejections (CMEs) at the starting time of associated metric type II bursts. We used the wave diameter and leading edge methods and measured the CME heights for a set of 32 metric type II bursts from solar cycle 24. We minimized the projection effects by making the measurements from a view that is roughly orthogonal to the direction of the ejection. We also chose image frames close to the onset times of the type II bursts, so no extrapolation was necessary. We found that the CMEs were located in the heliocentric distance range from 1.20 to 1.93 solar radii (Rs), with mean and median values of 1.43 and 1.38 Rs, respectively. We conclusively find that the shock formation can occur at heights substantially below 1.5 Rs. In a few cases, the CME height at type II onset was close to 2 Rs. In these cases, the starting frequency of the type II bursts was very low, in the range 25-40 MHz, which confirms that the shock can also form at larger heights. The starting frequencies of metric type II bursts have a weak correlation with the measured CME/shock heights and are consistent with the rapid decline of density with height in the inner corona.

  10. Stereoscopic study of the kinematic evolution of a coronal mass ejection and its driven shock from the sun to the earth and the prediction of their arrival times

    Energy Technology Data Exchange (ETDEWEB)

    Hess, Phillip; Zhang, Jie, E-mail: phess4@gmu.edu [School of Physics, Astronomy and Computational Sciences, George Mason University, 4400 University Drive, Fairfax, VA 22030 (United States)

    2014-09-01

    We present a detailed study of the complete evolution of a coronal mass ejection (CME). We have tracked the evolution of both the ejecta and its shock, and further fit the evolution of the fronts to a simple but physics-based analytical model. This study focuses on the CME initiated on the Sun on 2012 July 12 and arriving at the Earth on 2012 July 14. Shock and ejecta fronts were observed by white light images, as well as in situ by the Advanced Composition Explorer satellite. We find that the propagation of the two fronts is not completely dependent upon one another, but can each be modeled in the heliosphere with a drag model that assumes the dominant force of affecting CME evolution to be the aerodynamic drag force of the ambient solar wind. Results indicate that the CME ejecta front undergoes a more rapid deceleration than the shock front within 50 R {sub ☉} and therefore the propagation of the two fronts is not completely coupled in the heliosphere. Using the graduated cylindrical shell model, as well as data from time-elongation stack plots and in situ signatures, we show that the drag model can accurately describe the behavior of each front, but is more effective with the ejecta. We also show that without the in situ data, based on measurements out to 80 R {sub ☉} combined with the general values for drag model parameters, the arrival of both the shock and ejecta can be predicted within four hours of arrival.

  11. Non-linear force-free field modeling of a solar active region around the time of a major flare and coronal mass ejection

    CERN Document Server

    Schrijver, C J; Metcalf, T; Barnes, G; Lites, B; Tarbell, T; McTiernan, J; Valori, G; Wiegelmann, T; Wheatland, M S; Amari, T; Aulanier, G; Demoulin, P; Fuhrmann, M; Kusano, K; Régnier, S; Thalmann, J K

    2007-01-01

    Solar flares and coronal mass ejections are associated with rapid changes in field connectivity and powered by the partial dissipation of electrical currents in the solar atmosphere. A critical unanswered question is whether the currents involved are induced by the motion of pre-existing atmospheric magnetic flux subject to surface plasma flows, or whether these currents are associated with the emergence of flux from within the solar convective zone. We address this problem by applying state-of-the-art nonlinear force-free field (NLFFF) modeling to the highest resolution and quality vector-magnetographic data observed by the recently launched Hinode satellite on NOAA Active Region 10930 around the time of a powerful X3.4 flare. We compute 14 NLFFF models with 4 different codes and a variety of boundary conditions. We find that the model fields differ markedly in geometry, energy content, and force-freeness. We discuss the relative merits of these models in a general critique of present abilities to model the ...

  12. Mass-radius relationships in icy satellites after Voyager

    Science.gov (United States)

    Lupo, M. J.

    1982-01-01

    Using improved data for the masses and radii of the satellites of Jupiter and Saturn, models accounting for self-compression effects are presented for the interiors of Europa, Ganymede, Callisto, Rhea, and Titan. For the differentiated models, two different possible scenarios for heat transport are treated, as well as two different compositions for the silicate component. Undifferentiated models are also treated. In each case, the models of Ganymede, Callisto, and Titan show noticeable similarities. It is found that estimates of the ice-rock ratio are dependent upon the assumptions made about the heat transport mechanisms, the rock composition, and on the distribution of rock and ice in the satellite's interior.

  13. The Mass Dependence of Dwarf Satellite Galaxy Quenching

    Science.gov (United States)

    Slater, Colin T.; Bell, Eric F.

    2014-09-01

    We combine observations of the Local Group with data from the NASA-Sloan Atlas to show the variation in the quenched fraction of satellite galaxies from low-mass dwarf spheroidals and dwarf irregulars to more massive dwarfs similar to the Magellanic Clouds. While almost all of the low-mass (M sstarf 5 Gyr ago. We also characterize how the susceptibility of dwarfs to ram pressure must vary as a function of mass if it is to account for the change in quenched fractions. Though neither model predicts the quenching effectiveness a priori, this modeling illustrates the physical requirements that the observed quenched fractions place on possible quenching mechanisms.

  14. New Frontiers/Hale Prize Lecture: Coronal Mass Ejections, the Most Powerful Drivers of the Sun-Earth System

    Science.gov (United States)

    Antiochos, S. K.

    2005-05-01

    A large Coronal Mass Ejection (CME) can consist of billions of tonnes of matter, along with entangled magnetic field, erupting from the Sun at speeds well over 1,000 km/s. These giant disruptions of the solar atmosphere drive the most destructive space weather at Earth and throughout the solar system. Furthermore, CMEs are the most dramatic example of how slowly-evolving processes on the Sun can conspire to produce explosive activity. Understanding their origin has long been a central objective for space physics research. This talk will present some of the latest observations and theories for CMEs and discuss the outstanding challenges to modeling and predicting their initiation. This work was supported in part by NASA and ONR.

  15. Self-Consistent MHD Modeling of a Coronal Mass Ejection, Coronal Dimming, and a Giant Cusp-Shaped Arcade Formation

    CERN Document Server

    Shiota, D; Chen, P F; Yamamoto, T T; Sakajiri, T; Shibata, K; Shiota, Daikou; Isobe, Hiroaki; Yamamoto, Tetsuya T.; Sakajiri, Takuma; Shibata, Kazunari

    2005-01-01

    We performed magnetohydrodynamic simulation of coronal mass ejections (CMEs) and associated giant arcade formations, and the results suggested new interpretations of observations of CMEs. We performed two cases of the simulation: with and without heat conduction. Comparing between the results of the two cases, we found that reconnection rate in the conductive case is a little higher than that in the adiabatic case and the temperature of the loop top is consistent with the theoretical value predicted by the Yokoyama-Shibata scaling law. The dynamical properties such as velocity and magnetic fields are similar in the two cases, whereas thermal properties such as temperature and density are very different.In both cases, slow shocks associated with magnetic reconnectionpropagate from the reconnection region along the magnetic field lines around the flux rope, and the shock fronts form spiral patterns. Just outside the slow shocks, the plasma density decreased a great deal. The soft X-ray images synthesized from t...

  16. THE VERY UNUSUAL INTERPLANETARY CORONAL MASS EJECTION OF 2012 JULY 23: A BLAST WAVE MEDIATED BY SOLAR ENERGETIC PARTICLES

    Energy Technology Data Exchange (ETDEWEB)

    Russell, C. T. [University of California, Los Angeles, CA 90095-1567 (United States); Mewaldt, R. A.; Cohen, C. M. S.; Leske, R. A. [California Institute of Technology, Pasadena, CA 91125 (United States); Luhmann, J. G. [University of California, Berkeley, CA 94720 (United States); Mason, G. M. [Johns Hopkins University, Applied Physics Laboratory, Laurel, MD 20723 (United States); Von Rosenvinge, T. T. [Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Gomez-Herrero, R. [University of Alcala, E-28871 Alcala de Henares (Spain); Klassen, A. [Kiel University, D-24118 Kiel (Germany); Galvin, A. B.; Simunac, K. D. C., E-mail: ctrussell@igpp.ucla.edu [University of New Hampshire, Durham, NH 03824 (United States)

    2013-06-10

    The giant, superfast, interplanetary coronal mass ejection, detected by STEREO A on 2012 July 23, well away from Earth, appears to have reached 1 AU with an unusual set of leading bow waves resembling in some ways a subsonic interaction, possibly due to the high pressures present in the very energetic particles produced in this event. Eventually, a front of record high-speed flow reached STEREO. The unusual behavior of this event is illustrated using the magnetic field, plasma, and energetic ion observations obtained by STEREO. Had the Earth been at the location of STEREO, the large southward-oriented magnetic field component in the event, combined with its high speed, would have produced a record storm.

  17. Connecting speeds, directions and arrival times of 22 coronal mass ejections from the sun to 1 AU

    Energy Technology Data Exchange (ETDEWEB)

    Möstl, C.; Veronig, A. M.; Rollett, T.; Temmer, M.; Peinhart, V. [Kanzelhöhe Observatory-IGAM, Institute of Physics, University of Graz (Austria); Amla, K.; Hall, J. R.; Liewer, P. C.; De Jong, E. M. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA (United States); Colaninno, R. C. [Space Sciences Division, Naval Research Laboratory, Washington, DC (United States); Davies, J. A.; Harrison, R. A. [RAL Space, Harwell Oxford, Didcot (United Kingdom); Lugaz, N.; Farrugia, C. J.; Galvin, A. B. [Space Science Center and Department of Physics, University of New Hampshire, Durham, NH (United States); Liu, Y. D. [State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing (China); Luhmann, J. G. [Space Science Laboratory, University of California, Berkeley, CA (United States); Vršnak, B., E-mail: christian.moestl@uni-graz.at [Hvar Observatory, Faculty of Geodesy, University of Zagreb, Kačićeva 26, HR-10000, Zagreb (Croatia)

    2014-06-01

    Forecasting the in situ properties of coronal mass ejections (CMEs) from remote images is expected to strongly enhance predictions of space weather and is of general interest for studying the interaction of CMEs with planetary environments. We study the feasibility of using a single heliospheric imager (HI) instrument, imaging the solar wind density from the Sun to 1 AU, for connecting remote images to in situ observations of CMEs. We compare the predictions of speed and arrival time for 22 CMEs (in 2008-2012) to the corresponding interplanetary coronal mass ejection (ICME) parameters at in situ observatories (STEREO PLASTIC/IMPACT, Wind SWE/MFI). The list consists of front- and backsided, slow and fast CMEs (up to 2700 km s{sup –1}). We track the CMEs to 34.9 ± 7.1 deg elongation from the Sun with J maps constructed using the SATPLOT tool, resulting in prediction lead times of –26.4 ± 15.3 hr. The geometrical models we use assume different CME front shapes (fixed-Φ, harmonic mean, self-similar expansion) and constant CME speed and direction. We find no significant superiority in the predictive capability of any of the three methods. The absolute difference between predicted and observed ICME arrival times is 8.1 ± 6.3 hr (rms value of 10.9 hr). Speeds are consistent to within 284 ± 288 km s{sup –1}. Empirical corrections to the predictions enhance their performance for the arrival times to 6.1 ± 5.0 hr (rms value of 7.9 hr), and for the speeds to 53 ± 50 km s{sup –1}. These results are important for Solar Orbiter and a space weather mission positioned away from the Sun-Earth line.

  18. The Influence of Coronal Mass Ejections on the Gas Dynamics of the Atmosphere of a "Hot~Jupiter" Exoplanet

    CERN Document Server

    Bisikalo, D V

    2016-01-01

    The results of three-dimensional numerical simulations of the gas dynamics of the atmosphere of a "hot Jupiter" exoplanet during the passage of a coronal mass ejection (CME) from the central star are presented. These computations assumed the parameters for the stellar wind and the CME to be typical of the solar values. The characteristic variations of the flow pattern are considered for quasi-closed and closed (but appreciably distorted by the gravitational influence of the star) gaseous envelopes of the exoplanet. It is shown that a typical CME is sufficient to tear off the outer part of an asymmetric envelope that is located beyond the Roche lobe and carry it away from the exoplanet. This leads to a substantial increase in the mass-loss rate from the exoplanet envelope during the passage of CMEs. The mass-loss rate grows by about a factor of 11 for a closed envelope, and by about a factor of 14 for a quasi-closed envelope. Possible evolutionary consequences of the loss of part of the atmosphere during the p...

  19. COMBINED MULTIPOINT REMOTE AND IN SITU OBSERVATIONS OF THE ASYMMETRIC EVOLUTION OF A FAST SOLAR CORONAL MASS EJECTION

    Energy Technology Data Exchange (ETDEWEB)

    Rollett, T.; Möstl, C.; Temmer, M.; Veronig, A. M.; Amerstorfer, U. V. [IGAM-Kanzelhöhe Observatory, Institute of Physics, University of Graz, A-8010 Graz (Austria); Frahm, R. A. [Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238 (United States); Davies, J. A. [RAL Space, Rutherford Appleton Laboratory, Harwell Oxford, OX11 0QX (United Kingdom); Vršnak, B.; Žic, T. [Hvar Observatory, Faculty of Geodesy, University of Zagreb, 1000 Zagreb (Croatia); Farrugia, C. J. [Space Science Center and Department of Physics, University of New Hampshire, Durham, NH 03824 (United States); Zhang, T. L., E-mail: tanja.rollett@gmx.at [Space Research Institute, Austrian Academy of Sciences, A-8042 Graz (Austria)

    2014-07-20

    We present an analysis of the fast coronal mass ejection (CME) of 2012  March 7, which was imaged by both STEREO spacecraft and observed in situ by MESSENGER, Venus Express, Wind, and Mars Express. Based on detected arrivals at four different positions in interplanetary space, it was possible to strongly constrain the kinematics and the shape of the ejection. Using the white-light heliospheric imagery from STEREO-A and B, we derived two different kinematical profiles for the CME by applying the novel constrained self-similar expansion method. In addition, we used a drag-based model to investigate the influence of the ambient solar wind on the CME's propagation. We found that two preceding CMEs heading in different directions disturbed the overall shape of the CME and influenced its propagation behavior. While the Venus-directed segment underwent a gradual deceleration (from ∼2700 km s{sup –1} at 15 R {sub ☉} to ∼1500 km s{sup –1} at 154 R {sub ☉}), the Earth-directed part showed an abrupt retardation below 35 R {sub ☉} (from ∼1700 to ∼900 km s{sup –1}). After that, it was propagating with a quasi-constant speed in the wake of a preceding event. Our results highlight the importance of studies concerning the unequal evolution of CMEs. Forecasting can only be improved if conditions in the solar wind are properly taken into account and if attention is also paid to large events preceding the one being studied.

  20. Successive Homologous Coronal Mass Ejections Driven by Shearing and Converging Motions in Solar Active Region NOAA 12371

    Science.gov (United States)

    Vemareddy, P.

    2017-08-01

    We study the magnetic field evolution in AR 12371, related to its successive eruptive nature. During the disk transit of seven days, the active region (AR) launched four sequential fast coronal mass ejections (CMEs), which are associated with long duration M-class flares. Morphological study delineates a pre-eruptive coronal sigmoid structure above the polarity inversion line (PIL) similar to Moore et al.’s study. The velocity field derived from tracked magnetograms indicates persistent shear and converging motions of polarity regions about the PIL. While these shear motions continue, the crossed arms of two sigmoid elbows are being brought to interaction by converging motions at the middle of the PIL, initiating the tether-cutting reconnection of field lines and the onset of the CME explosion. The successive CMEs are explained by a cyclic process of magnetic energy storage and release referred to as “sigmoid-to-arcade-to-sigmoid” transformation driven by photospheric flux motions. Furthermore, the continued shear motions inject helicity flux with a dominant negative sign, which contributes to core field twist and its energy by building a twisted flux rope (FR). After a limiting value, the excess coronal helicity is expelled by bodily ejection of the FR, which is initiated by some instability as realized by intermittent CMEs. This AR is in contrast with the confined AR 12192 with a predominant negative sign and larger helicity flux, but much weaker (-0.02 turns) normalized coronal helicity content. While predominant signed helicity flux is a requirement for CME eruption, our study suggests that the magnetic flux normalized helicity flux is a necessary condition accommodating the role of background flux and appeals to a further study of a large sample of ARs.

  1. Interplanetary journey of a coronal mass ejection to Mars and to Comet 67P/Churyumov-Gerasimenko

    Science.gov (United States)

    Witasse, Olivier; Kajdic, Primoz; Sanchez-Cano, Beatriz; Mays, Leila; Lebreton, Jean-Pierre; Espley, Jared; Goetz, Charlotte; Richter, Ingo; Koenders, Christoph; Glassmeier, Karl-Heinz; Nilsson, Hans; Opgenoorth, Hermann; Andrews, David; Lester, Mark; Edberg, Niklas; Zouganelis, Yannis; Intzekara, Dimitra; Kuulkers, Erik; Turc, Lucile; Odstrcil, Dusan

    2016-04-01

    We discuss observations of a large coronal mass ejection (CME) ejected on 14 October 2014, which hit Mars on 17 October 2014, 1.5 days before the Mars close encounter with the Siding Spring comet. Clear disturbances of the Mars' upper atmosphere are identified in the Mars Express and MAVEN data sets. Interestingly, comet 67P/Churyumov-Gerasimenko was perfectly aligned with the Sun and Mars at 1.7 AU behind Mars, with the Rosetta spacecraft orbiting at 10 km above the cometary surface. The Rosetta plasma package and the radiation monitor detected the event on 22 October 2014. We describe the propagation of this CME from the Sun to Rosetta and show comparison with dedicated WSA-ENLIL (large-scale, physics-based prediction model of the heliosphere) simulations. CME effects on the Mars and comet 67P environments are reported. In particular, large and similar Forbush effects - a transient decrease followed by a gradual recovery in the observed galactic cosmic ray intensity- were observed at both places, as recorded by the MSL RAD instrument aboard the Curiosity rover at the surface of Mars and by the Radiation Environment Monitor aboard Rosetta. Fortuitously, the New Horizons spacecraft was also along the propagation direction of the CME, which can take 3-5 months to reach the distance of 31.7 AU. By the time the solar wind travels that far from the Sun, the fast solar wind parcels have interacted with slower wind parcels emitted at an earlier time along the same radial line. We investigate if the CME observed at Mars and Rosetta has a unique signature at New Horizons. This presents a challenge since many solar structures can either be worn down as they propagate, or they can merge into larger ones. We present also preliminary 3D WSA-ENLIL simulations out to 40 AU showing the evolution of the CME, including other CMEs during this period.

  2. Mass and metal ejection efficiency in disk galaxies driven by young stellar clusters of nuclear starburst

    CERN Document Server

    Rodriguez-Gonzalez, A; Raga, A C; Colin, P

    2011-01-01

    We present results from models of galactic winds driven by energy injected by nuclear starbursts. The total energy of the starburst is provided by young central stellar clusters and parts of the galactic interstellar medium are pushed out as part of the galactic wind (in some cases the galactic wind contains an important part of the metals produced in the new generation of stars). We have performed adiabatic and radiative 3D N-Body/Smooth Particle Hydrodynamics simulations of galactic winds using the GADGET-2 code. The numerical models cover a wide range of starburst (from $\\sim10^2$ to $\\sim10^7$ M$_\\odot$) and galactic gas masses (from $\\sim6\\times10^6$ to $\\sim10^{11}$ M$_\\odot$). The concentrated central starburst regions are an efficient engine for producing of the mass and metal loss in galaxies, and also for driving the metal redistribution in the galaxies.

  3. Initiation and early evolution of the Coronal Mass Ejection on May 13, 2009 from EUV and white-light observations

    CERN Document Server

    Reva, Anton; Bogachev, Sergey; Kuzin, Sergey

    2015-01-01

    We present the results of the observations of a coronal mass ejection (CME), which occurred on May 13, 2009. The most important feature of these observations is that the CME was observed from the very early stage (the solar surface) up to a distance of 15 solar radii ($R_\\odot$). Below 2 $R_\\odot$, we used the data from the TESIS EUV telescopes obtained in the Fe 171 A and He 304 A lines, and above 2 $R_\\odot$, we used the observations of the LASCO C2 and C3 coronagraphs. The CME was formed at a distance of 0.2-0.5 $R_\\odot$from the Sun's surface as a U-shaped structure, which was observed both in the 171 A images and in white-light. Observations in the He 304 A line showed that the CME was associated with an erupting prominence, which was located not above-as predicts the standard model-but in the lowest part of the U-shaped structure close to the magnetic X-point. The prominence location can be explained with the CME breakout model. Estimates showed that CME mass increased with time. The CME trajectory was ...

  4. The Change of the Orbital Periods Across Eruptions and the Ejected Mass For Recurrent Novae CI Aquilae and U Scorpii

    CERN Document Server

    Schaefer, Bradley E

    2011-01-01

    I report on the cumulative results from a program started 24 years ago designed to measure the orbital period change of recurrent novae (RNe) across an eruption. The goal is to use the orbital period change to measure the mass ejected during each eruption as the key part of trying to measure whether the RNe white dwarfs are gaining or losing mass over an entire eruption cycle, and hence whether they can be progenitors for Type Ia supernovae. This program has now been completed for two eclipsing RNe; CI Aquilae (CI Aql) across its eruption in 2000 and U Scorpii (U Sco) across its eruption in 1999. For CI Aql, I present 78 eclipse times from 1991-2009 (including four during the tail of the 2000 eruption) plus two eclipses from 1926 and 1935. For U Sco, I present 67 eclipse times, including 46 times during quiescence from 1989-2009, plus 21 eclipse times in the tails of the 1945, 1999, and 2010 eruptions. The eclipse times during the tails of eruptions are systematically and substantially shifted with respect to...

  5. Constraining the WDM Particle Mass with Milky Way Satellites

    CERN Document Server

    Kennedy, Rachel; Cole, Shaun; Benson, Andrew

    2013-01-01

    Well-motivated particle physics theories predict the existence of particles (such as sterile neutrinos) which acquire non-negligible thermal velocities in the early universe. These particles could behave as warm dark matter (WDM) and generate a small-scale cutoff in the linear density power spectrum which scales approximately inversely with the particle mass. If this mass is of order a keV, the cutoff occurs on the scale of dwarf galaxies. Thus, in WDM models the abundance of small galaxies, such as the satellites that orbit in the halo of the Milky Way, depends on the mass of the warm particle. The abundance also scales with the mass of the host galactic halo. We use the \\galform semi-analytic model of galaxy formation to calculate the properties of galaxies in universes in which the dark matter is warm. Using this method, we can compare the predicted satellite luminosity functions to the observed data for the Milky Way dwarf spheroidals, and determine a lower bound on the thermally produced WDM particle mas...

  6. A progenitor binary and an ejected mass donor remnant of faint type Ia supernovae

    CERN Document Server

    Geier, S; Wang, B; Dunlap, B; Barlow, B N; Schaffenroth, V; Chen, X; Irrgang, A; Maxted, P F L; Ziegerer, E; Kupfer, T; Miszalski, B; Heber, U; Han, Z; Shporer, A; Telting, J H; Gaensicke, B T; Oestensen, R H; O'Toole, S J; Napiwotzki, R

    2013-01-01

    Type Ia supernovae (SN Ia) are the most important standard candles for measuring the expansion history of the universe. The thermonuclear explosion of a white dwarf can explain their observed properties, but neither the progenitor systems nor any stellar remnants have been conclusively identified. Underluminous SN Ia have been proposed to originate from a so-called double-detonation of a white dwarf. After a critical amount of helium is deposited on the surface through accretion from a close companion, the helium is ignited causing a detonation wave that triggers the explosion of the white dwarf itself. We have discovered both shallow transits and eclipses in the tight binary system CD-30 11223 composed of a carbon/oxygen white dwarf and a hot helium star, allowing us to determine its component masses and fundamental parameters. In the future the system will transfer mass from the helium star to the white dwarf. Modelling this process we find that the detonation in the accreted helium layer is sufficiently st...

  7. Initiation and early evolution of a Coronal Mass Ejection on May 13, 2009 from EUV and white-light observations

    Science.gov (United States)

    Reva, Anton; Kuzin, Sergey; Bogachev, Sergey; Ulyanov, Artyom

    In this talk we present results of the observations of a CME, which occurred on May 13, 2009. The most important feature of these observations is that the CME was observed from the very beginning stage (the solar surface) up to the distance of 15 solar radii (R_⊙). Below 2 R_⊙ we used the data from the TESIS EUV telescopes obtained in the Fe 171 Å and He 304 Å lines, and above 2 R_⊙ we used the observations of the LASCO C2 and C3 coronagraphs. Using data of these three instruments, we have studied the evolution of the CME in details. The CME had a curved trajectory -- its helio-latitude decreased with time. The mass ejection originated at a latitudes of about 50(°) and reached the ecliptic plane at a distance of 2.5 R_⊙ from the Sun’s center. The CME velocity and acceleration increased as the CME went away from the Sun. At the distance of 15 R_⊙ from the Sun’s center the CME had a velocity of 250 km/s and an acceleration of 5 m/s(2) . The CME was not associated with a flare, and didn’t have an impulsive acceleration phase. The mass ejection had U-shaped structure which was observed both in the 171 Å images and in white-light. The CME was formed at a distance of about 0.2 -- 0.5 R_⊙ from the Sun’s surface. Observations in the line 304 Å showed that the CME was associated with the erupting prominence, which was located in the lowest part of the U-shaped structure close to the X-point of the magnetic reconnection. The prominence disappeared at the height of 0.4 R_⊙ above the solar limb. Some aspects of these observations can’t be explained in the standard CME model, which predicts that the prominence should be located inside the U-shaped structure, and the CME should be associated with a flare and have an impulsive acceleration phase.

  8. Morphological and Kinematic Evolution of Three Interacting Coronal Mass Ejections of 2011 February 13-15

    CERN Document Server

    Mishra, Wageesh

    2014-01-01

    During 2011 February 13 to 15, three Earth-directed CMEs launched in successively were recorded as limb CMEs by coronagraphs (COR) of STEREO. These CMEs provided an opportunity to study their geometrical and kinematic evolution from multiple vantage points. In this paper, we examine the differences in geometrical evolution of slow and fast speed CMEs during their propagation in the heliosphere. We also study their interaction and collision using STEREO/SECCHI COR and Heliospheric Imager (HI) observations. We have found evidence of interaction and collision between the CMEs of February 15 and 14 in COR2 and HI1 FOV, respectively, while the CME of February 14 caught the CME of February 13 in HI2 FOV. By estimating the true mass of these CMEs and using their pre and post-collision dynamics, the momentum and energy exchange between them during collision phase are studied. We classify the nature of observed collision between CME of February 14 and 15 as inelastic, reaching close to elastic regime. Relating imaging...

  9. Scaling Relations in Coronal Mass Ejections and Energetic Proton Events associated with Solar Superflares

    CERN Document Server

    Takahashi, Takuya; Shibata, Kazunari

    2016-01-01

    In order to discuss the potential impact of solar 'superflares' on space weather, we investigated statistical relations among energetic proton peak flux with energy higher than $ 10 \\rm MeV$ ($F_p$), CME speed near the Sun ($V_{CME}$) obtained by {\\it SOHO}/LASCO coronagraph and flare soft X-ray peak flux in 1-8\\AA band ($F_{SXR}$) during 110 major solar proton events (SPEs) recorded from 1996 to 2014. The linear regression fit results in the scaling relations $V_{CME} \\propto F_{SXR}^\\alpha$, $F_p\\propto F_{SXR}^\\beta$ and $F_p\\propto V_{CME}^\\gamma$ with $\\alpha = 0.30\\pm 0.04$, $\\beta = 1.19 \\pm 0.08$ and $\\gamma = 4.35 \\pm 0.50$, respectively. On the basis of simple physical assumptions, on the other hand, we derive scaling relations expressing CME mass ($M_{CME}$), CME speed and energetic proton flux in terms of total flare energy ($E_{flare}$) as, $M_{CME}\\propto E_{flare}^{2/3}$, $V_{CME}\\propto E_{flare}^{1/6}$ and $F_{p}\\propto E_{flare}^{5/6}\\propto V_{CME}^5$, respectively. We then combine the deri...

  10. Milky Way mass constraints from the Galactic satellite gap

    CERN Document Server

    Cautun, Marius; van de Weygaert, Rien; Hellwing, Wojciech A; Jones, Bernard J T

    2014-01-01

    We use the distribution of maximum circular velocities, $V_{max}$, of satellites in the Milky Way (MW) to constrain the virial mass, $M_{200}$, of the Galactic halo under an assumed prior of a $\\Lambda$CDM universe. This is done by analysing the subhalo populations of a large sample of halos found in the Millennium II cosmological simulation. The observation that the MW has at most three subhalos with $V_{max}\\ge30 km/s$ requires a halo mass $M_{200}\\le1.4\\times10^{12} M_\\odot$, while the existence of the Magellanic Clouds (assumed to have $V_{max}\\ge60 km/s$) requires $M_{200}\\ge1.0\\times10^{12} M_\\odot$. The first of these conditions is necessary to avoid the "too-big-to-fail" problem highlighted by Boylan-Kolchin et al., while the second stems from the observation that massive satellites like the Magellanic Clouds are rare. When combining both requirements, we find that the MW halo mass must lie in the range $0.25 \\le M_{200}/(10^{12} M_\\odot) \\le 1.4$ at $90\\%$ confidence. The gap in the abundance of Gala...

  11. The Formation and Early Evolution of a Coronal Mass Ejection and its Associated Shock Wave on 2014 January 8

    CERN Document Server

    Wan, Linfeng; Shi, Tong; Su, Wei; Ding, M D

    2016-01-01

    In this paper, we study the formation and early evolution of a limb coronal mass ejection (CME) and its associated shock wave that occurred on 2014 January 8. The extreme ultraviolet (EUV) images provided by the Atmospheric Imaging Assembly (AIA) on board \\textit{Solar Dynamics Observatory} disclose that the CME first appears as a bubble-like structure. Subsequently, its expansion forms the CME and causes a quasi-circular EUV wave. Interestingly, both the CME and the wave front are clearly visible at all of the AIA EUV passbands. Through a detailed kinematical analysis, it is found that the expansion of the CME undergoes two phases: a first phase with a strong but transient lateral over-expansion followed by a second phase with a self-similar expansion. The temporal evolution of the expansion velocity coincides very well with the variation of the 25--50 keV hard X-ray flux of the associated flare, which indicates that magnetic reconnection most likely plays an important role in driving the expansion. Moreover...

  12. Predicting the Arrival Time of Coronal Mass Ejections with the Graduated Cylindrical Shell and Drag Force Model

    CERN Document Server

    Shi, Tong; Wan, Linfeng; Cheng, Xin; Ding, Mingde; Zhang, Jie

    2015-01-01

    Accurately predicting the arrival of coronal mass ejections (CMEs) at the Earth based on remote images is of critical significance in the study of space weather. In this paper, we make a statistical study of 21 Earth directed CMEs, exploring in particular the relationship between CME initial speeds and transit times. The initial speed of a CME is obtained by fitting the CME with the Graduated Cylindrical Shell model and is thus free of projection effects. We then use the drag force model to fit results of the transit time versus the initial speed. By adopting different drag regimes, i.e., the viscous, aerodynamics, and hybrid regimes, we get similar results, with the least mean estimation error of the hybrid model of 12.9 hours. CMEs with a propagation angle (the angle between the propagation direction and the Sun-Earth line) larger than its half angular width arrive at the Earth with an angular deviation caused by factors other than the radial solar wind drag. The drag force model cannot be well applied to s...

  13. Distribution of Latitudes and Speeds of Coronal Mass Ejections in the Northern and Southern Hemispheres in Cycle 23

    Indian Academy of Sciences (India)

    P. X. Gao; Q. X. Li; S. H. Zhong

    2007-12-01

    Distribution of latitudes and speeds of Coronal Mass Ejections (CMEs) in the northern and southern hemispheres in cycle 23, from September 1996 to December 2006, have been analyzed. By calculating the actual probability of the hemispheric distribution of the activity of the CME, we find that a southern dominance of the activity of the CME is shown to occur in cycle 23 from September 1996 to December 2006. The CME activity occurs at all latitudes and is most common at low latitudes. This should furnish evidence to support that CMEs are associated with source magnetic structures on a large spatial scale, even with transequatorial source magnetic structures on a large spatial scale. The latitudinal distribution of CMEs in the northern and southern hemispheres are no different from a statistical point of view. The speed distribution in the northern and southern hemispheres are nearly identical and to a good approximation they can be fitted with a single lognormal distribution. This finding implies that, statistically, there is no physical distinction between the CME events in the southern and northern hemispheres and the same mechanism of a nonlinear nature acting in both the CME events in the northern and southern hemispheres. Our conclusions seem to suggest that the northern–southern asymmetry of the CME events is related to the northern–southern asymmetry in solar dynamo theory (Jiang et al. 2007).

  14. Chromosphere to 1 AU Simulation of the 2011 March 7th Event: A Comprehensive Study of Coronal Mass Ejection Propagation

    CERN Document Server

    Jin, M; van der Holst, B; Sokolov, I; Toth, G; Vourlidas, A; de Koning, C A; Gombosi, T I

    2016-01-01

    We perform and analyze results of a global magnetohydrodyanmic (MHD) simulation of the fast coronal mass ejection (CME) that occurred on 2011 March 7. The simulation is made using the newly developed Alfv\\'en Wave Solar Model (AWSoM), which describes the background solar wind starting from the upper chromosphere and extends to 24 R$_{\\odot}$. Coupling AWSoM to an inner heliosphere (IH) model with the Space Weather Modeling Framework (SWMF) extends the total domain beyond the orbit of Earth. Physical processes included in the model are multi-species thermodynamics, electron heat conduction (both collisional and collisionless formulations), optically thin radiative cooling, and Alfv\\'en-wave turbulence that accelerates and heats the solar wind. The Alfv\\'en-wave description is physically self-consistent, including non-Wentzel-Kramers-Brillouin (WKB) reflection and physics-based apportioning of turbulent dissipative heating to both electrons and protons. Within this model, we initiate the CME by using the Gibson...

  15. Simulations of Emerging Magnetic Flux. II. The Formation of Unstable Coronal Flux Ropes and the Initiation of Coronal Mass Ejections

    Science.gov (United States)

    Leake, James E.; Linton, Mark G.; Antiochos, Spiro K.

    2014-01-01

    We present results from three-dimensional magnetohydrodynamic simulations of the emergence of a twisted convection zone flux tube into a pre-existing coronal dipole field. As in previous simulations, following the partial emergence of the sub-surface flux into the corona, a combination of vortical motions and internal magnetic reconnection forms a coronal flux rope. Then, in the simulations presented here, external reconnection between the emerging field and the pre-existing dipole coronal field allows further expansion of the coronal flux rope into the corona. After sufficient expansion, internal reconnection occurs beneath the coronal flux rope axis, and the flux rope erupts up to the top boundary of the simulation domain (approximately 36 Mm above the surface).We find that the presence of a pre-existing field, orientated in a direction to facilitate reconnection with the emerging field, is vital to the fast rise of the coronal flux rope. The simulations shown in this paper are able to self-consistently create many of the surface and coronal signatures used by coronal mass ejection (CME) models. These signatures include surface shearing and rotational motions, quadrupolar geometry above the surface, central sheared arcades reconnecting with oppositely orientated overlying dipole fields, the formation of coronal flux ropes underlying potential coronal field, and internal reconnection which resembles the classical flare reconnection scenario. This suggests that proposed mechanisms for the initiation of a CME, such as "magnetic breakout," are operating during the emergence of new active regions.

  16. A Space Weather Information Service Based Upon Remote and In-Situ Measurements of Coronal Mass Ejections Heading for Earth

    CERN Document Server

    Ritter, Birgit; Miles, Oscar; Rußwurm, Michael; Scully, Stephen; Roldán, Andrés; Hartkorn, Oliver; Jüstel, Peter; Réville, Victor; Lupu, Sorina; Ruffenach, Alexis

    2015-01-01

    The Earth's magnetosphere is formed as a consequence of interaction between the planet's magnetic field and the solar wind, a continuous plasma stream from the Sun. A number of different solar wind phenomena have been studied over the past forty years with the intention of understanding and forecasting solar behavior. One of these phenomena in particular, Earth-bound interplanetary coronal mass ejections (CMEs), can significantly disturb the Earth's magnetosphere for a short time and cause geomagnetic storms. This publication presents a mission concept consisting of six spacecraft that are equally spaced in a heliocentric orbit at 0.72 AU. These spacecraft will monitor the plasma properties, the magnetic field's orientation and magnitude, and the 3D-propagation trajectory of CMEs heading for Earth. The primary objective of this mission is to increase space weather (SW) forecasting time by means of a near real-time information service, that is based upon in-situ and remote measurements of the aforementioned CM...

  17. Multi-wave band SMM-VLA observations of an M2 flare and an associated coronal mass ejection

    Science.gov (United States)

    Willson, Robert F.; Lang, Kenneth R.; Schmelz, Joan T.; Gonzalez, Raymond D.; Smith, Kermit L.

    1991-01-01

    Results are presented of observations of an M2 flare and an associated coronal mass ejection CME by instruments on the SMM as well as by the VLA and other ground-based observatories on September 30, 1988. The multiwave band data show a gradual slowly changing event which lasted several hours. The microwave burst emission was found to originate in compact moderately circularly polarized sources located near the sites of bright H-alpha and soft X-ray emission. These data are combined with estimates of an electron temperature of 1.5 x 10 to the 7th K and an emission measure of about 2.0 x 10 to the 49th/cu cm obtained from Ca XIX and Fe XXV spectra to show that the microwave emission can be attributed to thermal gyrosynchrotron radiation in regions where the magnetic field strength is 425-650 G. The CME acceleration at low altitudes is measured on the basis of ground- and space-based coronagraphs.

  18. Sun-to-Earth Characteristics of the 2012 July 12 Coronal Mass Ejection and Associated Geo-effectiveness

    CERN Document Server

    Hu, Huidong; Wang, Rui; Möstl, Christian; Yang, Zhongwei

    2016-01-01

    We analyze multi-spacecraft observations associated with the 2012 July 12 Coronal Mass Ejection (CME), covering the source region on the Sun from SDO, stereoscopic imaging observations from STEREO, magnetic field characteristics at MESSENGER, and type II radio burst and in situ measurements from Wind. A triangulation method based on STEREO stereoscopic observations is employed to determine the kinematics of the CME, and the outcome is compared with the result derived from the type II radio burst with a solar wind electron density model. A Grad-Shafranov technique is applied to Wind in situ data to reconstruct the flux-rope structure and compare it with the observation of the solar source region, which helps understand the geo-effectiveness associated with the CME structure. Conclusions are as follows: (1) the CME undergoes an impulsive acceleration, a rapid deceleration before reaching MESSENGER, and then a gradual deceleration out to 1 AU, which should be noticed in CME kinematics models; (2) the type II rad...

  19. CHARACTERISTICS OF KINEMATICS OF A CORONAL MASS EJECTION DURING THE 2010 AUGUST 1 CME-CME INTERACTION EVENT

    Energy Technology Data Exchange (ETDEWEB)

    Temmer, Manuela; Rollett, Tanja; Bein, Bianca; Moestl, Christian; Veronig, Astrid M.; Flor, Olga [Kanzelhoehe Observatory-IGAM, Institute of Physics, University of Graz, Universitaetsplatz 5, A-8010 Graz (Austria); Vrsnak, Bojan; Zic, Tomislav [Hvar Observatory, Faculty of Geodesy, University of Zagreb, Kaciceva 26, HR-10000 Zagreb (Croatia); De Koning, Curt A. [NOAA Space Weather Prediction Center, Boulder, CO 80305 (United States); Liu, Ying [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Bosman, Eckhard [Space Research Institute, Austrian Academy of Sciences, A-8042 Graz (Austria); Davies, Jackie A.; Bothmer, Volker [Institut fuer Astrophysik, Goettingen University, Friedrich-Hund Platz 1, D-37077 Goettingen (Germany); Harrison, Richard [RAL Space, Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0QX (United Kingdom); Nitta, Nariaki [Solar and Astrophysics Laboratory, Lockheed Martin Advanced Technology Centre, Palo Alto, CA 94304-1191 (United States); Bisi, Mario [Institute of Mathematics and Physics, Aberystwyth University, Ceredigion SY23 3BZ (United Kingdom); Eastwood, Jonathan; Forsyth, Robert [The Blackett Laboratory, Imperial College London, London SW7 2AZ (United Kingdom); Odstrcil, Dusan, E-mail: mat@igam.uni-graz.at [Computational and Data Sciences, George Mason University/NASA Goddard Space Flight Center, Mail Code 674, Greenbelt, MD 20771 (United States)

    2012-04-10

    We study the interaction of two successive coronal mass ejections (CMEs) during the 2010 August 1 events using STEREO/SECCHI COR and heliospheric imager (HI) data. We obtain the direction of motion for both CMEs by applying several independent reconstruction methods and find that the CMEs head in similar directions. This provides evidence that a full interaction takes place between the two CMEs that can be observed in the HI1 field of view. The full de-projected kinematics of the faster CME from Sun to Earth is derived by combining remote observations with in situ measurements of the CME at 1 AU. The speed profile of the faster CME (CME2; {approx}1200 km s{sup -1}) shows a strong deceleration over the distance range at which it reaches the slower, preceding CME (CME1; {approx}700 km s{sup -1}). By applying a drag-based model we are able to reproduce the kinematical profile of CME2, suggesting that CME1 represents a magnetohydrodynamic obstacle for CME2 and that, after the interaction, the merged entity propagates as a single structure in an ambient flow of speed and density typical for quiet solar wind conditions. Observational facts show that magnetic forces may contribute to the enhanced deceleration of CME2. We speculate that the increase in magnetic tension and pressure, when CME2 bends and compresses the magnetic field lines of CME1, increases the efficiency of drag.

  20. Magnetic topology of coronal mass ejection events out of the ecliptic: Ulysses/HI-SCALE energetic particle observations

    Directory of Open Access Journals (Sweden)

    O. E. Malandraki

    Full Text Available Solar energetic particle fluxes (Ee > 38 keV observed by the ULYSSES/HI-SCALE experiment are utilized as diagnostic tracers of the large-scale structure and topology of the Interplanetary Magnetic Field (IMF embedded within two well-identified Interplanetary Coronal Mass Ejections (ICMEs detected at 56° and 62° south heliolatitudes by ULYSSES during the solar maximum southern high-latitude pass. On the basis of the energetic solar particle observations it is concluded that: (A the high-latitude ICME magnetic structure observed in May 2000 causes a depression in the solar energetic electron intensities which can be accounted for by either a detached or an attached magnetic field topology for the ICME; (B during the traversal of the out-of-ecliptic ICME event observed in July 2000 energetic electrons injected at the Sun are channeled by the ICME and propagate freely along the ICME magnetic field lines to 62° S heliolatitude.

    Key words. Interplanetary physics (energetic particles; interplanetary magnetic fields

  1. The effects of coronal mass ejection on galactic cosmic rays in the high latitude heliosphere: Observations from Ulysses` first orbit

    Energy Technology Data Exchange (ETDEWEB)

    Bothmer, V.; Heber, B.; Kunow, H.; Mueller-Mellin, R.; Wibberenz, G. [Univ. of Kiel (Germany). Institut fuer Kernphysik; Gosling, J.T. [Los Alamos National Lab., NM (United States); Balogh, A. [Imperial College, London (United Kingdom). Blackett Lab.; Raviart, A. [CEA, Gif-sur-Yvette (France). Service d`Astrophysique; Paizis, C. [Univ. di Milano (Italy). Istituto di Fisica Cosmica CNR

    1997-10-01

    During its first solar orbit the Ulysses spacecraft detected several coronal mass ejections (CMEs) at high heliographic latitudes. The authors present first observations on the effects of these high latitude CMEs on galactic cosmic rays (GCRs) using measurements from the Kiel Electron Telescope (KET) which is part of the Cosmic Ray and Solar Particle Investigation (COSPIN) experiment, the Los Alamos SWOOPS (Solar Wind Observations Over the Poles of the Sun) experiment and the magnetic field experiments. They find the passage of these CMEs over the spacecraft to be associated with short term decreases of GCR intensities The relatively weak shocks in these events, driven by the CMEs` over-expansion, had no strong influence on the GCRs. The intensity minimums of GCRs occurred on closed magnetic field lines inside the CMEs themselves as indicated by bidirectional fluxes of suprathermal electrons. Short episodes of intensity increases of GCRs inside CMEs at times when the bidirectional fluxes of suprathermal electrons disappeared, can be interpreted as evidence that GCRs can easily access the interior of those CMEs in which open magnetic field lines are embedded.

  2. Formation of Magnetic Flux Ropes during Confined Flaring Well Before the Onset of a Pair of Major Coronal Mass Ejections

    CERN Document Server

    Chintzoglou, Georgios; Vourlidas, Angelos

    2015-01-01

    NOAA Active Region (AR) 11429 was the source of twin super-fast Coronal Mass Ejections (CMEs). The CMEs took place within a hour from each other, with the onset of the first taking place in the beginning of March 7, 2012. This AR fulfills all the requirements for a "super active region"; namely, Hale's law incompatibility and a $\\delta$-spot magnetic configuration. One of the biggest storms of Solar Cycle 24 to date ($D_{st}=-143$ nT) was associated with one of these events. Magnetic Flux Ropes (MFRs) are twisted magnetic structures in the corona, best seen in $\\sim$10 MK hot plasma emission and are often considered the core of erupting structures. However, their "dormant" existence in the solar atmosphere (i.e. prior to eruptions), is an open question. Aided by multi-wavelength observations (SDO/HMI/AIA and STEREO EUVI B) and a Non-Linear Force-Free (NLFFF) model for the coronal magnetic field, our work uncovers two separate, weakly-twisted magnetic flux systems which suggest the existence of pre-eruption MF...

  3. Plasma and Magnetic Field Characteristics of Solar Coronal Mass Ejections in Relation to Geomagnetic Storm Intensity and Variability

    CERN Document Server

    Liu, Ying D; Wang, Rui; Yang, Zhongwei; Zhu, Bei; Liu, Yi A; Luhmann, Janet G; Richardson, John D

    2015-01-01

    The largest geomagnetic storms of solar cycle 24 so far occurred on 2015 March 17 and June 22 with $D_{\\rm st}$ minima of $-223$ and $-195$ nT, respectively. Both of the geomagnetic storms show a multi-step development. We examine the plasma and magnetic field characteristics of the driving coronal mass ejections (CMEs) in connection with the development of the geomagnetic storms. A particular effort is to reconstruct the in situ structure using a Grad-Shafranov technique and compare the reconstruction results with solar observations, which gives a larger spatial perspective of the source conditions than one-dimensional in situ measurements. Key results are obtained concerning how the plasma and magnetic field characteristics of CMEs control the geomagnetic storm intensity and variability: (1) a sheath-ejecta-ejecta mechanism and a sheath-sheath-ejecta scenario are proposed for the multi-step development of the 2015 March 17 and June 22 geomagnetic storms, respectively; (2) two contrasting cases of how the CM...

  4. Forecast of Solar Energetic Particles Depending on Magnetic Connectivity and Coronal Mass Ejection Properties Using Multi-Spacecraft Observations

    Science.gov (United States)

    Park, Jinhye; Moon, Yong-Jae; Lee, Harim; Kahler, Stephen W.

    2017-08-01

    For the forecast of solar energetic particles (SEPs), we study the relationships between the peak fluxes of 18 SEP events and associated coronal mass ejection (CME) 3D parameters (speed, angular width and separation angle) obtained from SOHO, STEREO-A and/or B for the period from 2010 August to 2013 June. We apply the STEREO CME Analysis Tool (StereoCAT) to the SEP-associated CMEs to obtain 3D speeds and 3D angular widths. The separation angles are determined as the longitudinal angle between flaring regions and magnetic footpoints of the spacecraft, which are calculated by the assumption of Parker spiral field. The main results are as follows. 1) We find the dependence of the SEP peak fluxes on CME 3D speed and 3D angular width from multi-spacecraft. 2) There is a noticeable anti-correlation (r=-0.62) between SEP peak flux and separation angle. 3) We predict the SEP peak fluxes using a multiple regression method considering longitudinal separation angle, CME 3D speed and 3D angular width. It shows that the separation angle is the most important parameter, and the CME 3D speed is secondary on SEP peak flux.

  5. Observational Tracking of the 2D Structure of Coronal Mass Ejections Between the Sun and 1 AU

    CERN Document Server

    Savani,; Davies,; A., J; Davis,; J., C; Shiota,; D.,; Rouillard,; P., A; Owens,; J., M; Kusano,; K.,; Bothmer,; V.,; Bamford,; P., S; Lintott,; J., C; Smith,; A,

    2015-01-01

    The Solar TErrestrial RElations Observatory (STEREO) provides high cadence and high resolution images of the structure and morphology of coronal mass ejections (CMEs) in the inner heliosphere. CME directions and propagation speeds have often been estimated through the use of time-elongation maps obtained from the STEREO Heliospheric Imager (HI) data. Many of these CMEs have been identified by citizen scientists working within the SolarStormWatch project ( www.solarstormwatch.com ) as they work towards providing robust real-time identification of Earth-directed CMEs. The wide field of view of HI allows scientists to directly observe the two-dimensional (2D) structures, while the relative simplicity of time-elongation analysis means that it can be easily applied to many such events, thereby enabling a much deeper understanding of how CMEs evolve between the Sun and the Earth. For events with certain orientations, both the rear and front edges of the CME can be monitored at varying heliocentric distances (R) bet...

  6. An estimate of the coronal magnetic field near a solar coronal mass ejection from low-frequency radio observations

    Energy Technology Data Exchange (ETDEWEB)

    Hariharan, K.; Ramesh, R.; Kishore, P.; Kathiravan, C. [Indian Institute of Astrophysics, II Block, Koramangala, Bangalore 560 034 (India); Gopalswamy, N., E-mail: khariharan@iiap.res.in [Solar Physics Laboratory, NASA/GSFC, Code 671, Greenbelt, MD (United States)

    2014-11-01

    We report ground-based, low-frequency (<100 MHz) radio imaging, spectral, and polarimeter observations of the type II radio burst associated with the solar coronal mass ejection (CME) that occurred on 2013 May 2. The spectral observations indicate that the burst has fundamental (F) and harmonic (H) emission components with split-band and herringbone structures. The imaging observations at 80 MHz indicate that the H component of the burst was located close to leading edge of the CME at a radial distance of r ≈ 2 R {sub ☉} in the solar atmosphere. The polarimeter observations of the type II burst, also at 80 MHz, indicate that the peak degree of circular polarization (dcp) corresponding to the emission generated in the corona ahead of and behind the associated MHD shock front are ≈0.05 ± 0.02 and ≈0.1 ± 0.01, respectively. We calculated the magnetic field B in the above two coronal regions by adopting the empirical relationship between the dcp and B for the harmonic plasma emission and the values are ≈(0.7-1.4) ± 0.2 G and ≈(1.4-2.8) ± 0.1 G, respectively.

  7. Determination of Coronal Mass Ejection physical parameters from combination of polarized visible light and UV Lyman-$\\alpha$ observations

    CERN Document Server

    Susino, R

    2016-01-01

    Visible-light observations of Coronal Mass Ejections (CMEs) performed with coronagraphs and heliospheric imagers (in primis on board the SOHO and STEREO missions) have offered so far the best way to study the kinematics and geometrical structure of these fundamental events. Nevertheless, it has been widely demonstrated that only combination of multi-wavelength data (including X-ray spectra, EUV images, EUV-UV spectra, and radio dynamic spectra) can provide complete information on the plasma temperature and density distributions, non-thermal motions, magnetic fields, and other physical parameters, for both CMEs and CME-related phenomena. In this work, we analyze three CMEs by combining simultaneous data acquired in the polarized visible light by the LASCO-C2 coronagraph and in the UV H I Lyman-$\\alpha$ line (1216 \\AA) by the UVCS spectrometer, in order to estimate the CME plasma electron density (using the polarization-ratio technique to infer the 3D structure of the CME) and temperature (from the comparison b...

  8. Direct evidence of an eruptive, filament-hosting magnetic flux rope leading to a fast solar coronal mass ejection

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Bin; Gary, D. E. [Center for Solar-Terrestrial Research, New Jersey Institute of Technology, Newark, NJ 07102 (United States); Bastian, T. S., E-mail: bin.chen@cfa.harvard.edu [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States)

    2014-10-20

    Magnetic flux ropes (MFRs) are believed to be at the heart of solar coronal mass ejections (CMEs). A well-known example is the prominence cavity in the low corona that sometimes makes up a three-part white-light (WL) CME upon its eruption. Such a system, which is usually observed in quiet-Sun regions, has long been suggested to be the manifestation of an MFR with relatively cool filament material collecting near its bottom. However, observational evidence of eruptive, filament-hosting MFR systems has been elusive for those originating in active regions. By utilizing multi-passband extreme-ultraviolet (EUV) observations from Solar Dynamics Observatory/Atmospheric Imaging Assembly, we present direct evidence of an eruptive MFR in the low corona that exhibits a hot envelope and a cooler core; the latter is likely the upper part of a filament that undergoes a partial eruption, which is later observed in the upper corona as the coiled kernel of a fast, WL CME. This MFR-like structure exists more than 1 hr prior to its eruption, and displays successive stages of dynamical evolution, in which both ideal and non-ideal physical processes may be involved. The timing of the MFR kinematics is found to be well correlated with the energy release of the associated long-duration C1.9 flare. We suggest that the long-duration flare is the result of prolonged energy release associated with the vertical current sheet induced by the erupting MFR.

  9. The Properties of Solar Energetic Particle Event-Associated Coronal Mass Ejections Reported in Different CME Catalogs

    CERN Document Server

    Richardson, Ian G; Cane, Hilary V

    2015-01-01

    We compare estimates of the speed and width of coronal mass ejections (CMEs) in several catalogs for the CMEs associated with ~200 solar energetic particle (SEP) events in 2006-2013 that included 25 MeV protons. The catalogs used are: CDAW, CACTUS, SEEDS and CORIMP, all derived from observations by the LASCO coronagraphs on the SOHO spacecraft, the CACTUS catalog derived from the COR2 coronagraphs on the STEREO-A and -B spacecraft, and the DONKI catalog, which uses observations from SOHO and the STEREO spacecraft. We illustrate how, for this set of events, CME parameters can differ considerably in each catalog. The well-known correlation between CME speed and proton event intensity is shown to be similar for most catalogs, but this is largely because it is determined by a few large particle events associated with fast CMEs, and small events associated with slow CMEs. Intermediate particle events "shuffle" in position when speeds from different catalogs are used. Quadrature spacecraft CME speeds do not improve...

  10. On Sun-to-Earth Propagation of Coronal Mass Ejections: 2. Slow Events and Comparison with Others

    CERN Document Server

    Liu, Ying D; Wang, Chi; Luhmann, Janet G; Richardson, John D; Yang, Zhongwei; Wang, Rui

    2015-01-01

    As a follow-up study on Sun-to-Earth propagation of fast coronal mass ejections (CMEs), we examine the Sun-to-Earth characteristics of slow CMEs combining heliospheric imaging and in situ observations. Three events of particular interest, the 2010 June 16, 2011 March 25 and 2012 September 25 CMEs, are selected for this study. We compare slow CMEs with fast and intermediate-speed events, and obtain key results complementing the attempt of \\citet{liu13} to create a general picture of CME Sun-to-Earth propagation: (1) the Sun-to-Earth propagation of a typical slow CME can be approximately described by two phases, a gradual acceleration out to about 20-30 solar radii, followed by a nearly invariant speed around the average solar wind level, (2) comparison between different types of CMEs indicates that faster CMEs tend to accelerate and decelerate more rapidly and have shorter cessation distances for the acceleration and deceleration, (3) both intermediate-speed and slow CMEs would have a speed comparable to the a...

  11. LVGEMS Time-of-Flight Mass Spectrometry on Satellites

    Science.gov (United States)

    Herrero, Federico

    2013-01-01

    NASA fs investigations of the upper atmosphere and ionosphere require measurements of composition of the neutral air and ions. NASA is able to undertake these observations, but the instruments currently in use have their limitations. NASA has extended the scope of its research in the atmosphere and now requires more measurements covering more of the atmosphere. Out of this need, NASA developed multipoint measurements using miniaturized satellites, also called nanosatellites (e.g., CubeSats), that require a new generation of spectrometers that can fit into a 4 4 in. (.10 10 cm) cross-section in the upgraded satellites. Overall, the new mass spectrometer required for the new depth of atmospheric research must fulfill a new level of low-voltage/low-power requirements, smaller size, and less risk of magnetic contamination. The Low-Voltage Gated Electrostatic Mass Spectrometer (LVGEMS) was developed to fulfill these requirements. The LVGEMS offers a new spectrometer that eliminates magnetic field issues associated with magnetic sector mass spectrometers, reduces power, and is about 1/10 the size of previous instruments. LVGEMS employs the time of flight (TOF) technique in the GEMS mass spectrometer previously developed. However, like any TOF mass spectrometer, GEMS requires a rectangular waveform of large voltage amplitude, exceeding 100 V -- that means that the voltage applied to one of the GEMS electrodes has to change from 0 to 100 V in a time of only a few nanoseconds. Such electronic speed requires more power than can be provided in a CubeSat. In the LVGEMS, the amplitude of the rectangular waveform is reduced to about 1 V, compatible with digital electronics supplies and requiring little power.

  12. Regional patterns of ocean mass change from GRACE satellite data

    Science.gov (United States)

    Riva, R. E.; Bamber, J. L.; Lavallee, D. A.; Wouters, B.; Hashemi Farahani, H.; Ditmar, P.; Van Der Wal, W.

    2011-12-01

    The Gravity Recovery and Climate Experiment (GRACE) satellites provide a direct measure of mass exchange between continents and oceans over time. Here, we make use of 8 years (2003-2010) of optimally filtered monthly GRACE-based solutions produced at TUDelft to determine trends in the mass of land ice and continental water stocks. We pay particular attention to accounting for the main error sources in the estimation of the land load: the model of glacial isostatic adjustment, signal leakage caused by a limited spatial resolution, and geocentre motion. Through gravitational coupling, load changes over land induce a redistribution of ocean water, which is characterized by complex patterns with peak values in coastal areas. We focus on a few selected regions where those sea-level changes are going to have a particularly high impact on human activities and settlements.

  13. Sun-to-Earth Characteristics of the 2012 July 12 Coronal Mass Ejection and Associated Geo-effectiveness

    Science.gov (United States)

    Hu, Huidong; Liu, Ying D.; Wang, Rui; Möstl, Christian; Yang, Zhongwei

    2016-10-01

    We analyze multi-spacecraft observations associated with the 2012 July 12 coronal mass ejection (CME), covering the source region on the Sun from the Solar Dynamics Observatory, stereoscopic imaging observations from the Solar Terrestrial Relations Observatory (STEREO), magnetic field characteristics from Mercury Surface, Space Environment, Geochemistry, and Ranging (MESSENGER), and type II radio burst and in situ measurements from Wind. A triangulation method based on STEREO stereoscopic observations is employed to determine the kinematics of the CME, and the outcome is compared with the results derived from the type II radio burst using a solar wind electron density model. A Grad-Shafranov technique is applied to Wind in situ data to reconstruct the flux-rope structure and compare it with the observations of the solar source region, which helps in understanding the geo-effectiveness associated with the CME structure. Our conclusions are as follows: (1) the CME undergoes an impulsive acceleration, a rapid deceleration before reaching MESSENGER, and then a gradual deceleration out to 1 au, which should be considered in CME kinematics models; (2) the type II radio burst was probably produced from a high-density interaction region between the CME-driven shock and a nearby streamer or from the shock flank with lower heights, which implies uncertainties in the determination of CME kinematics using solely type II radio bursts; (3) the flux-rope orientation and chirality deduced from in situ reconstructions at Wind agree with those obtained from solar source observations; (4) the prolonged southward magnetic field near the Earth is mainly from the axial component of the largely southward inclined flux rope, which indicates the importance of predicting both the flux-rope orientation and magnetic field components in geomagnetic activity forecasting.

  14. Interplanetary Coronal Mass Ejections Resulting from Earth-Directed CMEs Using SOHO and ACE Combined Data During Solar Cycle 23

    Science.gov (United States)

    Paouris, Evangelos; Mavromichalaki, Helen

    2017-02-01

    In this work a total of 266 interplanetary coronal mass ejections observed by the Solar and Heliospheric Observatory/ Large Angle and Spectrometric Coronagraph (SOHO/LASCO) and then studied by in situ observations from Advanced Composition Explorer (ACE) spacecraft, are presented in a new catalog for the time interval 1996 - 2009 covering Solar Cycle 23. Specifically, we determine the characteristics of the CME which is responsible for the upcoming ICME and the associated solar flare, the initial/background solar wind plasma and magnetic field conditions before the arrival of the CME, the conditions in the sheath of the ICME, the main part of the ICME, the geomagnetic conditions of the ICME's impact at Earth and finally we remark on the visual examination for each event. Interesting results revealed from this study include the high correlation coefficient values of the magnetic field Bz component against the Ap index (r = 0.84), as well as against the Dst index (r = 0.80) and of the effective acceleration against the CME linear speed (r = 0.98). We also identify a north-south asymmetry for X-class solar flares and an east-west asymmetry for CMEs associated with strong solar flares (magnitude ≥ M1.0) which finally triggered intense geomagnetic storms (with Ap ≥179). The majority of the geomagnetic storms are determined to be due to the ICME main part and not to the extreme conditions which dominate inside the sheath. For the intense geomagnetic storms the maximum value of the Ap index is observed almost 4 hours before the minimum Dst index. The amount of information makes this new catalog the most comprehensive ICME catalog for Solar Cycle 23.

  15. An unusual giant spiral arc in the polar cap region during the northward phase of a Coronal Mass Ejection

    Directory of Open Access Journals (Sweden)

    L. Rosenqvist

    2007-03-01

    Full Text Available The shock arrival of an Interplanetary Coronal Mass Ejection (ICME at ~09:50 UT on 22 November 1997 resulted in the development of an intense (Dst<−100 nT geomagnetic storm at Earth. In the early, quiet phase of the storm, in the sheath region of the ICME, an unusual large spiral structure (diameter of ~1000 km was observed at very high latitudes by the Polar UVI instrument. The evolution of this structure started as a polewardly displaced auroral bulge which further developed into the spiral structure spreading across a large part of the polar cap. This study attempts to examine the cause of the chain of events that resulted in the giant auroral spiral. During this period the interplanetary magnetic field (IMF was dominantly northward (Bz>25 nT with a strong duskward component (By>15 nT resulting in a highly twisted tail plasma sheet. Geotail was located at the equatorial dawnside magnetotail flank and observed accelerated plasma flows exceeding the solar wind bulk velocity by almost 60%. These flows are observed on the magnetosheath side of the magnetopause and the acceleration mechanism is proposed to be typical for strongly northward IMF. Identified candidates to the cause of the spiral structure include a By induced twisted magnetotail configuration, the development of magnetopause surface waves due to the enhanced pressure related to the accelerated magnetosheath flows aswell as the formation of additional magnetopause deformations due to external solar wind pressure changes. The uniqeness of the event indicate that most probably a combination of the above effects resulted in a very extreme tail topology. However, the data coverage is insufficient to fully investigate the physical mechanism behind the observations.

  16. On the Origin of Coronal Mass Ejections: How Does the Emergence of a Magnetic Flux Rope Reorganize the Solar Corona?

    Science.gov (United States)

    Roussev, I. I.; Galsgaard, K.; Lugaz, N.; Sokolov, I.

    2010-12-01

    The physical causes leading to the occurrence of Coronal Mass Ejections (CMEs) on the Sun have been debated for almost four decades now. One of the leading mechanisms suggests that a CME may occur as the result of the emergence of a twisted magnetic flux rope from the convection zone into the solar corona. This process have been investigated by a number of researchers over the years, and it has been demonstrated that an eruption of the coronal magnetic field can in principle occur. The majority of these studies, however, involve some ad-hoc prescription of the electric field at the photosphere resembling flux emergence, and they neglect the ambient coronal magnetic field. In addition, most of these flux-emergence simulations are performed in a Cartesian domain, which extends only to a few dozen pressure scale-heights into the corona. Thus, it is difficult to assess the role of boundary driving and limited computational domain on the resulting evolution of the erupting coronal magnetic field. In this paper, we present a new model of CMEs that mitigates these two effects. To achieve this, we couple the "local" magnetic-flux-emergence (MFE) model of Archontis et al. (2004) with a global MHD model of the solar corona and solar wind. The model coupling is performed using the Space Weather Modeling Framework. In the coupled model, the MFE simulation provides time-dependent boundary conditions for all MHD quantities into the global model, where the physical coupling is done at the photospheric boundary. The physical evolution of the system is followed using the BATS-R-US "ideal" MHD code well beyond the complete emergence of the magnetic flux from the convection zone. We discuss the dynamics of the flux emergence process and the related response of the pre-existing coronal magnetic field in the context of CME production.

  17. Automatically Detecting and Tracking Coronal Mass Ejections. I. Separation of Dynamic and Quiescent Components in Coronagraph Images

    Science.gov (United States)

    Morgan, Huw; Byrne, Jason P.; Habbal, Shadia Rifai

    2012-06-01

    Automated techniques for detecting and tracking coronal mass ejections (CMEs) in coronagraph data are of ever increasing importance for space weather monitoring and forecasting. They serve to remove the biases and tedium of human interpretation, and provide the robust analysis necessary for statistical studies across large numbers of observations. An important requirement in their operation is that they satisfactorily distinguish the CME structure from the background quiescent coronal structure (streamers, coronal holes). Many studies resort to some form of time differencing to achieve this, despite the errors inherent in such an approach—notably spatiotemporal crosstalk. This article describes a new deconvolution technique that separates coronagraph images into quiescent and dynamic components. A set of synthetic observations made from a sophisticated model corona and CME demonstrates the validity and effectiveness of the technique in isolating the CME signal. Applied to observations by the LASCO C2 and C3 coronagraphs, the structure of a faint CME is revealed in detail despite the presence of background streamers that are several times brighter than the CME. The technique is also demonstrated to work on SECCHI/COR2 data, and new possibilities for estimating the three-dimensional structure of CMEs using the multiple viewing angles are discussed. Although quiescent coronal structures and CMEs are intrinsically linked, and although their interaction is an unavoidable source of error in any separation process, we show in a companion paper that the deconvolution approach outlined here is a robust and accurate method for rigorous CME analysis. Such an approach is a prerequisite to the higher-level detection and classification of CME structure and kinematics.

  18. Determination of Coronal Mass Ejection Physical Parameters from a Combination of Polarized Visible Light and UV Lyα Observations

    Science.gov (United States)

    Susino, R.; Bemporad, A.

    2016-10-01

    Visible-light observations of Coronal Mass Ejections (CMEs) performed with coronagraphs and heliospheric imagers (in primis on board the Solar and Heliospheric Observatory and STEREO missions) have offered the best way to study the kinematics and geometrical structure of these fundamental events so far. Nevertheless, it has been widely demonstrated that only combination of multi-wavelength data (including X-ray spectra, EUV images, EUV-UV spectra, and radio dynamic spectra) can provide complete information on the plasma temperature and density distributions, non-thermal motions, magnetic fields, and other physical parameters, for both CMEs and CME-related phenomena. In this work, we analyze three CMEs by combining simultaneous data acquired in the polarized visible light by the LASCO-C2 coronagraph and in the UV H i Lyα line (1216 Å) by the UVCS spectrometer, in order to estimate the CME plasma electron density (using the polarization-ratio technique to infer the 3D structure of the CME) and temperature (from the comparison between the expected and measured Lyα intensities) along the UVCS field of view. This analysis is primarily aimed at testing the diagnostic methods that will be applied to coronagraphic observations of CMEs delivered by the Metis instrument on board the next ESA-Solar Orbiter mission. We find that CME cores are usually associated with cooler plasma (T∼ {10}6 K), and that a significant increase of the electron temperatures is observed from the core to the front of the CME (where T\\gt {10}6.3 K), which seems to be correlated, in all cases, with the morphological structure of the CME as derived from visible-light images.

  19. NUMERICAL SIMULATIONS OF CORONAL MASS EJECTION ON 2011 MARCH 7: ONE-TEMPERATURE AND TWO-TEMPERATURE MODEL COMPARISON

    Energy Technology Data Exchange (ETDEWEB)

    Jin, M.; Manchester, W. B.; Van der Holst, B.; Oran, R.; Sokolov, I.; Toth, G.; Gombosi, T. I. [Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Liu, Y.; Sun, X. D., E-mail: jinmeng@umich.edu [W. W. Hansen Experimental Physics Laboratory, Stanford University, CA 94305 (United States)

    2013-08-10

    During Carrington rotation (CR) 2107, a fast coronal mass ejection (CME; >2000 km s{sup -1}) occurred in active region NOAA 11164. This event is also associated with a solar energetic particle event. In this study, we present simulations of this CME with one-temperature (1T) and two-temperature (2T: coupled thermodynamics of the electron and proton populations) models. Both the 1T and 2T models start from the chromosphere with heat conduction and radiative cooling. The background solar wind is driven by Alfven-wave pressure and heated by Alfven-wave dissipation in which we have incorporated the balanced turbulence at the top of the closed field lines. The magnetic field of the inner boundary is set up using a synoptic map from Solar Dynamics Observatory/Helioseismic and Magnetic Imager. The Titov-Demoulin flux-rope model is used to initiate the CME event. We compare the propagation of fast CMEs and the thermodynamics of CME-driven shocks in both the 1T and 2T CME simulations. Also, the synthesized white light images are compared with the Solar and Heliospheric Observatory/Large Angle and Spectrometric Coronagraph observations. Because there is no distinction between electron and proton temperatures, heat conduction in the 1T model creates an unphysical temperature precursor in front of the CME-driven shock and makes the shock parameters (e.g., shock Mach number, compression ratio) incorrect. Our results demonstrate the importance of the electron heat conduction in conjunction with proton shock heating in order to produce the physically correct CME structures and CME-driven shocks.

  20. Remote and In Situ Observations of an Unusual Earth-Directed Coronal Mass Ejection from Multiple Viewpoints

    Science.gov (United States)

    Nieves-Chinchilla, T.; Colaninno, R.; Vourlidas, A.; Szabo, A.; Lepping, R. P.; Boardsen, S. A.; Anderson, B. J.; Korth, H.

    2012-01-01

    During June 16-21, 2010, an Earth-directed Coronal Mass Ejection (CME) event was observed by instruments onboard STEREO, SOHO, MESSENGER and Wind. This event was the first direct detection of a rotating CME in the middle and outer corona. Here, we carry out a comprehensive analysis of the evolution of the CME in the interplanetary medium comparing in-situ and remote observations, with analytical models and three-dimensional reconstructions. In particular, we investigate the parallel and perpendicular cross section expansion of the CME from the corona through the heliosphere up to 1 AU. We use height-time measurements and the Gradual Cylindrical Shell (GCS) technique to model the imaging observations, remove the projection effects, and derive the 3-dimensional extent of the event. Then, we compare the results with in-situ analytical Magnetic Cloud (MC) models, and with geometrical predictions from past works. We nd that the parallel (along the propagation plane) cross section expansion agrees well with the in-situ model and with the Bothmer & Schwenn [1998] empirical relationship based on in-situ observations between 0.3 and 1 AU. Our results effectively extend this empirical relationship to about 5 solar radii. The expansion of the perpendicular diameter agrees very well with the in-situ results at MESSENGER ( 0:5 AU) but not at 1 AU. We also find a slightly different, from Bothmer & Schwenn [1998], empirical relationship for the perpendicular expansion. More importantly, we find no evidence that the CME undergoes a significant latitudinal over-expansion as it is commonly assumed

  1. Symmetric or asymmetric energy transfer from Interplanetary Coronal Mass Ejections to the magnetosphere depending on the solar dipole

    Science.gov (United States)

    Baranyi, T.; Ludmány, A.

    The annual behaviour of monthly number of hours spent by the Earth in domains of either positive or negative By component of the interplanetary magnetic field (IMF) was studied. We used the hourly OMNI data in the cases of Kp > 3. The study was confined to the ascending phases of the four recent sunspot cycles when Interplanetary Coronal Mass Ejections (ICMEs) dominate among the sources of geoeffectiveness. Definite differences were found between the annual variations of the hourly sums. When the solar dipole is opposite to the terrestrial one, the sums exhibit the the combined effect of Rosenberg-Coleman and Russell-McPherron effects. Thus, in the geomagnetically active hours the negative By dominates during the first half of the year and the positive By dominates during the second half of the year. However, these effects can not be detected in the occurrence of the negative and positive GSM By values when the solar and terrestrial dipoles are parallel. In this case one can see polarity-independent semiannual variations instead of the polarity-dependent opposite annual variations. It is well-known that the By component modulates the energy transfer from the solar wind to the magnetosphere causing marked asymmetries in magnetospheric convective flow patterns at high latitudes. Our results hint that the occurrences of these asymmetries related to the ICMEs depend on the solar dipole cycle. In the antiparallel years one of them dominates during half a year causing asymmetric energy transfer to the magnetosphere. In the parallel years the occurrences of the two kind of asymmetries are equal on monthly time scale, thus the energy transfer is symmetric within a monthly and yearly time interval.

  2. USING MULTIPLE-VIEWPOINT OBSERVATIONS TO DETERMINE THE INTERACTION OF THREE CORONAL MASS EJECTIONS OBSERVED ON 2012 MARCH 5

    Energy Technology Data Exchange (ETDEWEB)

    Colaninno, Robin C. [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States); Vourlidas, Angelos, E-mail: robin.colaninno@nrl.navy.mil, E-mail: angelos.vourlidas@jhuapl.edu [The Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723 (United States)

    2015-12-10

    We examine the interaction of three coronal mass ejections (CMEs) that took place on 2012 March 5 at heights less than 20 R{sub ⊙} in the corona. We used a forward fitting model to reconstruct the three-dimensional trajectories and kinematics of the CMEs and determine their interaction in the observations from three viewpoints: Solar and Heliospheric Observatory (SOHO), STEREO-A, and STEREO-B. The first CME (CME-1), a slow-rising eruption near disk center, is already in progress at 02:45 UT when the second CME (CME-2) erupts from AR 11429 on the east limb. These two CMEs are present in the corona not interacting when a third CME (CME-3) erupts from AR 11429 at 03:34 UT. CME-3 has a constant velocity of 1456[±31] km s{sup −1} and drives a shock that is observed as a halo from all viewpoints. We find that the shock driven by CME-3 passed through CME-1 with no observable change in the geometry, trajectory, or velocity of CME-1. However, the elevated temperatures detected in situ when CME-1 reached Earth indicate that the plasma inside CME-1 may have been heated by the passage of the shock. CME-2 is accelerated by CME-3 to more than twice its initial velocity and remains a separate structure ahead of the CME-3 front. CME-2 is deflected 24° northward by CME-3 for a total deflection of 40° from its source region. These results suggest that the collision of CME-2 and CME-3 is superelastic. This work demonstrates the capability and utility of fitting forward models to complex and interacting CMEs observed in the corona from multiple viewpoints.

  3. Chromosphere to 1 AU Simulation of the 2011 March 7th Event: A Comprehensive Study of Coronal Mass Ejection Propagation

    Science.gov (United States)

    Jin, M.; Manchester, W. B.; van der Holst, B.; Sokolov, I.; Tóth, G.; Vourlidas, A.; de Koning, C. A.; Gombosi, T. I.

    2017-01-01

    We perform and analyze the results of a global magnetohydrodynamic simulation of the fast coronal mass ejection (CME) that occurred on 2011 March 7. The simulation is made using the newly developed Alfvén Wave Solar Model (AWSoM), which describes the background solar wind starting from the upper chromosphere and extends to 24 R⊙. Coupling AWSoM to an inner heliosphere model with the Space Weather Modeling Framework extends the total domain beyond the orbit of Earth. Physical processes included in the model are multi-species thermodynamics, electron heat conduction (both collisional and collisionless formulations), optically thin radiative cooling, and Alfvén-wave turbulence that accelerates and heats the solar wind. The Alfvén-wave description is physically self-consistent, including non-Wentzel–Kramers–Brillouin reflection and physics-based apportioning of turbulent dissipative heating to both electrons and protons. Within this model, we initiate the CME by using the Gibson-Low analytical flux rope model and follow its evolution for days, in which time it propagates beyond STEREO A. A detailed comparison study is performed using remote as well as in situ observations. Although the flux rope structure is not compared directly due to lack of relevant ejecta observation at 1 au in this event, our results show that the new model can reproduce many of the observed features near the Sun (e.g., CME-driven extreme ultraviolet [EUV] waves, deflection of the flux rope from the coronal hole, “double-front” in the white light images) and in the heliosphere (e.g., shock propagation direction, shock properties at STEREO A).

  4. ON SUN-TO-EARTH PROPAGATION OF CORONAL MASS EJECTIONS: II. SLOW EVENTS AND COMPARISON WITH OTHERS

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ying D.; Hu, Huidong; Wang, Chi; Yang, Zhongwei; Wang, Rui [State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190 (China); Luhmann, Janet G. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Richardson, John D., E-mail: liuxying@spaceweather.ac.cn [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2016-02-15

    As a follow-up study on Sun-to-Earth propagation of fast coronal mass ejections (CMEs), we examine the Sun-to-Earth characteristics of slow CMEs combining heliospheric imaging and in situ observations. Three events of particular interest, the 2010 June 16, 2011 March 25, and 2012 September 25 CMEs, are selected for this study. We compare slow CMEs with fast and intermediate-speed events, and obtain key results complementing the attempt of Liu et al. to create a general picture of CME Sun-to-Earth propagation: (1) the Sun-to-Earth propagation of a typical slow CME can be approximately described by two phases, a gradual acceleration out to about 20–30 solar radii, followed by a nearly invariant speed around the average solar wind level; (2) comparison between different types of CMEs indicates that faster CMEs tend to accelerate and decelerate more rapidly and have shorter cessation distances for the acceleration and deceleration; (3) both intermediate-speed and slow CMEs would have speeds comparable to the average solar wind level before reaching 1 au; (4) slow CMEs have a high potential to interact with other solar wind structures in the Sun–Earth space due to their slow motion, providing critical ingredients to enhance space weather; and (5) the slow CMEs studied here lack strong magnetic fields at the Earth but tend to preserve a flux-rope structure with an axis generally perpendicular to the radial direction from the Sun. We also suggest a “best” strategy for the application of a triangulation concept in determining CME Sun-to-Earth kinematics, which helps to clarify confusions about CME geometry assumptions in the triangulation and to improve CME analysis and observations.

  5. Treatment of Viscosity in the Shock Waves Observed After Two Consecutive Coronal Mass Ejection Activities CME08/03/2012 and CME15/03/2012

    Science.gov (United States)

    Cavus, Huseyin

    2016-11-01

    A coronal mass ejection (CME) is one of the most the powerful activities of the Sun. There is a possibility to produce shocks in the interplanetary medium after CMEs. Shock waves can be observed when the solar wind changes its velocity from being supersonic nature to being subsonic nature. The investigations of such activities have a central place in space weather purposes, since; the interaction of shocks with viscosity is one of the most important problems in the supersonic and compressible gas flow regime (Blazek in Computational fluid dynamics: principles and applications. Elsevier, Amsterdam 2001). The main aim of present work is to achieve a search for the viscosity effects in the shocks occurred after two consecutive coronal mass ejection activities in 2012 (i.e. CME08/03/2012 and CME15/03/2012).

  6. A shocked-Bz event caused by fast steady flow-slow transient flow interaction. [with coronal mass ejection in interplanetary space

    Science.gov (United States)

    Zhao, X.

    1992-01-01

    We show that the 25 November 1978 shock pair was caused by the interaction of a fast steady flow with a slow coronal mass ejection in interplanetary space (ICME). It is suggested that the slow ICME may be disconnected from the sun. In addition, a new method to infer the shock angle and Mach number from the observed upstream plasma beta and the jump ratios of proton density and magnetic flux density across a shock is described.

  7. STEREO卫星的CME观测研究进展%Progress in the Observations of Coronal Mass Ejections by STEREO

    Institute of Scientific and Technical Information of China (English)

    张雪飞; 刘煜; 申远灯; 田占军

    2012-01-01

    We briefly review the important observational results for CMEs based on the stereoscopic data by STEREO, including: (1) the study of the structural characteristic of CMEs evolution, by the determination of their mass from the EUV dimming observed by the two EUVI (EUV Imager) telescopes; (2) the study of the propagating characteristic of CMEs in three dimensions, by analyzing the stereo image pairs from the two coronagraphs on board STEREO; (3) the study of the ICMEs as well as their evolution and dynamics through the inner heliosphere to the Earth, by tracking their source regions on the solar surface and the following propagations in the heliosphere from the two HI (Heliospheric Imager) telescopes. Finally, we introduce the new methods for measuring the parameters of CMEs using triangulation techniques.%简要回顾利用“日地关系天文台”(Solar Terrestrial Relations Observatory,STEREO)卫星的立体观测资料在日冕物质抛射(Coronal Mass Ejection,CME)研究方面已取得的一些重要进展,主要包括:(1)通过极紫外成像仪观测到的日冕极紫外暗化来更准确地估计CME质量,研究CME演化的结构特征;(2)利用STEREO卫星日冕仪的双角度观测,在CME立体传播特征方面取得的新进展;(3)STEREO卫星日球成像仪具有广阔的视场范围,可以跟踪研究CME从太阳表面爆发到形成行星际日冕物质抛射(Interplanetary CME,ICME),及其在内日球层和近地空间的演化特征以及运动特征等.同时,也介绍了利用三角测量技术测定CME特征物理量的新方法.

  8. Listening to Shells: Galaxy Masses from Disrupted Satellites

    Science.gov (United States)

    Westfall, Kyle; Sanderson, R.

    2014-01-01

    Our ability to measure the dynamical mass of an individual galaxy is limited by the radial extent of the luminous tracers of its potential. For elliptical galaxies, it is difficult to go much beyond two effective radii using integrated light. Appealing to particle tracers like globular clusters has allowed for mass measurements out to ten effective radii. The extended atomic-gas disks of spiral galaxies allow one to measure rotation curves well beyond the optical disk to a few effective radii; however, such mass measurements are limited to a single plane and can often be confused by warps. As surface-brightness limits have pushed ever deeper, the revealed abundance of disrupted satellites in galaxy halos may present a unique opportunity for determining the enclosed mass at very large radii (more than five effective radii), provided our technology is up to the challenge. Here, we discuss the prospect of using integrated light spectroscopy of tidal shells to measure the masses of individual galaxies at redshifts of up to 0.1. Our study considers the limitations of current and projected instrumentation on 4-, 10-, and 30-meter class telescopes. The observational constraints are indeed very stringent, requiring both high sensitivity (with V-band surface brightness limits below 25 mag per square arsecond) and high spectral resolution (R>10k), whereas spatial resolution is effectively irrelevant. Bigger is not necessarily better for our application because of the limited field-of-view (FOV) of large telescopes, which dramatically limits their total grasp. We find the two most-promising setups are (1) a large FOV (1 square arcminute) integral-field unit (IFU) on a 4-meter class telescope and (2) a multiplexed suite of small FOV (10 square arcseconds) IFUs on a 10- or 30-meter class telescope. Two prospective instruments that may meet these requirements are WEAVE, an instrument currently planned for the William Herschel Telescope at La Palma, and an OPTIMOS

  9. The 2011 Outburst of Recurrent Nova T Pyx: X-ray Observations Expose the White Dwarf Mass and Ejection Dynamics

    CERN Document Server

    Chomiuk, Laura; Mukai, Koji; Sokoloski, J L; Rupen, Michael P; Page, Kim L; Osborne, Julian P; Kuulkers, Erik; Mioduszewski, Amy J; Roy, Nirupam; Weston, Jennifer; Krauss, Miriam I

    2014-01-01

    The recurrent nova T Pyx underwent its sixth historical outburst in 2011, and became the subject of an intensive multi-wavelength observational campaign. We analyze data from the Swift and Suzaku satellites to produce a detailed X-ray light curve augmented by epochs of spectral information. X-ray observations yield mostly non-detections in the first four months of outburst, but both a super-soft and hard X-ray component rise rapidly after Day 115. The super-soft X-ray component, attributable to the photosphere of the nuclear-burning white dwarf, is relatively cool (~45 eV) and implies that the white dwarf in T Pyx is significantly below the Chandrasekhar mass (~1 M_sun). The late turn-on time of the super-soft component yields a large nova ejecta mass (>~10^-5 M_sun), consistent with estimates at other wavelengths. The hard X-ray component is well fit by a ~1 keV thermal plasma, and is attributed to shocks internal to the 2011 nova ejecta. The presence of a strong oxygen line in this thermal plasma on Day 194...

  10. The influence of stellar-dynamical ejections and collisions on the relation between the maximum-star and star-cluster-mass

    CERN Document Server

    Oh, Seungkyung

    2012-01-01

    We perform the largest currently available set of direct N-body calculations of young star cluster models to study the dynamical influence, especially through the ejections of the most massive star in the cluster, on the current relation between the maximum-stellar-mass and the star-cluster-mass. We vary several initial parameters such as the initial half-mass radius of the cluster, the initial binary fraction, and the degree of initial mass segregation. Two different pairing methods are used to construct massive binaries for more realistic initial conditions of massive binaries. We find that lower mass clusters (= 1000 Msun), no most-massive star escapes the cluster within 3 Myr regardless of the initial conditions if clusters have initial half-mass radii, r_0.5, >= 0.8 pc. However, a few of the initially smaller sized clusters (r_0.5 = 0.3 pc), which have a higher density, eject their most massive star within 3 Myr. If clusters form with a compact size and their massive stars are born in a binary system wit...

  11. A Space weather information service based upon remote and in-situ measurements of coronal mass ejections heading for Earth

    Directory of Open Access Journals (Sweden)

    Ritter Birgit

    2015-01-01

    Full Text Available The Earth’s magnetosphere is formed as a consequence of interaction between the planet’s magnetic field and the solar wind, a continuous plasma stream from the Sun. A number of different solar wind phenomena have been studied over the past 40 years with the intention of understanding and forecasting solar behavior. One of these phenomena in particular, Earth-bound interplanetary coronal mass ejections (CMEs, can significantly disturb the Earth’s magnetosphere for a short time and cause geomagnetic storms. This publication presents a mission concept consisting of six spacecraft that are equally spaced in a heliocentric orbit at 0.72 AU. These spacecraft will monitor the plasma properties, the magnetic field’s orientation and magnitude, and the 3D-propagation trajectory of CMEs heading for Earth. The primary objective of this mission is to increase space weather forecasting time by means of a near real-time information service, that is based upon in-situ and remote measurements of the aforementioned CME properties. The obtained data can additionally be used for updating scientific models. This update is the mission’s secondary objective. In-situ measurements are performed using a Solar Wind Analyzer instrumentation package and fluxgate magnetometers, while for remote measurements coronagraphs are employed. The proposed instruments originate from other space missions with the intention to reduce mission costs and to streamline the mission design process. Communication with the six identical spacecraft is realized via a deep space network consisting of six ground stations. They provide an information service that is in uninterrupted contact with the spacecraft, allowing for continuous space weather monitoring. A dedicated data processing center will handle all the data, and then forward the processed data to the SSA Space Weather Coordination Center which will, in turn, inform the general public through a space weather forecast. The data

  12. M-I coupling across the auroral oval at dusk and midnight: repetitive substorm activity driven by interplanetary coronal mass ejections (CMEs)

    Science.gov (United States)

    Sandholt, P. E.; Farrugia, C. J.; Denig, W. F.

    2014-04-01

    We study substorms from two perspectives, i.e., magnetosphere-ionosphere coupling across the auroral oval at dusk and at midnight magnetic local times. By this approach we monitor the activations/expansions of basic elements of the substorm current system (Bostrøm type I centered at midnight and Bostrøm type II maximizing at dawn and dusk) during the evolution of the substorm activity. Emphasis is placed on the R1 and R2 types of field-aligned current (FAC) coupling across the Harang reversal at dusk. We distinguish between two distinct activity levels in the substorm expansion phase, i.e., an initial transient phase and a persistent phase. These activities/phases are discussed in relation to polar cap convection which is continuously monitored by the polar cap north (PCN) index. The substorm activity we selected occurred during a long interval of continuously strong solar wind forcing at the interplanetary coronal mass ejection passage on 18 August 2003. The advantage of our scientific approach lies in the combination of (i) continuous ground observations of the ionospheric signatures within wide latitude ranges across the auroral oval at dusk and midnight by meridian chain magnetometer data, (ii) "snapshot" satellite (DMSP F13) observations of FAC/precipitation/ion drift profiles, and (iii) observations of current disruption/near-Earth magnetic field dipolarizations at geostationary altitude. Under the prevailing fortunate circumstances we are able to discriminate between the roles of the dayside and nightside sources of polar cap convection. For the nightside source we distinguish between the roles of inductive and potential electric fields in the two substages of the substorm expansion phase. According to our estimates the observed dipolarization rate (δ Bz/δt) and the inferred large spatial scales (in radial and azimuthal dimensions) of the dipolarization process in these strong substorm expansions may lead to 50-100 kV enhancements of the cross

  13. M-I coupling across the auroral oval at dusk and midnight. Repetitive substorm activity driven by interplanetary coronal mass ejections (CMEs)

    Energy Technology Data Exchange (ETDEWEB)

    Sandholt, P.E. [Oslo Univ. (Norway). Dept. of Physics; Farrugia, C.J. [New Hampshire Univ., Durham (United Kingdom). Space Science Center; Denig, W.F. [NOAA, Boulder, CO (United States)

    2014-07-01

    We study substorms from two perspectives, i.e., magnetosphere-ionosphere coupling across the auroral oval at dusk and at midnight magnetic local times. By this approach we monitor the activations/expansions of basic elements of the substorm current system (Bostroem type I centered at midnight and Bostroem type II maximizing at dawn and dusk) during the evolution of the substorm activity. Emphasis is placed on the R1 and R2 types of field-aligned current (FAC) coupling across the Harang reversal at dusk. We distinguish between two distinct activity levels in the substorm expansion phase, i.e., an initial transient phase and a persistent phase. These activities/phases are discussed in relation to polar cap convection which is continuously monitored by the polar cap north (PCN) index. The substorm activity we selected occurred during a long interval of continuously strong solar wind forcing at the interplanetary coronal mass ejection passage on 18 August 2003. The advantage of our scientific approach lies in the combination of (i) continuous ground observations of the ionospheric signatures within wide latitude ranges across the auroral oval at dusk and midnight by meridian chain magnetometer data, (ii) 'snapshot' satellite (DMSP F13) observations of FAC/precipitation/ion drift profiles, and (iii) observations of current disruption/near-Earth magnetic field dipolarizations at geostationary altitude. Under the prevailing fortunate circumstances we are able to discriminate between the roles of the dayside and nightside sources of polar cap convection. For the nightside source we distinguish between the roles of inductive and potential electric fields in the two substages of the substorm expansion phase. According to our estimates the observed dipolarization rate (δB{sub z}/δt) and the inferred large spatial scales (in radial and azimuthal dimensions) of the dipolarization process in these strong substorm expansions may lead to 50-100 kV enhancements of the

  14. Greenland Ice sheet mass balance from satellite and airborne altimetry

    Science.gov (United States)

    Khan, S. A.; Bevis, M. G.; Wahr, J. M.; Wouters, B.; Sasgen, I.; van Dam, T. M.; van den Broeke, M. R.; Hanna, E.; Huybrechts, P.; Kjaer, K.; Korsgaard, N. J.; Bjork, A. A.; Kjeldsen, K. K.

    2013-12-01

    Ice loss from the Greenland Ice Sheet (GrIS) is dominated by loss in the marginal areas. Dynamic induced ice loss and its associated ice surface lowering is often largest close to the glacier calving front and may vary from rates of tens of meters per years to a few meters per year over relatively short distances. Hence, high spatial resolution data are required to accurately estimate volume changes. Here, we estimate ice volume change rate of the Greenland ice sheet using data from Ice, Cloud and land Elevation Satellite (ICESat) laser altimeter during 2003-2009 and CryoSat-2 data during 2010-2012. To improve the volume change estimate we supplement the ICESat and CryoSat data with altimeter surveys from NASA's Airborne Topographic Mapper (ATM) during 2003-2012 and NASA's Land, Vegetation and Ice Sensor (LVIS) during 2007-2012. The Airborne data are mainly concentrated along the ice margin and therefore significantly improve the estimate of the total volume change. Furthermore, we divide the GrIS into six major drainage basins and provide volume loss estimates during 2003-2006, 2006-2009 and 2009-2012 for each basin and separate between melt induced and dynamic ice loss. In order to separate dynamic ice loss from melt processes, we use SMB values from the Regional Atmospheric Climate Model (RACMO2) and SMB values from a positive degree day runoff retention model (Janssens & Huybrechts 2000, Hanna et al. 2011 JGR, updated for this study). Our results show increasing SMB ice loss over the last decade, while dynamic ice loss increased during 2003-2009, but has since been decreasing. Finally, we assess the estimated mass loss using GPS observations from stations located along the edge of the GrIS and measurements from the Gravity Recovery and Climate Experiment (GRACE) satellite gravity mission. Hanna, E., et al. (2011), Greenland Ice Sheet surface mass balance 1870 to 2010 based on Twentieth Century Reanalysis, and links with global climate forcing, J. Geophys. Res

  15. FORMATION OF MULTIPLE-SATELLITE SYSTEMS FROM LOW-MASS CIRCUMPLANETARY PARTICLE DISKS

    Energy Technology Data Exchange (ETDEWEB)

    Hyodo, Ryuki; Ohtsuki, Keiji [Department of Earth and Planetary Sciences, Kobe University, Kobe 657-8501 (Japan); Takeda, Takaaki, E-mail: ryukih@stu.kobe-u.ac.jp, E-mail: ohtsuki@tiger.kobe-u.ac.jp [VASA Entertainment Co. Ltd. (Japan)

    2015-01-20

    Circumplanetary particle disks would be created in the late stage of planetary formation either by impacts of planetary bodies or disruption of satellites or passing bodies, and satellites can be formed by accretion of disk particles spreading across the Roche limit. Previous N-body simulation of lunar accretion focused on the formation of single-satellite systems from disks with large disk-to-planet mass ratios, while recent models of the formation of multiple-satellite systems from disks with smaller mass ratios do not take account of gravitational interaction between formed satellites. In the present work, we investigate satellite accretion from particle disks with various masses, using N-body simulation. In the case of accretion from somewhat less massive disks than the case of lunar accretion, formed satellites are not massive enough to clear out the disk, but can become massive enough to gravitationally shepherd the disk outer edge and start outward migration due to gravitational interaction with the disk. When the radial location of the 2:1 mean motion resonance of the satellite reaches outside the Roche limit, the second satellite can be formed near the disk outer edge, and then the two satellites continue outward migration while being locked in the resonance. Co-orbital satellites are found to be occasionally formed on the orbit of the first satellite. Our simulations also show that stochastic nature involved in gravitational interaction and collision between aggregates in the tidal environment can lead to diversity in the final mass and orbital architecture, which would be expected in satellite systems of exoplanets.

  16. Binaries discovered by the SPY survey. VI. Discovery of a low mass companion to the hot subluminous planetary nebula central star EGB 5 - a recently ejected common envelope?

    Science.gov (United States)

    Geier, S.; Napiwotzki, R.; Heber, U.; Nelemans, G.

    2011-04-01

    Hot subdwarf B stars (sdBs) in close binary systems are assumed to be formed via common envelope ejection. According to theoretical models, the amount of energy and angular momentum deposited in the common envelope scales with the mass of the companion. That low mass companions near or below the core hydrogen-burning limit are able to trigger the ejection of this envelope is well known. The currently known systems have very short periods ≃0.1-0.3 d. Here we report the discovery of a low mass companion (M2 > 0.14 M⊙) orbiting the sdB star and central star of a planetary nebula EGB 5 with an orbital period of 16.5 d at a minimum separation of 23 R⊙. Its long period is only just consistent with the energy balance prescription of the common envelope. The marked difference between the short and long period systems will provide strong constraints on the common envelope phase, in particular if the masses of the sdB stars can be measured accurately. Due to selection effects, the fraction of sdBs with low mass companions and similar or longer periods may be quite high. Low mass stellar and substellar companions may therefore play a significant role for the still unclear formation of hot subdwarf stars. Furthermore, the nebula around EGB 5 may be the remnant of the ejected common envelope making this binary a unique system to study this short und poorly understood phase of binary evolution. Based on observations at the Paranal Observatory of the European Southern Observatory for programmes No. 167.H-0407(A) and 71.D-0383(A). Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC). Some of the data used in this work were obtained at the William Herschel Telescope (WHT) operated by the Isaac Newton Group of Telescopes (ING).

  17. Multi-point shock and flux rope analysis of multiple interplanetary coronal mass ejections around 2010 August 1 in the inner heliosphere

    CERN Document Server

    Möstl, C; Kilpua, E K J; Jian, L K; Liu, Y; Eastwood, J; Harrison, R A; Webb, D F; Temmer, M; Odstrcil, D; Davies, J A; Rollett, T; Luhmann, J G; Nitta, N; Mulligan, T; Jensen, E A; Forsyth, R; Lavraud, B; De Koning, C A; Veronig, A M; Galvin, A B; Zhang, T L; Anderson, B J

    2012-01-01

    We present multi-point in situ observations of a complex sequence of coronal mass ejections (CMEs) which may serve as a benchmark event for numerical and empirical space weather prediction models. On 2010 August 1, instruments on various space missions (Solar Dynamics Observatory/ Solar and Heliospheric Observatory/Solar-TErrestrial-RElations-Observatory) monitored several CMEs originating within tens of degrees from solar disk center. We compare their imprints on four widely separated locations, spanning 120 degree in heliospheric longitude, with radial distances from the Sun ranging from MESSENGER (0.38 AU) to Venus Express (VEX, at 0.72 AU) to Wind, ACE and ARTEMIS near Earth, and STEREO-B close to 1 AU. Calculating shock and flux rope parameters at each location points to a non-spherical shape of the shock, and shows the global configuration of the interplanetary coronal mass ejections (ICMEs), which have interacted, but do not seem to have merged. VEX and STEREO-B observed similar magnetic flux ropes (MF...

  18. The Mass Dependance of Satellite Quenching in Milky Way-like Halos

    CERN Document Server

    Phillips, John I; Cooper, Michael C; Boylan-Kolchin, Michael; Bullock, James S; Tollerud, Erik

    2014-01-01

    Using the Sloan Digital Sky Survey, we examine the quenching of satellite galaxies around isolated Milky Way-like hosts in the local Universe. We find that the efficiency of satellite quenching around isolated galaxies is low and roughly constant over two orders of magnitude in satellite stellar mass ($M_{*}$ = $10^{8.5}-10^{10.5} \\, M_{\\odot}$), with only $\\sim~20\\%$ of systems quenched as a result of environmental processes. While largely independent of satellite stellar mass, satellite quenching does exhibit clear dependence on the properties of the host. We show that satellites of passive hosts are substantially more likely to be quenched than those of star-forming hosts, and we present evidence that more massive halos quench their satellites more efficiently. These results extend trends seen previously in more massive host halos and for higher satellite masses. Taken together, it appears that galaxies with stellar masses larger than about $10^{8}~M_{\\odot}$ are uniformly resistant to environmental quench...

  19. A new view of solar coronal mass ejections with the Heliophysics System Observatory (Arne Richter Award for Outstanding Young Scientists Lecture)

    Science.gov (United States)

    Moestl, Christian

    2016-04-01

    Solar coronal mass ejections (CMEs) play a pivotal role in solar, heliospheric and planetary physics because they lead to connections of plasma phenomena from the Sun to the planets throughout the solar system. CMEs drive the strongest geomagnetic storms, fill the heliosphere with energetic particles, illuminate planetary skies with aurorae, modulate cosmic rays on planetary surfaces, and lead to erosion of planetary atmospheres over long time scales. Thus, even for studying the detection of life on exoplanets, the role of possible stellar CMEs should not be neglected. However, besides the simple fascination of studying the biggest explosions in the solar system, they are of increasingly high practical significance concerning risk mitigation of natural desasters and the protection of our common wealth. As the impact of a "super-CME", a rare but possible event, may affect the entire planet Earth, coordinated international efforts for their fundamental understanding, as well as building dedicated space weather missions for daily forecasts is necessary. There is a chance of a CME on the order of a Carrington event, with a minimum Dst of about -1000 nT, impacting Earth once every 100 years - or a 10% chance in a given solar cycle. An impact of such a super-CME is expected to cause e.g. wide-spread electricity blackouts and satellite failures. In the last 10 years, the field has made major advantages in understanding how CMEs evolve from the Sun to the planets. Because of the extension of CMEs on the order of 60-100 degree heliospheric longitude and radial sizes around 0.1-0.2 AU, multipoint imaging and in situ observations are inevitably necessary to understand basic CME physics. To this end, I will show data, as provided by the Heliophysics System Observatory (HSO), and their interpretation with various modeling effors. The HSO can be understood as a web of sensors placed throughout the heliosphere, consisting of spacecraft such as STEREO, Wind, ACE, Venus Express and

  20. Baryons and their Effects on Planes of Satellites Around Milky Way-Mass Galaxies

    Science.gov (United States)

    Ahmed, Sheehan H.

    2017-01-01

    Both the Milky Way and Andromeda have thin, coherently rotating planes of satellites. In this study I try to find similar satellite planes around four different Milky Way-mass simulations, each run both as dark matter-only and with baryons included. In all halos I am able to identify a planar configuration that significantly maximizes the number of satellites that are members of a plane. The member satellites that make up this maximum plane are consistently different between the dark matter-only and baryonic versions of the same run. In the baryonic runs, satellites are more likely to be destroyed through interactions with the disk, and substructure tends to infall later. Hence, studying satellite planes in dark matter-only simulations is misleading, because they will be composed of different satellite members than those that would exist if baryons were included. Additionally, baryonic runs tend to have less radially concentrated satellite distributions. Since all planes pass through the center of the galaxy, it is much harder to create a plane containing a large number of satellites from a random distribution if the satellites have a low radial concentration. Andromeda’s low radial satellite concentration is possibly a key reason behind why the plane in Andromeda is highly significant. Despite this, when co-rotation is considered, none of the satellite planes identified for the simulated galaxies are as statistically significant as the observed planes around the Milky Way and Andromeda. I will then show that co-rotation in our satellite planes can be attributed to how the satellites are accreted through filaments from the cosmic web. When two sets of opposing filaments contribute, coherent planes are more likely to form, when there are no well-defined filaments, there is a lack of coherent satellite rotation.

  1. Satellite Infall and Mass Deposition on the Galactic Centre

    CERN Document Server

    Gallego, Sofia G

    2016-01-01

    We model the infall of a 2e5 Msun satellite galaxy on to the inner 200 parsec of our Galaxy, to test whether the satellite could perturb the gas previously on stable orbits in the central molecular zone (CMZ), as proposed by Lang et al. (2013). This process would have driven a large gas inflow around 10 Myr ago, necessary to explain the past high accretion rate onto the super-massive black hole, and the presence of young stars in the inner parsecs of the Galaxy. Our hydrodynamical simulations show a much smaller inflow of gas, not sufficient to produce the aforementioned effects.

  2. Dynamical mass ejection from the merger of asymmetric binary neutron stars: Radiation-hydrodynamics study in general relativity

    CERN Document Server

    Sekiguchi, Yuichiro; Kyutoku, Koutarou; Shibata, Masaru; Taniguchi, Keisuke

    2016-01-01

    We perform neutrino radiation-hydrodynamics simulations for the merger of asymmetric binary neutron stars in numerical relativity. Neutron stars are modeled by soft and moderately stiff finite-temperature equations of state (EOS). We find that the properties of the dynamical ejecta such as the total mass, neutron richness profile, and specific entropy profile depend on the mass ratio of the binary systems for a given EOS in a unique manner. For the soft EOS (SFHo), the total ejecta mass depends weakly on the mass ratio, but the average of electron number per baryon ($Y_e$) and specific entropy ($s$) of the ejecta decreases significantly with the increase of the degree of mass asymmetry. For the stiff EOS (DD2), with the increase of the mass asymmetry degree, the total ejecta mass significantly increases while the average of $Y_e$ and $s$ moderately decreases. We find again that only for the soft EOS (SFHo), the total ejecta mass exceeds $0.01M_\\odot$ irrespective of the mass ratio chosen in this paper. The ej...

  3. Gravitational detection of a low-mass dark satellite at cosmological distance

    CERN Document Server

    Vegetti, S; McKean, J P; Auger, M W; Fassnacht, C D; Koopmans, L V E

    2012-01-01

    The mass-function of dwarf satellite galaxies that are observed around Local Group galaxies substantially differs from simulations based on cold dark matter: the simulations predict many more dwarf galaxies than are seen. The Local Group, however, may be anomalous in this regard. A massive dark satellite in an early-type lens galaxy at z = 0.222 was recently found using a new method based on gravitational lensing, suggesting that the mass fraction contained in substructure could be higher than is predicted from simulations. The lack of very low mass detections, however, prohibited any constraint on their mass function. Here we report the presence of a 1.9 +/- 0.1 x 10^8 M_sun dark satellite in the Einstein-ring system JVAS B1938+666 at z = 0.881, where M_sun denotes solar mass. This satellite galaxy has a mass similar to the Sagittarius galaxy, which is a satellite of the Milky Way. We determine the logarithmic slope of the mass function for substructure beyond the local Universe to be alpha = 1.1^+0.6_-0.4, ...

  4. The Strength and Radial Profile of the Coronal Magnetic Field from the Standoff Distance of a Coronal Mass Ejection-driven Shock

    Science.gov (United States)

    Gopalswamy, Nat; Yashiro, Seiji

    2011-07-01

    We determine the coronal magnetic field strength in the heliocentric distance range 6-23 solar radii (Rs) by measuring the shock standoff distance and the radius of curvature of the flux rope during the 2008 March 25 coronal mass ejection imaged by white-light coronagraphs. Assuming the adiabatic index, we determine the Alfvén Mach number, and hence the Alfvén speed in the ambient medium using the measured shock speed. By measuring the upstream plasma density using polarization brightness images, we finally get the magnetic field strength upstream of the shock. The estimated magnetic field decreases from ~48 mG around 6 Rs to 8 mG at 23 Rs. The radial profile of the magnetic field can be described by a power law in agreement with other estimates at similar heliocentric distances.

  5. The Strength and Radial Profile of the Coronal Magnetic Field from the Standoff Distance of a Coronal Mass Ejection-Driven Shock

    Science.gov (United States)

    Gopalswamy, Nat; Yashiro, Seiji

    2011-01-01

    We determine the coronal magnetic field strength in the heliocentric distance range 6-23 solar radii (Rs) by measuring the shock standoff distance and the radius of curvature of the flux rope during the 2008 March 25 coronal mass ejection imaged by white-light coronagraphs. Assuming the adiabatic index, we determine the Alfven Mach number, and hence the Alfven speed in the ambient medium using the measured shock speed. By measuring the upstream plasma density using polarization brightness images, we finally get the magnetic field strength upstream of the shock. The estimated magnetic field decreases from approximately 48 mG around 6 Rs to 8 mG at 23 Rs. The radial profile of the magnetic field can be described by a power law in agreement with other estimates at similar heliocentric distances.

  6. MULTI-POINT SHOCK AND FLUX ROPE ANALYSIS OF MULTIPLE INTERPLANETARY CORONAL MASS EJECTIONS AROUND 2010 AUGUST 1 IN THE INNER HELIOSPHERE

    Energy Technology Data Exchange (ETDEWEB)

    Moestl, C.; Liu, Y.; Luhmann, J. G. [Space Science Laboratory, University of California, Berkeley, CA (United States); Farrugia, C. J. [Space Science Center and Department of Physics, University of New Hampshire, Durham, NH (United States); Kilpua, E. K. J. [Department of Physics, University of Helsinki, FI-00560 Helsinki (Finland); Jian, L. K. [Department of Astronomy, University of Maryland, College Park, MD (United States); Eastwood, J. P.; Forsyth, R. [The Blackett Laboratory, Imperial College, London (United Kingdom); Harrison, R. A.; Davies, J. A. [RAL Space, Harwell Oxford, Didcot (United Kingdom); Webb, D. F. [Institute for Scientific Research, Boston College, Newton, MA (United States); Temmer, M.; Rollett, T.; Veronig, A. M. [Kanzelhoehe Observatory-IGAM, Institute of Physics, University of Graz, A-8010 Graz (Austria); Odstrcil, D. [NASA Goddard Space Flight Center, Greenbelt, MD (United States); Nitta, N. [Solar and Astrophysics Laboratory, Lockheed Martin Advanced Technology Center, Palo Alto, CA (United States); Mulligan, T. [Space Science Applications Laboratory, The Aerospace Corporation, El Segundo, CA (United States); Jensen, E. A. [ACS Consulting, Houston, TX (United States); Lavraud, B. [Institut de Recherche en Astrophysique et Planetologie, Universite de Toulouse (UPS), F-31400 Toulouse (France); De Koning, C. A., E-mail: christian.moestl@uni-graz.at [NOAA/SWPC, Boulder, Colorado (United States); and others

    2012-10-10

    We present multi-point in situ observations of a complex sequence of coronal mass ejections (CMEs) which may serve as a benchmark event for numerical and empirical space weather prediction models. On 2010 August 1, instruments on various space missions, Solar Dynamics Observatory/Solar and Heliospheric Observatory/Solar-TErrestrial-RElations-Observatory (SDO/SOHO/STEREO), monitored several CMEs originating within tens of degrees from the solar disk center. We compare their imprints on four widely separated locations, spanning 120 Degree-Sign in heliospheric longitude, with radial distances from the Sun ranging from MESSENGER (0.38 AU) to Venus Express (VEX, at 0.72 AU) to Wind, ACE, and ARTEMIS near Earth and STEREO-B close to 1 AU. Calculating shock and flux rope parameters at each location points to a non-spherical shape of the shock, and shows the global configuration of the interplanetary coronal mass ejections (ICMEs), which have interacted, but do not seem to have merged. VEX and STEREO-B observed similar magnetic flux ropes (MFRs), in contrast to structures at Wind. The geomagnetic storm was intense, reaching two minima in the Dst index ( Almost-Equal-To - 100 nT), and was caused by the sheath region behind the shock and one of two observed MFRs. MESSENGER received a glancing blow of the ICMEs, and the events missed STEREO-A entirely. The observations demonstrate how sympathetic solar eruptions may immerse at least 1/3 of the heliosphere in the ecliptic with their distinct plasma and magnetic field signatures. We also emphasize the difficulties in linking the local views derived from single-spacecraft observations to a consistent global picture, pointing to possible alterations from the classical picture of ICMEs.

  7. A Tool for Empirical Forecasting of Major Flares, Coronal Mass Ejections, and Solar Particle Events from a Proxy of Active-Region Free Magnetic Energy

    Science.gov (United States)

    Barghouty, A. F.; Falconer, D. A.; Adams, J. H., Jr.

    2010-01-01

    This presentation describes a new forecasting tool developed for and is currently being tested by NASA s Space Radiation Analysis Group (SRAG) at JSC, which is responsible for the monitoring and forecasting of radiation exposure levels of astronauts. The new software tool is designed for the empirical forecasting of M and X-class flares, coronal mass ejections, as well as solar energetic particle events. Its algorithm is based on an empirical relationship between the various types of events rates and a proxy of the active region s free magnetic energy, determined from a data set of approx.40,000 active-region magnetograms from approx.1,300 active regions observed by SOHO/MDI that have known histories of flare, coronal mass ejection, and solar energetic particle event production. The new tool automatically extracts each strong-field magnetic areas from an MDI full-disk magnetogram, identifies each as an NOAA active region, and measures a proxy of the active region s free magnetic energy from the extracted magnetogram. For each active region, the empirical relationship is then used to convert the free magnetic energy proxy into an expected event rate. The expected event rate in turn can be readily converted into the probability that the active region will produce such an event in a given forward time window. Descriptions of the datasets, algorithm, and software in addition to sample applications and a validation test are presented. Further development and transition of the new tool in anticipation of SDO/HMI is briefly discussed.

  8. A tool for empirical forecasting of major flares, coronal mass ejections, and solar particle events from a proxy of active-region free magnetic energy

    Science.gov (United States)

    Falconer, David; Barghouty, Abdulnasser F.; Khazanov, Igor; Moore, Ron

    2011-04-01

    This paper describes a new forecasting tool developed for and currently being tested by NASA's Space Radiation Analysis Group (SRAG) at Johnson Space Center, which is responsible for the monitoring and forecasting of radiation exposure levels of astronauts. The new software tool is designed for the empirical forecasting of M- and X-class flares, coronal mass ejections, and solar energetic particle events. For each type of event, the algorithm is based on the empirical relationship between the event rate and a proxy of the active region's free magnetic energy. Each empirical relationship is determined from a data set of ˜40,000 active-region magnetograms from ˜1300 active regions observed by SOHO/Michelson Doppler Imager (MDI) that have known histories of flare, coronal mass ejection, and solar energetic particle event production. The new tool automatically extracts each strong-field magnetic area from an MDI full-disk magnetogram, identifies each as a NOAA active region, and measures the proxy of the active region's free magnetic energy from the extracted magnetogram. For each active region, the empirical relationship is then used to convert the free-magnetic-energy proxy into an expected event rate. The expected event rate in turn can be readily converted into the probability that the active region will produce such an event in a given forward time window. Descriptions of the data sets, algorithm, and software in addition to sample applications and a validation test are presented. Further development and transition of the new tool in anticipation of SDO/HMI are briefly discussed.

  9. Deriving the radial distances of wide coronal mass ejections from elongation measurements in the heliosphere – application to CME-CME interaction

    Directory of Open Access Journals (Sweden)

    I. I. Roussev

    2009-09-01

    Full Text Available We present general considerations regarding the derivation of the radial distances of coronal mass ejections (CMEs from elongation angle measurements such as those provided by SECCHI and SMEI, focusing on measurements in the Heliospheric Imager 2 (HI-2 field of view (i.e. past 0.3 AU. This study is based on a three-dimensional (3-D magneto-hydrodynamics (MHD simulation of two CMEs observed by SECCHI on 24–27 January 2007. Having a 3-D simulation with synthetic HI images, we are able to compare the two basic methods used to derive CME positions from elongation angles, the so-called "Point-P" and "Fixed-φ" approximations. We confirm, following similar works, that both methods, while valid in the most inner heliosphere, yield increasingly large errors in HI-2 field of view for fast and wide CMEs. Using a simple model of a CME as an expanding self-similar sphere, we derive an analytical relationship between elongation angles and radial distances for wide CMEs. This relationship is simply the harmonic mean of the "Point-P" and "Fixed-φ" approximations and it is aimed at complementing 3-D fitting of CMEs by cone models or flux rope shapes. It proves better at getting the kinematics of the simulated CME right when we compare the results of our line-of-sights to the MHD simulation. Based on this approximation, we re-analyze the J-maps (time-elongation maps in 26–27 January 2007 and present the first observational evidence that the merging of CMEs is associated with a momentum exchange from the faster ejection to the slower one due to the propagation of the shock wave associated with the fast eruption through the slow eruption.

  10. Effects of mass transfer between Martian satellites on surface geology

    Science.gov (United States)

    Nayak, Michael; Nimmo, Francis; Udrea, Bogdan

    2016-03-01

    Impacts on planetary bodies can lead to both prompt secondary craters and projectiles that reimpact the target body or nearby companions after an extended period, producing so-called "sesquinary" craters. Here we examine sesquinary cratering on the moons of Mars. We model the impact that formed Voltaire, the largest crater on the surface of Deimos, and explore the orbital evolution of resulting high-velocity ejecta across 500 years using four-body physics and particle tracking. The bulk of mass transfer to Phobos occurs in the first 102 years after impact, while reaccretion of ejecta to Deimos is predicted to continue out to a 104 year timescale (cf. Soter, S. [1971]. Studies of the Terrestrial Planets. Cornell University). Relative orbital geometry between Phobos and Deimos plays a significant role; depending on the relative true longitude, mass transfer between the moons can change by a factor of five. Of the ejecta with a velocity range capable of reaching Phobos, 25-42% by mass reaccretes to Deimos and 12-21% impacts Phobos. Ejecta mass transferred to Mars is caused by Deimos material. However the high-velocity ejecta mass reaccreted to Deimos from a Voltaire-sized impact is comparable to the expected background mass accumulated on Deimos between Voltaire-size events. Considering that the high-velocity ejecta contains only 0.5% of the total mass sent into orbit, sesquinary ejecta from a Voltaire-sized impact could feasibly resurface large parts of the Moon, erasing the previous geological record. Dating the surface of Deimos may be more challenging than previously suspected.

  11. Short-term variability and mass loss in Be stars. I. BRITE satellite photometry of η and μ Centauri

    Science.gov (United States)

    Baade, D.; Rivinius, Th.; Pigulski, A.; Carciofi, A. C.; Martayan, Ch.; Moffat, A. F. J.; Wade, G. A.; Weiss, W. W.; Grunhut, J.; Handler, G.; Kuschnig, R.; Mehner, A.; Pablo, H.; Popowicz, A.; Rucinski, S.; Whittaker, G.

    2016-04-01

    Context. Empirical evidence for the involvement of nonradial pulsations (NRPs) in the mass loss from Be stars ranges from (i) a singular case (μ Cen) of repetitive mass ejections triggered by multi-mode beating to (ii) several photometric reports about enormous numbers of pulsation modes that suddenly appear during outbursts and on to (iii) effective single-mode pulsators. Aims: The purpose of this study is to develop a more detailed empirical description of the star-to-disk mass transfer and to check the hypothesis that spates of transient nonradial pulsation modes accompany and even drive mass-loss episodes. Methods: The BRITE Constellation of nanosatellites was used to obtain mmag photometry of the Be stars η and μ Cen. Results: In the low-inclination star μ Cen, light pollution by variable amounts of near-stellar matter prevented any new insights into the variability and other properties of the central star. In the equator-on star η Cen, BRITE photometry and Heros echelle spectroscopy from the 1990s reveal an intricate clockwork of star-disk interactions. The mass transfer is modulated with the frequency difference of two NRP modes and an amplitude three times as large as the amplitude sum of the two NRP modes. This process feeds a high-amplitude circumstellar activity running with the incoherent and slightly lower so-called Štefl frequency. The mass-loss-modulation cycles are tightly coupled to variations in the value of the Štefl frequency and in its amplitude, albeit with strongly drifting phase differences. Conclusions: The observations are well described by the decomposition of the mass loss into a pulsation-related engine in the star and a viscosity-dominated engine in the circumstellar disk. Arguments are developed that large-scale gas-circulation flows occur at the interface. The propagation rates of these eddies manifest themselves as Štefl frequencies. Bursts in power spectra during mass-loss events can be understood as the noise inherent to

  12. The Milky Way's Mass Inferered by Satellite Kinematics from the Illustris Simulation

    Science.gov (United States)

    Lazar, Alexander; Boylan-Kolchin, Michael

    2017-06-01

    A precise interpretion of the Milky Way’s dark matter halo mass has limited our ability to depict the Milky Way in cosmological context. One of the noteworthy issues is that only a handful of tracers — satellite galaxies — probe the gravitational potential at large radii, and converting observed velocities into a constraint on the mass profile requires significant assumptions. High resolution cosmological simulations provide a powerful tool for interpreting data, but most results to date rely on dark-matter-only simulations that neglect the effects of galaxy formation physics. We compare the orbital kinematics of satellite galaxies in the Illustris simulation with its dark-matter-only counterpart, which allows us to compare, on an object-by-object basis, the differences influenced in orbits from baryonic physics. We quantify the effects of galaxy formation physics on orbital distributions of satellites and describe how these differences affect inferences for the mass of the Milky Way.

  13. Listening to Shells: Galaxy Masses from Disrupted Satellites

    NARCIS (Netherlands)

    Westfall, Kyle; Sanderson, R.

    2014-01-01

    Our ability to measure the dynamical mass of an individual galaxy is limited by the radial extent of the luminous tracers of its potential. For elliptical galaxies, it is difficult to go much beyond two effective radii using integrated light. Appealing to particle tracers like globular clusters has

  14. What can we learn about solar coronal mass ejections, coronal dimmings, and Extreme-Ultraviolet jets through spectroscopic observations?

    CERN Document Server

    Tian, Hui; Xia, Lidong; He, Jiansen; Wang, Xin

    2012-01-01

    We analyze several data sets obtained by Hinode/EIS and find various types of flows during CMEs and EUV jet eruptions. CME-induced dimming regions are found to be characterized by significant blueshift and enhanced line width by using a single Gaussian fit. While a red-blue (RB) asymmetry analysis and a RB-guided double Gaussian fit of the coronal line profiles indicate that these are likely caused by the superposition of a strong background emission component and a relatively weak (~10%) high-speed (~100 km s-1) upflow component. This finding suggests that the outflow velocity in the dimming region is probably of the order of 100 km s-1, not ~20 km s-1 as reported previously. Density and temperature diagnostics suggest that dimming is primarily an effect of density decrease rather than temperature change. The mass losses in dimming regions as estimated from different methods are roughly consistent with each other and they are 20%-60% of the masses of the associated CMEs. With the guide of RB asymmetry analys...

  15. Central mass and luminosity of Milky Way satellites in the LCDM model

    CERN Document Server

    Maccio', Andrea V; Moore, Ben

    2008-01-01

    It has been recently pointed out that Milky Way satellites all have a common mass around 1.0e7 Msun within 300 pc (M_{0.3}), while they span almost four orders of magnitude in luminosity. It is argued that this may reflect a specific scales for galaxy formation or a scale for dark matter clustering. Here we use numerical simulations coupled with a semi-analytic model for galaxy formation, to predict the central mass and luminosity of galactic satellites in the LCDM model. We show that this common mass scale can be easily explained within the Cold Dark Matter scenario when the physics of galaxy formation is taken into account. The narrow range of M_{0.3} comes from the narrow distribution of circular velocities at time of accretion (peaking around 20 km/s) for satellites able to form stars. The wide range of satellite luminosities is due to the broad distribution of accretion redshift for a given circular velocity. This causes the satellite baryonic content to be suppressed by photo-ionization to different ext...

  16. Ejection Tower Lab

    Data.gov (United States)

    Federal Laboratory Consortium — The Ejection Tower Facility's mission is to test and evaluate new ejection seat technology being researched and developed for future defense forces. The captive and...

  17. Arrival time calculation for interplanetary coronal mass ejections with circular fronts and application to STEREO observations of the 2009 February 13 eruption

    CERN Document Server

    Möstl, C; Lugaz, N; Farrugia, C J; Davies, J A; Temmer, M; Veronig, A M; Harrison, R; Crothers, S; Luhmann, J G; Galvin, A B; Zhang, T L; Baumjohann, W; Biernat, H K

    2011-01-01

    A goal of the NASA STEREO mission is to study the feasibility of forecasting the direction, arrival time and internal structure of solar coronal mass ejections (CMEs) from a vantage point outside the Sun-Earth line. Through a case study, we discuss the arrival time calculation of interplanetary CMEs (ICMEs) in the ecliptic plane using data from STEREO/SECCHI at large elongations from the Sun in combination with different geometric assumptions about the ICME front shape (Fixed-\\Phi (FP): a point and harmonic Mean (HM): a circle). These forecasting techniques use single-spacecraft imaging data and are based on the assumptions of constant velocity and direction. We show that for the slow (350 km/s) ICME on 2009 February 13-18, observed at quadrature by the two STEREO spacecraft, the results for the arrival time given by the HM approximation are more accurate by 12 hours than those for FP in comparison to in situ observations of solar wind plasma and magnetic field parameters by STEREO/IMPACT/PLASTIC, and by 6 ho...

  18. On the Relationship between Solar Wind Speed, Earthward-Directed Coronal Mass Ejections, Geomagnetic Activity, and the Sunspot Cycle Using 12-Month Moving Averages

    Science.gov (United States)

    Wilson, Robert M.; Hathaway, David H.

    2008-01-01

    For 1996 .2006 (cycle 23), 12-month moving averages of the aa geomagnetic index strongly correlate (r = 0.92) with 12-month moving averages of solar wind speed, and 12-month moving averages of the number of coronal mass ejections (CMEs) (halo and partial halo events) strongly correlate (r = 0.87) with 12-month moving averages of sunspot number. In particular, the minimum (15.8, September/October 1997) and maximum (38.0, August 2003) values of the aa geomagnetic index occur simultaneously with the minimum (376 km/s) and maximum (547 km/s) solar wind speeds, both being strongly correlated with the following recurrent component (due to high-speed streams). The large peak of aa geomagnetic activity in cycle 23, the largest on record, spans the interval late 2002 to mid 2004 and is associated with a decreased number of halo and partial halo CMEs, whereas the smaller secondary peak of early 2005 seems to be associated with a slight rebound in the number of halo and partial halo CMEs. Based on the observed aaM during the declining portion of cycle 23, RM for cycle 24 is predicted to be larger than average, being about 168+/-60 (the 90% prediction interval), whereas based on the expected aam for cycle 24 (greater than or equal to 14.6), RM for cycle 24 should measure greater than or equal to 118+/-30, yielding an overlap of about 128+/-20.

  19. Modeling the initiation of the 2006 December 13 coronal mass ejection in AR 10930: the structure and dynamics of the erupting flux rope

    CERN Document Server

    Fan, Yuhong

    2016-01-01

    We carry out a three-dimensional magneto-hydrodynamic (MHD) simulation to model the initiation of the coronal mass ejection (CME) on 13 December 2006 in the emerging {\\delta}-sunspot active region NOAA 10930. The setup of the simulation is similar to a previous simulation by Fan (2011), but with a significantly widened simulation domain to accommodate the wide CME. The simulation shows that the CME can result from the emergence of a east-west oriented twisted flux rope whose positive, following emerging pole corresponds to the observed positive rotating sunspot emerging against the southern edge of the dominant pre-existing negative sunspot. The erupting flux rope in the simulation accelerates to a terminal speed that exceeds 1500 km/s and undergoes a counter-clockwise rotation of nearly 180 degrees such that its front and flanks all exhibit southward directed magnetic fields, explaining the observed southward magnetic field in the magnetic cloud impacting the Earth. With continued driving of flux emergence, ...

  20. Modeling the Initiation of the 2006 December 13 Coronal Mass Ejection in AR 10930: The Structure and Dynamics of the Erupting Flux Rope

    Science.gov (United States)

    Fan, Yuhong

    2016-06-01

    We carry out a 3D magnetohydrodynamic simulation to model the initiation of the coronal mass ejection (CME) on 2006 December 13 in the emerging δ-sunspot active region NOAA 10930. The setup of the simulation is similar to a previous simulation by Fan, but with a significantly widened simulation domain to accommodate the wide CME. The simulation shows that the CME can result from the emergence of a east-west oriented twisted flux rope whose positive, following emerging pole corresponds to the observed positive rotating sunspot emerging against the southern edge of the dominant pre-existing negative sunspot. The erupting flux rope in the simulation accelerates to a terminal speed that exceeds 1500 km s-1 and undergoes a counter-clockwise rotation of nearly 180° such that its front and flanks all exhibit southward directed magnetic fields, explaining the observed southward magnetic field in the magnetic cloud impacting the Earth. With continued driving of flux emergence, the source region coronal magnetic field also shows the reformation of a coronal flux rope underlying the flare current sheet of the erupting flux rope, ready for a second eruption. This may explain the build up for another X-class eruptive flare that occurred the following day from the same region.

  1. A Robust Method to Predict the Near-Sun and Interplanetary Magnetic Field Strength of Coronal Mass Ejections: Parametric and Case Studies

    Science.gov (United States)

    Patsourakos, Spiros; Georgoulis, Manolis K.

    2016-07-01

    Predicting the near-Sun, and particularly the Interplanetary (IP), magnetic field structure of Coronal Mass Ejections (CMEs) and interplanetary counterparts (ICMEs) is a topic of intense research activity. This is because Earth-directed CMEs with strong southward magnetic fields are responsible for the most powerful geomagnetic storms. We have recently developed a simple two-tier method to predict the magnetic field strength of CMEs in the outer corona and in the IP medium, using as input the magnetic-helicity budget of the source solar active region and stereoscopic coronagraphic observations. Near-Sun CME magnetic fields are obtained by utilizing the principle of magnetic helicity conservation of flux-rope CMEs for coronagraphic observations. Interplanetary propagation of the inferred values is achieved by employing power-law prescriptions of the radial evolution of the CME-ICME magnetic fields. We hereby present a parametric study of our method, based on the observed statistics of input parameters, to infer the anticipated range of values for the near-Sun and interplanetary CME-ICME magnetic fields. This analysis is complemented by application of our method to several well-observed major CME-ICME events.

  2. Geoeffectiveness (D (sub st) and K (sub p)) of Interplanetary Coronal Mass Ejections During 1995-2009 and Implications for Storm Forecasting

    Science.gov (United States)

    Richardson, I. G.; Cane, H. V.

    2011-01-01

    We summarize the geoeffectiveness (based on the Dst and Kp indices) of the more than 300 interplanetary coronal mass ejections (ICMEs) that passed the Earth during 1996-2009, encompassing solar cycle 23. We subsequently estimate the probability that an ICME will generate geomagnetic activity that exceeds certain thresholds of Dst or Kp, including the NOAA "G" storm scale, based on maximum values of the southward magnetic field component (Bs), the solar wind speed (V), and the y component (Ey) of the solar wind convective electric field E = -V x B, in the ICME or sheath ahead of the ICME. Consistent with previous studies, the geoeffectiveness of an ICME is correlated with Bs or Ey approx.= VBs in the ICME or sheath, indicating that observations from a solar wind monitor upstream of the Earth are likely to provide the most reliable forecasts of the activity associated with an approaching ICME. There is also a general increase in geoeffectiveness with ICME speed, though the overall event-to-event correlation is weaker than for Bs and Ey. Nevertheless, using these results, we suggest that the speed of an ICME approaching the Earth inferred, for example, from routine remote sensing by coronagraphs on spacecraft well separated from the Earth or by all-sky imagers, could be used to estimate the likely geoeffectiveness of the ICME (our "comprehensive" ICME database provides a proxy for ICMEs identified in this way) with a longer lead time than may be possible using an upstream monitor

  3. Magnetohydrodynamic Simulation of the X2.2 Solar Flare on 2011 February 15: II. A Dynamics Connecting the Solar Flare and the Coronal Mass Ejection

    CERN Document Server

    Inoue, S; Magara, T; Choe, G S; Park, Y D

    2015-01-01

    We clarify a relationship of the dynamics of a solar flare and a growing Coronal Mass Ejection (CME) by investigating the dynamics of magnetic fields during the X2.2-class flare taking place in the solar active region 11158 on 2011 February 15, based on simulation results obtained from Inoue et al. 2014. We found that the strongly twisted lines formed through the tether-cutting reconnection in the twisted lines of a nonlinear force-free field (NLFFF) can break the force balance within the magnetic field, resulting in their launch from the solar surface. We further discover that a large-scale flux tube is formed during the eruption as a result of the tether-cutting reconnection between the eruptive strongly twisted lines and these ambient weakly twisted lines. Then the newly formed large flux tube exceeds the critical height of the torus instability. The tether-cutting reconnection thus plays an important role in the triggering a CME. Furthermore, we found that the tangential fields at the solar surface illust...

  4. Three-dimensional Geometry of a Current Sheet in the High Solar Corona: Evidence for Reconnection in the Late Stage of the Coronal Mass Ejections

    Science.gov (United States)

    Kwon, Ryun-Young; Vourlidas, Angelos; Webb, David

    2016-07-01

    Motivated by the standard flare model, ray-like structures in the wake of coronal mass ejections (CMEs) have been often interpreted as proxies of the reconnecting current sheet connecting the CME with the postflare arcade. We present the three-dimensional properties of a post-CME ray derived from white light images taken from three different viewing perspectives on 2013 September 21. By using a forward modeling method, the direction, cross section, and electron density are determined within the heliocentric distance range of 5-9 R ⊙. The width and depth of the ray are 0.42 ± 0.08 R ⊙ and 1.24 ± 0.35 R ⊙, respectively, and the electron density is (2.0 ± 0.5) × 104 cm-3, which seems to be constant with height. Successive blobs moving outward along the ray are observed around 13 hr after the parent CME onset. We model the three-dimensional geometry of the parent CME with the Gradual Cylindrical Shell model and find that the CME and ray are coaxial. We suggest that coaxial post-CME rays, seen in coronagraph images, with successive formation of blobs could be associated with current sheets undergoing magnetic reconnection in the late stage of CMEs.

  5. Mass Spectra and Yields of Intact Charged Biomolecules Ejected by Massive Cluster Impact for Bioimaging in a Time-of-Flight Secondary Ion Microscope.

    Science.gov (United States)

    Zhang, Jitao; Franzreb, Klaus; Aksyonov, Sergei A; Williams, Peter

    2015-11-03

    Impacts of massive, highly charged glycerol clusters (≳10(6) Da, ≳ ± 100 charges) have been used to eject intact charged molecules of peptides, lipids, and small proteins from pure solid samples, enabling imaging using these ion species in a time-of-flight secondary ion microscope with few-micrometer spatial resolution. Here, we report mass spectra and useful ion yields (ratio of intact charged molecules detected to molecules sputtered) for several molecular species-two peptides, bradykinin and angiotensin II; two lipids, phosphatidylcholine and sphingomyelin; Irganox 1010 (a detergent); insulin; and rhodamine B-and show that useful ion yields are high enough to enable bioimaging of peptides and lipids in biological samples with few-micrometer resolution and acceptable signals. For example, several hundred molecular ion counts should be detectable from a 3 × 3 μm(2) area of a pure lipid bilayer given appropriate instrumentation or tens of counts from a minor constituent of such a layer.

  6. A Self-Consistent Numerical Magnetohydrodynamic (MHD) Model of Helmet Streamer and Flux-Rope Interactions: Initiation and Propagation of Coronal Mass Ejections (CMEs)

    Science.gov (United States)

    Wu, S. T.; Guo, W. P.

    1997-01-01

    We present results for an investigation of the interaction of a helmet streamer arcade and a helical flux-rope emerging from the sub-photosphere. These results are obtained by using a three-dimensional axisymmetric, time-dependent ideal magnetohydrodynamic (MHD) model. Because of the physical nature of the flux-rope, we investigate two types of flux-ropes; (1) high density flux-rope (i.e. flux-rope without cavity), and (2) low density flux rope (i.e. flux-rope with cavity). When the streamer is disrupted by the flux-rope, it will evolve into a configuration resembling the typical observed loop-like Coronal Mass Ejection (CMES) for both cases. The streamer-flux rope system with cavity is easier to be disrupted and the propagation speed of the CME is faster than the streamer-flux rope system without cavity. Our results demonstrate that magnetic buoyancy force plays an important role in disrupting the streamer.

  7. Ion mobility-mass spectrometry of charge-reduced protein complexes reveals general trends in the collisional ejection of compact subunits.

    Science.gov (United States)

    Bornschein, Russell E; Ruotolo, Brandon T

    2015-10-21

    Multiprotein complexes have been shown to play critical roles across a wide range of cellular functions, but most probes of protein quaternary structure are limited in their ability to analyze complex mixtures and polydisperse structures using small amounts of total protein. Ion mobility-mass spectrometry offers a solution to many of these challenges, but relies upon gas-phase measurements of intact multiprotein complexes, subcomplexes, and subunits that correlate well with solution structures. The greatest bottleneck in such workflows is the generation of representative subcomplexes and subunits. Collisional activation of complexes can act to produce product ions reflective of protein complex composition, but such product ions are typically challenging to interpret in terms of their relationship to solution structure due to their typically string-like conformations following activation and subsequent dissociation. Here, we used ion-ion chemistry to perform a broad survey of the gas-phase dissociation of charge-reduced protein complex ions, revealing general trends associated with the collisional ejection of compact, rather than unfolded, protein subunits. Furthermore, we also discover peptide and co-factor dissociation channels that dominate the product ion populations generated for such charge reduced complexes. We assess both sets of observations and discuss general principles that can be extended to the analysis of protein complex ions having unknown structures.

  8. Sun-to-Earth Characteristics of Two Coronal Mass Ejections Interacting near 1 AU: Formation of a Complex Ejecta and Generation of a Two-Step Geomagnetic Storm

    CERN Document Server

    Liu, Ying D; Wang, Rui; Luhmann, Janet G; Richardson, John D; Lugaz, Noé

    2014-01-01

    On 2012 September 30 - October 1 the Earth underwent a two-step geomagnetic storm. We examine the Sun-to-Earth characteristics of the coronal mass ejections (CMEs) responsible for the geomagnetic storm with combined heliospheric imaging and in situ observations. The first CME, which occurred on 2012 September 25, is a slow event and shows an acceleration followed by a nearly invariant speed in the whole Sun-Earth space. The second event, launched from the Sun on 2012 September 27, exhibits a quick acceleration, then a rapid deceleration and finally a nearly constant speed, a typical Sun-to-Earth propagation profile for fast CMEs \\citep{liu13}. These two CMEs interacted near 1 AU as predicted by the heliospheric imaging observations and formed a complex ejecta observed at Wind, with a shock inside that enhanced the pre-existing southward magnetic field. Reconstruction of the complex ejecta with the in situ data indicates an overall left-handed flux rope-like configuration, with an embedded concave-outward shoc...

  9. SUN-TO-EARTH CHARACTERISTICS OF TWO CORONAL MASS EJECTIONS INTERACTING NEAR 1 AU: FORMATION OF A COMPLEX EJECTA AND GENERATION OF A TWO-STEP GEOMAGNETIC STORM

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ying D.; Yang, Zhongwei; Wang, Rui [State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190 (China); Luhmann, Janet G. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Richardson, John D. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Lugaz, Noé, E-mail: liuxying@spaceweather.ac.cn [Space Science Center, University of New Hampshire, Durham, NH 03824 (United States)

    2014-10-01

    On 2012 September 30-October 1 the Earth underwent a two-step geomagnetic storm. We examine the Sun-to-Earth characteristics of the coronal mass ejections (CMEs) responsible for the geomagnetic storm with combined heliospheric imaging and in situ observations. The first CME, which occurred on 2012 September 25, is a slow event and shows an acceleration followed by a nearly invariant speed in the whole Sun-Earth space. The second event, launched from the Sun on 2012 September 27, exhibits a quick acceleration, then a rapid deceleration, and finally a nearly constant speed, a typical Sun-to-Earth propagation profile for fast CMEs. These two CMEs interacted near 1 AU as predicted by the heliospheric imaging observations and formed a complex ejecta observed at Wind, with a shock inside that enhanced the pre-existing southward magnetic field. Reconstruction of the complex ejecta with the in situ data indicates an overall left-handed flux-rope-like configuration with an embedded concave-outward shock front, a maximum magnetic field strength deviating from the flux rope axis, and convex-outward field lines ahead of the shock. While the reconstruction results are consistent with the picture of CME-CME interactions, a magnetic cloud-like structure without clear signs of CME interactions is anticipated when the merging process is finished.

  10. First High-resolution Spectroscopic Observations of an Erupting Prominence Within a Coronal Mass Ejection by the Interface Region Imaging Spectrograph (IRIS)

    CERN Document Server

    Liu, Wei; Vial, Jean-Claude; Title, Alan M; Carlsson, Mats; Uitenbroek, Han; Okamoto, Takenori J; Berger, Thomas E; Antolin, Patrick

    2015-01-01

    Spectroscopic observations of prominence eruptions associated with coronal mass ejections (CMEs), although relatively rare, can provide valuable plasma and 3D geometry diagnostics. We report the first observations by the Interface Region Imaging Spectrograph (IRIS) mission of a spectacular fast CME/prominence eruption associated with an equivalent X1.6 flare on 2014 May 9. The maximum plane-of-sky and Doppler velocities of the eruption are 1200 and 460 km/s, respectively. There are two eruption components separated by ~200 km/s in Doppler velocity: a primary, bright component and a secondary, faint component, suggesting a hollow, rather than solid, cone-shaped distribution of material. The eruption involves a left-handed helical structure undergoing counter-clockwise (viewed top-down) unwinding motion. There is a temporal evolution from upward eruption to downward fallback with less-than-free-fall speeds and decreasing nonthermal line widths. We find a wide range of Mg II k/h line intensity ratios (less than ...

  11. Gravitational detection of a low-mass dark satellite galaxy at cosmological distance

    NARCIS (Netherlands)

    Vegetti, S.; Lagattuta, D. J.; McKean, J. P.; Auger, M. W.; Fassnacht, C. D.; Koopmans, L. V. E.

    2012-01-01

    The mass function of dwarf satellite galaxies that are observed around Local Group galaxies differs substantially from simulations(1-5) based on cold dark matter: the simulations predict many more dwarf galaxies than are seen. The Local Group, however, may be anomalous in this regard(6,7). A massive

  12. Combining satellite altimetry and gravimetry data to improve Antarctic mass balance and gia estimates

    NARCIS (Netherlands)

    Gunter, B.C.; Didova, O.; Riva, R.E.M.; van den Broeke, M.R.; Ligtenberg, S.R.M.; Lenaerts, J.T.M.; King, M.; Urban, T.

    2012-01-01

    This study explores an approach that simultaneously estimates Antarctic mass balance and glacial isostatic adjustment (GIA) through the combination of satellite gravity and altimetry data sets. The results improve upon previous efforts by incorporating reprocessed data sets over a longer period of t

  13. Combining satellite altimetry and gravimetry data to improve Antarctic mass balance and gia estimates

    NARCIS (Netherlands)

    Gunter, B.C.; Didova, O.; Riva, R.E.M.; van den Broeke, M.R.; Ligtenberg, S.R.M.; Lenaerts, J.T.M.; King, M.; Urban, T.

    2012-01-01

    This study explores an approach that simultaneously estimates Antarctic mass balance and glacial isostatic adjustment (GIA) through the combination of satellite gravity and altimetry data sets. The results improve upon previous efforts by incorporating reprocessed data sets over a longer period of

  14. Orbits and Masses of the Satellites of the Dwarf Planet Haumea = 2003 EL61

    CERN Document Server

    Ragozzine, Darin

    2009-01-01

    Using precise relative astrometry from the Hubble Space Telescope and the W. M. Keck Telescope, we have determined the orbits and masses of the two dynamically interacting satellites of the dwarf planet (136108) Haumea, formerly 2003 EL61. The orbital parameters of Hi'iaka, the outer, brighter satellite, match well the previously derived orbit. On timescales longer than a few weeks, no Keplerian orbit is sufficient to describe the motion of the inner, fainter satellite Namaka. Using a fully-interacting three point-mass model, we have recovered the orbital parameters of both orbits and the mass of Haumea and Hi'iaka; Namaka's mass is marginally detected. The data are not sufficient to uniquely determine the gravitational quadrupole of the non-spherical primary (described by $J_2$). The nearly co-planar nature of the satellites, as well as an inferred density similar to water ice, strengthen the hypothesis that Haumea experienced a giant collision billions of years ago. The excited eccentricities and mutual inc...

  15. Gravitational detection of a low-mass dark satellite galaxy at cosmological distance

    NARCIS (Netherlands)

    Vegetti, S.; Lagattuta, D. J.; McKean, J. P.; Auger, M. W.; Fassnacht, C. D.; Koopmans, L. V. E.

    2012-01-01

    The mass function of dwarf satellite galaxies that are observed around Local Group galaxies differs substantially from simulations based on cold dark matter: the simulations predict many more dwarf galaxies than are seen. The Local Group, however, may be anomalous in this regard. A massive dark sate

  16. Next-generation satellite gravimetry for measuring mass transport in the Earth system

    NARCIS (Netherlands)

    Teixeira Encarnação, J.

    2015-01-01

    The main objective of the thesis is to identify the optimal set-up for future satellite gravimetry missions aimed at monitoring mass transport in the Earth’s system.The recent variability of climatic patterns, the spread of arid regions and associ- ated changes in the hydrological cycle, and vigorou

  17. Reconciling satellite aerosol optical thickness and surface fine particle mass through aerosol liquid water

    Science.gov (United States)

    Nguyen, Thien Khoi V.; Ghate, Virendra P.; Carlton, Annmarie G.

    2016-11-01

    Summertime aerosol optical thickness (AOT) over the southeast U.S. is sharply enhanced over wintertime values. This seasonal pattern is unique and of particular interest because temperatures there have not warmed over the past 100 years. Patterns in surface fine particle mass are inconsistent with satellite reported AOT. In this work, we attempt to reconcile the spatial and temporal distribution of AOT over the U.S. with particle mass measurements at the surface by examining trends in aerosol liquid water (ALW), a particle constituent that scatters radiation and affects satellite AOT but is removed in mass measurements at routine surface monitoring sites. We employ the thermodynamic model ISORROPIAv2.1 to estimate ALW mass concentrations at Interagency Monitoring of PROtected Visual Environments sites using measured ion mass concentrations and North American Regional Reanalysis meteorological data. Excellent agreement between Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations AOT and estimated ALW provides a plausible explanation for the discrepancies in the geographical patterns of AOT and aerosol mass measurements.

  18. Time-evolving mass loss of the Greenland ice sheet from satellite altimetry

    Directory of Open Access Journals (Sweden)

    R. T. W. L. Hurkmans

    2014-02-01

    Full Text Available Mass changes of the Greenland ice sheet may be estimated by the Input Output Method (IOM, satellite gravimetry, or via surface elevation change rates (dH / dt. Whereas the first two have been shown to agree well in reconstructing mass changes over the last decade, there are few decadal estimates from satellite altimetry and none that provide a time evolving trend that can be readily compared with the other methods. Here, we interpolate radar and laser altimetry data between 1995 and 2009 in both space and time to reconstruct the evolving volume changes. A firn densification model forced by the output of a regional climate model is used to convert volume to mass. We consider and investigate the potential sources of error in our reconstruction of mass trends, including geophysical biases in the altimetry, and the resulting mass change rates are compared to other published estimates. We find that mass changes are dominated by SMB until about 2001, when mass loss rapidly accelerates. The onset of this acceleration is somewhat later, and less gradual, compared to the IOM. Our time averaged mass changes agree well with recently published estimates based on gravimetry, IOM, laser altimetry, and with radar altimetry when merged with airborne data over outlet glaciers. We demonstrate, that with appropriate treatment, satellite radar altimetry can provide reliable estimates of mass trends for the Greenland ice sheet. With the inclusion of data from CryoSat II, this provides the possibility of producing a continuous time series of regional mass trends from 1992 onward.

  19. Initiation and Early Evolution of the Coronal Mass Ejection on 2009 May 13 from Extreme-ultraviolet and White-light Observations

    Science.gov (United States)

    Reva, A. A.; Ulyanov, A. S.; Bogachev, S. A.; Kuzin, S. V.

    2014-10-01

    We present the results of the observations of a coronal mass ejection (CME) that occurred on 2009 May 13. The most important feature of these observations is that the CME was observed from the very early stage (the solar surface) up to a distance of 15 solar radii (R ⊙). Below 2 R ⊙, we used the data from the TESIS extreme-ultraviolet telescopes obtained in the Fe 171 Å and He 304 Å lines, and above 2 R ⊙, we used the observations of the LASCO C2 and C3 coronagraphs. The CME was formed at a distance of 0.2-0.5R ⊙ from the Sun's surface as a U-shaped structure, which was observed both in the 171 Å images and in the white light. Observations in the He 304 Å line showed that the CME was associated with an erupting prominence, which was not located above—as the standard model predicts—but rather in the lowest part of the U-shaped structure close to the magnetic X point. The prominence location can be explained with the CME breakout model. Estimates showed that CME mass increased with time. The CME trajectory was curved—its heliolatitude decreased with time. The CME started at a latitude of 50° and reached the ecliptic plane at distances of 2.5 R ⊙. The CME kinematics can be divided into three phases: initial acceleration, main acceleration, and propagation with constant velocity. After the CME, onset GOES registered a sub-A-class flare.

  20. Initiation and early evolution of the coronal mass ejection on 2009 May 13 from extreme-ultraviolet and white-light observations

    Energy Technology Data Exchange (ETDEWEB)

    Reva, A. A.; Ulyanov, A. S.; Bogachev, S. A.; Kuzin, S. V., E-mail: reva.antoine@gmail.com [Lebedev Physical Institute, Russian Academy of Sciences, 53 Leninskij Prospekt, 119991 Moscow (Russian Federation)

    2014-10-01

    We present the results of the observations of a coronal mass ejection (CME) that occurred on 2009 May 13. The most important feature of these observations is that the CME was observed from the very early stage (the solar surface) up to a distance of 15 solar radii (R {sub ☉}). Below 2 R {sub ☉}, we used the data from the TESIS extreme-ultraviolet telescopes obtained in the Fe 171 Å and He 304 Å lines, and above 2 R {sub ☉}, we used the observations of the LASCO C2 and C3 coronagraphs. The CME was formed at a distance of 0.2-0.5R {sub ☉} from the Sun's surface as a U-shaped structure, which was observed both in the 171 Å images and in the white light. Observations in the He 304 Å line showed that the CME was associated with an erupting prominence, which was not located above—as the standard model predicts—but rather in the lowest part of the U-shaped structure close to the magnetic X point. The prominence location can be explained with the CME breakout model. Estimates showed that CME mass increased with time. The CME trajectory was curved—its heliolatitude decreased with time. The CME started at a latitude of 50° and reached the ecliptic plane at distances of 2.5 R {sub ☉}. The CME kinematics can be divided into three phases: initial acceleration, main acceleration, and propagation with constant velocity. After the CME, onset GOES registered a sub-A-class flare.

  1. Association between circulating fibroblast growth factor 23, α-Klotho, and the left ventricular ejection fraction and left ventricular mass in cardiology inpatients.

    Directory of Open Access Journals (Sweden)

    Kensaku Shibata

    Full Text Available BACKGROUND: Fibroblast growth factor 23 (FGF23, with its co-receptor Klotho, plays a crucial role in phosphate metabolism. Several recent studies suggested that circulating FGF23 and α-Klotho concentrations might be related to cardiovascular abnormalities in patients with advanced renal failure. PURPOSE: Using data from 100 cardiology inpatients who were not undergoing chronic hemodialysis, the association of circulating levels of FGF23, α-Klotho, and other calcium-phosphate metabolism-related parameters with the left ventricular ejection fraction (LVEF and left ventricular mass (LVM was analyzed. METHODS AND RESULTS: LVEF was measured using the modified Simpson method for apical 4-chamber LV images and the LVM index (LVMI was calculated by dividing the LVM by body surface area. Univariate analysis showed that log transformed FGF23, but not that of α-Klotho, was significantly associated with LVEF and LVMI with a standardized beta of -0.35 (P<0.001 and 0.26 (P<0.05, respectively. After adjusting for age, sex, estimated glomerular filtration rate, and serum concentrations of intact parathyroid hormone, and 25-hydroxyvitamin D as covariates into the statistical model, log-transformed FGF23 was found to be a statistically positive predictor for decreased left ventricular function and left ventricular hypertrophy. CONCLUSIONS: In cardiology department inpatients, circulating FGF23 concentrations were found to be associated with the left ventricular mass and LVEF independent of renal function and other calcium-phosphate metabolism-related parameters. Whether modulation of circulating FGF23 levels would improve cardiac outcome in such a high risk population awaits further investigation.

  2. Ice Mass Change in Greenland and Antarctica Between 1993 and 2013 from Satellite Gravity Measurements

    Science.gov (United States)

    Talpe, Matthieu J.; Nerem, R. Steven; Forootan, Ehsan; Schmidt, Michael; Lemoine, Frank G.; Enderlin, Ellyn M.; Landerer, Felix W.

    2017-01-01

    We construct long-term time series of Greenland and Antarctic ice sheet mass change from satellite gravity measurements. A statistical reconstruction approach is developed based on a principal component analysis (PCA) to combine high-resolution spatial modes from the Gravity Recovery and Climate Experiment (GRACE) mission with the gravity information from conventional satellite tracking data. Uncertainties of this reconstruction are rigorously assessed; they include temporal limitations for short GRACE measurements, spatial limitations for the low-resolution conventional tracking data measurements, and limitations of the estimated statistical relationships between low- and high-degree potential coefficients reflected in the PCA modes. Trends of mass variations in Greenland and Antarctica are assessed against a number of previous studies. The resulting time series for Greenland show a higher rate of mass loss than other methods before 2000, while the Antarctic ice sheet appears heavily influenced by interannual variations.

  3. The Role of Baryons in Creating Statistically Significant Planes of Satellites around Milky Way-Mass Galaxies

    CERN Document Server

    Ahmed, Sheehan H; Christensen, Charlotte R

    2016-01-01

    We investigate whether the inclusion of baryonic physics influences the formation of thin, coherently rotating planes of satellites such as those seen around the Milky Way and Andromeda. For four Milky Way-mass simulations, each run both as dark matter-only and with baryons included, we are able to identify a planar configuration that significantly maximizes the number of plane satellite members. The maximum plane member satellites are consistently different between the dark matter-only and baryonic versions of the same run due to the fact that satellites are both more likely to be destroyed and to infall later in the baryonic runs. Hence, studying satellite planes in dark matter-only simulations is misleading, because they will be composed of different satellite members than those that would exist if baryons were included. Additionally, the destruction of satellites in the baryonic runs leads to less radially concentrated satellite distributions, a result that is critical to making planes that are statistica...

  4. Halo-coronal mass ejections near the 23rd solar minimum: lift-off, inner heliosphere, and in situ (1 AU signatures

    Directory of Open Access Journals (Sweden)

    D. B. Berdichevsky

    Full Text Available The extreme ultraviolet (EUV signatures of a solar lift-off, decametric and kilometric radio burst emissions and energetic particle (EP inner heliospheric signatures of an interplanetary shock, and in situ identification of its driver through solar wind observations are discussed for 12 isolated halo coronal mass ejections (H-CMEs occurring between December 1996 and 1997. For the aforementioned twelve and the one event added in the discussion, it is found that ten passed several necessary conditions for being a "Sun-Earth connection". It is found that low corona EUV and Ha chromospheric signatures indicate filament eruption as the cause of H-CME. These signatures indicate that the 12 events can be divided into two major subsets, 7 related to active regions (ARs and 5 unrelated or related to decayed AR. In the case of events related to AR, there is indication of a faster lift-off, while a more gradual lift-off appears to characterize the second set. Inner heliospheric signatures – the presence of long lasting enhanced energetic particle flux and/or kilometric type II radio bursts – of a driven shock were identified in half of the 12 events. The in situ (1 AU analyses using five different solar wind ejecta signatures and comparisons with the bidirectional flow of suprathermal particles and Forbush decreases result in indications of a strong solar wind ejecta signatures for 11 out of 12 cases. From the discussion of these results, combined with work by other authors for overlapping events, we conclude that good Sun-Earth connection candidates originate most likely from solar filament eruptions with at least one of its extremities located closer to the central meridian than ~ 30° E or ~ 35° W with a larger extension in latitudinal location possible. In seven of the twelve cases it appears that the encountered ejecta was driving a shock at 1 AU. Support for this interpretation is found on the approximately equal

  5. A STUDY OF THE HELIOCENTRIC DEPENDENCE OF SHOCK STANDOFF DISTANCE AND GEOMETRY USING 2.5D MAGNETOHYDRODYNAMIC SIMULATIONS OF CORONAL MASS EJECTION DRIVEN SHOCKS

    Energy Technology Data Exchange (ETDEWEB)

    Savani, N. P. [University Corporation for Atmospheric Research (UCAR), Boulder, CO 80307 (United States); Shiota, D. [Computational Astrophysics Laboratory, Advanced Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Kusano, K. [Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya 464-8601 (Japan); Vourlidas, A. [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States); Lugaz, N., E-mail: neel.savani02@imperial.ac.uk [Experimental Space Plasma Group, University of New Hampshire, Durham, NH 03824 (United States)

    2012-11-10

    We perform four numerical magnetohydrodynamic simulations in 2.5 dimensions (2.5D) of fast coronal mass ejections (CMEs) and their associated shock fronts between 10 Rs and 300 Rs. We investigate the relative change in the shock standoff distance, {Delta}, as a fraction of the CME radial half-width, D {sub OB} (i.e., {Delta}/D {sub OB}). Previous hydrodynamic studies have related the shock standoff distance for Earth's magnetosphere to the density compression ratio (DR; {rho} {sub u}/{rho} {sub d}) measured across the bow shock. The DR coefficient, k {sub dr}, which is the proportionality constant between the relative standoff distance ({Delta}/D {sub OB}) and the compression ratio, was semi-empirically estimated as 1.1. For CMEs, we show that this value varies linearly as a function of heliocentric distance and changes significantly for different radii of curvature of the CME's leading edge. We find that a value of 0.8 {+-} 0.1 is more appropriate for small heliocentric distances (<30 Rs) which corresponds to the spherical geometry of a magnetosphere presented by Seiff. As the CME propagates its cross section becomes more oblate and the k {sub dr} value increases linearly with heliocentric distance, such that k {sub dr} = 1.1 is most appropriate at a heliocentric distance of about 80 Rs. For terrestrial distances (215 Rs) we estimate k {sub dr} = 1.8 {+-} 0.3, which also indicates that the CME cross-sectional structure is generally more oblate than that of Earth's magnetosphere. These alterations to the proportionality coefficients may serve to improve investigations into the estimates of the magnetic field in the corona upstream of a CME as well as the aspect ratio of CMEs as measured in situ.

  6. Data-driven Simulations of Magnetic Connectivity in Behind-the-Limb Gamma-ray Flares and Associated Coronal Mass Ejections

    Science.gov (United States)

    Jin, Meng; Petrosian, Vahe; Liu, Wei; Omodei, Nicola

    2017-08-01

    Recent Fermi detection of high-energy gamma-ray emission from the behind-the-limb (BTL) solar flares pose a puzzle on the particle acceleration and transport mechanisms in such events. Due to the large separation between the flare site and the location of gamma-ray emission, it is believed that the associated coronal mass ejections (CMEs) play an important role in accelerating and subsequently transporting particles back to the Sun to produce obseved gamma-rays. We explore this scenario by simulating the CME associated with a well-observed flare on 2014 September 1 about 40 degrees behind the east solar limb and by comparing the simulation and observational results. We utilize a data-driven global magnetohydrodynamics model (AWSoM: Alfven-wave Solar Model) to track the dynamical evolution of the global magnetic field during the event and investigate the magnetic connectivity between the CME/CME-driven shock and the Fermi emission region. Moreover, we derive the time-varying shock parameters (e.g., compression ratio, Alfven Mach number, and ThetaBN) over the area that is magnetically connected to the visible solar disk where Fermi gamma-ray emission originates. Our simulation shows that the visible solar disk develops connections both to the flare region and to the CME-driven shock during the eruption, which indicate that the CME’s interaction with the global solar corona is critical for understanding such Fermi BTL events and gamma-ray flares in general. We discuss the causes and implications of Fermi BTL events, in the framework of a potential shift of paradigm on particle acceleration in solar flares/CMEs.

  7. Heliocentric Distance of Coronal Mass Ejections at the Time of Energetic Particle Release: Revisiting the Ground Level Enhancement Events of Solar Cycle 23

    Science.gov (United States)

    Gopalswamy, Natchimuthuk

    2011-01-01

    Using the kinematics of coronal mass ejections (CMEs), onset time of soft X-ray flares, and the finite size of the pre-eruption CME structure, we derive the heliocentric distane at which the energetic particles during the ground level enhancement (GLE) events of Solar Cycle 23. We find that the GLE particles are released when the CMEs reach an average heliocentric distance of approx.3.25 solar radii (Rs). From this we infer that the shocks accelerating the particles are located at similar heights. Type II radio burst observations indicate that the CMEs are at much lower distances (average approx.1.4 Rs) when the CME-driven shock first forms. The shock seems to travel approx.1.8 Rs over a period of approox.30 min on the average before releasing the GLE particles. In deriving these results, we made three assumptions that have observational support: (i) the CME lift off occurs from an initial distance of about 1.25 Rs; (ii) the flare onset and CME onset are one and the same because these are two different manifestations of the same eruption; and (iii) the CME has positive acceleration from the onset to the first appearance in the coronagraphic field of view (2.5 to 6 Rs). Observations of coronal cavities in eclipse pictures and in coronagraphic images justify the assumption (i). The close relationship between the flare reconnection magnetic flux and the azimuthal flux of interplanetary magnetic clouds justify assumption (ii) consistent with the standard model (CSHKP) of solar eruption. Coronagraphic observations made close to the solar surface indicate a large positive acceleration of CMEs to a heliocentric distance of approx.3 Rs before they start slowing down due to the drag force. The inferred acceleration (approx.1.5 km/s/s) is consistent with reported values in the literature.

  8. Role of solar wind speed and interplanetary magnetic field during two-step Forbush decreases caused by Interplanetary Coronal Mass Ejections

    Science.gov (United States)

    Bhaskar, Ankush; Vichare, Geeta; Arunbabu, K. P.; Raghav, Anil

    2016-07-01

    The relationship of Forbush decreases (FDs) observed in Moscow neutron monitor with the interplanetary magnetic field (B) and solar wind speed (Vsw) is investigated in detail for the FDs associated with Interplanetary Coronal Mass Ejections (ICMEs) during 2001-2004. The classical two-step FD events are selected, and characteristics of the first step (mainly associated with shock), as well as of complete decrease (main phase) and recovery phase, are studied here. It is observed that the onset of FD occurs generally after zero to a few hours of shock arrival, indicating in the post-shock region that mainly sheath and ICME act as important drivers of FD. A good correlation is observed between the amplitude of B and associated FD magnitude observed in the neutron count rate of the main phase. The duration of the main phase observed in the neutron count rate also shows good correlation with B. This might indicate that stronger interplanetary disturbances have a large dimension of magnetic field structure which causes longer fall time of FD main phase when they transit across the Earth. It is observed that Vsw and neutron count rate time profiles show considerable similarity with each other during complete FD, especially during the recovery phase of FD. Linear relationship is observed between time duration/e-folding time of FD recovery phase and Vsw. These observations indicate that the FDs are influenced by the inhibited diffusion of cosmic rays due to the enhanced convection associated with the interplanetary disturbances. We infer that the inhibited cross-field diffusion of the cosmic rays due to enhanced B is mainly responsible for the main phase of FD whereas the expansion of ICME contributes in the early recovery phase and the gradual variation of Vsw beyond ICME boundaries contributes to the long duration of FD recovery through reduced convection-diffusion.

  9. On the statistical characteristics of radio-loud and radio-quiet halo coronal mass ejections and their associated flares during solar cycles 23 and 24

    Science.gov (United States)

    Mittal, Nishant; Sharma, Joginder; Verma, Virendar Kumar; Garg, Vijay

    2016-08-01

    We have studied the characteristics of radio-loud (RL) and radio-quiet (RQ) front side halo coronal mass ejections (HCMEs) (angular width 360°) observed between the time period years 1996-2014. RL-HCMEs are associated with type II radio bursts, while RQ-HCMEs are not associated with type II radio bursts. CMEs near the Sun in the interplanetary medium associated with radio bursts also affect the magnetosphere. The type II radio burst data was observed by WIND/WAVES instrument and HCMEs were observed by LASCO/ SOHO instruments. In our study, we have examined the properties of RL-HCMEs and RQ-HCMEs and found that RL-HCMEs follow the solar cycle variation. Our study also shows that the 26% of slow speed HCMEs and 82% of fast speed HCMEs are RL. The average speed of RL-HCMEs and RQ-HCMEs are 1370 km/s and 727 km/s, respectively. Most of the RQ-HCMEs occur around the solar disc center while most of RL-HCMEs are uniformly distributed across the solar disc. The mean value of acceleration of RL-HCMEs is more than twice that of RQ-HCMEs and mean value of deceleration of RL- HCMEs is very small compare to RQ-HCMEs events. It is also found that RQ-HCMEs events are associated with C- and M-class of SXR flares, while RL-HCMEs events are associated with M and X-class of SXR flares, which indicates that the RQ-HCMEs are less energetic than the RL-HCMEs. We have also discussed the various results obtained in present investigation in view of recent scenario of solar physics.

  10. Analysis of a coronal mass ejection and corotating interaction region as they travel from the Sun passing Venus, Earth, Mars, and Saturn

    Science.gov (United States)

    Prise, A. J.; Harra, L. K.; Matthews, S. A.; Arridge, C. S.; Achilleos, N.

    2015-03-01

    During June 2010 a good alignment in the solar system between Venus, STEREO-B, Mars, and Saturn provided an excellent opportunity to study the propagation of a coronal mass ejection (CME) and closely occurring corotating interaction region (CIR) from the Sun to Saturn. The CME erupted from the Sun at 01:30 UT on 20 June 2010,with v≈ 600 km s-1, as observed by STEREO-B, Solar Dynamics Observatory, and SOHO/Large Angle and Spectrometric Coronagraph. It arrived at Venus over 2 days later, some 3.5 days after a CIR is also detected here. The CIR was also observed at STEREO-B and Mars, prior to the arrival of the CME. The CME is not directed earthward, but the CIR is detected here less than 2 days after its arrival at Mars. Around a month later, a strong compression of the Saturn magnetosphere is observed by Cassini, consistent with the scenario that the CME and CIR have merged into a single solar transient. The arrival times of both the CME and the CIR at different locations were predicted using the ENLIL solar wind model. The arrival time of the CME at Venus, STEREO-B, and Mars is predicted to within 20 h of its actual detection, but the predictions for the CIR showed greater differences from observations, all over 1.5 days early. More accurate predictions for the CIR were found by extrapolating the travel time between different locations using the arrival times and speeds detected by STEREO-B and ACE. We discuss the implications of these results for understanding the propagation of solar transients.

  11. Chronoastrobiology の視点から見た高所住民の健康 : CME(coronal mass ejection)とラダークの洪水

    OpenAIRE

    中岡, 隆志; 川崎, 孝広; Norboo, Tsering; 松林, 公蔵; 大塚, 邦明; 奥宮, 清人

    2013-01-01

    Background: On 1 August 2010, an entire hemisphere of the sun erupted. Filaments of magnetism snapped and exploded, shock waves raced across the stellar surface, and billion-ton clouds of hot gas billowed into space. A coronal mass ejection (CME) headed directly for Earth. The huge solar storm triggered unusual northern and southern auroras appearing on the night of August 3. Geomagnetic turbulence in Japan was observed on 4 August. The CME could have driven disastrous flooding occurring in L...

  12. Under Pressure: Quenching Star Formation in Low-Mass Satellite Galaxies via Stripping

    CERN Document Server

    Fillingham, Sean P; Pace, Andrew B; Boylan-Kolchin, Michael; Bullock, James S; Garrison-Kimmel, Shea; Wheeler, Coral

    2016-01-01

    Recent studies of galaxies in the local Universe, including those in the Local Group, find that the efficiency of environmental (or satellite) quenching increases dramatically at satellite stellar masses below ~ $10^8\\ {\\rm M}_{\\odot}$. This suggests a physical scale where quenching transitions from a slow "starvation" mode to a rapid "stripping" mode at low masses. We investigate the plausibility of this scenario using observed HI surface density profiles for a sample of 66 nearby galaxies as inputs to analytic calculations of ram-pressure and viscous stripping. Across a broad range of host properties, we find that stripping becomes increasingly effective at $M_{*} < 10^{8-9}\\ {\\rm M}_{\\odot}$, reproducing the critical mass scale observed. However, for canonical values of the circumgalactic medium density ($n_{\\rm halo} < 10^{-3.5}$ ${\\rm cm}^{-3}$), we find that stripping is not fully effective; infalling satellites are, on average, stripped of < 40 - 70% of their cold gas reservoir, which is insuf...

  13. Time evolving mass loss of the Greenland ice sheet from satellite altimetry

    Science.gov (United States)

    Hurkmans, Ruud; Bamber, Jonathan; Davis, Curt

    2013-04-01

    Mass changes of the Greenland ice sheet (GrIS) may be estimated by the mass budget method (MBM), satellite gravimetry, or via surface elevation changes (dH/dt). Whereas the first two have been shown to agree well in reconstructing mass changes over the last decade, there are few decadal estimates from satellite altimetry and none that provide a time evolving trend that can be readily compared with the other methods. Here, we interpolate radar and laser altimetry data between 1995 and 2009 in both space and time to reconstruct the evolving volume changes. The interpolation algorithm uses ice velocity to constrain the interpolated dH/dt in sparsely sampled areas, in particular narrow, rapidly changing outlet glaciers. The underlying assumption that the spatial patterns of surface velocity and dH/dt are linearly related, which was previously demonstrated for Jakobshavn Isbrae, is here validated for other major outlet glaciers and extended to the entire GrIS. A firn densification model forced by the output of a regional climate model is used to convert volume to mass. We consider and investigate the potential sources of error in our reconstruction of mass trends, and the resulting mass changes are compared to other published estimates. We find that mass changes are dominated by SMB until about 2001, when mass loss rapidly accelerates. The onset of this acceleration is somewhat later, and less gradual, compared to MBM. Our time averaged mass changes agree with published estimates based on gravimetry, MBM, laser altimetry, and with radar altimetry when this is merged with airborne data over outlet glaciers.

  14. Study of the triple-mass Tethered Satellite System under aerodynamic drag and J2 perturbations

    Science.gov (United States)

    Razzaghi, Pourya; Assadian, Nima

    2015-11-01

    The dynamics of multi-tethered satellite formations consisting of three masses are studied in this paper. The triple-mass triple-tethered satellite system is modeled under the low Earth orbit perturbations of drag and Earth's oblateness and its equilibrium conditions are derived. It is modeled as three equal end-masses connected by a uniform-mass straight tether. The lengths of tethers are supposed to be constant and in this manner the angles of the plane consisting the masses are taken as the state variables of the system. The governing equations of motion are derived using Lagrangian approach. The aerodynamic drag perturbation is expressed as an external non-conservative force and the Earth oblateness (J2 perturbation) is considered as a term of potential energy. The equilibrium conditions of this system are found and their stability is investigated through the linear stability theory. Then, the results are verified by using a nonlinear simulation for three types of equilibrium conditions.

  15. Hot prominence detected in the core of a coronal mass ejection: Analysis of SOHO/UVCS Lα and SOHO/LASCO visible-light observations

    Science.gov (United States)

    Heinzel, P.; Susino, R.; Jejčič, S.; Bemporad, A.; Anzer, U.

    2016-05-01

    Context. The paper deals with the physics of erupting prominences in the core of coronal mass ejections (CME). Aims: We determine the physical parameters of an erupting prominence embedded in the core of a CME using SOHO/UVCS hydrogen Lα and Lβ lines and SOHO/LASCO visible light observations. In particular we analyze the CME event observed on August 2, 2000. We develop the non-LTE (NLTE; i.e. considering departures from the local thermodynamic equilibrium - LTE) spectral diagnostics based on Lα and visible light observations. Methods: Our method is based on 1D NLTE modeling of eruptive prominences and takes into account the effect of large flow velocities, which reach up to 300 km s-1 for the studied event (the so-called Doppler dimming). The NLTE radiative-transfer method can be used for both optically thin and thick prominence structures. We combine spectroscopic UVCS observations of an erupting prominence in the core of a CME with visible light images from LASCO-C2 in order to derive the geometrical parameters like projected thickness and velocity, together with the effective temperature and column density of electrons. These are then used to constrain our NLTE radiative transfer modeling which provides the kinetic temperature, microturbulent velocity, gas pressure, ionization degree, the line opacities, and the prominence effective thickness (geometrical filling factor). Results: Analysis was made for 69 observational points (spatial pixels) inside the whole erupting prominence. Roughly one-half of them show a non-negligible Lα optical thickness for flow velocity 300 km s-1 and about one-third for flow velocity 150 km s-1. All pixels with Lατ0 ≤ 0.3 have been considered for further analysis, which is presented in the form of statistical distributions (histograms) of various physical quantities such as the kinetic temperature, gas pressure, and electron density for two representative flow velocities (150 and 300 km s-1) and non-zero microturbulence. For

  16. Vibration Isolation Platform with Multiple Tuned Mass Dampers for Reaction Wheel on Satellites

    Directory of Open Access Journals (Sweden)

    Yao Zhang

    2013-01-01

    Full Text Available Vibration isolation is a direct and effective approach to improve the ultraprecise pointing capability of an imaging satellite. To have a good trade-off between the resonance amplitude and the high frequency attenuation for the original vibration isolation platform, a novel vibration isolation system for reaction wheel (RW, including a multistrut vibration isolation platform and multiple tuned mass dampers, is proposed. The first step constructs the integrated satellite dynamic model including the RWs and the vibration isolation systems, while the static and dynamic imbalances of the rotor and base movements are considered in the modeling process. The transmissibility matrix of the vibration isolation system is then obtained, and its frequency domain characteristics are described. The third part presents the application of the vibration isolation system for RWs. The effective attenuation of RW disturbances by the new vibration isolation system is illustrated, and its safety performance is also verified. Finally, using the reasonable parameters of the vibration isolation system, its performance on the satellite is testified by numerical simulations. The study shows that the novel vibration isolation system presented cannot only be successfully applied to a satellite but also improve the attitude stability.

  17. Geocenter motion due to surface mass transport from GRACE satellite data

    Science.gov (United States)

    Riva, R. E. M.; van der Wal, W.; Lavallée, D. A.; Hashemi Farahani, H.; Ditmar, P.

    2012-04-01

    Measurements of mass redistribution from satellite gravimetry are insensitive to geocenter motions. However, geocenter motions can be constrained by satellite gravity data alone if we partition mass changes between land and oceans, under the assumption that the ocean is passive (i.e., in gravitational equilibrium with the land load and the solid earth). Here, we make use of 8 years (2003-2010) of optimally filtered monthly GRACE-based solutions produced at TU Delft to determine changes in the land load and the corresponding geocenter motion, through an iterative procedure. We pay particular attention to correcting for signal leakage caused by the limited spatial resolution of GRACE. We also investigate how the choice of a model of glacial isostatic adjustment (GIA) affects the estimated geocenter motion trend due to present-day surface mass transport. Finally, we separate the contribution of ice masses from that of land hydrology and show how they have a different sensitivity to the chosen GIA model and observational time-span.

  18. SATURNʼS INNER SATELLITES: ORBITS, MASSES, AND THE CHAOTIC MOTION OF ATLAS FROM NEW CASSINI IMAGING OBSERVATIONS

    National Research Council Canada - National Science Library

    Cooper, Nicholas J; Renner, Stéfan; Murray, Carl D; Evans, Michael W

    2015-01-01

    We present numerically derived orbits and mass estimates for the inner Saturnian satellites, Atlas, Prometheus, Pandora, Janus, and Epimetheus from a fit to 2580 new Cassini Imaging Science Subsystem...

  19. Gas Loss by Ram Pressure Stripping and Internal Feedback From Low Mass Milky Way Satellites

    CERN Document Server

    Emerick, Andrew; Grcevich, Jana; Gatto, Andrea

    2016-01-01

    The evolution of dwarf satellites of the Milky Way is affected by the combination of ram pressure and tidal stripping, and internal feedback from massive stars. We investigate gas loss processes in the smallest satellites of the Milky Way using three-dimensional, high resolution, idealized wind tunnel simulations, accounting for gas loss through both ram pressure stripping and expulsion by supernova feedback. Using initial conditions appropriate for a dwarf galaxy like Leo T, we investigate whether or not environmental gas stripping and internal feedback can quench these low mass galaxies on the expected timescales, shorter than 2 Gyr. We find that supernova feedback contributes negligibly to the stripping rate for these low star formation rate galaxies. However, we also find that ram pressure stripping is less efficient than expected in the stripping scenarios we consider. Our work suggests that, although ram pressure stripping can eventually completely strip these galaxies, other physics is likely at play t...

  20. Black Hole Induced Ejections

    OpenAIRE

    Pelletier, G.

    2004-01-01

    Black Holes generate a particular kind of environments dominated by an accretion flow which concentrates a magnetic field. The interplay of gravity and magnetism creates this paradoxical situation where relativistic ejection is allowed and consequently high energy phenomena take place. Therefore Black Holes, which are very likely at the origin of powerfull astrophysical phenomena such as AGNs, micro- quasars and GRBs where relativistic ejections are observed, are at the heart of high energy a...

  1. Calculation of smoke plume mass from passive UV satellite measurements by GOME-2 polarization measurement devices

    Science.gov (United States)

    Penning de Vries, M. J. M.; Tuinder, O. N. E.; Wagner, T.; Fromm, M.

    2012-04-01

    The Wallow wildfire of 2011 was one of the most devastating fires ever in Arizona, burning over 2,000 km2 in the states of Arizona and New Mexico. The fire originated in the Bear Wallow Wilderness area in June, 2011, and raged for more than a month. The intense heat of the fire caused the formation of a pyro-convective cloud. The resulting smoke plume, partially located above low-lying clouds, was detected by several satellite instruments, including GOME-2 on June 2. The UV Aerosol Index, indicative of aerosol absorption, reached a maximum of 12 on that day, pointing to an elevated plume with moderately absorbing aerosols. We have performed extensive model calculations assuming different aerosol optical properties to determine the total aerosol optical depth of the plume. The plume altitude, needed to constrain the aerosol optical depth, was obtained from independent satellite measurements. The model results were compared with UV Aerosol Index and UV reflectances measured by the GOME-2 polarization measurement devices, which have a spatial resolution of roughly 10x40 km2. Although neither the exact aerosol optical properties nor optical depth can be obtained with this method, the range in aerosol optical depth values that we calculate, combined with the assumed specific extinction mass factor of 5 m2/kg lead us to a rough estimate of the smoke plume mass that cannot, at present, be assessed in another way.

  2. The masses of satellites in GAMA galaxy groups from 100 square degrees of KiDS weak lensing data

    CERN Document Server

    Sifón, Cristóbal; Hoekstra, Henk; Brouwer, Margot; van Uitert, Edo; Viola, Massimo; Baldry, Ivan; Brough, Sarah; Brown, Michael J I; Choi, Ami; Driver, Simon P; Erben, Thomas; Grado, Aniello; Heymans, Catherine; Hildebrandt, Hendrik; Joachimi, Benjamin; de Jong, Jelte T A; Kuijken, Konrad; McFarland, John; Miller, Lance; Nakajima, Reiko; Napolitano, Nicola; Norberg, Peder; Robotham, Aaron S G; Schneider, Peter; Klein, Gijs Verdoes

    2015-01-01

    We use the first 100 sq. deg. of overlap between the Kilo-Degree Survey (KiDS) and the Galaxy And Mass Assembly (GAMA) survey to determine the galaxy halo mass of ~10,000 spectroscopically-confirmed satellite galaxies in massive ($M > 10^{13}h^{-1}{\\rm M}_\\odot$) galaxy groups. Separating the sample as a function of projected distance to the group centre, we jointly model the satellites and their host groups with Navarro-Frenk-White (NFW) density profiles, fully accounting for the data covariance. The probed satellite galaxies in these groups have total masses $\\log M_{\\rm sub} /(h^{-1}{\\rm M}_\\odot) \\approx 11.7 - 12.2$ consistent across group-centric distance within the errorbars. Given their typical stellar masses, $\\log M_{\\rm \\star,sat}/(h^{-2}{\\rm M}_\\odot) \\sim 10.5$, such total masses imply stellar mass fractions of $M_{\\rm \\star,sat} /M_{\\rm sub} \\approx 0.04 h^{-1}$ . The average subhalo hosting these satellite galaxies has a mass $M_{\\rm sub} \\sim 0.015M_{\\rm host}$ independent of host halo mass, i...

  3. Periodic motions of a satellite-gyrostat relative to its center of mass under the action of gravitational torque

    Science.gov (United States)

    Sazonov, V. V.

    2013-03-01

    We investigated periodic motions of the axis of symmetry of a model satellite of the Earth, which are similar to the motions of the longitudinal axes of the Mir orbital station in 1999-2001 and the Foton-M3 satellite in 2007. The motions of these spacecraft represented weakly disturbed regular Euler precession with the angular momentum vector of motion relative to the center of mass close to the orbital plane. The direction of this vector during the motion was not practically changed. The model satellite represents an axisymmetric gyrostat with gyrostatic moment directed along the axis of symmetry. The satellite moves in a circular orbit and undergoes the action of the gravitational torque. The motion of the axis of symmetry of this satellite relative to the absolute space is described by fourth-order differential equations with periodic coefficients. The periodic solutions to this system with special symmetry properties are constructed using analytical and numerical methods.

  4. Mass loss of the Greenland peripheral glaciers and ice caps from satellite altimetry

    Science.gov (United States)

    Wouters, Bert; Noël, Brice; Moholdt, Geir; Ligtenberg, Stefan; van den Broeke, Michiel

    2017-04-01

    At its rapidly warming margins, the Greenland Ice Sheet is surrounded by (semi-)detached glaciers and ice caps (GIC). Although they cover only roughly 5% of the total glaciated area in the region, they are estimated to account for 15-20% of the total sea level rise contribution of Greenland. The spatial and temporal evolution of the mass changes of the peripheral GICs, however, remains poorly constrained. In this presentation, we use satellite altimetry from ICESat and Cryosat-2 combined with a high-resolution regional climate model to derive a 14 year time series (2003-2016) of regional elevation and mass changes. The total mass loss has been relatively constant during this period, but regionally, the GICs show marked temporal variations. Whereas thinning was concentrated along the eastern margin during 2003-2009, western GICs became the prime sea level rise contributors in recent years. Mass loss in the northern region has been steadily increasing throughout the record, due to a strong atmospheric warning and a deterioration of the capacity of the firn layer to buffer the resulting melt water.

  5. Source mass eruption rate retrieved from satellite-based data using statistical modelling

    Science.gov (United States)

    Gouhier, Mathieu; Guillin, Arnaud; Azzaoui, Nourddine; Eychenne, Julia; Valade, Sébastien

    2015-04-01

    Ash clouds emitted during volcanic eruptions have long been recognized as a major hazard likely to have dramatic consequences on aircrafts, environment and people. Thus, the International Civil Aviation Organization (ICAO) established nine Volcanic Ash Advisory Centers (VAACs) around the world, whose mission is to forecast the location and concentration of ash clouds over hours to days, using volcanic ash transport and dispersion models (VATDs). Those models use input parameters such as plume height (PH), particle size distribution (PSD), and mass eruption rate (MER), the latter being a key parameter as it directly controls the amount of ash injected into the atmosphere. The MER can be obtained rather accurately from detailed ground deposit studies, but this method does not match the operational requirements in case of a volcanic crisis. Thus, VAACs use empirical laws to determine the MER from the estimation of the plume height. In some cases, this method can be difficult to apply, either because plume height data are not available or because uncertainties related to this method are too large. We propose here an alternative method based on the utilization of satellite data to assess the MER at the source, during explosive eruptions. Satellite-based techniques allow fine ash cloud loading to be quantitatively retrieved far from the source vent. Those measurements can be carried out in a systematic and real-time fashion using geostationary satellite, in particular. We tested here the relationship likely to exist between the amount of fine ash dispersed in the atmosphere and of coarser tephra deposited on the ground. The sum of both contributions yielding an estimate of the MER. For this purpose we examined 19 eruptions (of known duration) in detail for which both (i) the amount of fine ash dispersed in the atmosphere, and (ii) the mass of tephra deposited on the ground have been estimated and published. We combined these data with contextual information that may

  6. Advancements of in-flight mass moment of inertia and structural deflection algorithms for satellite attitude simulators

    Science.gov (United States)

    Wright, Jonathan W.

    Experimental satellite attitude simulators have long been used to test and analyze control algorithms in order to drive down risk before implementation on an operational satellite. Ideally, the dynamic response of a terrestrial-based experimental satellite attitude simulator would be similar to that of an on-orbit satellite. Unfortunately, gravitational disturbance torques and poorly characterized moments of inertia introduce uncertainty into the system dynamics leading to questionable attitude control algorithm experimental results. This research consists of three distinct, but related contributions to the field of developing robust satellite attitude simulators. In the first part of this research, existing approaches to estimate mass moments and products of inertia are evaluated followed by a proposition and evaluation of a new approach that increases both the accuracy and precision of these estimates using typical on-board satellite sensors. Next, in order to better simulate the micro-torque environment of space, a new approach to mass balancing satellite attitude simulator is presented, experimentally evaluated, and verified. Finally, in the third area of research, we capitalize on the platform improvements to analyze a control moment gyroscope (CMG) singularity avoidance steering law. Several successful experiments were conducted with the CMG array at near-singular configurations. An evaluation process was implemented to verify that the platform remained near the desired test momentum, showing that the first two components of this research were effective in allowing us to conduct singularity avoidance experiments in a representative space-like test environment.

  7. Air-sea fluxes and satellite-based estimation of water masses formation

    Science.gov (United States)

    Sabia, Roberto; Klockmann, Marlene; Fernandez-Prieto, Diego; Donlon, Craig

    2015-04-01

    Recent work linking satellite-based measurements of sea surface salinity (SSS) and sea surface temperature (SST) with traditional physical oceanography has demonstrated the capability of generating routinely satellite-derived surface T-S diagrams [1] and analyze the distribution/dynamics of SSS and its relative surface density with respect to in-situ measurements. Even more recently [2,3], this framework has been extended by exploiting these T-S diagrams as a diagnostic tool to derive water masses formation rates and areas. A water mass describes a water body with physical properties distinct from the surrounding water, formed at the ocean surface under specific conditions which determine its temperature and salinity. The SST and SSS (and thus also density) at the ocean surface are largely determined by fluxes of heat and freshwater. The surface density flux is a function of the latter two and describes the change of the density of seawater at the surface. To obtain observations of water mass formation is of great interest, since they serve as indirect observations of the thermo-haline circulation. The SSS data which has become available through the SMOS [4] and Aquarius [5] satellite missions will provide the possibility of studying also the effect of temporally-varying SSS fields on water mass formation. In the present study, the formation of water masses as a function of SST and SSS is derived from the surface density flux by integrating the latter over a specific area and time period in bins of SST and SSS and then taking the derivative of the total density flux with respect to density. This study presents a test case using SMOS SSS, OSTIA SST, as well as Argo ISAS SST and SSS for comparison, heat fluxes from the NOCS Surface Flux Data Set v2.0, OAFlux evaporation and CMORPH precipitation. The study area, initially referred to the North Atlantic, is extended over two additional ocean basins and the study period covers the 2011-2012 timeframe. Yearly, seasonal

  8. Kinematics of Milky Way Satellites: Mass Estimates, Rotation Limits, and Proper Motions

    Directory of Open Access Journals (Sweden)

    Louis E. Strigari

    2010-01-01

    Full Text Available In the past several years kinematic data sets from Milky Way satellite galaxies have greatly improved, furthering the evidence that these systems are the most dark matter dominated objects known. This paper discusses a maximum likelihood formalism that extracts important quantities from these kinematic data sets, including the amplitude of a rotational signal, proper motions, and the mass distributions. Using a simple model for galaxy rotation it is shown that the expected error on the amplitude of a rotational signal is ∼0.5 km s−1 with ∼103 stars from either classical or ultra-faint satellites. As an example Sculptor is analyzed for the presence of a rotational signal; no significant detection of rotation is found, with a 90% c.l. upper limit of ∼2 km s−1. A criterion for model selection is presented that determines the parameters required to describe the dark matter halo density profiles and the stellar velocity anisotropy. Applied to four data sets with a wide range of velocities, models with variable velocity anisotropy are preferred relative to those with constant velocity anisotropy, and that central dark matter profiles both less cuspy and more cuspy than Lambda-Cold Dark Matter-based fits are equally acceptable.

  9. Mapping the mass distribution of Earth's mantle using satellite-derived gravity gradients

    Science.gov (United States)

    Panet, Isabelle; Pajot-Métivier, Gwendoline; Greff-Lefftz, Marianne; Métivier, Laurent; Diament, Michel; Mandea, Mioara

    2014-02-01

    The dynamics of Earth's mantle are not well known. Deciphering mantle flow patterns requires an understanding of the global distribution of mantle density. Seismic tomography has been used to derive mantle density distributions, but converting seismic velocities into densities is not straightforward. Here we show that data from the GOCE (Gravity field and steady-state Ocean Circulation Explorer) mission can be used to probe our planet's deep mass structure. We construct global anomaly maps of the Earth's gravitational gradients at satellite altitude and use a sensitivity analysis to show that these gravitational gradients image the geometry of mantle mass down to mid-mantle depths. Our maps highlight north-south-elongated gravity gradient anomalies over Asia and America that follow a belt of ancient subduction boundaries, as well as gravity gradient anomalies over the central Pacific Ocean and south of Africa that coincide with the locations of deep mantle plumes. We interpret these anomalies as sinking tectonic plates and convective instabilities between 1,000 and 2,500km depth, consistent with seismic tomography results. Along the former Tethyan Margin, our data also identify an east-west-oriented mass anomaly likely in the upper mantle. We suggest that by combining gravity gradients with seismic and geodynamic data, an integrated dynamic model for Earth can be achieved.

  10. Nearest Neighbor: The Low-Mass Milky Way Satellite Tucana III

    CERN Document Server

    Simon, J D; Drlica-Wagner, A; Bechtol, K; Marshall, J L; James, D J; Wang, M Y; Strigari, L; Balbinot, E; Kuehn, K; Walker, A R; Abbott, T M C; Allam, S; Annis, J; Benoit-Levy, A; Brooks, D; Buckley-Geer, E; Burke, D L; Rosell, A Carnero; Kind, M Carrasco; Carretero, J; Cunha, C E; D'Andrea, C B; da Costa, L N; DePoy, D L; Desai, S; Doel, P; Fernandez, E; Flaugher, B; Frieman, J; Garcia-Bellido, J; Gaztanaga, E; Goldstein, D A; Gruen, D; Gutierrez, G; Kuropatkin, N; Maia, M A G; Martini, P; Menanteau, F; Miller, C J; Miquel, R; Neilsen, E; Nord, B; Ogando, R; Plazas, A A; Romer, A K; Rykoff, E S; Sanchez, E; Santiago, B; Scarpine, V; Schubnell, M; Sevilla-Noarbe, I; Smith, R C; Sobreira, F; Suchyta, E; Swanson, M E C; Tarle, G; Whiteway, L; Yanny, B

    2016-01-01

    We present Magellan/IMACS spectroscopy of the recently discovered Milky Way satellite Tucana III (Tuc III). We identify 26 member stars in Tuc III, from which we measure a mean radial velocity of v_hel = -102.3 +/- 0.4 (stat.) +/- 2.0 (sys.) km/s, a velocity dispersion of 0.1^+0.7_-0.1 km/s, and a mean metallicity of [Fe/H] = -2.42^+0.07_-0.08. The upper limit on the velocity dispersion is sigma < 1.5 km/s at 95.5% confidence, and the corresponding upper limit on the mass within the half-light radius of Tuc III is 9.0 x 10^4 Msun. We cannot rule out mass-to-light ratios as large as 240 Msun/Lsun for Tuc III, but much lower mass-to-light ratios that would leave the system baryon-dominated are also allowed. We measure an upper limit on the metallicity spread of the stars in Tuc III of 0.19 dex at 95.5% confidence. Tuc III has a smaller metallicity dispersion and likely a smaller velocity dispersion than any known dwarf galaxy, but a larger size and lower surface brightness than any known globular cluster. It...

  11. Satellite Orbital Precessions Caused by the Octupolar Mass Moment of a Non-Spherical Body Arbitrarily Oriented in Space

    Indian Academy of Sciences (India)

    G. Renzetti

    2013-12-01

    I consider a satellite moving around a non-spherical body of mass and equatorial radius , and calculate its orbital precessions caused by the body’s octupolar mass moment 4. I consider only the effects averaged over one orbital period of the satellite. I give exact formulas, not restricted to any special values of either the eccentricity or the inclination of the satellite’s orbit. I do not assume any preferential orientation for the body’s spin axis $\\hat{\\mathbf{k}}$ because in many cases of potential interest (exoplanets, neutron stars, black holes) it is poorly known or unknown at all.

  12. A Guide to Satellite Communication. Reports and Papers on Mass Communication Number 66.

    Science.gov (United States)

    United Nations Educational, Scientific, and Cultural Organization, Paris (France).

    Basic information about the characteristics, uses, and implications of communication satellites is presented. Characteristics covered include the various types of systems--such as point-to-point, distribution, and broadcasting satellites--and the flexibility, capacity, geographical coverage, cost and disadvantages of satellites. The section on…

  13. LOW-MASS SUPPRESSION OF THE SATELLITE LUMINOSITY FUNCTION DUE TO THE SUPERSONIC BARYON-COLD-DARK-MATTER RELATIVE VELOCITY

    Energy Technology Data Exchange (ETDEWEB)

    Bovy, Jo; Dvorkin, Cora [Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540 (United States)

    2013-05-01

    We study the effect of the supersonic baryon-cold-dark-matter (CDM) flow, which has recently been shown to have a large effect on structure formation during the dark ages 10 {approx}< z {approx}< 1000, on the abundance of luminous, low-mass satellite galaxies around galaxies like the Milky Way. As the supersonic baryon-CDM flow significantly suppresses both the number of halos formed and the amount of baryons accreted onto such halos of masses 10{sup 6} < M{sub halo}/M{sub Sun} < 10{sup 8} at z {approx}> 10, a large effect results on the stellar luminosity function before reionization. As halos of these masses are believed to have very little star formation after reionization due to the effects of photoheating by the ultraviolet background, this effect persists to the present day. We calculate that the number of low-mass 10{sup 6} < M{sub halo}/M{sub Sun} < 5 Multiplication-Sign 10{sup 7} halos that host luminous satellite galaxies today is typically suppressed by 50%, with values ranging up to 90% in regions where the initial supersonic velocity is high. We show that this previously ignored cosmological effect resolves some of the tension between the observed and predicted number of low-mass satellites in the Milky Way, reducing the need for other mass-dependent star-formation suppression before reionization.

  14. Black Hole Induced Ejections

    CERN Document Server

    Pelletier, G

    2004-01-01

    Black Holes generate a particular kind of environments dominated by an accretion flow which concentrates a magnetic field. The interplay of gravity and magnetism creates this paradoxical situation where relativistic ejection is allowed and consequently high energy phenomena take place. Therefore Black Holes, which are very likely at the origin of powerfull astrophysical phenomena such as AGNs, micro- quasars and GRBs where relativistic ejections are observed, are at the heart of high energy astrophysics. The combination of General Relativity and Magneto-HydroDynamics (MHD) makes theory difficult; however great pionneers opened beautiful tracks in the seventies and left important problems to be solved for the next decades. These lectures will present the status of these issues. They have a tutorial aspect together with critical review aspect and contain also some new issues. Most of these lectures has been presented at the "School on Black Hole in the Universe" at Cargese, in May 2003.

  15. Antarctic ice-mass balance 2003 to 2012: regional reanalysis of GRACE satellite gravimetry measurements with improved estimate of glacial-isostatic adjustment based on GPS uplift rates

    NARCIS (Netherlands)

    Sasgen, I.; Konrad, H.; Ivins, E.R.; van den Broeke, M.R.|info:eu-repo/dai/nl/073765643; Bamber, J.L.; Martinec, Z.; Klemann, V.

    2013-01-01

    We present regional-scale mass balances for 25 drainage basins of the Antarctic Ice Sheet (AIS) from satellite observations of the Gravity and Climate Experiment (GRACE) for time period January 2003 to September 2012. Satellite gravimetry estimates of the AIS mass balance are strongly influenced by

  16. Antarctic ice-mass balance 2003 to 2012: regional reanalysis of GRACE satellite gravimetry measurements with improved estimate of glacial-isostatic adjustment based on GPS uplift rates

    NARCIS (Netherlands)

    Sasgen, I.; Konrad, H.; Ivins, E.R.; van den Broeke, M.R.; Bamber, J.L.; Martinec, Z.; Klemann, V.

    2013-01-01

    We present regional-scale mass balances for 25 drainage basins of the Antarctic Ice Sheet (AIS) from satellite observations of the Gravity and Climate Experiment (GRACE) for time period January 2003 to September 2012. Satellite gravimetry estimates of the AIS mass balance are strongly influenced by

  17. H-alpha survey of low-mass satellites of the neighbouring galaxies M31 and M81

    CERN Document Server

    Kaisin, S S

    2013-01-01

    Images have been obtained at the 6-m telescope at the Special Astrophysical Observatory (SAO) of the Russian Academy of Sciences in the H-alpha line and in the continuum for 20 dwarf spheroidal satellites of M31: And XI-And XXX, plus the distant Globular cluster Bol 520. Their star formation rates (FR) are estimated using the H-alpha flux and the ultraviolet FUV flux measured with the GALEX space telescope. Most of the dSph satellites of M31 have extremely low star formation rates with a characteristic upper limit of SFR~5x10^{-7}. We have made similar estimates of SFR from the H-alpha and FUV fluxes for 13 galaxies with low surface brightness recently discovered in the neighborhood of M81. Eleven of them are physical satellites of M81 with typical SFR< 5x10^{-5}. The median stellar masses of these satellites of M31 and M81 are 0.9 and 1.9 million solar masses, respectively. Our H-alpha observations place a 2-3 times stricter limit on the value of SFR than the data from the GALEX satellite, with a substant...

  18. Taking Care of Business in a Flash: Constraining the Timescale for Low-Mass Satellite Quenching with ELVIS

    CERN Document Server

    Fillingham, Sean P; Wheeler, Coral; Garrison-Kimmel, Shea; Boylan-Kolchin, Michael; Bullock, James S

    2015-01-01

    The vast majority of dwarf satellites orbiting the Milky Way and M31 are quenched, while comparable galaxies in the field are gas-rich and star-forming. Assuming that this dichotomy is driven by environmental quenching, we use the ELVIS suite of N-body simulations to constrain the characteristic timescale upon which satellites must quench following infall into the virial volumes of their hosts. The high satellite quenched fraction observed in the Local Group demands an extremely short quenching timescale (~ 2 Gyr) for dwarf satellites in the mass range Mstar ~ 10^6-10^8 Msun. This quenching timescale is significantly shorter than that required to explain the quenched fraction of more massive satellites (~ 8 Gyr), both in the Local Group and in more massive host halos, suggesting a dramatic change in the dominant satellite quenching mechanism at Mstar < 10^8 Msun. Combining our work with the results of complementary analyses in the literature, we conclude that the suppression of star formation in massive sa...

  19. Winter mass balance of Drangajökull ice cap (NW Iceland) derived from satellite sub-meter stereo images

    OpenAIRE

    J. M. C. Belart; E. Berthier; E. Magnússon; Anderson, L.S.; F. Pálsson; Thorsteinsson, T; Howat, I. M.; Aðalgeirsdóttir, G.; Jóhannesson, T.; A. H. Jarosch

    2017-01-01

    Sub-meter resolution, stereoscopic satellite images allow for the generation of accurate and high-resolution digital elevation models (DEMs) over glaciers and ice caps. Here, repeated stereo images of Drangajökull ice cap (NW Iceland) from Pléiades and WorldView2 (WV2) are combined with in situ estimates of snow density and densification of firn and fresh snow to provide the first estimates of the glacier-wide geodetic winter mass balance obtained from satellite imagery. Sta...

  20. Numerical Simulations of a Flux Rope Ejection

    Indian Academy of Sciences (India)

    P. Pagano; D. H. Mackay; S. Poedts

    2015-03-01

    Coronal mass ejections (CMEs) are the most violent phenomena observed on the Sun. One of the most successful models to explain CMEs is the flux rope ejection model, where a magnetic flux rope is expelled from the solar corona after a long phase along which the flux rope stays in equilibrium while magnetic energy is being accumulated. However, still many questions are outstanding on the detailed mechanism of the ejection and observations continuously provide new data to interpret and put in the context. Currently, extreme ultraviolet (EUV) images from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory (SDO) are providing new insights into the early phase of CME evolution. In particular, observations show the ejection of magnetic flux ropes from the solar corona and how they evolve into CMEs. However, these observations are difficult to interpret in terms of basic physical mechanisms and quantities, thus, we need to compare equivalent quantities to test and improve our models. In our work, we intend to bridge the gap between models and observations with our model of flux rope ejection where we consistently describe the full life span of a flux rope from its formation to ejection. This is done by coupling the global non-linear force-free model (GNLFFF) built to describe the slow low- formation phase, with a full MHD simulation run with the software MPI-AMRVAC, suitable to describe the fast MHD evolution of the flux rope ejection that happens in a heterogeneous regime. We also explore the parameter space to identify the conditions upon which the ejection is favoured (gravity stratification and magnetic field intensity) and we produce synthesised AIA observations (171 Å and 211 Å). To carry this out, we run 3D MHD simulation in spherical coordinates where we include the role of thermal conduction and radiative losses, both of which are important for determining the temperature distribution of the solar corona during a CME. Our model of flux

  1. Saturn's inner satellites : orbits, masses and the chaotic motion of Atlas from new Cassini imaging observations

    CERN Document Server

    Cooper, N J; Murray, C D; Evans, M W

    2014-01-01

    We present numerically-derived orbits and mass estimates for the inner Saturnian satellites, Atlas, Prometheus, Pandora, Janus and Epimetheus from a fit to 2580 new Cassini ISS astrometric observations spanning February 2004 to August 2013. The observations are provided in a supplementary table. We estimate GM_ Atlas=0.384+/-0.001 x 10^(-3)km^3s^(-2), a value 13% smaller than the previously published estimate but with an order of magnitude reduction in the uncertainty. We also find GM_ Prometheus=10.677+/-0.006x10(-3)km^3s^(-2), GM_Pandora=9.133+/-0.009x10^(-3)km^3s^(-2), GM_Janus=126.51+/-0.03x10^(-3)km^3s^(-2) and GM_Epimetheus=35.110+/-0.009x10^(-3)km^3s^(-2), consistent with previously published values, but also with significant reductions in uncertainties. We show that Atlas is currently librating in both the 54:53 co-rotation-eccentricity resonance (CER) and the 54:53 inner Lindblad (ILR) resonance with Prometheus, making it the latest example of a coupled CER-ILR system, in common with the Saturnian sa...

  2. Determination of the centre of mass kinematics in alpine skiing using differential global navigation satellite systems.

    Science.gov (United States)

    Gilgien, Matthias; Spörri, Jörg; Chardonnens, Julien; Kröll, Josef; Limpach, Philippe; Müller, Erich

    2015-01-01

    In the sport of alpine skiing, knowledge about the centre of mass (CoM) kinematics (i.e. position, velocity and acceleration) is essential to better understand both performance and injury. This study proposes a global navigation satellite system (GNSS)-based method to measure CoM kinematics without restriction of capture volume and with reasonable set-up and processing requirements. It combines the GNSS antenna position, terrain data and the accelerations acting on the skier in order to approximate the CoM location, velocity and acceleration. The validity of the method was assessed against a reference system (video-based 3D kinematics) over 12 turn cycles on a giant slalom skiing course. The mean (± s) position, velocity and acceleration differences between the CoM obtained from the GNSS and the reference system were 9 ± 12 cm, 0.08 ± 0.19 m · s(-1) and 0.22 ± 1.28 m · s(-2), respectively. The velocity and acceleration differences obtained were smaller than typical differences between the measures of several skiers on the same course observed in the literature, while the position differences were slightly larger than its discriminative meaningful change. The proposed method can therefore be interpreted to be technically valid and adequate for a variety of biomechanical research questions in the field of alpine skiing with certain limitations regarding position.

  3. Cookie-cutter halos: the remarkable constancy of the stellar mass function of satellite galaxies at 0.2

    CERN Document Server

    Tal, Tomer; Muzzin, Adam; Marchesini, Danilo; Stefanon, Mauro

    2014-01-01

    We present an observational study of the stellar mass function of satellite galaxies around central galaxies at 0.2satellite stellar mass distributions in four bins of central galaxy mass in three redshift ranges. Our results show that the stellar mass function of satellite galaxies increases with central galaxy mass, and that the distribution of satellite masses at fixed central mass is at most weakly dependent on redshift. We conclude that the average mass distribution of galaxies in groups is remarkably universal even out to z=1.2 and that it can be uniquely characterized by the group central galaxy mass. This further suggests that as central galaxies grow in stellar mass, they do so in tandem with the mass growth of their satellites. Finally, we classify all galaxies as either star forming or quiescent, and derive the mass functions of each subpopulation separately. We find that the mass distribution of both star for...

  4. Structural uncertainty in air mass factor calculation for NO2 and HCHO satellite retrievals

    Science.gov (United States)

    Lorente, Alba; Folkert Boersma, K.; Yu, Huan; Dörner, Steffen; Hilboll, Andreas; Richter, Andreas; Liu, Mengyao; Lamsal, Lok N.; Barkley, Michael; De Smedt, Isabelle; Van Roozendael, Michel; Wang, Yang; Wagner, Thomas; Beirle, Steffen; Lin, Jin-Tai; Krotkov, Nickolay; Stammes, Piet; Wang, Ping; Eskes, Henk J.; Krol, Maarten

    2017-03-01

    Air mass factor (AMF) calculation is the largest source of uncertainty in NO2 and HCHO satellite retrievals in situations with enhanced trace gas concentrations in the lower troposphere. Structural uncertainty arises when different retrieval methodologies are applied within the scientific community to the same satellite observations. Here, we address the issue of AMF structural uncertainty via a detailed comparison of AMF calculation methods that are structurally different between seven retrieval groups for measurements from the Ozone Monitoring Instrument (OMI). We estimate the escalation of structural uncertainty in every sub-step of the AMF calculation process. This goes beyond the algorithm uncertainty estimates provided in state-of-the-art retrievals, which address the theoretical propagation of uncertainties for one particular retrieval algorithm only. We find that top-of-atmosphere reflectances simulated by four radiative transfer models (RTMs) (DAK, McArtim, SCIATRAN and VLIDORT) agree within 1.5 %. We find that different retrieval groups agree well in the calculations of altitude resolved AMFs from different RTMs (to within 3 %), and in the tropospheric AMFs (to within 6 %) as long as identical ancillary data (surface albedo, terrain height, cloud parameters and trace gas profile) and cloud and aerosol correction procedures are being used. Structural uncertainty increases sharply when retrieval groups use their preference for ancillary data, cloud and aerosol correction. On average, we estimate the AMF structural uncertainty to be 42 % over polluted regions and 31 % over unpolluted regions, mostly driven by substantial differences in the a priori trace gas profiles, surface albedo and cloud parameters. Sensitivity studies for one particular algorithm indicate that different cloud correction approaches result in substantial AMF differences in polluted conditions (5 to 40 % depending on cloud fraction and cloud pressure, and 11 % on average) even for low

  5. Global surface density of water mass variations by using a two-step inversion by cumulating daily satellite gravity information

    Science.gov (United States)

    Ramillien, Guillaume; Frappart, Frédéric; Seoane, Lucia

    2016-04-01

    We propose a new method to produce time series of global maps of surface mass variations by progressive integration of daily geopotential variations measured by orbiting satellites. In the case of the GRACE mission, these geopotential variations can be determined from very accurate inter-satellite K-Band Range Rate (KBRR) measurements of 5-second daily orbits. In particular, the along-track gravity contribution of hydrological mass changes is extracted by removing de-aliasing models for static field, atmosphere, oceans mass variations (including periodical tides), as well as polar movements. Our determination of surface mass sources is composed of two successive dependent Kalman filter stages. The first one consists of reducing the satellite-based potential anomalies by adjusting the longest spatial wavelengths (i.e., low-degree spherical harmonics lower than 2). In the second stage, the residual potential anomalies from the previous stage are used to recover surface mass density changes - in terms of Equivalent-Water Height (EWH) - over a global network of juxtaposed triangular elements. These surface tiles of ~100,000 km x km (or equivalently 330 km by 330 km) are defined to be of equal areas over the terrestrial sphere. However they can be adapted to the local geometry of the surface mass. Our global approach was tested by inverting geopotential data, and successfully applied to estimate time-varying surface mass densities from real GRACE-based residuals. This strategy of combined Kalman filter-type inversions can also be useful for exploring the possibility of improving time and space resolutions for ocean and land studies that would be hopefully brought by future low altitude geodetic missions.

  6. COMMUNICATION SATELLITES FOR EDUCATION, SCIENCE AND CULTURE. REPORTS AND PAPERS ON MASS COMMUNICATION, NO. 53.

    Science.gov (United States)

    SCHRAMM, WILBUR

    THE TECHNOLOGY OF COMMUNICATION SATELLITES IS SUFFICIENTLY ADVANCED THAT CONCERNED AGENCIES, SUCH AS UNESCO, SHOULD BEGIN TO PLAN FOR THEIR USE IN EXCHANGE OF DATA, NEWS TRANSMISSION, CULTURAL EXCHANGE, AND EDUCATION. GROUNDWORK IN TECHNOLOGY, IN THE DESIGN OF A SATELLITE COMMUNICATION SYSTEM, IN VALUE JUDGMENTS, IN AGREEMENTS OF COOPERATION AND…

  7. Parallel Molecular Dynamics Simulations of Ejection from the Metal Cu and Al Under Shock Loading

    Institute of Scientific and Technical Information of China (English)

    CHEN Qi-Feng; CAO Xiao-Lin; ZHANG Ying; CAI Ling-Cang; CHEN Dong-Quan

    2005-01-01

    @@ Large-scale non-equilibrium molecular dynamics simulations are used to investigate the ejection of the metal under a shock loading. The present work focus on the dynamic process of ejection from the metal Cu and Al surface groove under shock loading, using parallel MD implementation and the Morse potential. The ejected mass coefficient and the size distribution of ejected particles (cluster for atoms) are investigated with changes of the half-angle or the depth of groove and shock strength.

  8. Action as ejection.

    Science.gov (United States)

    Franco, Daisy

    2006-01-01

    The systematic analysis of acting-out episodes can be used in assessing analytic progress. Variables to be considered are the nature of the wish, the type of defense, and the degree of concreteness (versus symbolization) of the mental processes used in attempting actualization (as distinct from the resort to action). Two acting-out episodes of a borderline patient who acted out as a character trait, both occurring outside the analytic setting, are presented as illustrations. In the first one, occurring relatively early in the analysis, when split-off negative and positive self-images had to be rigidly maintained, ejection of the negative self-image was actualized via the regressive use of a symbolic equation and the mechanism of displacement, obliterating the distinction between an internal feeling and an external thing that here was literally thrown out. The later episode, occurring after the split was healed and within the context of a frustrating heterosexual involvement, contained an acted-out allusion to identification and competition with the mother. As in a dream, via associations, an unconscious wish for oedipal victory was revealed. Whereas in the first episode the goal of ejection was central, with splitting and denial the underlying defenses, it was absent from the second, in which an attempt was made to actualize a repressed infantile wish and made greater use of symbolization. It is concluded that acting-out episodes at different periods of the analysis, when systematically analyzed, can serve in assessing a patient's progress.

  9. SATURNʼS INNER SATELLITES: ORBITS, MASSES, AND THE CHAOTIC MOTION OF ATLAS FROM NEW CASSINI IMAGING OBSERVATIONS

    OpenAIRE

    Cooper, Nicholas J.; Renner, Stéfan; Murray, Carl D.; Evans, Michael W.

    2015-01-01

    International audience; We present numerically derived orbits and mass estimates for the inner Saturnian satellites, Atlas, Prometheus, Pandora, Janus, and Epimetheus from a fit to 2580 new Cassini Imaging Science Subsystem astrometric observations spanning 2004 February to 2013 August. The observations are provided as machine-readable and Virtual Observatory tables. We estimate GM Atlas = (0.384 ± 0.001) × 10 −3 km 3 s −2 , a value 13% smaller than the previously published estimate but with ...

  10. Surface Elevation Changes in West Antarctica from Satellite Altimetry: Mass Balance Implications

    Science.gov (United States)

    Zwally, H. Jay; Brenner, Anita C.; Cornejo, Helen; Koblinsky, Chester J. (Technical Monitor)

    2001-01-01

    Time-series of surface elevation change, which are constructed from 7-years (1992-1999) of ERS-1 and 2 satellite radar altimeter data of Antarctica, show significant seasonal, inter-annual, and long-term changes. Elevation time-series are created from altimeter crossovers among 90-day data periods on a 50 km grid to 81.5 degrees S and fit with a multivariate linear/sinusoidal function to give the average rate of elevation change (dH/dt) and account for seasonal changes. On the major Ronne, Filchner, and Ronne ice shelves, the dH/dt are small or near zero. In contrast, the ice shelves of the Antarctic Peninsula and along the West Antarctic coast appear to be thinning significantly, with a 23 +/- 3 cm a(exp -1) surface elevation decrease on the Larsen ice shelf and a 65 +/- 4 cm a(exp -1) decrease on the Dotson ice shelf. Significant elevation decreases are obtained over most of the drainage basins of the Pine Island and Thwaites glaciers. Significant increases are obtained over most of the other grounded ice in Marie Byrd Land, the Antarctic Peninsula, and Coates Land. Over the sector from 85 degrees W to 115 degrees W, which includes the Pine Island and Thwaites basins, the average elevation is significantly decreasing by 8.1 cm a(exp -1). The corresponding ice thickness change is about -11 cm a(exp -1), with a corresponding mass loss of 82 Gt a(exp -1), and a 0.22 mm a(exp -1) contribution to global sea level rise. In terms of elevation change, the decrease in the Pine Island-Thwaites sector is largely balanced by the increase in the Marie Byrd Land, but only balanced by about 1/4 in terms of ice thickness change and contribution to sea level rise. The overall average elevation change for the grounded ice is + 1.2 cm a(exp -1). Using an average bedrock uplift of 2.5 cm a(exp -1), implies an average ice thickness decrease of 1.3 cm a(exp -1), a mass loss of 22 Gt a(exp -1), and a 0.06 mm a(exp -1) contribution to global sea level rise.

  11. Galaxy halo masses and satellite fractions from galaxy-galaxy lensing in the SDSS: stellar mass, luminosity, morphology, and environment dependencies

    CERN Document Server

    Mandelbaum, R; Kauffmann, G; Hirata, C M; Brinkmann, J; Mandelbaum, Rachel; Seljak, Uros; Kauffmann, Guinevere; Hirata, Christopher M.; Brinkmann, Jonathan

    2006-01-01

    The relationship between galaxies and dark matter can be characterized by the halo mass of the central galaxy and the fraction of galaxies that are satellites. Here we present observational constraints from the SDSS on these quantities as a function of r-band luminosity and stellar mass using galaxy-galaxy weak lensing, with a total of 351,507 lenses. We use stellar masses derived from spectroscopy and virial halo masses derived from weak gravitational lensing to determine the efficiency with which baryons in the halo of the central galaxy have been converted into stars. We find that an L* galaxy with a stellar mass of 6x10^{10} M_{sun} is hosted by a halo with mass of 1.4x10^{12} M_{sun}/h, independent of morphology, yielding baryon conversion efficiencies of 17_{-5}^{+10} (early types) and 16_{-6}^{+15} (late types) per cent at the 95 per cent CL (statistical, not including systematic uncertainty due to assumption of a universal initial mass function, or IMF). We find that for a given stellar mass, the halo...

  12. Constraints on the Dark Matter Particle Mass from the Number of Milky Way Satellites

    Science.gov (United States)

    2010-04-12

    few years 16 new dwarf spheroidal galax- ies have been discovered in the Sloan Digital Sky Survey ( SDSS ) [11] (see Table 3 and references therein). Af...data from the SDSS may provide in- teresting limits on how cold the dark matter is. Motivated by the recent increase in the number of ob- served...discovered in the SDSS , currently in Data Release 7. We list all known Milky Way satellites in Table II. We use the satellite distances given in

  13. Short-term variability and mass loss in Be stars I. BRITE satellite photometry of $\\eta$ and $\\mu$ Centauri

    CERN Document Server

    Baade, D; Pigulski, A; Carciofi, A C; Martayan, Ch; Moffat, A F J; Wade, G A; Weiss, W W; Grunhut, J; Handler, G; Kuschnig, R; Mehner, A; Pablo, H; Popowicz, A; Rucinski, S; Whittaker, G

    2016-01-01

    Empirical evidence for the involvement of nonradial pulsations (NRP's) in the mass loss from Be stars ranges from (i) a singular case (\\object{$\\mu$ Cen}) of repetitive mass ejections triggered by multi-mode beating to (ii) several photometric reports about enormous numbers of pulsation modes popping up during outbursts and on to (iii) effective single-mode pulsators. The BRITE Constellation of nanosatellites was used to obtain mmag photometry of the Be stars $\\eta$ and \\object{$\\mu$ Cen}. In the low-inclination star \\object{$\\mu$ Cen}, light pollution by variable amounts of near-stellar matter prevented any new insights into the variability and other properties of the central star. In the equator-on star \\object{$\\eta$ Cen}, BRITE photometry and {\\sc Heros} echelle spectroscopy from the 1990s reveal an intricate clockwork of star-disk interactions. The mass transfer is modulated with the frequency difference of two NRP modes and an amplitude three times as large as the amplitude sum of the two NRP modes. Thi...

  14. Ejection Fraction Heart Failure Measurement

    Science.gov (United States)

    ... Disease Venous Thromboembolism Aortic Aneurysm More Ejection Fraction Heart Failure Measurement Updated:Feb 15,2017 The ejection fraction ( ... failure This content was last reviewed April 2015. Heart Failure • Home • About Heart Failure • Causes and Risks for ...

  15. Mass Deposition Fluxes of Asian Dust to the Bohai Sea and Yellow Sea from Geostationary Satellite MTSAT: A Case Study

    Directory of Open Access Journals (Sweden)

    Qianguang Tu

    2015-11-01

    Full Text Available Windblown dust aerosol plays an important role in marine ecosystems once they are deposited and dissolved. At present, methods for estimating the deposition flux are mainly limited to direct measurements or model outputs. Additionally, satellite remote sensing was often used to estimate the integral dust column concentration (DCC. In this paper, an algorithm is developed to estimate the mass deposition fluxes of Asian dust by satellite. The dust aerosol is identified firstly and then the DCC is derived based on the relationships between the pre-calculated lookup table (LUT and observations from Japanese geostationary Multi-functional Transport Satellites (MTSAT. The LUT is built on the dust cloud and surface parameters by a radiation transfer model Streamer. The average change rate of deposition is derived, which shows an exponential decay dependence on transport time along the pathway. Thus, the deposition flux is acquired via integrating the hourly deposition. This simple algorithm is applied to a dust storm that occurred in the Bohai Sea and Yellow Sea from 1 to 3 March 2008. Results indicate that the properties of the dust cloud over the study area changed rapidly and the mass deposition flux is estimated to be 2.59 Mt.

  16. Reduced global longitudinal strain in association to increased left ventricular mass in patients with aortic valve stenosis and normal ejection fraction: a hybrid study combining echocardiography and magnetic resonance imaging

    Directory of Open Access Journals (Sweden)

    Scheffold Thomas

    2010-07-01

    Full Text Available Abstract Background Increased muscle mass index of the left ventricle (LVMi is an independent predictor for the development of symptoms in patients with asymptomatic aortic stenosis (AS. While the onset of clinical symptoms and left ventricular systolic dysfunction determines a poor prognosis, the standard echocardiographic evaluation of LV dysfunction, only based on measurements of the LV ejection fraction (EF, may be insufficient for an early assessment of imminent heart failure. Contrary, 2-dimensional speckle tracking (2DS seems to be superior in detecting subtle changes in myocardial function. The aim of the study was to assess these LV function deteriorations with global longitudinal strain (GLS analysis and the relations to LVMi in patients with AS and normal EF. Methods 50 patients with moderate to severe AS and 31 controls were enrolled. All patients underwent echocardiography, including 2DS imaging. LVMi measures were performed with magnetic resonance imaging in 38 patients with AS and indexed for body surface area. Results The total group of patients with AST showed a GLS of -15,2 ± 3,6% while the control group reached -19,5 ± 2,7% (p Conclusions In conclusion, increased LVMi is reflected in abnormalities of GLS and the proportion of GLS impairment depends on the extent of LV hypertrophy. Therefore, simultaneous measurement of LVMi and GLS might be useful to identify patients at high risk for transition into heart failure who would benefit from aortic valve replacement irrespectively of LV EF.

  17. On the Stability of Satellite Planes I: Effects of Mass, Velocity, Halo Shape and Alignment

    CERN Document Server

    Fernando, Nuwanthika; Guglielmo, Magda; Lewis, Geraint F; Ibata, Rodrigo A; Power, Chris

    2016-01-01

    The recently discovered vast thin plane of dwarf satellites orbiting the Andromeda Galaxy (M31) adds to the mystery of the small scale distribution of the Local Group's galaxy population. Such well defined planar structures are apparently rare occurrences in cold dark matter cosmological simulations, and we lack a coherent explanation of their formation and existence. In this paper, we explore the long-term survivability of thin planes of dwarfs in galactic halos, focusing, in particular, on systems mimicking the observed Andromeda distribution. The key results show that, in general, planes of dwarf galaxies are fragile, sensitive to the shape of the dark matter halo and other perturbing effects. In fact, long lived planes of satellites only exist in polar orbits in spherical dark matter halos, presenting a challenge to the observed Andromeda plane which is significantly tilted with respect to the optical disk. Our conclusion is that, in standard cosmological models, planes of satellites are generally short l...

  18. Antarctic outlet glacier mass change resolved at basin scale from satellite gravity gradiometry

    NARCIS (Netherlands)

    Bouman, J.; Fuchs, M.; Ivins, E.; Van der Wal, W.; Schrama, E.J.O.; Visser, P.N.A.M.; Horwath, M.

    2014-01-01

    The orbit and instrumental measurement of the Gravity Field and Steady State Ocean Circulation Explorer (GOCE) satellite mission offer the highest ever resolution capabilities for mapping Earth's gravity field from space. However, past analysis predicted that GOCE would not detect changes in ice

  19. Antarctic outlet glacier mass change resolved at basin scale from satellite gravity gradiometry

    NARCIS (Netherlands)

    Bouman, J.; Fuchs, M.; Ivins, E.; Van der Wal, W.; Schrama, E.J.O.; Visser, P.N.A.M.; Horwath, M.

    2014-01-01

    The orbit and instrumental measurement of the Gravity Field and Steady State Ocean Circulation Explorer (GOCE) satellite mission offer the highest ever resolution capabilities for mapping Earth's gravity field from space. However, past analysis predicted that GOCE would not detect changes in ice she

  20. Present Day Regional Mass Loss of Greenland Observed with Satellite Gravimetry

    NARCIS (Netherlands)

    Schrama, E.J.O.; Wouters, B.; Vermeersen, L.L.A.

    2011-01-01

    This paper summarizes results obtained for Greenland’s mass balance observed with NASA’s GRACE mission. We estimate a Greenland ice sheet mass loss at −201 ± 19 Gt/year including a discernible acceleration of −8 ± 7 Gt/year2 between March 2003 and February 2010. The mass loss of glacier systems on

  1. Present Day Regional Mass Loss of Greenland Observed with Satellite Gravimetry

    NARCIS (Netherlands)

    Schrama, E.J.O.; Wouters, B.; Vermeersen, L.L.A.

    2011-01-01

    This paper summarizes results obtained for Greenland’s mass balance observed with NASA’s GRACE mission. We estimate a Greenland ice sheet mass loss at −201 ± 19 Gt/year including a discernible acceleration of −8 ± 7 Gt/year2 between March 2003 and February 2010. The mass loss of glacier systems on t

  2. Initiation and Propagation of Coronal Mass Ejections

    Indian Academy of Sciences (India)

    P. F. Chen

    2008-03-01

    This paper reviews recent progress in the research on the initiation and propagation of CMEs. In the initiation part, several trigger mechanisms are discussed; in the propagation part, the observations and modelings of EIT waves/dimmings, as the EUV counterparts of CMEs, are described.

  3. Star on the horizon: The emergence of the direct broadcast satellite in American mass communications

    Science.gov (United States)

    Thomas, J. H.

    1984-12-01

    The purpose of this thesis is to describe the concept of broadcasting from satellites directly to the viewer equipped with a small, inexpensive receiving antenna, and the evolution of this technology as a means of commercial broadcast. Emphasis is placed on the problems of developing a regulatory framework for DBS by the Federal Communications Commission. The opposition of the existing broadcasters to the unregulated development of direct broadcast satellite (DBS) is explored in light of the possible effect that DBS may have on the economic base, audience, and advertising revenue of existing broadcasters. The information for this study was obtained from government documents, legal journals, books and the popular press. Two basic conclusions are drawn from this study: First, that the existing broadcasters have opposed the marketplace development of DBS, and second, that DBS does not pose as great a threat, at least in the near term, as the broadcasters fear.

  4. On the stability of satellite planes - I. Effects of mass, velocity, halo shape and alignment

    Science.gov (United States)

    Fernando, Nuwanthika; Arias, Veronica; Guglielmo, Magda; Lewis, Geraint F.; Ibata, Rodrigo A.; Power, Chris

    2017-02-01

    The recently discovered vast thin plane of dwarf satellites orbiting the Andromeda Galaxy (M31) adds to the mystery of the small-scale distribution of the Local Group's galaxy population. Such well-defined planar structures are apparently rare occurrences in cold dark matter cosmological simulations, and we lack a coherent explanation of their formation and existence. In this paper, we explore the long-term survivability of thin planes of dwarfs in galactic haloes, focusing, in particular, on systems mimicking the observed Andromeda distribution. The key results show that, in general, planes of dwarf galaxies are fragile, sensitive to the shape of the dark matter halo and other perturbing effects. In fact, long-lived planes of satellites only exist in polar orbits in spherical dark matter haloes, presenting a challenge to the observed Andromeda plane that is significantly tilted with respect to the optical disc. Our conclusion is that, in the standard cosmological models, planes of satellites are generally short lived, and hence we must be located at a relatively special time in the evolution of the Andromeda Plane, lucky enough to see its coherent pattern.

  5. Ejection of gaseous clumps from gravitationally unstable protostellar disks

    CERN Document Server

    Vorobyov, Eduard I

    2016-01-01

    We investigate the dynamics of gaseous clumps formed via gravitational fragmentation in young protostellar disks, focusing on the fragments that are ejected from the disk via many-body gravitational interaction. Numerical hydrodynamics simulations were employed to study the evolution of young protostellar disks formed from the collapse of rotating pre-stellar cores with mass in the 1.1-1.6 M_sun range. Protostellar disks formed in our models undergo gravitational fragmentation driven by continuing mass loading from parental collapsing cores. A few fragments can be ejected from the disk during the early evolution, but the low-mass fragments (< 15~M_Jup) disperse creating spectacular bow-type structures while passing through the disk and collapsing core. The least massive fragment that survived the ejection (21 M_Jup) straddles the planetary-mass limit, while the most massive ejected fragments (145 M_Jup) can break up into several pieces, leading to the ejection of wide separation binary clumps in the brown-...

  6. Formation of satellites from cold collapse

    Science.gov (United States)

    Benhaiem, David; Sylos Labini, Francesco

    2017-02-01

    We study the collapse of an isolated, initially cold, irregular (but almost spherical) and slightly inhomogeneous cloud of self-gravitating particles.The cloud is driven towards a virialized quasi-equilibrium state by a fast relaxation mechanism, occurring in a typical time τc, whose signature is a large change in the particle energy distribution. Post-collapse particles are divided into two main species: bound and free, the latter being ejected from the system. Because of the initial system's anisotropy, the time varying gravitational field breaks spherical symmetry so that the ejected mass can carry away angular momentum and the bound system can gain a non-zero angular momentum. In addition, while strongly bound particles form a compact core, weakly bound ones may form, in a time scale of the order of τc, several satellite sub-structures. These satellites have a finite lifetime that can be longer than τc and generally form a flattened distribution. Their origin and their abundance are related to the amplitude and nature ofinitial density fluctuations and to the initial cloud deviations from spherical symmetry, which are both amplified during the collapse phase. Satellites show a time dependent virial ratio that can be different from the equilibrium value b ≈ -1: although they are bound to the main virialized object, they are not necessarily virially relaxed.

  7. Failure and Ejection Behavior of Concrete Materials under Internal Blast

    Directory of Open Access Journals (Sweden)

    Haifu Wang

    2016-01-01

    Full Text Available In order to investigate the failure and ejection behavior of concrete materials under internal blast, the default Riedel-Hiermaier-Thoma (RHT concrete model in AUTODYN and a meshfree processor called SPH are employed in this numerical simulation. It is shown that the failure mechanisms are significantly different in these damaged zones. Crushed zone is caused by shear failure while fractured zone is induced by tensile failure, and spalled zone is formed by a combination of shear and tensile failure. In addition, the ejection velocity distribution of the fragmented concrete mass on free surface is examined. The results indicate that the ejection velocity declines monotonously with the increase of the distance to symmetry axis of computational model. On the wall of the prefabricated borehole, two types of fragmented concrete mass are analyzed, and bottom initiation is recommended to eject the fragmented concrete mass effectively. Moreover, an algorithm of average ejection speed is developed to effectively estimate the drill capacity of high velocity, energetic (HE projectiles. At last, the validity of numerical simulation is verified by physical experiments.

  8. Enobosarm (GTx-024) Modulates Adult Skeletal Muscle Mass Independently of the Androgen Receptor in the Satellite Cell Lineage.

    Science.gov (United States)

    Dubois, Vanessa; Simitsidellis, Ioannis; Laurent, Michaël R; Jardi, Ferran; Saunders, Philippa T K; Vanderschueren, Dirk; Claessens, Frank

    2015-12-01

    Androgens increase skeletal muscle mass, but their clinical use is hampered by a lack of tissue selectivity and subsequent side effects. Selective androgen receptor modulators elicit muscle-anabolic effects while only sparingly affecting reproductive tissues. The selective androgen receptor modulator, GTx-024 (enobosarm), is being investigated for cancer cachexia, sarcopenia, and muscle wasting diseases. Here we investigate the role of muscle androgen receptor (AR) in the anabolic effect of GTx-024. In mice lacking AR in the satellite cell lineage (satARKO), the weight of the androgen-sensitive levator ani muscle was lower but was decreased further upon orchidectomy. GTx-024 was as effective as DHT in restoring levator ani weights to sham levels. Expression of the muscle-specific, androgen-responsive genes S-adenosylmethionine decarboxylase and myostatin was decreased by orchidectomy and restored by GTx-024 and DHT in control mice, whereas the expression was low and unaffected by androgen status in satARKO. In contrast, insulin-like growth factor 1Ea expression was not different between satARKO and control muscle, decreased upon castration, and was restored by DHT and GTx-024 in both genotypes. These data indicate that GTx-024 does not selectively modulate AR in the satellite cell lineage and that cells outside this lineage remain androgen responsive in satARKO muscle. Indeed, residual AR-positive cells were present in satARKO muscle, coexpressing the fibroblast-lineage marker vimentin. AR positive, muscle-resident fibroblasts could therefore be involved in the indirect effects of androgens on muscle. In conclusion, both DHT and GTx-024 target AR pathways in the satellite cell lineage, but cells outside this lineage also contribute to the anabolic effects of androgens.

  9. Detection of Isotopes of Mercury Ions by Resonant Ejection in Paul Trap

    Institute of Scientific and Technical Information of China (English)

    WANG Wen-Ming; SHE Lei; LI Jiao-Mei; GAO Ke-Lin

    2007-01-01

    A simple method to detect mercury ions confined in a Paul trap has been developed by resonant ejection. In this method, frequency of the additional ejection ac voltage is scanned instead of the amplitude of the rf drive voltage in conventional methods. It is possible not only to observe the spectra of the secular oscillation of the trapped ions directly, but also to eject the confined ions from the trap mass-selectively.

  10. Quantifying Freshwater Mass Balance in the Central Tibetan Plateau by Integrating Satellite Remote Sensing, Altimetry, and Gravimetry

    Directory of Open Access Journals (Sweden)

    Kuo-Hsin Tseng

    2016-05-01

    Full Text Available The Tibetan Plateau (TP has been observed by satellite optical remote sensing, altimetry, and gravimetry for a variety of geophysical parameters, including water storage change. However, each of these sensors has its respective limitation in the parameters observed, accuracy and spatial-temporal resolution. Here, we utilized an integrated approach to combine remote sensing imagery, digital elevation model, and satellite radar and laser altimetry data, to quantify freshwater storage change in a twin lake system named Chibuzhang Co and Dorsoidong Co in the central TP, and compared that with independent observations including mass changes from the Gravity Recovery and Climate Experiment (GRACE data. Our results show that this twin lake, located within the Tanggula glacier system, remained almost steady during 1973–2000. However, Dorsoidong Co has experienced a significant lake level rise since 2000, especially during 2000–2005, that resulted in the plausible connection between the two lakes. The contemporary increasing lake level signal at a rate of 0.89 ± 0.05 cm·yr−1, in a 2° by 2° grid equivalent water height since 2002, is higher than the GRACE observed trend at 0.41 ± 0.17 cm·yr−1 during the same time span. Finally, a down-turning trend or inter-annual variability shown in the GRACE signal is observed after 2012, while the lake level is still rising at a consistent rate.

  11. Dynamical ejections of massive stars from young star clusters under diverse initial conditions

    Science.gov (United States)

    Oh, Seungkyung; Kroupa, Pavel

    2016-05-01

    We study the effects that initial conditions of star clusters and their massive star population have on dynamical ejections of massive stars from star clusters up to an age of 3 Myr. We use a large set of direct N-body calculations for moderately massive star clusters (Mecl ≈ 103.5 M⊙). We vary the initial conditions of the calculations, such as the initial half-mass radius of the clusters, initial binary populations for massive stars and initial mass segregation. We find that the initial density is the most influential parameter for the ejection fraction of the massive systems. The clusters with an initial half-mass radius rh(0) of 0.1 (0.3) pc can eject up to 50% (30)% of their O-star systems on average, while initially larger (rh(0) = 0.8 pc) clusters, that is, lower density clusters, eject hardly any OB stars (at most ≈ 4.5%). When the binaries are composed of two stars of similar mass, the ejections are most effective. Most of the models show that the average ejection fraction decreases with decreasing stellar mass. For clusters that are efficient at ejecting O stars, the mass function of the ejected stars is top-heavy compared to the given initial mass function (IMF), while the mass function of stars that remain in the cluster becomes slightly steeper (top-light) than the IMF. The top-light mass functions of stars in 3 Myr old clusters in our N-body models agree well with the mean mass function of young intermediate-mass clusters in M 31, as reported previously. This implies that the IMF of the observed young clusters is the canonical IMF. We show that the multiplicity fraction of the ejected massive stars can be as high as ≈ 60%, that massive high-order multiple systems can be dynamically ejected, and that high-order multiples become common especially in the cluster. We also discuss binary populations of the ejected massive systems. Clusters that are initially not mass-segregated begin ejecting massive stars after a time delay that is caused by mass

  12. Strong Lensing Mass of a Galaxy Cluster Discovered by the Planck Satellite

    CERN Document Server

    Sifón, Cristóbal; Hughes, John P; Carrasco, Mauricio; Barrientos, L Felipe

    2013-01-01

    Context. The recent discovery of a large number of galaxy clusters using the Sunyaev-Zel'dovich (SZ) effect has opened a new era on the study of the most massive clusters in the Universe. Multi-wavelength analyses are required to understand the properties of these new sets of clusters, which are a sensitive probe of cosmology. Aims. We aim at a multi-wavelength characterization of PLCK G004.5-19.5, one of the most massive X-ray validated SZ effect-selected galaxy clusters discovered by the Planck satellite. Methods. We have observed PLCK G004.5-19.5 with GMOS on the 8.1m-Gemini South Telescope for optical imaging and spectroscopy, and performed a strong lensing analysis. We also searched for associated radio emission in published catalogs. Results. An analysis of the optical images confirms that this is a massive cluster, with a dominant central galaxy (the BCG) and an accompanying red sequence of galaxies, plus many strongly lensed background galaxies including a 14"-long arc. Longslit spectroscopy of 6 clus...

  13. Antarctic Ice-Sheet Mass Balance from Satellite Altimetry 1992 to 2001

    Science.gov (United States)

    Zwally, H. Jay; Brenner, Anita C.; Cornejo, Helen; Giovinetto, Mario; Saba, Jack L.; Yi, Donghui

    2003-01-01

    A major uncertainty in understanding the causes of the current rate of sea level rise is the potential contributions from mass imbalances of the Greenland and Antarctic ice sheets. Estimates of the current mass balance of the Antarctic ice sheet are derived from surface- elevation changes obtained from 9 years of ERS - 1 & 2 radar altimeter data. Elevation time-series are created from altimeter crossovers among 90-day data periods on a 50 km grid to 81.5 S. The time series are fit with a multivariate linear/sinusoidal function to give the average rate of elevation change (dH/dt). On the major Rome-Filchner, Ross, and Amery ice shelves, the W d t are small or near zero. In contrast, the ice shelves of the Antarctic Peninsula and along the West Antarctic coast appear to be thinning significantly, with a 23 +/- 3 cm per year surface elevation decrease on the Larsen ice shelf and a 65 +/- 4 cm per year decrease on the Dotson ice shelf. On the grounded ice, significant elevation decreases are obtained over most of the drainage basins of the Pine Island and Thwaites glaciers in West Antarctica and inland of Law Dome in East Antarctica. Significant elevation increases are observed within about 200 km of the coast around much of the rest of the ice sheet. Farther inland, the changes are a mixed pattern of increases and decreases with increases of a few centimeters per year at the highest elevations of the East Antarctic plateau. The derived elevation changes are combined with estimates of the bedrock uplift from several models to provide maps of ice thickness change. The ice thickness changes enable estimates of the ice mass balances for the major drainage basins, the overall mass balance, and the current contribution of the ice sheet to global sea level change.

  14. Effects on satellite orbits in the gravitational field of an axisymmetric central body with a mass monopole and arbitrary spin multipole moments

    CERN Document Server

    Meichsner, J

    2015-01-01

    Perturbations of satellite orbits in the gravitational field of a body with a mass monopole and arbitrary spin multipole moments are considered for an axisymmetric and stationary situation. Periodic and secular effects caused by the central gravitomagnetic field are derived by a first order perturbation theory. For a central spin-dipole field these results reduce to the well known Lense-Thirring effects.

  15. PS, septum magnet for ejection of antiprotons

    CERN Multimedia

    1980-01-01

    Antiprotons circulated in the PS in the sense opposite to that of the so far normal protons (or positive ions). A new ejection system with a new septum magnet was installed in straight section 58 for antiproton ejection, first towards the ISR and then to the principal customer, the SPS p-pbar Collider. Later on, when the PS delivered leptons for LEP, the antiproton ejection system was use for the ejection of electrons.

  16. Analysis of melt ejection during long pulsed laser drilling

    Science.gov (United States)

    Ting-Zhong, Zhang; Zhi-Chao, Jia; Hai-Chao, Cui; De-Hua, Zhu; Xiao-Wu, Ni; Jian, Lu

    2016-05-01

    In pulsed laser drilling, melt ejection greatly influences the keyhole shape and its quality as well, but its mechanism has not been well understood. In this paper, numerical simulation and experimental investigations based on 304 stainless steel and aluminum targets are performed to study the effects of material parameters on melt ejection. The numerical method is employed to predict the temperatures, velocity fields in the solid, liquid, and vapour front, and melt pool dynamics of targets as well. The experimental methods include the shadow-graphic technique, weight method, and optical microscope imaging, which are applied to real-time observations of melt ejection phenomena, measurements of collected melt and changes of target mass, observations of surface morphology and the cross-section of the keyhole, respectively. Numerical and experimental results show that the metallic material with high thermal diffusivity like aluminum is prone to have a thick liquid zone and a large quantity of melt ejection. Additionally, to the best of our knowledge, the liquid zone is used to illustrate the relations between melt ejection and material thermal diffusivity for the first time. The research result in this paper is useful for manufacturing optimization and quality control in laser-material interaction. Project supported by the Natural Science Foundation of Jiangsu Province, China (Grant No. KYLX_0341) and the National Natural Science Foundation of China (Grant No. 61405147).

  17. Hypervelocity intracluster stars ejected by supermassive black hole binaries

    CERN Document Server

    Holley-Bockelmann, K; Mihos, J C; Feldmeier, J J; Ciardullo, R; McBride, C; Holley-Bockelmann, Kelly; Sigurdsson, Steinn; Feldmeier, John J.; Ciardullo, Robin; Bride, Cameron Mc

    2005-01-01

    Hypervelocity stars have been recently discovered in the outskirts of galaxies, such as the unbound star in the Milky Way halo, or the three anomalously fast intracluster planetary nebulae (ICPNe) in the Virgo Cluster. These may have been ejected by close 3-body interactions with a binary supermassive black hole (SMBBH), where a star which passes within the semimajor axis of the SMBBH can receive enough energy to eject it from the system. Stars ejected by SMBBHs may form a significant sub-population with very different kinematics and mean metallicity than the bulk of the intracluster stars. The number, kinematics, and orientation of the ejected stars may constrain the mass ratio, semimajor axis, and even the orbital plane of the SMBBH. We investigate the evolution of the ejected debris from a SMBBH within a clumpy and time-dependent cluster potential using a high resolution, self-consistent cosmological N-body simulation of a galaxy cluster. We show that the predicted number and kinematic signature of the fas...

  18. Orbits of massive satellite galaxies - II. Bayesian estimates of the Milky Way and Andromeda masses using high-precision astrometry and cosmological simulations

    Science.gov (United States)

    Patel, Ekta; Besla, Gurtina; Mandel, Kaisey

    2017-07-01

    In the era of high-precision astrometry, space observatories like the Hubble Space Telescope (HST) and Gaia are providing unprecedented 6D phase-space information of satellite galaxies. Such measurements can shed light on the structure and assembly history of the Local Group, but improved statistical methods are needed to use them efficiently. Here we illustrate such a method using analogues of the Local Group's two most massive satellite galaxies, the Large Magellanic Cloud (LMC) and Triangulum (M33), from the Illustris dark-matter-only cosmological simulation. We use a Bayesian inference scheme combining measurements of positions, velocities and specific orbital angular momenta (j) of the LMC/M33 with importance sampling of their simulated analogues to compute posterior estimates of the Milky Way (MW) and Andromeda's (M31) halo masses. We conclude that the resulting host halo mass is more susceptible to bias when using measurements of the current position and velocity of satellites, especially when satellites are at short-lived phases of their orbits (i.e. at pericentre). Instead, the j value of a satellite is well conserved over time and provides a more reliable constraint on host mass. The inferred virial mass of the MW (M31) using j of the LMC (M33) is {{M}}_{vir, MW} = 1.02^{+0.77}_{-0.55} × 10^{12} M⊙ ({{M}}_{vir, M31} = 1.37^{+1.39}_{-0.75} × 10^{12} M⊙). Choosing simulated analogues whose j values are consistent with the conventional picture of a previous (<3 Gyr ago), close encounter (<100 kpc) of M33 about M31 results in a very low virial mass for M31 (˜1012 M⊙). This supports the new scenario put forth in Patel, Besla & Sohn, wherein M33 is on its first passage about M31 or on a long-period orbit. We conclude that this Bayesian inference scheme, utilizing satellite j, is a promising method to reduce the current factor of 2 spread in the mass range of the MW and M31. This method is easily adaptable to include additional satellites as new 6D

  19. Space Solar Power Satellite Systems, Modern Small Satellites, and Space Rectenna

    Science.gov (United States)

    Bergsrud, Corey Alexis Marvin

    Space solar power satellite (SSPS) systems is the concept of placing large satellite into geostationary Earth orbit (GEO) to harvest and convert massive amounts of solar energy into microwave energy, and to transmit the microwaves to a rectifying antenna (rectenna) array on Earth. The rectenna array captures and converts the microwave power into usable power that is injected into the terrestrial electric grid for use. This work approached the microwave power beam as an additional source of power (with solar) for lower orbiting satellites. Assuming the concept of retrodirectivity, a GEO-SSPS antenna array system tracks and delivers microwave power to lower orbiting satellites. The lower orbiting satellites are equipped with a stacked photovoltaic (PV)/rectenna array hybrid power generation unit (HPGU) in order to harvest solar and/or microwave energy for on-board use during orbit. The area, and mass of the PV array part of the HPGU was reduced at about 32% beginning-of-life power in order to achieve the spacecraft power requirements. The HPGU proved to offer a mass decrease in the PGU, and an increase in mission life due to longer living component life of the rectenna array. Moreover, greater mission flexibility is achieved through a track and power delivery concept. To validate the potential advantages offered by a HPGU, a mission concept was presented that utilizes modern small satellites as technology demonstrators. During launch, a smaller power receiving "daughter" satellite sits inside a larger power transmitting "mother" satellite. Once separated from the launch vehicle the daughter satellite is ejected away from the mother satellite, and each satellite deploys its respective power transmitting or power receiving hardware's for experimentation. The concept of close proximity mission operations between the satellites is considered. To validate the technology of the space rectenna array part of the HPGU, six milestones were completed in the design. The first

  20. Dynamical ejections of massive stars from young star clusters under diverse initial conditions

    CERN Document Server

    Oh, Seungkyung

    2016-01-01

    We study the effects of initial conditions of star clusters and their massive star population on dynamical ejections of stars from star clusters up to an age of 3 Myr, particularly focusing on massive systems, using a large set of direct N-body calculations for moderately massive star clusters (Mecl=$10^{3.5}$ Msun). We vary the initial conditions of the calculations such as the initial half-mass radius of the clusters, initial binary populations for massive stars and initial mass segregation. We find that the initial density is the most influential parameter for the ejection fraction of the massive systems. The clusters with an initial half-mass radius of 0.1 (0.3) pc can eject up to 50% (30)% of their O-star systems on average. Most of the models show that the average ejection fraction decreases with decreasing stellar mass. For clusters efficient at ejecting O stars, the mass function of the ejected stars is top-heavy compared to the given initial mass function (IMF), while the mass function of stars remai...

  1. Assessing the Sensitivity of Satellite-Derived Estimates of Ice Sheet Mass Balance to Regional Climate Model Simulations of Snow Accumulation and Firn Compaction

    Science.gov (United States)

    Briggs, K.; Shepherd, A.; Horwath, M.; Horvath, A.; Nagler, T.; Wuite, J.; Muir, A.; Gilbert, L.; Mouginot, J.

    2015-12-01

    Surface mass balance (SMB) estimates from Regional Climate Models (RCMs) are fundamental for assessing and understanding ice sheet mass trends. Mass budget and altimetry assessments rely on RCMs both directly for estimates of the SMB contribution to the total mass trend, and indirectly for ancillary data in the form of firn compaction corrections. As such, mass balance assessments can be highly sensitive to RCM outputs and therefore their accuracy. Here we assess the extent to which geodetic measurements of mass balance are sensitive to RCM model outputs at different resolutions. We achieve this by comparing SMB dependent estimates of mass balance from the mass budget method and altimetry, with those from satellite gravimetry that are independent of SMB estimates. Using the outputs of the RACMO/ANT 2.3 model at 5.5 km and 27 km horizontal spatial resolution, we generate estimates of mass balance using the mass budget method and altimetry for the Western Palmer Land region of the Antarctic Peninsula between 2003 and 2014. We find a 19% increase in the long-term (1980 to 2014) mean annual SMB for the region when enhancing the model resolution to 5.5 km. This translates into an approximate 50% reduction in the total mass loss from 2003 to 2014 calculated with the mass budget method and a 15% increase in the altimetry estimate. The use of the enhanced resolution product leads to consistency between the estimates of mass loss from the altimetry and the mass budget method that is not observed with the coarser resolution product, in which estimates of cumulative mass fall beyond the relative errors. Critically, when using the 5.5 km product, we find excellent agreement, both in pattern and magnitude, with the independent estimate derived from gravimetry. Our results point toward the crucial need for high resolution SMB products from RCMs for mass balance assessments, particularly in regions of high mass turnover and complex terrain as found over the Antarctic Peninsula.

  2. Saturn's inner satellites: Orbits, masses, and the chaotic motion of atlas from new Cassini imaging observations

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, N. J.; Murray, C. D. [Astronomy Unit, School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS (United Kingdom); Renner, S. [Université Lille 1, Laboratoire d' Astronomie de Lille (LAL), 1 impasse de l' Observatoire, F-59000 Lille (France); Evans, M. W. [Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States)

    2015-01-01

    We present numerically derived orbits and mass estimates for the inner Saturnian satellites, Atlas, Prometheus, Pandora, Janus, and Epimetheus from a fit to 2580 new Cassini Imaging Science Subsystem astrometric observations spanning 2004 February to 2013 August. The observations are provided as machine-readable and Virtual Observatory tables. We estimate GM{sub Atlas} = (0.384 ± 0.001) × 10{sup −3} km{sup 3} s{sup −2}, a value 13% smaller than the previously published estimate but with an order of magnitude reduction in the uncertainty. We also find GM{sub Prometheus} = (10.677 ± 0.006) × 10{sup −3} km{sup 3} s{sup −2}, GM{sub Pandora} = (9.133 ± 0.009) × 10{sup −3} km{sup 3} s{sup −2}, GM{sub Janus} = (126.51 ± 0.03) × 10{sup −3} km{sup 3} s{sup −2}, and GM{sub Epimetheus} = (35.110 ± 0.009) × 10{sup −3} km{sup 3} s{sup −2}, consistent with previously published values, but also with significant reductions in uncertainties. We show that Atlas is currently librating in both the 54:53 co-rotation-eccentricity resonance (CER) and the 54:53 inner Lindblad (ILR) resonance with Prometheus, making it the latest example of a coupled CER-ILR system, in common with the Saturnian satellites Anthe, Aegaeon, and Methone, and possibly Neptune's ring arcs. We further demonstrate that Atlas's orbit is chaotic, with a Lyapunov time of ∼10 years, and show that its chaotic behavior is a direct consequence of the coupled resonant interaction with Prometheus, rather than being an indirect effect of the known chaotic interaction between Prometheus and Pandora. We provide an updated analysis of the second-order resonant perturbations involving Prometheus, Pandora, and Epimetheus based on the new observations, showing that these resonant arguments are librating only when Epimetheus is the innermost of the co-orbital pair, Janus and Epimetheus. We also find evidence that the known chaotic changes in the orbits of Prometheus and Pandora are not

  3. Saturnʼs Inner Satellites: Orbits, Masses, and the Chaotic Motion of Atlas from New Cassini Imaging Observations

    Science.gov (United States)

    Cooper, N. J.; Renner, S.; Murray, C. D.; Evans, M. W.

    2015-01-01

    We present numerically derived orbits and mass estimates for the inner Saturnian satellites, Atlas, Prometheus, Pandora, Janus, and Epimetheus from a fit to 2580 new Cassini Imaging Science Subsystem astrometric observations spanning 2004 February to 2013 August. The observations are provided as machine-readable and Virtual Observatory tables. We estimate G{{M}Atlas} = (0.384 ± 0.001) × 10-3 km3 s-2, a value 13% smaller than the previously published estimate but with an order of magnitude reduction in the uncertainty. We also find G{{M}Prometheus} = (10.677 ± 0.006) × 10-3 km3 s-2, G{{M}Pandora} = (9.133 ± 0.009) × 10-3 km3 s-2, G{{M}Janus} = (126.51 ± 0.03) × 10-3 km3 s-2, and G{{M}Epimetheus} = (35.110 ± 0.009) × 10-3 km3 s-2, consistent with previously published values, but also with significant reductions in uncertainties. We show that Atlas is currently librating in both the 54:53 co-rotation-eccentricity resonance (CER) and the 54:53 inner Lindblad (ILR) resonance with Prometheus, making it the latest example of a coupled CER-ILR system, in common with the Saturnian satellites Anthe, Aegaeon, and Methone, and possibly Neptune's ring arcs. We further demonstrate that Atlas's orbit is chaotic, with a Lyapunov time of ˜10 years, and show that its chaotic behavior is a direct consequence of the coupled resonant interaction with Prometheus, rather than being an indirect effect of the known chaotic interaction between Prometheus and Pandora. We provide an updated analysis of the second-order resonant perturbations involving Prometheus, Pandora, and Epimetheus based on the new observations, showing that these resonant arguments are librating only when Epimetheus is the innermost of the co-orbital pair, Janus and Epimetheus. We also find evidence that the known chaotic changes in the orbits of Prometheus and Pandora are not confined to times of apse anti-alignment.

  4. On collisional capture rates of irregular satellites around the gas-giant planets and the minimum mass of the solar nebula

    Science.gov (United States)

    Koch, F. Elliott; Hansen, Bradley M. S.

    2011-09-01

    We investigate the probability that an inelastic collision of planetesimals within the Hill sphere of the Jovian planets could explain the presence and orbits of observed irregular satellites. Capture of satellites via this mechanism is highly dependent on not only the mass of the protoplanetary disc, but also the shape of the planetesimal size distribution. We performed 2000 simulations for integrated time intervals ˜2 Myr and found that, given the currently accepted value for the minimum mass solar nebula and planetesimal number density based upon the Nesvorný et al. and Charnoz & Morbidelli size distribution dN˜D-3.5dD, the collision rates for the different Jovian planets range between ˜0.6 and ≳170 Myr-1 for objects with radii 1 km ≤r≤ 10 km. Additionally, we found that the probability that these collisions remove enough orbital energy to yield a bound orbit was ≲10-5 and had very little dependence on the relative size of the planetesimals. Of these collisions, the collision energy between two objects was ≳103 times the gravitational binding energy for objects with radii ˜100 km. We find that capturing irregular satellites via collisions between unbound objects can only account for ˜0.1 per cent of the observed population, hence this cannot be the sole method of producing irregular satellites.

  5. Successive Resonances for Ion Ejection at Arbitrary Frequencies in an Ion Trap

    Science.gov (United States)

    Snyder, Dalton T.; Cooks, R. Graham

    2016-09-01

    The use of successive resonances for ion ejection is demonstrated here as a method of scanning quadrupole ion traps with improvement in both resolution and sensitivity compared with single frequency resonance ejection. The conventional single frequency resonance ejection waveform is replaced with a dual-frequency waveform. The two included frequencies are spaced very closely and their relative amplitudes are adjusted so that the first frequency that ions encounter excites them to higher amplitudes where space charge effects are less prominent, thereby giving faster and more efficient ejection when the ions come into resonance with the second frequency. The method is applicable at any arbitrary frequency, unlike double and triple resonance methods. However, like double and triple resonance ejection, ejection using successive resonances requires the rf and AC waveforms to be phase-locked in order to retain mass accuracy and mass precision. The improved performance is seen in mass spectra acquired by rf amplitude scans (resonance ejection) as well as by secular frequency scans.

  6. Estimation of glacier mass balance: An approach based on satellite-derived transient snowlines and a temperature index driven by meteorological observations

    Science.gov (United States)

    Tawde, S. A.; Kulkarni, A. V.; Bala, G.

    2015-12-01

    In the Himalaya, large area is comprised of glaciers and seasonal snow, mainly due to its high elevated mountain ranges. Long term and continuous assessment of glaciers in this region is important for climatological and hydrological applications. However, rugged terrains and severe weather conditions in the Himalaya lead to paucity in field observations. Therefore, in recent decades, glacier dynamics are extensively monitored using remote sensing in inaccessible terrain like Himalaya. Estimation of glacier mass balance using empirical relationship between mass balance and area accumulation ratio (AAR) requires an accurate estimate of equilibrium-line altitude (ELA). ELA is defined as the snowline at the end of the hydrological year. However, identification of ELA, using remote sensing is difficult because of temporal gaps, cloud cover and intermediate snowfall on glaciers. This leads to large uncertainty in glacier mass-balance estimates by the conventional AAR method that uses satellite-derived highest snowline in ablation season as an ELA. The present study suggests a new approach to improve estimates of ELA location. First, positions of modelled snowlines are optimized using satellite-derived snowlines in the early melt season. Secondly, ELA at the end of the glaciological year is estimated by the melt and accumulation models driven using in situ temperature and precipitation records. From the modelled ELA, mass balance is estimated using the empirical relationship between AAR and mass balance. The modelled mass balance is validated using field measurements on Chhota Shigri and Hamtah glaciers, Himachal Pradesh, India. The new approach shows a substantial improvement in glacier mass-balance estimation, reducing bias by 46% and 108% for Chhota Shigiri and Hamtah glaciers respectively. The cumulative mass loss reconstructed from our approach is 0.85 Gt for nine glaciers in the Chandra basin from 2001 to 2009. The result of the present study is in agreement with

  7. Antarctic ice-mass balance 2002 to 2011: regional re-analysis of GRACE satellite gravimetry measurements with improved estimate of glacial-isostatic adjustment

    Directory of Open Access Journals (Sweden)

    I. Sasgen

    2012-09-01

    Full Text Available We present regional-scale mass balances for 25 drainage basins of the Antarctic Ice Sheet (AIS from satellite observations of the Gravity and Climate Experiment (GRACE for the years 2002–2011. Satellite gravimetry estimates of the AIS mass balance are strongly influenced by mass movement in the Earth interior caused by ice advance and retreat during the last glacial cycle. Here, we develop an improved glacial-isostatic adjustment (GIA estimate for Antarctica using newly available GPS uplift rates, allowing us to more accurately separate GIA-induced trends in the GRACE gravity fields from those caused by current imbalances of the AIS. Our revised GIA estimate is considerably lower than previous predictions, yielding an (upper estimate of apparent mass change of 48 ± 18 Gt yr−1. Therefore, our AIS mass balance of −103 ± 23 Gt yr−1 is considerably less negative than previous GRACE estimates. The Northern Antarctic Peninsula and the Amundsen Sea Sector exhibit the largest mass loss (−25 ± 6 Gt yr−1 and −126 ± 11 Gt yr−1, respectively. In contrast, East Antarctica exhibits a slightly positive mass balance (19 ± 16 Gt yr−1, which is, however, mostly the consequence of compensating mass anomalies in Dronning Maud and Enderby Land (positive and Wilkes and George V Land (negative due to interannual accumulation variations. In total, 7% of the area constitute more than half of the AIS imbalance (53%, contributing −151 ± 9 Gt yr−1 to global mean sea-level change. Most of this imbalance is caused by long-term ice-dynamic speed up expected to prevail in the future.

  8. Material ejection from shock-loaded free surfaces of aluminum and lead

    Energy Technology Data Exchange (ETDEWEB)

    Asay, J.R.

    1976-10-01

    A discussion is presented regarding interferometer experiments conducted on free surfaces which are impulsively loaded with high amplitude shock waves. It is shown that material ejection from shocked surfaces can significantly degrade interferometer experiments. In particular, loss of both light intensity and contrast of interferometer signals can result from various scattering and absorption processes occurring in a cloud of ejected material. An experimental technique is presented which allows determination of the mass and velocity of material ejected from free surfaces during shock loading. The technique has been applied to a study of mass ejection occurring naturally from shocked surfaces of two aluminium alloys and from lead. These results show that the total ejected mass ranges from a few ..mu..g/cm/sup 2/ in the aluminum alloys studied to a few mg/cm/sup 2/ in lead, for shock pressures ranging from about 10 to 50 GPa (100 to 500 kbar). Surface defects, such as pits and scratches, are thought to strongly influence mass ejection in aluminum; whereas in lead, localized shock-induced melting and vaporization are thought to be the dominant mechanisms at the higher shock pressures. Experimental results are also presented for aluminum surfaces which contain artificial defects in the form of wedge-shaped cavities. These results show that the maximum ejecta velocities of approximately two to four times the free surface velocity which are observed in these experiments can be correlated with predictions of steady jetting theory.

  9. CONCEPTUAL PAPER : Utilization of GPS Satellites for Precise Irradiation Measurement and Monitoring

    Indian Academy of Sciences (India)

    S. Vijayan

    2008-03-01

    Precise measurement of irradiance over the earth under various circumstances like solar flares, coronal mass ejections, over an 11-year solar cycle, etc. leads to better understanding of Sun–earth relationship. To continuously monitor the irradiance over earth-space regions several satellites at several positions are required. For that continuous and multiple satellite monitoring we can use GPS (Global Positioning System) satellites (like GLONASS, GALILEO, future satellites) installed with irradiance measuring and monitoring instruments. GPS satellite system consists of 24 constellations of satellites. Therefore usage of all the satellites leads to 24 measurements of irradiance at the top of the atmosphere (or 12 measurements of those satellites which are pointing towards the Sun) at an instant. Therefore in one day, numerous irradiance observations can be obtained for the whole globe, which will be very helpful for several applications like Albedo calculation, Earth Radiation Budget calculation, monitoring of near earth-space atmosphere, etc. Moreover, measuring irradiance both in ground (using ground instruments) and in space at the same instant of time over a same place, leads to numerous advantages. That is, for a single position we obtain irradiance at the top of the atmosphere, irradiance at ground and the difference in irradiance from over top of the atmosphere to the ground. Measurement of irradiance over the atmosphere and in ground at a precise location gives more fine details about the solar irradiance influence over the earth, path loss and interaction of irradiance with the atmosphere.

  10. Spatial and Temporal Antarctic Ice Sheet Mass Trends, Glacio-Isostatic Adjustment, and Surface Processes from a Joint Inversion of Satellite Altimeter, Gravity, and GPS Data

    Science.gov (United States)

    Martin-Espanol, Alba; Zammit-Mangion, Andrew; Clarke, Peter J.; Flament, Thomas; Helm, Veit; King, Matt A.; Luthcke, Scott B.; Petrie, Elizabeth; Remy, Frederique; Schon, Nana; hide

    2016-01-01

    We present spatiotemporal mass balance trends for the Antarctic Ice Sheet from a statistical inversion of satellite altimetry, gravimetry, and elastic-corrected GPS data for the period 2003-2013. Our method simultaneously determines annual trends in ice dynamics, surface mass balance anomalies, and a time-invariant solution for glacio-isostatic adjustment while remaining largely independent of forward models. We establish that over the period 2003-2013, Antarctica has been losing mass at a rateof -84 +/- 22 Gt per yr, with a sustained negative mean trend of dynamic imbalance of -111 +/- 13 Gt per yr. West Antarctica is the largest contributor with -112 +/- 10 Gt per yr, mainly triggered by high thinning rates of glaciers draining into the Amundsen Sea Embayment. The Antarctic Peninsula has experienced a dramatic increase in mass loss in the last decade, with a mean rate of -28 +/- 7 Gt per yr and significantly higher values for the most recent years following the destabilization of the Southern Antarctic Peninsula around 2010. The total mass loss is partly compensated by a significant mass gain of 56 +/- 18 Gt per yr in East Antarctica due to a positive trend of surface mass balance anomalies.

  11. Annual and Seasonal Glacier-Wide Surface Mass Balance Quantified from Changes in Glacier Surface State: A Review on Existing Methods Using Optical Satellite Imagery

    Directory of Open Access Journals (Sweden)

    Antoine Rabatel

    2017-05-01

    Full Text Available Glaciers are one of the terrestrial essential climate variables (ECVs as they respond very sensitively to climate change. A key driver of their response is the glacier surface mass balance that is typically derived from field measurements. It deserves to be quantified over long time scales to better understand the accumulation and ablation processes at the glacier surface and their relationships with inter-annual changes in meteorological conditions and long-term climate changes. Glaciers with in situ monitoring of surface mass balance are scarce at the global scale, and satellite remote sensing provides a powerful tool to increase the number of monitored glaciers. In this study, we present a review of three optical remote sensing methods developed to quantify seasonal and annual glacier surface mass balances. These methodologies rely on the multitemporal monitoring of the end-of-summer snow line for the equilibrium-line altitude (ELA method, the annual cycle of glacier surface albedo for the albedo method and the mapping of the regional snow cover at the seasonal scale for the snow-map method. Together with a presentation of each method, an application is illustrated. The ELA method shows promising results to quantify annual surface mass balance and to reconstruct multi-decadal time series. The other two methods currently need a calibration on the basis of existing in situ data; however, a generalization of these methods (without calibration could be achieved. The two latter methods show satisfying results at the annual and seasonal scales, particularly for the summer surface mass balance in the case of the albedo method and for the winter surface mass balance in the case of the snow-map method. The limits of each method (e.g., cloud coverage, debris-covered glaciers, monsoon-regime and cold glaciers, their complementarities and the future challenges (e.g., automating of the satellite images processing, generalization of the methods needing

  12. Estimation of volcanic ash emissions with satellite data: The inclusion of mass loading and plume height information in modified 4D-Var

    Science.gov (United States)

    Lu, Sha; Lin, Hai Xiang; Heemink, Arnold; Segers, Arjo; Fu, Guangliang

    2015-04-01

    Volcanic ash forecasting is a critical tool in hazard assessment and operational volcano monitoring. Emission parameters such as injection height, total emission mass and vertical distribution of the emission plume rate are essential and important in the implementation of volcanic ash models. Satellite instrument is a powerful tool to monitor volcanic aerosol evolution and satellite total-column data has been integrated in the modeling process to achieve a better initial condition for the forecasting. However, the use of total-column data,which has no vertical resolution, usually leads to an ill-conditioned problem and ineffective estimation of emission parameters. Fortunately, techniques to retrieve the information of total ash mass loading and injection height from satellite data has been developed recently. It provides a new possibility to increase the accuracy of estimation results by integrating them into data assimilation systems. In this work we propose a modified 4D-Var approach which seek the vertical emission distribution by observing ash cloud transport patterns from satellite total-ash-columns data, and two ways of including the information of mass loading and plume height in the assimilation process. The modified 4D-Var based on trajectory statistics forms a reformulated cost function which computes the total difference between observed ash columns and a linear combination of simulated ensemble columns coupled with a priori emission knowledge ('background' term). The ensembles are generated by a volcanic ash transport model with the tracer released form different layers. Experiment shows such straightforward method does not always guarantee the identification of injection height with a short assimilation time window, and additional information of injection height is needed to correct the solution. We propose two tricks to incorporate the information: 1. add extra terms containing the information to the cost function as restriction term; 2. generate a

  13. Geomagnetic disturbances imprints in ground and satellite altitude observatories

    Science.gov (United States)

    Yahiat, Yasmina; Lamara, Souad; Zaourar, Naima; Hamoudi, Mohamed

    2016-04-01

    The temporal evolution of the geomagnetic field and its variations have been repeatedly studied from both ground observatories and near-earth orbiting platforms. With the advent of the space ageand the launches of geomagnetic low altitude orbits satellites, a global coverage has been achieved. Since Magsat mission, more satellites were put into orbit and some of them are still collecting data enhancing the spatial and temporal descriptions of the field. Our study uses new data gathered by the latest SWARM satellite mission launched on November, 22nd 2013. It consists of a constellation of three identical satellites carrying on board high resolution and accuracy scientific equipment. Data from this constellation will allow better understanding the multiscale behavior of the geomagnetic field. Our goal is to analyze and interpret the geomagnetic data collected by this Swarm mission, for a given period and try to separate the external disturbances from internal contributions. We consider in the study the variation of the horizontal component H, for different virtual geomagnetic observatories at the satellite altitude. The analysis of data by Swarm orbital segments shows clearly the external disturbances of the magnetic field like that occurring on 27th of August 2014. This perturbation is shown on geomagnetic indexes and is related to a coronal mass ejection (CME). These results from virtual observatories are confirmed, by the equivalent analysis using ground observatories data for the same geographic positions and same epochs. Key words: Geomagnetic field, external field, geomagnetic index, SWARM mission, virtual observatories.

  14. The scatter about the "Universal" dwarf spheroidal mass profile: A kinematic study of the M31 satellites, And V and And VI

    CERN Document Server

    Collins, M L M; Rich, R M; Ibata, R A; Irwin, M J; Peñarrubia, J; Arimoto, N; Brooks, A M; Lewis, G F; McConnachie, A W; Venn, K

    2011-01-01

    While the satellites of the Milky Way (MW) have been shown to be largely consistent in terms of their mass contained within one half--light radius (M_{half}) with a "Universal" mass profile, a number of M31 satellites are found to be inconsistent with such relations, and seem kinematically colder in their central regions than their MW cousins. In this work, we present new kinematic and updated structural properties for two M31 dSphs, And V and And VI using data from the Keck Low Resolution Imaging Spectrograph (LRIS) and the DEep Imaging Multi-Object Spectrograph (DEIMOS) instruments and the Subaru Suprime-Cam imager. We measure systemic velocities of v_r=-393.1+/-4.2km/s and -344.8+/-2.5km/s, and dispersions of sigma_v=11.5{+5.3}{-4.4}km/s and sigma_v=9.4{+3.2}{-2.4}km/s for And V and And VI respectively, meaning these two objects are consistent with the trends in sigma_v and r_{half} set by their MW counterparts. We also investigate the nature of this scatter about the MW dSph mass profiles for the "Classic...

  15. Mass gain of glaciers in Lahaul and Spiti region (North India during the nineties revealed by in-situ and satellite geodetic measurements

    Directory of Open Access Journals (Sweden)

    C. Vincent

    2012-09-01

    Full Text Available The volume change of Chhota Shigri Glacier (India, 32° N between 1988 and 2010 has been determined using in-situ geodetic measurements. This glacier has experienced only a slight mass loss over the last 22 yr (–3.8 ± 1.8 m w.e.. Using satellite digital elevation models (DEM differencing and field measurements, we measure a negative mass balance (MB between 1999 and 2011 (–4.7 ± 1.8 m w.e.. Thus, we deduce a positive MB between 1988 and 1999 (+1.0 ± 2.5 m w.e.. Furthermore, satellite DEM differencing reveals a good correspondence between the MB of Chhota Shigri Glacier and the MB of an over 2000 km2 glaciarized area in the Lahaul and Spiti region during 1999–2011. We conclude that there has been no large ice wastage in this region over the last 22 yr, ice mass loss being limited to the last decade. This contrasts to the most recent compilation of MB data in the Himalayan range that indicates ice wastage since 1975, accelerating after 1990. For the rest of western Himalaya, available observations of glacier MBs are too sparse and discontinuous to provide a clear and relevant regional pattern of glacier volume change over the last two decades.

  16. Slope mass movements on SPOT satellite images: A case of the Železniki area (W Slovenia after flash floods in September 2007

    Directory of Open Access Journals (Sweden)

    Mateja Jemec

    2008-12-01

    Full Text Available Flash floods in Slovenia, which was exposed on September 18th 2007, demanded 6 lives, several thousand houses and over one thousand kilometres of roads were damaged and more also than 50 bridges. The highest amount of rain fell at west and north-west parts of Slovenia (northern Primorska region and southern Gorenjska region,from where heavy rain spread eastwards over the central Slovenia and in east part of Slovenia. In the article we focused on area of western and north-western part of Slovenia. The aim of present research was in the first phase to describe methodology to determine landslide occurrences from satellite images before and after natural disaster on Železniki region. Second phase was based on comparison of obtained results with the existing models for prediction of slope mass movements, and finally also to determine identificability of landslide types on a satellite image.Results have shown, that the highest part of obtaining area from supervised and unsupervised classification of satellite images, are comparable with classes of landslide susceptibility, where occurrences of landslide are largest.

  17. The Eating Habits of Milky Way Mass Halos: Destroyed Dwarf Satellites and the Metallicity Distribution of Accreted Stars

    CERN Document Server

    Deason, Alis J; Wechsler, Risa H

    2016-01-01

    We study the mass spectrum of destroyed dwarfs that contribute to the accreted stellar mass of Milky Way (MW) mass M_vir ~ 10^12.1 M_sun) halos using a suite of 45 zoom-in, dissipationless simulations. Empirical models are employed to relate (peak) subhalo mass to dwarf stellar mass, and we use constraints from z=0 observations and hydrodynamical simulations to estimate the metallicity distribution of the accreted stellar material. The dominant contributors to the accreted stellar mass are relatively massive dwarfs with M_star ~ 10^8-10^10 M_sun. Halos with more quiescent accretion histories tend to have lower mass progenitors (10^8-10^9 M_sun), and lower overall accreted stellar masses. Ultra-faint mass (M_star 10^8 M_sun can contribute a considerable fraction (~20-60 %) of metal-poor stars if their metallicity distributions have significant metal-poor tails. Finally, we find that the generic assumption of a quiescent assembly history for the MW halo seems to be in tension with the mass spectrum of its surv...

  18. The Eating Habits of Milky Way-mass Halos: Destroyed Dwarf Satellites and the Metallicity Distribution of Accreted Stars

    Science.gov (United States)

    Deason, Alis J.; Mao, Yao-Yuan; Wechsler, Risa H.

    2016-04-01

    We study the mass spectrum of destroyed dwarfs that contribute to the accreted stellar mass of Milky Way (MW)-mass (Mvir ˜ 1012.1 M⊙) halos using a suite of 45 zoom-in dissipationless simulations. Empirical models are employed to relate (peak) subhalo mass to dwarf stellar mass, and we use constraints from z = 0 observations and hydrodynamical simulations to estimate the metallicity distribution of the accreted stellar material. The dominant contributors to the accreted stellar mass are relatively massive dwarfs with Mstar ˜ 108-1010M⊙. Halos with more quiescent accretion histories tend to have lower mass progenitors (108-109 M⊙), and lower overall accreted stellar masses. Ultra-faint mass (Mstar 108 M⊙ can contribute a considerable fraction (˜20%-60%) of metal-poor stars if their metallicity distributions have significant metal-poor tails. Finally, we find that the generic assumption of a quiescent assembly history for the MW halo seems to be in tension with the mass spectrum of its surviving dwarfs. We suggest that the MW could be a “transient fossil” a quiescent halo with a recent accretion event(s) that disguises the preceding formation history of the halo.

  19. Temporal and spatial changes of Laika Glacier, Canadian Arctic, since 1959, inferred from satellite remote sensing and mass-balance modelling

    Science.gov (United States)

    Huss, Matthias; Stöckli, Reto; Kappenberger, Giovanni; Blatter, Heinz

    The retreat of Laika Glacier (4.4 km2), part of a small ice cap situated on Coburg Island, Canadian Arctic Archipelago, is analyzed using field data, satellite remote sensing and mass-balance modelling. We present a methodology for merging various data types and numerical models and investigate the temporal and spatial changes of a remote glacier during the past five decades. A glacier mass-balance and surface-evolution model is run for the period 1959-2006, forced with in situ weather observations and climate re-analysis data (ERA-40, NARR). The model is calibrated using the ice-volume change observed between 1959 and 1971, and measured seasonal mass balances. Calculated glacier surface elevation is validated against ICESat GLAS altimeter data and ASTER-derived elevation. Landsat-derived glacier outlines are used to validate calculated ice extent. The piedmont tongue of Laika Glacier has retreated considerably and is in a state of disintegration. The modelled glacier mass balance between 1959 and 2006 was -0.41 m w.e.a-1, on average. Model results indicate a significant trend towards higher mass-balance gradients. A complete wastage of Laika Glacier by 2100 is predicted by model runs based on climate scenarios.

  20. AD Ejection Line Studies and Optics Improvements

    CERN Document Server

    Belochitskii, P

    2013-01-01

    This paper is a summary of the work we made to understand and improve the AD ejection line optics. In 2011 significant differences were noticed between the optical properties of the AD ejection line and the MAD model. Investigations started to find out the sources of discrepancy. Better understanding of the ejection line optics was obtained and corrections were applied to the model of ejection line. The beam delivery to the experiments is better understood now. The results obtained might be useful as well for the optics design of AD to ELENA transfer line. Potential problems with the fringing field model in MAD were pointed out, when bending magnets with large bending angles and small bending radius are involved.

  1. Advanced 360o FOV, wide energy range, non-HV, gated time of flight mass spectrometers for Small Satellites and Cubesats

    Science.gov (United States)

    Paschalidis, N.; Jones, S.; Rodriguez, M.; Sittler, E. C., Jr.; Chornay, D. J.; Uribe, P.; Cameron, T.; Nanan, G.

    2015-12-01

    The time of flight technique is widely used for composition analysis of space plasma instruments. The foil - MCP/CEM combination is commonly used for E x TOF mass analysis at the cost of energy threshold, scattering, and direct particle interaction which ultimately affect performance. An alternative method especially effective at low energies is gated time of flight where the start foil is replaced with electric gating. There are several advantages of electric gating, including elimination of heavy HVPS required for pre-reacceleration to overcome foil thresholds, non- destructive interaction with atomic and molecular ions before analysis, and electronic controllability including geometric factor adjustment for flux dynamic range, FOV optimization, electronic filtering of most abundant elements in favor of minor species, and other properties affecting directly the scientific and engineering performance of the instruments. In addition special secondary emission surfaces can be used for triple coincidence when needed. The combination of electric gating and special surfaces works in an extensive energy range from 0 to tens of KeV without the need of start foil/HVPS making thus the use attractive to small satellites and cubesats. Those characteristics will be elaborated in the context of a gated time of flight wide field of view and energy range ion spectrometer combined with a neutral mass spectrometer (WINMS) developed at GSFC. The instrument prototypes have mass resolution adequate to separate N, O, OH, OH2; also static from ram moving H allowing thus separation of outgassing from ambient gases. A first implementation INMS with a mass <600 grams and size <1.5U is the main payload of the EXOCUBE Cubesat mission launched in January 2015 and already produced flight data; a second upgraded implementation is on onboard the GSFC Dellingr 6U CubeSat scheduled for launch in late 2015; and ongoing developments are baselined for other satellite missions.

  2. CFD Simulations of Vibration Induced Droplet Ejection.

    Science.gov (United States)

    James, Ashley; Smith, Marc K.; Glezer, Ari

    1998-11-01

    Vibration-induced droplet ejection is a process that occurs when a liquid droplet is placed on a vibrating membrane. Above a critical value of the excitation amplitude, Faraday waves form on the surface of the drop. As the amplitude is increased secondary drops are ejected from the wave crests. A Navier-Stokes solver designed to simulate the transient fluid mechanics of the process is presented. The solver is based on a MAC method on a staggered grid. A volume of fluid method is implemented to track the free surface. The volume fraction is advected via a second-order, unsplit method that minimizes numerical diffusion of the interface. Surface tension is incorporated as a continuum surface force. This work is intended to provide a comprehensive description of the fluid dynamics involved in vibration-induced droplet ejection, with the aim of understanding the mechanism behind the ejection process. The evolution of the interface through droplet ejection will be simulated. The dependence of the ejection process on the driving parameters will be evaluated and the resonance characteristics of the drop will be determined. The results of the computations will be compared with experimental results.

  3. Mergers and ejections of black holes in globular clusters

    CERN Document Server

    Aarseth, Sverre

    2012-01-01

    We report on results of fully consistent N-body simulations of globular cluster models with N = 100 000 members containing neutron stars and black holes. Using the improved `algorithmic regularization' method of Hellstrom and Mikkola for compact subsystems, the new code NBODY7 enables for the first time general relativistic coalescence to be achieved for post-Newtonian terms and realistic parameters. Following an early stage of mass segregation, a few black holes form a small dense core which usually leads to the formation of one dominant binary. The subsequent evolution by dynamical shrinkage involves the competing processes of ejection and mergers by radiation energy loss. Unless the binary is ejected, long-lived triple systems often exhibit Kozai cycles with extremely high inner eccentricity (e > 0.999) which may terminate in coalescence at a few Schwarzschild radii. A characteristic feature is that ordinary stars as well as black holes and even BH binaries are ejected with high velocities. On the basis of...

  4. Recent studies in satellite observations of three-dimensional magnetic reconnection

    Institute of Scientific and Technical Information of China (English)

    XIAO ChiJie; WANG XiaoGang; PU ZuYin; MA ZhiWei; ZHAO Hui; ZHOU GuiPing; WANG JingXiu; LIU ZhenXing

    2007-01-01

    Magnetic reconnection is a main process converting the magnetic energy into thermal and kinetic energy in plasmas. It is one of the fundamental problems of crucial importance not only to space plasmas physics and space weather studies,such as the solar flare, coronal mass ejections and magnetospheric substorms, but also to the stability analysis in magnetically confined fusion. In general, except for cases with periodical boundary conditions, three-dimensional (3D) magnetic reconnection occurs on magnetic separatrices generated by magnetic nulls. Here we briefly introduce/review the theories and some recent satellite observations of 3D magnetic reconnection. Topics to be further studied are also discussed.

  5. Remote Sensing of the EnviSat and Cbers-2B satellites rotation around the centre of mass by photometry

    Science.gov (United States)

    Koshkin, N.; Korobeynikova, E.; Shakun, L.; Strakhova, S.; Tang, Z. H.

    2016-08-01

    During 2013-2015 the photometric observations of the EnviSat satellite, which became space debris after the failure in April 2012 in low Earth orbit, were performed. The rotation pole position and slow change in sidereal rotation period were updated on the basis of analysis of specular glints observed in 222 light curves using reduction of synodic periods. Apparently, there are minor oscillations of the rotation pole near the normal to the orbital plane. The sense of the EnviSat's spinning is opposite to the sense of its orbital rotation. The sidereal period is best approximated by the second-order polynomial: Psid (sec) = 0.000021534 ·T2 + 0.04936003 · T + 121.18195 where T is measured in days from the beginning of 2013. This method being applied to another representative of space debris, namely the Cbers-2B satellite, has shown a similar result: there is not precise solution for the rotation pole either as it undergoes oscillations with various time scale from several hours to several months. In 2014, the spin axis made the 10 ° angle with the normal to the orbital plane while the sense of spinning is direct in this case, i.e. coincides with the sense of orbital rotation. The sidereal period is best approximated by the following expression: Psid (sec) = 0.000029543 ·T2 + 0.08094931 · T + 81.31775 where T is measured in days starting from March 10, 2014. This method allows of controlling slow changes in the spatial orientation of the rotation axis of the satellites in which specular reflection of light from flat faces of the surface is inherent.

  6. Advancements of In-Flight Mass Moment of Inertia and Structural Deflection Algorithms for Satellite Attitude Simulators

    Science.gov (United States)

    2015-03-26

    on the air-bearing satellite attitude simulator at Shenyang University of Technology. Additionally, Chesi et al., [3] advanced the EKF developed by Kim...in a disturbance torque. The data for hrw about the test axis is then used to calculate the coefficients Arw and Brw that best fit the equation hrw...oscillation; and m, b, D, and E are coefficients that best fit the 51 0 10 20 30 40 50 −0.4 −0.3 −0.2 −0.1 0 0.1 0.2 0.3 0.4 time (s) A ng ul ar M om en

  7. Measurement of Surface Displacement and Deformation of Mass Movements Using Least Squares Matching of Repeat High Resolution Satellite and Aerial Images

    Directory of Open Access Journals (Sweden)

    Misganu Debella-Gilo

    2012-01-01

    Full Text Available Displacement and deformation are fundamental measures of Earth surface mass movements such as glacier flow, rockglacier creep and rockslides. Ground-based methods of monitoring such mass movements can be costly, time consuming and limited in spatial and temporal coverage. Remote sensing techniques, here matching of repeat optical images, are increasingly used to obtain displacement and deformation fields. Strain rates are usually computed in a post-processing step based on the gradients of the measured velocity field. This study explores the potential of automatically and directly computing velocity, rotation and strain rates on Earth surface mass movements simultaneously from the matching positions and the parameters of the geometric transformation models using the least squares matching (LSM approach. The procedures are exemplified using bi-temporal high resolution satellite and aerial images of glacier flow, rockglacier creep and land sliding. The results show that LSM matches the images and computes longitudinal strain rates, transverse strain rates and shear strain rates reliably with mean absolute deviations in the order of 10−4 (one level of significance below the measured values as evaluated on stable grounds. The LSM also improves the accuracy of displacement estimation of the pixel-precision normalized cross-correlation by over 90% under ideal (simulated circumstances and by about 25% for real multi-temporal images of mass movements.

  8. Overconsumption, outflows and the quenching of satellite galaxies

    Science.gov (United States)

    McGee, Sean L.; Bower, Richard G.; Balogh, Michael L.

    2014-07-01

    The baryon cycle of galaxies is a dynamic process involving the intake, consumption and ejection of vast quantities of gas. In contrast, the conventional picture of satellite galaxies has them methodically turning a large gas reservoir into stars until this reservoir is forcibly removed due to external ram pressure. This picture needs revision. Our modern understanding of the baryon cycle suggests that in some regimes the simple interruption of the fresh gas supply may quench satellite galaxies long before stripping events occur, a process we call overconsumption. We compile measurements from the literature of observed satellite quenching times at a range of redshifts to determine if satellites are principally quenched through orbit-based gas stripping events - either direct stripping of the disc (ram pressure stripping) or the extended gas halo (strangulation) - or from internally driven star formation outflows via overconsumption. These time-scales show significant deviations from the evolution expected for gas stripping mechanisms and suggest that either ram pressure stripping is much more efficient at high redshift, or that secular outflows quench satellites before orbit-based stripping occurs. Given the strong redshift evolution of star formation rates, at high redshift even moderate outflow rates will lead to extremely short delay times with the expectation that high-redshift (z > 1.5) satellites will be quenched almost immediately following the cessation of cosmological inflow. Observations of high-redshift satellites give an indirect but sensitive measure of the outflow rate, with current measurements suggesting that outflows are no larger than 2.5 times the star formation rate for galaxies with a stellar mass of 1010.5 M⊙.

  9. THE EATING HABITS OF MILKY WAY-MASS HALOS: DESTROYED DWARF SATELLITES AND THE METALLICITY DISTRIBUTION OF ACCRETED STARS

    Energy Technology Data Exchange (ETDEWEB)

    Deason, Alis J.; Mao, Yao-Yuan; Wechsler, Risa H., E-mail: adeason@stanford.edu [Kavli Institute for Particle Astrophysics and Cosmology and Physics Department, Stanford University, Stanford, CA 94305 (United States)

    2016-04-10

    We study the mass spectrum of destroyed dwarfs that contribute to the accreted stellar mass of Milky Way (MW)-mass (M{sub vir} ∼ 10{sup 12.1} M{sub ⊙}) halos using a suite of 45 zoom-in dissipationless simulations. Empirical models are employed to relate (peak) subhalo mass to dwarf stellar mass, and we use constraints from z = 0 observations and hydrodynamical simulations to estimate the metallicity distribution of the accreted stellar material. The dominant contributors to the accreted stellar mass are relatively massive dwarfs with M{sub star} ∼ 10{sup 8}–10{sup 10}M{sub ⊙}. Halos with more quiescent accretion histories tend to have lower mass progenitors (10{sup 8}–10{sup 9} M{sub ⊙}), and lower overall accreted stellar masses. Ultra-faint mass (M{sub star} < 10{sup 5} M{sub ⊙}) dwarfs contribute a negligible amount (≪1%) to the accreted stellar mass and, despite having low average metallicities, supply a small fraction (∼2%–5%) of the very metal-poor stars with [Fe/H] < −2. Dwarfs with masses 10{sup 5} < M{sub star}/M{sub ⊙} < 10{sup 8} provide a substantial amount of the very metal-poor stellar material (∼40%–80%), and even relatively metal-rich dwarfs with M{sub star} > 10{sup 8} M{sub ⊙} can contribute a considerable fraction (∼20%–60%) of metal-poor stars if their metallicity distributions have significant metal-poor tails. Finally, we find that the generic assumption of a quiescent assembly history for the MW halo seems to be in tension with the mass spectrum of its surviving dwarfs. We suggest that the MW could be a “transient fossil”; a quiescent halo with a recent accretion event(s) that disguises the preceding formation history of the halo.

  10. Proton ejection project for Saturne; Projet d'ejection des protons de saturne

    Energy Technology Data Exchange (ETDEWEB)

    Bronca, G.; Gendreau, G

    1959-07-01

    The reasons for choosing the ejection system are given. The characteristics required for the ejected beam are followed by a description of the ejection process, in chronological order from the viewpoint of the protons: movement of the particles, taking into account the various elements which make up the system (internal magnet, external magnet, quadrupoles, ejection correction coils, thin and thick cables,...) and specification of these elements. Then follows an estimation of the delay in manufacture and the cost of the project. Finally, the characteristics of the magnets and quadrupoles are listed in an appendix. (author) [French] On donne d'abord les raisons du choix du systeme d'ejection, puis le principe. Apres les caracteristiques requises pour le faisceau ejecte, on decrit le processus d'ejection selon l'ordre chronologique vu par les protons: mouvement des particules compte tenu des divers elements composant le systeme (aimant interne, aimant externe, quadrupoles, enroulements correcteurs ejection, cibles mince et epaisse,. ..) et cahier de charge de ces elements. On estime, ensuite les delais de realisation et le cout du projet. Enfin, un resume des caracteristiques des aimants et quadrupoles est donne en appendice. (auteur)

  11. TUBSAT-1, satellite technology for educational purposes

    Science.gov (United States)

    Ginati, A.

    1988-01-01

    TUBSAT-1 (Technical University of Berlin Satellite) is an experimental low-cost satellite within the NASA Get Away Special (GAS) program. This project is being financed by the German BMFT (Federal Ministry for Research and Technology), mainly for student education. The dimensions and weight are determined by GAS requirements and the satellite will be ejected from the space shuttle into an approximately 300-km circular orbit. It is a sun/star oriented satellite with an additional spin stabilization mode. The first planned payload is to be used for observing flight paths of migratory birds from northern Europe to southern Africa and back.

  12. A satellite-borne ion mass spectrometer for the energy range 0 to 16 keV

    Science.gov (United States)

    Balsiger, H.; Eberhardt, P.; Geiss, J.; Ghielmetti, A.; Walker, H. P.; Young, D. T.; Loidl, H.; Rosenbauer, H.

    1976-01-01

    The Ion Composition Experiment (ICE) on GEOS represents the first comprehensive attempt to measure the positive ion composition at high altitudes in the magnetosphere. Due to the heterogeneous nature of the magnetospheric plasma a novel mass spectrometer has been developed to cover the mass per charge range from H-1(+) to beyond Ba-138(+) and the energy per charge range from 0 to 16 keV/e. The ICE consists primarily of a cylindrical electrostatic analyzer followed by a curved analyzer incorporating crossed magnetic and electric fields. This combination has limited angular and energy focusing properties, but it maintains a mass resolution of about 4 over a wide range in energy and mass, sufficient for the objectives of measuring plasmas of both solar and terrestrial origin. High sensitivity and low background should allow measurements of rarer ion constituents down to flux levels of 0.01 ions/sq cm sec ster eV. A sophisticated electronics combined with powerful ground computer and telecommand systems allow for very efficient scanning of the mass-energy space.

  13. Pyroclast Tracking Velocimetry illuminates bomb ejection and explosion dynamics at Stromboli (Italy) and Yasur (Vanuatu) volcanoes

    Science.gov (United States)

    Gaudin, Damien; Taddeucci, Jacopo; Scarlato, Piergiorgio; Moroni, Monica; Freda, Carmela; Gaeta, Mario; Palladino, Danilo Mauro

    2014-07-01

    A new image processing technique—Pyroclast Tracking Velocimetry—was used to analyze a set of 30 high-speed videos of Strombolian explosions from different vents at Stromboli (Italy) and Yasur (Vanuatu) volcanoes. The studied explosions invariably appear to result from the concatenation of up to a hundred individual pyroclast ejection pulses. All these pulses share a common evolution over time, including (1) a non-linear decrease of the pyroclast ejection velocity, (2) an increasing spread of ejection angle, and (3) an increasing size of the ejected pyroclasts. These features reflect the dynamic burst of short-lived gas pockets, in which the rupture area enlarges while pressure differential decreases. We estimated depth of pyroclast release to be approximately 1 and 8 m below the surface at Stromboli and Yasur, respectively. In addition, explosions featuring more frequent pulses also have higher average ejection velocities and larger total masses of pyroclasts. These explosions release a larger overall amount of energy stored in the pressurized gas by a combination of more frequent and stronger ejection pulses. In this context, the associated kinetic energy per explosion, ranging 103-109 J appears to be a good proxy for the explosion magnitude. Differences in the pulse-defining parameters among the different vents suggest that this general process is modulated by geometrical factors in the shallow conduit, as well as magma-specific rheology. Indeed, the more viscous melt of Yasur, compared to Stromboli, is associated with larger vents producing fewer pulses but larger pyroclasts.

  14. Linear theory on temporal instability of megahertz faraday waves for monodisperse microdroplet ejection.

    Science.gov (United States)

    Tsai, Shirley C; Tsai, Chen S

    2013-08-01

    A linear theory on temporal instability of megahertz Faraday waves for monodisperse microdroplet ejection based on mass conservation and linearized Navier-Stokes equations is presented using the most recently observed micrometer- sized droplet ejection from a millimeter-sized spherical water ball as a specific example. The theory is verified in the