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Sample records for comet encke meteor

  1. Meteor Streams of Comet Encke Taurid Meteor Complex

    CERN Document Server

    Klacka, J

    1999-01-01

    Application of the theoretical results of the author are presented for the case of meteor streams of comet Encke. Theoretical determination of meteor orbit for comet Encke, as a parent body, is presented. Four significant theoretical meteor streams, corresponding to Tauds N, Tauds S, $\\beta$ Tauds and $\\xi$ Perds are found. The meteor stream membership criterion is applied to the photographic orbits of The IAU Meteor Data Center in Lund: Taurid meteor stream is found for several possible areas in phase-space of orbital elements.

  2. Use of long-term nongravitational force models for fitting astrometric observations of comet Encke

    Science.gov (United States)

    Usanin, V.; Nefedyev, Y.; Andreev, A.

    2017-09-01

    Based on the equations derived in (Usanin et al., 2016) a new solution combining the observations of 30 apparitions of the comet Encke from 1911 to 2010 is obtained. For the first time in the worldwide practice the solution is obtained by using converging differential correction of all 60 observed returns of the comet, however, the deviations are still unsatisfactory. The single solution has allowed to draw some preliminary conclusions. The contributions of planetary and nongravitational perturbations to the change of the elements of the orbit during the entire period of observation are determined. The extrapolation of the solution shows that for the past two thousand years the elements of the orbit orientation could change for a half of turnover, which should be taken into account when identifying the comet and associated meteor showers in ancient records. The predictions made by Z. Sekanina and I. Ferrín about oncoming termination of the comet activity are confirmed.

  3. Aging comets and their meteor showers

    Science.gov (United States)

    Ye, Quan-Zhi

    2016-10-01

    Comets are thought to be responsible for the terrestrial accretion of water and organic materials. The aging of comets is one of the most critical yet poorly understood problems in planetary astronomy. Here we attack this problem by examining different parts of the cometary aging spectrum of Jupiter-family comets (JFCs), a group of comets that dominates the cometary influx in the near-Earth space, using both telescopic and meteor observations.We examine two representative JFCs and the population of dormant comets. At the younger end of the aging spectrum, we examine a moderately active JFC, 15P/Finlay, and review the puzzle of the non-detection of the associated Finlayid meteor shower. We find that, although having been behaved like a dying comet in the past several 102 years, 15P/Finlay does possess ability for energetic outbursts without a clear reason. Towards the more aged end of the spectrum, we examine a weakly active JFC, 209P/LINEAR. By bridging telescopic observations at visible and infrared wavelength, meteor observations and dynamical investigations, we find that 209P/LINEAR is indeed likely an aged yet long-lived comet. At the other end of the spectrum, we examine the population of dormant near-Earth comets, by conducting a comprehensive meteor-based survey looking for dormant comets that have recently been active. We find the lower limit of the dormant comet fraction in the near-Earth object (NEO) population to be 2.0 ± 1.7%. This number is at the lower end of the numbers found using dynamical and telescopic techniques, which may imply that a significant fraction of comets in the true JFC population are weakly active and are not yet detected.These results have revealed interesting diversities in dying or dead comets, both in their behaviors as well as their natures. An immediate quest in the understanding of cometary aging would be to examine a large number of dying or dead comets and understand their general characteristics.

  4. Chandra observations of comet 2P/Encke 2003 : First detection of a collisionally thin, fast solar wind charge exchange system

    NARCIS (Netherlands)

    Lisse, CM; Christian, DJ; Dennerl, K; Wolk, SJ; Bodewits, D; Hoekstra, R; Combi, MR; Makinen, T; Dryer, M; Fry, CD; Weaver, H

    2005-01-01

    We report the results of 15 hr of Chandra observations of comet 2P/Encke 2003 on November 24. X-ray emission from comet Encke was resolved on scales of 500-40,000 km, with unusual morphology due to the presence of a low-density, collisionally thin (to charge exchange) coma. A light curve with peak-t

  5. Comets and meteors in the beliefs of ancient mayas

    Science.gov (United States)

    Yershova, G. G.

    2001-12-01

    Data concerning the Mayan approach to comets and meteors have till now been available mostly from ethnographical and folklore sources which dealt, as a rule, with various beliefs and tokens. The studies of hieroglyphic texts of the Classic Period (AD 600-900) have proved that comets and meteors were undoubtedly known in this culture through astronomical observations and their periodicity.

  6. Use of long-term models for analysis of comet Encke's motion

    Science.gov (United States)

    Usanin, V.; Nefedyev, Y.; Andreev, A.

    2016-12-01

    This paper is focused on the problem of the reactive non-gravitational effects change in the cometary motion caused by the comet's activity fading. The modern researches have been reviewed. The necessity of a new model compatible with Marsden's model of non-gravitational forces is shown. Modifications of Marsden's model for the cases in which the main factors of the parameters change are the deposition of the significant non-volatile mass and the growth of the superficial crust are developed. They contain besides the usual Marsden's parameters two and three additional values correspondingly. The developed equations have been used to explain the known change of Marsden's non-gravitational parameters for the comet Encke during 225 years of its observational interval. Although the model with significant non-volatile mass contains less free values, it explains the characteristic features of the comet's non-gravitational parameters behavior better. The model can be further applied for the comet's observed astrometric positions fitting.

  7. Photometry and polarimetry of the nucleus of comet 2P/Encke

    CERN Document Server

    Boehnhardt, H; Bagnulo, S; Muinonen, K; Nathues, A; Kolokolova, L

    2008-01-01

    Broadband imaging photometry, and broadband and narrowband linear polarimetry was measured for the nucleus of 2P/Encke over the phase-angle range 4 - 28 deg. An analysis of the point spread function of the comet reveals only weak coma activity, corresponding to a dust production of the order of 0.05 kg/s. The nucleus displays a color independent photometric phase function of almost linear slope. The absolute R filter magnitude at zero phase angle is 15.05 +/- 0.05, and corresponds to an equivalent radius for the nucleus of 2.43 +/- 0.06 km (for an adopted albedo of 0.047). The nucleus color V - R is 0.47 +/- 0.07, suggesting a spectral slope of 11 +/- 8 %/100nm. The phase function of linear polarimetry in the V and R filters shows a widely color independent linear increase with phase angle (0.12 +/- 0.02%/deg). We find discrepancies in the photometric and polarimetric parameters between 2P/Encke and other minor bodies in the solar system, which may indicate significant differences in the surface material prop...

  8. The Asymmetric Coma of Comets. I. Asymmetric Outgassing from the Nucleus of Comet 2P/Encke

    Science.gov (United States)

    Festou, M. C.; Barale, O.

    2000-06-01

    Very little is known about how outgassing regions are distributed over the nucleus of comets. In periodic comets, active regions are believed to be few and of small extent. Since periodic comets are notorious for their lack of (small) solid particles that efficiently scatter sunlight, we try to find traces of the existence of production sites by examining the morphology of the gas coma. We use a new coma model in which results from hydrodynamics calculations describing the inner coma are used as limit conditions for a collisionless description of the outer coma. The production pattern of the parent species mainly depends on the extent and location of the production region(s) and on the rotational state of the nucleus. Analyzing 1980 observations of comet 2P/Encke, we find that free emission from a single, small, active region located near the subsolar point of a nonrotating nucleus is excluded. But such an active region on a rotating nucleus produces well the observed coma morphology. Our data then allow us to determine the orientation of the comet spin axis and the cometocentric latitude of the source. Emission from a few small production regions spread over the sunward part of a nonrotating nucleus or emission at a very low rate from a larger subsolar area could also fit the data. Although we do not find a unique solution to our problem, the excellent quality of our fits indicates that our approach, if used with enough care, can provide a new tool to investigate the properties of comet nuclei when the coma is far from spherically symmetric and, ultimately, to study the effects of the nongravitational force that is acting on comet nuclei.

  9. MESSENGER's special delivery: Comets 2P/Encke and C/2012 S1 (ISON) at small heliocentric distances

    Science.gov (United States)

    Fernandez, Yanga R.; Vervack, Ronald J., Jr.; Knight, Matthew M.; McCandliss, Stephan R.; Dello Russo, Neil; Feldman, Paul D.; Lisse, Casey M.; Tamblyn, Peter

    2016-10-01

    Observations of comets when they are close to the Sun can potentially reveal interesting aspects of their behavior thanks to the rapid change of both seasons on the nucleus and the local insolation environment. However this is typically the most difficult time to make observations from Earth because the solar elongation is small, so studies of comets that are near the Sun generally require special facilities. In autumn 2013, the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft observed comets 2P/Encke and C/2012 S1 (ISON) from its orbital perch around Mercury when both comets were poorly located for most Earth-based telescopes. The observations included visible-wavelength, multi-filter imaging as well as ultraviolet spectroscopy. Both comets were observed down to about 0.3 AU from the Sun; in Encke's case it was followed through perihelion, which has rarely been done before. The data provide us with a look at the behavior of the dust and gas (e.g., OH, CO, OI, CI, SI, HI) production rates over several weeks, and we can investigate how the rates change with time, rotational phase, and heliocentric distance. In this poster we will present preliminary analyses of the time-series photometry and spectroscopy of these MESSENGER-observed comets, and place their behaviors into context.

  10. Comet Encke - Precession of the spin axis, nongravitational motion, and sublimation

    Science.gov (United States)

    Whipple, F. L.; Sekanina, Z.

    1979-01-01

    From the observed light curve of P/Encke the jet force from sublimation is calculated both as a (precessing) torque and as a (perturbing) force transverse to the radius vector. An integral iteration is carried out over 59 perihelion passages, 1786-1977, to fit the previously determined nongravitational transverse force and to derive the precession of the spin axis. It is shown that the spin axis turned more than 100 degrees in longitude and almost 30 degrees in latitude from 1786 to 1977, but appears to have been almost fixed in direction for hundreds of revolutions before 1700. It is suggested that ejected meteoroidal debris accumulated on the currently less active hemisphere, insulating it to maintain a low activity level. A tentative rotation period of 6 h 33 min is derived, using Whipple's halo method. The suggested spinup rate is 21 min/century, while the current rate of relative mass loss by sublimation is 0.09% of the comet's mass per revolution. Moreover, the mass of the nucleus is estimated at less than 10 to the 16th grams, and its oblateness at less than 4%.

  11. Asteroids, comets, meteors, and their interrelations. Part II: Editorial review

    Science.gov (United States)

    Muinonen, Karri; Granvik, Mikael; Penttilä, Antti; Gritsevich, Maria

    2016-04-01

    The Asteroids, Comets, Meteors 2014 (ACM 2014) conference was organized in Helsinki in June 30-July 4, 2014, with the first collection of the peer-reviewed papers published in December 2015 in the Special Issue of Planetary and Space Science (Muinonen et al., 2015). The present issue contains the second collection of papers from ACM 2014.

  12. The prediction of meteor showers from all potential parent comets

    CERN Document Server

    Neslusan, Lubos; Tomko, Dusan; Kanuchova, Zuzana; Jakubik, Marian

    2014-01-01

    The objectives of this project are to predict new meteor showers associated with as many as possible known periodic comets and to find a generic relationship of some already known showers with these comets. For a potential parent comet, we model a theoretical stream at the moment of its perihelion passage in a far past, and follow its dynamical evolution until the present. Subsequently, we analyze the orbital characteristics of the parts of the stream that approach the Earth's orbit. Modelled orbits of the stream particles are compared with the orbits of actual photographic, video, and radar meteors from several catalogues. The whole procedure is repeated for several past perihelion passages of the parent comet. To keep our description compact but detailed, we usually present only either a single or a few parent comets with their associated showers in one paper. Here, an overview of the results from the modelling of the meteor-shower complexes of more than ten parent bodies will be presented. This enables the...

  13. Limited variance control in statistical low thrust guidance analysis. [stochastic algorithm for SEP comet Encke flyby mission

    Science.gov (United States)

    Jacobson, R. A.

    1975-01-01

    Difficulties arise in guiding a solar electric propulsion spacecraft due to nongravitational accelerations caused by random fluctuations in the magnitude and direction of the thrust vector. These difficulties may be handled by using a low thrust guidance law based on the linear-quadratic-Gaussian problem of stochastic control theory with a minimum terminal miss performance criterion. Explicit constraints are imposed on the variances of the control parameters, and an algorithm based on the Hilbert space extension of a parameter optimization method is presented for calculation of gains in the guidance law. The terminal navigation of a 1980 flyby mission to the comet Encke is used as an example.

  14. A Short Cultural-Astronomical History on Asteroids, Comets and Meteors in Romania

    Science.gov (United States)

    Grigore, V.; Gheorghe, A. D.

    2012-05-01

    The poster presents significant moments in astronomy history and culture of meteors, comets and asteroids in Romania and the modern role of the Romanian Society for Meteors and Astronomy (SARM) in research, education, and culture in these fields.

  15. When Comets Get Old: A Synthesis of Comet and Meteor Observations of the Low Activity Comet 209P/LINEAR

    CERN Document Server

    Ye, Quan-Zhi; Brown, Peter G; Campbell-Brown, Margaret D; Pokorný, Petr; Wiegert, Paul A; Gao, Xing

    2015-01-01

    It is speculated that some weakly active comets may be transitional objects between active and dormant comets. These objects are at a unique stage of the evolution of cometary nuclei, as they are still identifiable as active comets, in contrast to inactive comets that are observationally indistinguishable from low albedo asteroids. In this paper, we present a synthesis of comet and meteor observations of Jupiter-family comet 209P/LINEAR, one of the most weakly active comets recorded to-date. Images taken by the Xingming 0.35-m telescope and the Gemini Flamingo-2 camera are modeled by a Monte Carlo dust model, which yields a low dust ejection speed ($1/10$ of that of moderately active comets), dominance of large dust grains, and a low dust production of $0.4~\\mathrm{kg \\cdot s^{-1}}$ at 19~d after the 2014 perihelion passage. We also find a reddish nucleus of 209P/LINEAR that is similar to D-type asteroids and most Trojan asteroids. Meteor observations with the Canadian Meteor Orbit Radar (CMOR), coupled with ...

  16. INFRARED AND OPTICAL IMAGINGS OF THE COMET 2P/ENCKE DUST CLOUD IN THE 2003 RETURN

    Energy Technology Data Exchange (ETDEWEB)

    Sarugaku, Yuki; Ueno, Munetaka [Kiso Observatory, Institute of Astronomy, School of Science, The University of Tokyo, 10762-30 Mitake, Kiso-machi, Kiso-gun, Nagano 397-0101 (Japan); Ishiguro, Masateru [Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Usui, Fumihiko [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210 (Japan); Reach, William T., E-mail: sarugaku@kiso.ioa.s.u-tokyo.ac.jp [Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2015-05-10

    We report contemporaneous imaging observations of the short-period comet 2P/Encke in infrared and optical wavelengths during the 2003 return. Both images show the same unique morphology consisting of a spiky dust cloud near the nucleus and a dust trail extending along the orbit. We conducted a dynamical simulation of dust particles to characterize the morphology and found that dust particles were ejected intensively for a short duration (≲10 days) a few days after perihelion passage. The maximum particle size is at least on the order of 1 cm in radius following a differential power-law size distribution with an index of −3.2 to −3.6. The total mass ejected in the 2003 return is at least 1.5 × 10{sup 9}–1.2 × 10{sup 10} kg, which corresponds to 0.003%–0.03% of the nucleus mass. We derived the albedo of the dust cloud as 0.01–0.04 at a solar phase angle of 26.°2, which is consistent with or possibly greater than that of the nucleus. We suppose that impulsive activity such as an outburst is a key to understanding the peculiar appearance of 2P/Encke.

  17. Political astronomy: Comet and meteor observations by Muslim historians

    Science.gov (United States)

    Chander Kapoor, Ramesh

    2015-08-01

    Eclipses and unexpected phenomena like comets, meteors, novae and earthquakes were viewed among various cultures as violating the established order of the heavens. They were considered to be ill omens for kings and emperors and were routinely monitored. The present work looks into the texts of history and literature by Muslim historians and chroniclers in West Asia and India that carry stray references to such phenomena. The accounts often relate the apparitions to specific disastrous events or prognosticate revolts, deaths, epidemics, earthquakes all that that took place in later times. Obviously, the occurrences interested the astrologers more. Comet appearances would last for days and weeks but nearly all the writings lack sequential observations. Meteor showers are annual features but the Islamic calendar being lunar would not easily lead one to notice periodic nature of the incidents, let alone sensing a periodicity in comet appearances. These are non-astronomy texts with little scientific content but being from different ages permit us to see how the astronomical perceptions changed over the times. The recorded details and firm chronology, tested against modern back calculations, can provide valuable information on them, keeping in mind the text and the context in which the original reference was made. We also notice a qualitative change in the Indian writings of the 18th century and later where the authors begin to show up with influence of exposure to the European scientific progress.

  18. Investigation of the possible effects of comet's encke metoeroid stream on the ca-exosphere of mercury

    Science.gov (United States)

    Plainaki, Christina; Mura, Alessandro; Milillo, Anna; Orsini, Stefano; Livi, Stefano; Mangano, Valeria; Massetti, Stefano; Rispoli, Rosanna; De Angelis, Elisabetta

    2017-04-01

    The MESSENGER observations of the Ca-exosphere seasonal variability were consistent with the general idea that the Ca-atoms originate from the bombardment of the surface by particles from comet 2P/Encke. The generating process is a chain and combination of different processes including atomic and molecular release of surface particles and photo-dissociation. Including generation and loss mechanisms due to different planet-environment interactions, we perform simulations using a 3D Monte Carlo model based on the exosphere generation model by Mura et al. (2009). We present for the first time the 3D spatial distribution of the CaO and Ca exospheres generated through Micrometeoroid Impact Vaporization (MIV) and we show that the morphology of the latter is consistent with the available MESSENGER/MASCS observations. The results presented in this paper can be of help during the preparation phase of the exosphere observations to be performed with Bepi Colombo in the next years

  19. A tale of two very different comets: ISO and MSX measurements of dust emission from 126P/IRAS (1996) and 2P/Encke (1997)

    Science.gov (United States)

    Lisse, C. M.; Fernández, Y. R.; A'Hearn, M. F.; Grün, E.; Käufl, H. U.; Osip, D. J.; Lien, D. J.; Kostiuk, T.; Peschke, S. B.; Walker, R. G.

    2004-10-01

    We present the characteristics of the dust comae of two comets, 126P/IRAS, a member of the Halley family (a near-isotropic comet), and 2P/Encke, an ecliptic comet. We have primarily used mid- and far-infrared data obtained by the ISOPHOT instrument aboard the Infrared Space Observatory (ISO) in 1996 and 1997, and mid-infrared data obtained by the SPIRIT III instrument aboard the Midcourse Space Experiment (MSX) in 1996. We find that the dust grains emitted by the two comets have markedly different thermal and physical properties. P/IRAS's dust grain size distribution appears to be similar to that of fellow family member 1P/Halley, with grains smaller than 5 microns dominating by surface area, whereas P/Encke emits a much higher fraction of big (20 μm and higher) grains, with the grain mass distribution being similar to that which is inferred for the interplanetary dust population. P/Encke's dearth of micron-scale grains accounts for its visible-wavelength classification as a "gassy" comet. These conclusions are based on analyses of both imaging and spectrophotometry of the two comets; this combination provides a powerful way to constrain cometary dust properties. Specifically, P/IRAS was observed preperihelion while 1.71 AU from the Sun, and seen to have a 15-arcmin long mid-infrared dust tail pointing in the antisolar direction. No sunward spike was seen despite the vantage point being nearly in the comet's orbital plane. The tail's total mass at the time was about 8×10 9 kg. The spectral energy distribution (SED) is best fit by a modified greybody with temperature T=265±15 K and emissivity ɛ proportional to a steep power law in wavelength λ: ɛ∝ λ- α, where α=0.50±0.20 (2σ) . This temperature is elevated with respect to the expected equilibrium temperature for this heliocentric distance. The dust mass loss rate was between 150-600 kg/s (95% confidence), the dust-to-gas mass loss ratio was about 3.3, and the albedo of the dust was 0.15±0

  20. Dormant Comets Among the Near-Earth Object Population: A Meteor-Based Survey

    CERN Document Server

    Ye, Quan-Zhi; Pokorný, Petr

    2016-01-01

    Dormant comets in the near-Earth object (NEO) population are thought to be involved in the terrestrial accretion of water and organic materials. Identification of dormant comets is difficult as they are observationally indistinguishable from their asteroidal counterparts, however they may have produced dust during their final active stages which potentially are detectable today as weak meteor showers at the Earth. Here we present the result of a reconnaissance survey looking for dormant comets using 13~567~542 meteor orbits measured by the Canadian Meteor Orbit Radar (CMOR). We simulate the dynamical evolution of the hypothetical meteoroid streams originated from 407 near-Earth asteroids in cometary orbits (NEACOs) that resemble orbital characteristics of Jupiter-family comets (JFCs). Out of the 44 hypothetical showers that are predicted to be detectable by CMOR, we identify 5 positive detections that are statistically unlikely to be chance associations, including 3 previously known associations. This transla...

  1. Fire in the Sky: Comets and Meteors, the Decisive Centuries, in British Art and Science

    Science.gov (United States)

    Olson, R. J. M.; Pasachoff, J. M.

    Comets and meteors are spectacular and awe-inspiring natural phenomena, which are among nature's most compelling icons. Since the beginning of recorded time, they have mesmerized people, not least among them artists and astronomers. Britain during the eighteenth and nineteenth centuries produced a larger number and greater variety of representations of comets and meteors than any other country. The development of new technologies, and the burgeoning interest of the general public in science and art, dovetailed with the inherent British interest in nature and a strong literary tradition of comet and meteor symbolism. This beautifully illustrated book examines the link between these works and the achievements of British science in the wake of Newton and Halley. This book will be stimulating to anyone interested in the art or astronomy of comets.

  2. Prebiotic Processing induced by Comet and Meteor Impact

    Science.gov (United States)

    Dateo, Christopher E.; Kwak, Dochan (Technical Monitor)

    2002-01-01

    In their study of organic synthesis from impact shocks using the laser-induced-plasma (LIP) technique, McKay and Borucki(l) found that organic synthesis preferentially occurred in a reducing gas mixture rich in methane, and not in a mixture rich in carbon dioxide. This result means chemical models based on the thermodynamical equilibrium approach do not apply to shock chemistry. In this study, we employ the technique of reacting flow, i.e., chemical kinetics in a fluid flow, to simulate the chemistry occurring in LIP and in the wake region from comet or meteor impact. Three different air compositions have been used: (1) 1/3 CO2 and 2/3 H2, (2) pure CH4, and (3) 1/4 CH4, 1/4 CO2, and 1/2 H2O. The stoichiometric ratio of gas mixtures (1) and (3) are kept the same. For (1) we obtain equal mole fractions of CO and H2O as the major products and for (2) C2H2 is the major product. In both cases our results are in agreement with Ref. (1). For (3) we find an interesting case where the nature of chemicals produced to be critically dependent on the flowfield temperature. At the higher temperature part of the wake region, CO and H2O are the dominant products, whereas in the cooler region C2H2 is the dominant product. Further studies of these reactions, as well as for the gas mixture including N2, are being pursued.

  3. Are 2P/Encke, the Taurid complex NEOs and CM chondrites related?

    Science.gov (United States)

    Tubiana, C.; Snodgrass, C.; Michelsen, R.; Haack, H.; Fitzsimmons, A.; Williams, I.; Boehnhardt, H.

    2013-09-01

    Comet 2P/Encke is a short-period comet that was discovered in 1786 and has been extensively observed and studied for more than 200 years. It has an orbital period of 3.3 years and its orbit is dynamically decoupled from Jupiter's control due to gravitational interaction with terrestrial planets [6]. It is the only comet known on such an orbit, making it unique. Capture from the outer solar system onto its current orbit is very unlikely and even a continuous smooth dynamical evolution has a low probability as this requires a continuous period when it is dormant in order to avoid the volatiles from the nucleus becoming exhausted and making the current observed activity impossible. An origin in the asteroid belt is a possibility especially in view of the recently discovered main belt comets. The nucleus of 2P/Encke is dark (geometric albedo of 0.047 ± 0.023 [3]), has an effective radius of 2.4 ± 0.3 km [3] and it has polarimetric properties that are unique compared to other measured types of solar system objects, such as asteroids, TNOs, cometary dust, Centaurs [2]. The colors of 2P/Encke's nucleus are typical for comets, but no spectra of the nucleus in the visible wavelength range exist so far. The Taurid meteoroid stream has long been linked with 2P/Encke, but the activity of the comet is not strong enough to explain the number of observed meteors. It has been suggested that the meteoroid stream was caused by the break up of a larger parent body, which left comet 2P/Encke and other various small bodies along with a stream of dust. Various small near-Earth objects (NEOs) have been discovered with orbits that can be linked with 2P/Encke and the Taurid meteoroid stream [1]. Though many of the associations are spurious due to the low inclination of 2P/Encke's orbit, many NEO's have evolved in a similar way to 2P/Encke overa period of 5000 years [8] suggesting some relationship. In addition to dynamical properties, common taxonomic properties can also provide an

  4. Dormant comets among the near-Earth object population: a meteor-based survey

    Science.gov (United States)

    Ye, Quan-Zhi; Brown, Peter G.; Pokorný, Petr

    2016-11-01

    Dormant comets in the near-Earth object (NEO) population are thought to be involved in the terrestrial accretion of water and organic materials. Identification of dormant comets is difficult as they are observationally indistinguishable from their asteroidal counterparts, however, they may have produced dust during their final active stages which potentially are detectable today as weak meteor showers at the Earth. Here we present the result of a reconnaissance survey looking for dormant comets using 13 567 542 meteor orbits measured by the Canadian Meteor Orbit Radar (CMOR). We simulate the dynamical evolution of the hypothetical meteoroid streams originated from 407 near-Earth asteroids in cometary orbits that resemble orbital characteristics of Jupiter-family comets (JFCs). Out of the 44 hypothetical showers that are predicted to be detectable by CMOR, we identify five positive detections that are statistically unlikely to be chance associations, including three previously known associations. This translates to a lower limit to the dormant comet fraction of 2.0 ± 1.7 per cent in the NEO population and a dormancy rate of ˜10-5 yr-1 per comet. The low dormancy rate confirms disruption and dynamical removal as the dominant end state for near-Earth JFCs. We also predict the existence of a significant number of meteoroid streams whose parents have already been disrupted or dynamically removed.

  5. Comets, meteors, and eclipses: Art and science in early Renaissance Italy

    Science.gov (United States)

    Olson, R. J. M.; Pasachoff, J. M.

    2002-11-01

    We discuss eight trecento (fourteenth century) paintings containing depictions of astronomical events to reveal the revolutionary advances made in both astronomy and naturalistic painting in early Renaissance Italy, noting that an artistic interest in naturalism predisposed these pioneering painters to make their scientific observations. In turn, the convincing representations of their observations of astronomical phenomena in works of art rendered their paintings more believable, convincing. Padua was already a renowned center for mathematics and nascent astronomy (which was separating from astrology) when Enrico Scrovegni commissioned the famous Florentine artist Giotto di Bondone to decorate his lavish family chapel (circa 1301-1303). Giotto painted a flaming comet in lieu of the traditional Star of Bethlehem in the Adoration of the Magi scene. Moreover, he painted a historical apparition that he recently had observed with a great accuracy even by modern standards. Halley's Comet of 1301 (Olson, 1979). While we do not know the identity of the artist's theological advisor, we discuss the possibility that Pietro d'Abano, the Paduan medical doctor and "astronomer" who wrote on comets, might have been influential. We also compare Giotto's blazing comet with two others painted by the artist's shop in San Francesco at Assisi (before 1316) and account for the differences. In addition, we discuss Giotto's pupil, Taddeo Gaddi, reputed to have been partially blinded by a solar eclipse, whose calamity may find expression in his frescoes in Santa Croce, Florence (1328-30; 1338?). Giotto also influenced the Sienese painter Pietro Lorenzetti, two of whose Passion cycle frescoes at Assisi (1316-20) contain dazzling meteor showers that reveal the artist's observed astronomical phenomena, such as the "radiant" effect of meteor showers, first recorded by Alexander von Humboldt in 1799 and only accepted in the nineteenth century. Lorenzetti also painted sporadic, independent

  6. Comets, Meteors, and Eclipses: Art and Science in Early Renaissance Italy (Invited)

    Science.gov (United States)

    Olson, R. J. M.; Pasachoff, J. M.

    1999-09-01

    We discuss several topics relating artists and their works with actual astronomical events in early Renaissance Italy to reveal the revolutionary advances made in both astronomy and naturalistic painting. Padua, where Galileo would eventually hold a chair at the University, was already by the fourteenth century (trecento) a renowned center for mathematics and nascent astronomy (which was separating from astrology). It is no wonder that when Enrico Scrovegni commissioned the famous Florentine artist Giotto di Bondone to decorate his lavish family chapel (c. 1303) that in the scene of the Adoration of the Magi Giotto painted a flaming comet in lieu of the traditional Star of Bethlehem. Moreover, he painted an historical apparition he recently had observed with a great understanding of its scientific structure: Halley's Comet of 1301 (since Olson's first publication of this idea in Scientific American we have expanded the argument in several articles and talks). While we do not know the identity of the artist's theological advisor, we discuss the possibility that Pietro d'Abano, the Paduan medical doctor and ``astronomer" who wrote on comets, might have been influential. We also compare Giotto's blazing comet with two others painted by the artist's shop in San Francesco at Assisi (before 1316) and account for the differences. In addition, we tackle the question how Giotto's pupil, Taddeo Gaddi, who is documented as having been partially blinded by lengthy unprotected observation of the partial phase of an annular solar eclipse, reflects his observations in his frescoes in Santa Croce, Florence (1328-30). Giotto also influenced the Sienese painter Pietro Lorenzetti, two of whose Passion cycle frescoes at Assisi (1316-20), contain dazzling meteor showers that hold important symbolic meanings in the cyle's argument but more importantly reveal that the artist observed astronomical phenomena, such as the ``radiant" effect, which was first recorded by Alexander von Humboldt

  7. A study to improve the past orbit of comet C/1917 F1 (Mellish) on the basis of its observed meteor showers

    Science.gov (United States)

    Neslušan, L.; Vaubaillon, J.; Hajduková, M.

    2016-05-01

    Context. Periodic comets are known to be the parent bodies of meteoroid streams. The stream of a given comet can split into several filaments. These can be observed in the Earth's atmosphere as more than just a single meteor shower. One such comet is C/1917 F1 (Mellish), which associates at least two, possibly four, meteor showers that have been recorded in the meteor databases. In a recent study, the dynamical evolution of the C/1917 F1's theoretical stream was followed by only considering the gravitational perturbations. The properties of individual filaments of this stream, corresponding to the appropriate meteor showers, were not predicted perfectly. Aims: To reach better agreement between theory and observation, we repeatedly model the theoretical stream of C/1917 F1. In the modeling, we also include the Poynting-Robertson drag acting on meteoroids and assume an action of the non-gravitational effects on the parent comet dynamics. If success was achieved, the modeling could become a tool that would enable us to recover the past orbital history of the parent comet. Methods: Considering the nominal orbit, as well as several cloned orbits, of the comet C/1917 F1, we modeled its theoretical streams. The modeling was performed for several past perihelion passages. Each modeled stream consists of 10 000 test particles that are influenced by the Poynting-Robertson drag of various strengths. Results: We achieve a partial improvement in the prediction of the properties of all four meteor showers. The Poynting-Robertson drag helps to improve the match between the theory and observation of three of the four showers. However, when considering the nominal orbit of the parent comet, a perfect match seems to be impossible. A close match in the case of the most problematic shower is achieved using a cloned orbit, but this is not applicable to reality because the simultaneous predictions of the properties of the other three showers fail.

  8. DIRBE Comet Trails

    CERN Document Server

    Arendt, Richard G

    2014-01-01

    Re-examination of the COBE DIRBE data reveals the thermal emission of several comet dust trails. The dust trails of 1P/Halley, 169P/NEAT, and 3200 Phaethon have not been previously reported. The known trails of 2P/Encke, and 73P/Schwassmann-Wachmann 3 are also seen. The dust trails have 12 and 25 micron surface brightnesses of <0.1 and <0.15 MJy/sr, respectively, which is <1% of the zodiacal light intensity. The trails are very difficult to see in any single daily image of the sky, but are evident as rapidly moving linear features in movies of the DIRBE data. Some trails are clearest when crossing through the orbital plane of the parent comet, but others are best seen at high ecliptic latitudes as the Earth passes over or under the dust trail. All these comets have known associations with meteor showers. This re-examination also reveals one additional comet and 13 additional asteroids that had not previously been recognized in the DIRBE data.

  9. DRBE comet trails

    Energy Technology Data Exchange (ETDEWEB)

    Arendt, Richard G., E-mail: Richard.G.Arendt@nasa.gov [CREST/UMBC, Code 665, NASA/GSFC, Greenbelt, MD 20771 (United States)

    2014-12-01

    Re-examination of the Cosmic Background Explorer Diffuse Infrared Background Experiment (DIRBE) data reveals the thermal emission of several comet dust trails. The dust trails of 1P/Halley, 169P/NEAT, and 3200 Phaethon have not been previously reported. The known trails of 2P/Encke and 73P/Schwassmann–Wachmann 3 are also seen. The dust trails have 12 and 25 μm surface brightnesses of <0.1 and <0.15 MJy sr{sup −1}, respectively, which is <1% of the zodiacal light intensity. The trails are very difficult to see in any single daily image of the sky, but are evident as rapidly moving linear features in movies of the DIRBE data. Some trails are clearest when crossing through the orbital plane of the parent comet, but others are best seen at high ecliptic latitudes as the Earth passes over or under the dust trail. All these comets have known associations with meteor showers. This re-examination also reveals 1 additional comet and 13 additional asteroids that had not previously been recognized in the DIRBE data.

  10. 2P/Encke, the Taurid complex NEOs and the Maribo and Sutter's Mill meteorites

    CERN Document Server

    Tubiana, C; Michelsen, R; Haack, H; Boehnhardt, H; Fitzsimmons, A; Williams, I P

    2015-01-01

    The Taurid meteoroid stream has long been linked with 2P/Encke owing to a good match of their orbital elements, even though the comet's activity is not strong enough to explain the number of observed meteors. Various small NEOs have been discovered with orbits that can be linked to 2P and the Taurid meteoroid stream. Maribo and Sutter's Mill are CM type carbonaceous chondrites that fell in Denmark on Jan 17, 2009 and Apr 22, 2012, respectively. Their pre-atmospheric orbits place them in the middle of the Taurid meteoroid stream, which raises the intriguing possibility that comet 2P could be the parent body of CM chondrites. To investigate whether a relationship between comet 2P, the Taurid complex associated NEOs, and CM chondrites exists, we performed photometric and spectroscopic studies of these objects in the visible wavelength range. We observed 2P and 10 NEOs on Aug 2, 2011 with FORS at the VLT. Images in the R filter, used to investigate the possible presence of cometary activity around the nucleus of ...

  11. Camelopardalids in 2019 (meteor shower of the comet 209P/LINEAR)

    Science.gov (United States)

    Maslov, Mikhail

    2017-03-01

    After an outburst of Camelopardalids shower in 2014, the next interesting year is 2019, when two small outbursts are possible. The first one with ZHR up to 10 is expected from the 1939 trail of the comet 209P/LINEAR at 7h44m UT on 24 May, the second with ZHR up to 5 could be produced by the 1994-2009 trails around 11h UT on 24 May. Details are here: http://feraj.ru/Radiants/Predictions/209p-ids2019eng.html

  12. Search for the OH (X(2)Pi) Meinel band emission in meteors as a tracer of mineral water in comets: detection of N(2)(+) (A-X)

    Science.gov (United States)

    Jenniskens, Peter; Laux, Christophe O.

    2004-01-01

    We report the discovery of the N(2)(+) A-X Meinel band in the 780-840 nm meteor emission from two Leonid meteoroids that were ejected less than 1000 years ago by comet 55P/Tempel-Tuttle. Our analysis indicates that the N(2)(+) molecule is at least an order of magnitude less abundant than expected, possibly as a result of charge transfer reactions with meteoric metal atoms. This new band was found while searching for rovibrational transitions in the X(2)Pi electronic ground state of OH (the OH Meinel band), a potential tracer of water bound to minerals in cometary matter. The electronic A-X transition of OH has been identified in other Leonid meteors. We did not detect this OH Meinel band, which implies that the excited A state is not populated by thermal excitation but by a mechanism that directly produces OH in low vibrational levels of the excited A(2)Sigma state. Ultraviolet dissociation of atmospheric or meteoric water vapor is such a mechanism, as is the possible combustion of meteoric organics.

  13. Dust from Comet 209P/LINEAR during its 2014 Return: Parent Body of a New Meteor Shower, the May Camelopardalids

    CERN Document Server

    Ishiguro, Masateru; Hanayama, Hidekazu; Takahashi, Jun; Hasegawa, Sunao; Sarugaku, Yuki; Watanabe, Makoto; Imai, Masataka; Goda, Shuhei; Akitaya, Hiroshi; Takagi, Yuhei; Morihana, Kumiko; Honda, Satoshi; Arai, Akira; Sekiguchi, Kazuhiro; Oasa, Yumiko; Saito, Yoshihiko; Morokuma, Tomoki; Murata, Katsuhiro; Nogami, Daisaku; Nagayama, Takahiro; Yanagisawa, Kenshi; Yoshida, Michitoshi; Ohta, Kouji; Kawai, Nobuyuki; Miyaji, Takeshi; Fukushima, Hideo; Watanabe, Jun-ichi; Opitom, Cyrielle; Jehin, Emmanuel; Gillon, Michael; Vaubaillon, Jeremie J

    2014-01-01

    We report a new observation of the Jupiter-family comet 209P/LINEAR during its 2014 return. The comet is recognized as a dust source of a new meteor shower, the May Camelopardalids. 209P/LINEAR was apparently inactive at a heliocentric distance rh = 1.6 au and showed weak activity at rh < 1.4 au. We found an active region of <0.001% of the entire nuclear surface during the comet's dormant phase. An edge-on image suggests that particles up to 1 cm in size (with an uncertainty of factor 3-5) were ejected following a differential power-law size distribution with index q=-3.25+-0.10. We derived a mass loss rate of 2-10 kg/s during the active phase and a total mass of ~5x10^7 kg during the 2014 return. The ejection terminal velocity of millimeter- to centimeter-sized particles was 1-4 m/s, which is comparable to the escape velocity from the nucleus (1.4 m/s). These results imply that such large meteoric particles marginally escaped from the highly dormant comet nucleus via the gas drag force only within a fe...

  14. DUST FROM COMET 209P/LINEAR DURING ITS 2014 RETURN: PARENT BODY OF A NEW METEOR SHOWER, THE MAY CAMELOPARDALIDS

    Energy Technology Data Exchange (ETDEWEB)

    Ishiguro, Masateru [Department of Physics and Astronomy, Seoul National University, Gwanak, Seoul 151-742 (Korea, Republic of); Kuroda, Daisuke [Okayama Astrophysical Observatory, National Astronomical Observatory of Japan, Asakuchi, Okayama 719-0232 (Japan); Hanayama, Hidekazu [Ishigakijima Astronomical Observatory, National Astronomical Observatory of Japan, Ishigaki, Okinawa 907-0024 (Japan); Takahashi, Jun; Takagi, Yuhei; Morihana, Kumiko; Honda, Satoshi; Arai, Akira [Nishi-Harima Astronomical Observatory, Center for Astronomy, University of Hyogo, Sayo, Hyogo 679-5313 (Japan); Hasegawa, Sunao; Sarugaku, Yuki [Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara, Kanagawa 252-5210 (Japan); Watanabe, Makoto; Imai, Masataka; Goda, Shuhei [Department of Cosmosciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Akitaya, Hiroshi [Hiroshima Astrophysical Science Center, Hiroshima University, Higashihiroshima, Hiroshima 739-8526 (Japan); Sekiguchi, Kazuhiro [National Astronomical Observatory of Japan, National Institute of Natural Sciences, Mitaka, Tokyo 181-8588 (Japan); Oasa, Yumiko [Faculty of Education, Saitama University, Sakura, Saitama 338-8570 (Japan); Saito, Yoshihiko [Department of Physics, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551 (Japan); Morokuma, Tomoki [Institute of Astronomy, Graduate School of Science, The University of Tokyo, Mitaka, Tokyo 181-0015 (Japan); Murata, Katsuhiro [Department of Astrophysics, Nagoya University, Chikusa-ku, Nagoya 464-8602 (Japan); Nogami, Daisaku [Department of Astronomy, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); and others

    2015-01-10

    We report a new observation of the Jupiter family comet 209P/LINEAR during its 2014 return. The comet is recognized as a dust source of a new meteor shower, the May Camelopardalids. 209P/LINEAR was apparently inactive at a heliocentric distance r{sub h} = 1.6 AU and showed weak activity at r{sub h} ≤ 1.4 AU. We found an active region of <0.001% of the entire nuclear surface during the comet's dormant phase. An edge-on image suggests that particles up to 1 cm in size (with an uncertainty of factor 3-5) were ejected following a differential power-law size distribution with index q = –3.25 ± 0.10. We derived a mass-loss rate of 2-10 kg s{sup –1} during the active phase and a total mass of ≈5 × 10{sup 7} kg during the 2014 return. The ejection terminal velocity of millimeter- to centimeter-sized particles was 1-4 m s{sup –1}, which is comparable to the escape velocity from the nucleus (1.4 m s{sup –1}). These results imply that such large meteoric particles marginally escaped from the highly dormant comet nucleus via the gas drag force only within a few months of the perihelion passage.

  15. Bangs and Meteors from the Quiet Comet 15P/Finlay

    CERN Document Server

    Ye, Quan-Zhi; Bell, Charles; Gao, Xing; Mašek, Martin; Hui, Man-To

    2015-01-01

    Jupiter-family comet 15P/Finlay has been reportedly quiet in activity for over a century but has harbored two outbursts during its 2014/2015 perihelion passage. Here we present an analysis of these two outbursts using a set of cometary observations. The outbursts took place between 2014 Dec. 15.4--16.0 UT and 2015 Jan. 15.5--16.0 UT as constrained by ground-based and spacecraft observations. We find a characteristic ejection speed of $V_0=300$ to $650 \\mathrm{m \\cdot s^{-1}}$ for the ejecta of the first outburst and $V_0=550$ to $750 \\mathrm{m \\cdot s^{-1}}$ for that of the second outburst using a Monte Carlo dust model. The mass of the ejecta is calculated to be $M_\\mathrm{d}=2$ to $3\\times10^5 \\mathrm{kg}$ for the first outburst and $M_\\mathrm{d}=4$ to $5\\times10^5 \\mathrm{kg}$ for the second outburst, corresponds to less than $10^{-7}$ of the nucleus mass. The specific energy of the two outbursts is found to be $0.3$ to $2\\times10^5 \\mathrm{J \\cdot kg^{-1}}$. We also revisit the long-standing puzzle of the...

  16. Meteor Beliefs Project: Meteors in the Maori astronomical traditions of New Zealand

    Science.gov (United States)

    Britton, Tui R.; Hamacher, Duane W.

    2014-02-01

    We review the literature for perceptions of meteors in the Maori culture of Aotearoa or New Zealand. We examine representations of meteors in religion, story, and ceremony. We find that meteors are sometimes personified as gods or children, or are seen as omens of death and destruction. The stories we found highlight the broad perception of meteors found throughout the Maori culture, and note that some early scholars conflated the terms comet and meteor.

  17. Meteors in the Maori Astronomical Traditions of New Zealand

    CERN Document Server

    Britton, Tui R

    2013-01-01

    We review the literature for perceptions of meteors in the Maori cultures of New Zealand. We examine representations of meteors in religion, story, and ceremony. We find that meteors are sometimes personified as gods or children, or are seen as omens of death and destruction. The stories we found highlight the broad perception of meteors found throughout the Maori culture and demonstrate that some early scholars conflated the terms comet and meteor.

  18. The origin of comets

    Science.gov (United States)

    Bailey, M. E.; Clube, S. V. M.; Napier, W. M.

    Theories of the nature and origin of comets are discussed in a historical review covering the period from ancient times to the present. Consideration is given to the ancient controversy as to the atmospheric or celestial nature of comets, Renaissance theories of comet orbits, superstitions regarding the effects of comets, Kant's (1755) theory of solar-system origin, the nineteenth-century discovery of the relationship between comets and meteor showers, and the continuing solar-system/interstellar debate. Oort's (1950) model of a comet swarm surrounding the solar system is examined in detail; arguments advanced to explain the formation of comets within this model are summarized; and the question of cometary catastrophism is addressed.

  19. Radio Meteors Observations Techniques at RI NAO

    Science.gov (United States)

    Vovk, Vasyl; Kaliuzhnyi, Mykola

    2016-07-01

    The Solar system is inhabited with large number of celestial bodies. Some of them are well studied, such as planets and vast majority of big asteroids and comets. There is one group of objects which has received little attention. That is meteoroids with related to them meteors. Nowadays enough low-technology high-efficiency radio-technical solutions are appeared which allow to observe meteors daily. At RI NAO three methodologies for meteor observation are developed: single-station method using FM-receiver, correlation method using FM-receiver and Internet resources, and single-station method using low-cost SDR-receiver.

  20. All-sky Meteor Orbit System AMOS and preliminary analysis of three unusual meteor showers

    Science.gov (United States)

    Tóth, Juraj; Kornoš, Leonard; Zigo, Pavol; Gajdoš, Štefan; Kalmančok, Dušan; Világi, Jozef; Šimon, Jaroslav; Vereš, Peter; Šilha, Jiří; Buček, Marek; Galád, Adrián; Rusňák, Patrik; Hrábek, Peter; Ďuriš, František; Rudawska, Regina

    2015-12-01

    All-sky Meteor Orbit System (AMOS) is a semi-autonomous video observatory for detection of transient events on the sky, mostly the meteors. Its hardware and software development and permanent placement on several locations in Slovakia allowed the establishment of Slovak Video Meteor Network (SVMN) monitoring meteor activity above the Central Europe. The data reduction, orbital determination and additional results from AMOS cameras - the SVMN database - as well as from observational expeditions on Canary Islands and in Canada provided dynamical and physical data for better understanding of mutual connections between parent bodies of asteroids and comets and their meteoroid streams. We present preliminary results on exceptional and rare meteor streams such as September ɛ Perseids (SPE) originated from unknown long periodic comet on a retrograde orbit, suspected asteroidal meteor stream of April α Comae Berenicids (ACO) in the orbit of meteorites Příbram and Neuschwanstein and newly observed meteor stream Camelopardalids (CAM) originated from Jupiter family comet 209P/Linear.

  1. Encke-Beta Predictor for Orion Bum Targeting and Guidance

    Science.gov (United States)

    Robinson, Shane; Scarritt, Sara; Goodman, John L.

    2016-01-01

    The state vector prediction algorithm selected for Orion on-board targeting and guidance is known as the Encke-Beta method. Encke-Beta uses a universal anomaly (beta) as the independent variable, valid for circular, elliptical, parabolic, and hyperbolic orbits. The variable, related to the change in eccentric anomaly, results in integration steps that cover smaller arcs of the trajectory at or near perigee, when velocity is higher. Some burns in the EM-1 and EM-2 mission plans are much longer than burns executed with the Apollo and Space Shuttle vehicles. Burn length, as well as hyperbolic trajectories, has driven the use of the Encke-Beta numerical predictor by the predictor/corrector guidance algorithm in place of legacy analytic thrust and gravity integrals.

  2. Predicting Spacecraft Trajectories by the WeavEncke Method

    Science.gov (United States)

    Weaver, Jonathan K.; Adamo, Daniel R.

    2011-01-01

    A combination of methods is proposed of predicting spacecraft trajectories that possibly include multiple maneuvers and/or perturbing accelerations, with greater speed, accuracy, and repeatability than were heretofore achievable. The combination is denoted the WeavEncke method because it is based on unpublished studies by Jonathan Weaver of the orbit-prediction formulation of the noted astronomer Johann Franz Encke. Weaver evaluated a number of alternatives that arise within that formulation, arriving at an orbit-predicting algorithm optimized for complex trajectory operations. In the WeavEncke method, Encke's method of prediction of perturbed orbits is enhanced by application of modern numerical methods. Among these methods are efficient Kepler s-equation time-of-flight solutions and self-starting numerical integration with time as the independent variable. Self-starting numerical integration satisfies the requirements for accuracy, reproducibility, and efficiency (and, hence, speed). Self-starting numerical integration also supports fully analytic regulation of integration step sizes, thereby further increasing speed while maintaining accuracy.

  3. Dynamical modeling validation of parent bodies associated with newly discovered CMN meteor showers

    CERN Document Server

    Šegon, Damir; Gural, Peter S; Vida, Denis; Andreić, Željko; Korlević, Korado; Skokić, Ivica

    2016-01-01

    Context: Results from previous searches for new meteor showers in the combined Croatian Meteor Network and SonotaCo meteor databases suggested possible parent bodies for several newly identified showers. Aims: We aim to perform an analysis to validate the connection between the identified showers and candidate parent bodies. Methods: Simulated particles were ejected from candidate parent bodies, a dynamical modeling was performed and the results were compared to the real meteor shower observations. Results: From the 13 analysed cases, three were found to be connected with comets, four with asteroids which are possibly dormant comets, four were inconclusive or negative, and two need more observational data before any conclusions can be drawn.

  4. Constraints on Comet 332P/Ikeya-Murakami

    Science.gov (United States)

    Hui, Man-To; Ye, Quan-Zhi; Wiegert, Paul

    2017-01-01

    Encke-type comet 332P/Ikeya-Murakami is experiencing cascading fragmentation events during its 2016 apparition. It is likely the first splitting Encke-type comet ever observed. A nongravitational solution to the astrometry reveals a statistical detection of the radial and transverse nongravitational parameters, {A}1=(1.54+/- 0.39)× {10}-8 au day‑2 and {A}2=(7.19+/- 1.92)× {10}-9 au day‑2, respectively, which implies a nucleus erosion rate of (9.1+/- 1.7)‰ per orbital revolution. The mass-loss rate likely has to be supported by a much larger fraction of an active surface area than known cases of short-period comets; it may be relevant to the ongoing fragmentation. We failed to detect any serendipitous pre-discovery observations of the comet in archival data from major sky surveys, whereby we infer that 332P used to be largely inactive, and is perhaps among the few short-period comets that have been reactivated from weakly active or dormant states. We therefore constrain an upper limit to the nucleus size as 2.0 ± 0.2 km in radius. A search for small bodies in similar orbits to that of 332P reveals comet P/2010 B2 (WISE) to be the best candidate. From an empirical generalized Jupiter-family (Encke-type included) comet population model, we estimate the likelihood of a chance alignment of the 332P–P/2010 B2 pair to be 1 in 33, a small number indicative of a genetic linkage between the two comets on a statistical basis. The pair possibly originated from a common progenitor, which underwent a disintegration event well before the twentieth century.

  5. Meteor Beliefs Project: Shakespeare revisited and the Elizabethan stage's `blazing star'

    Science.gov (United States)

    Gheorghe, Andrei Dorian; McBeath, Alastair

    2007-06-01

    Some fresh Shakespearean citations of meteors, further to those given previously in the Project, are presented, along with a discussion of the Elizabethan stage's use of the `blazing star', with especial reference to the great comet of 1577.

  6. Investigation of meteor shower parent bodies using various metrics

    Science.gov (United States)

    Dumitru, B. A.; Birlan, M.; Nedelcu, A.; Popescu, M.

    2016-01-01

    The present knowledge of meteor showers identifies the small bodies of our Solar System as supply sources for meteor streams. Both comets and asteroids are considered as the origin of meteor showers. The new paradigm of "active asteroids" opens up a large field of investigation regarding the relationships between asteroids and meteors. Processes like ejection and disaggregation at impacts, rotational instabilities, electrostatic repulsion, radiation pressure, dehydration stress followed by thermal fractures, sublimation of ices are sources of matter loss from asteroids. Our objective is to find genetic relationships between asteroids and meteor showers using metrics based on orbital elements. For this objective we selected three metrics (Southworth and Hawkins, 1963; Asher et al. 1993, and Jopek, 1993, respectively), the recent MPC database and the more recent IAU meteor shower database. From our analysis, 41 of the meteor showers have probabilities of being produced (or to be fueled) by asteroids. Our sample of asteroids contains more than 1000 objects, all of them belonging to the Near-Earth Asteroid population. The systematic approach performed, based on the physical properties of our sample, reinforced the link between asteroids and their associated meteor shower.

  7. Constraints on Comet 332P/Ikeya-Murakami

    CERN Document Server

    Hui, Man-To; Wiegert, Paul

    2016-01-01

    Encke-type comet 332P/Ikeya-Murakami is experiencing cascading fragmentation events during its 2016 apparition. It is likely the first splitting Encke-type comet ever being observed. A nongravitational solution to the astrometry reveals a statistical detection of the radial and transverse nongravitational parameters, $A_{1} = \\left(1.54 \\pm 0.39\\right) \\times 10^{-8}$ AU day$^{-2}$, and $A_{2} = \\left(7.19 \\pm 1.92\\right) \\times 10^{-9}$ AU day$^{-2}$, respectively, which implies a nucleus erosion rate of $\\left(0.91 \\pm 0.17\\right)$% per orbital revolution. The mass-loss rate likely has to be supported by a much larger fraction of an active surface area than known cases of short-period comets; it may be relevant to the ongoing fragmentation. We failed to detect any serendipitous pre-discovery observations of the comet in archival data from major sky surveys, whereby we infer that 332P used to be largely inactive, and is perhaps among the few short-period comets which have been reactivated from weakly active ...

  8. Constraints on Comet 332P/Ikeya-Murakami

    Science.gov (United States)

    Hui, Man-To; Ye, Quan-Zhi

    2016-10-01

    Encke-type comet 332P/Ikeya-Murakami is experiencing a series of cascading fragmentation events during its 2016 apparition. It is likely the first splitting Encke-type comet ever being observed. A nongravitational solution to the available astrometry including high quality observations from the Canada-France-Hawaii Telescope by Kleyna et al. (private communication) reveals a statistical detection of the radial and transverse nongravitational parameters, A1 = (1.54 ± 0.39) × 10-8 AU day-2, and A2 = (7.19 ± 1.92) × 10-9 AU day-2, respectively, based upon which we calculated the erosion rate of the comet, which is large and hence is likely related to the ongoing fragmentation events. We have constrained the nucleus size from our archival search for serendipitously pre-discovery observations of the comet from major sky surveys. Our study also suggests a potential generic relationship between comet P/2010 B2 (WISE) and 332P. Detailed information will be presented.

  9. Meteor Search by Spirit, Sol 668

    Science.gov (United States)

    2005-01-01

    [figure removed for brevity, see original site] Annotated Meteor Search by Spirit, Sol 668 The panoramic cameras on NASA's Mars Exploration Rovers are about as sensitive as the human eye at night. The cameras can see the same bright stars that we can see from Earth, and the same patterns of constellations dot the night sky. Scientists on the rover team have been taking images of some of these bright stars as part of several different projects. One project is designed to try to capture 'shooting stars,' or meteors, in the martian night sky. 'Meteoroids' are small pieces of comets and asteroids that travel through space and eventually run into a planet. On Earth, we can sometimes see meteoroids become brilliant, long 'meteors' streaking across the night sky as they burn up from the friction in our atmosphere. Some of these meteors survive their fiery flight and land on the surface (or in the ocean) where, if found, they are called 'meteorites.' The same thing happens in the martian atmosphere, and Spirit even accidentally discovered a meteor while attempting to obtain images of Earth in the pre-dawn sky back in March, 2004 (see http://marsrovers.jpl.nasa.gov/gallery/press/spirit/20040311a.html, and Selsis et al. (2005) Nature, vol 435, p. 581). On Earth, some meteors come in 'storms' or 'showers' at predictable times of the year, like the famous Perseid meteor shower in August or the Leonid meteor shower in November. These 'storms' happen when Earth passes through the same parts of space where comets sometimes pass. The meteors we see at these times are from leftover debris that was shed off of these comets. The same kind of thing is predicted for Mars, as well. Inspired by calculations about Martian meteor storms by meteor scientists from the University of Western Ontario in Canada and the Centre de Recherche en Astrophysique de Lyon in France, and also aided by other meteor research colleagues from NASA's Marshall Space Flight Center, scientists on the rover team

  10. Particle dynamics in the central ringlet of Saturn's Encke gap

    CERN Document Server

    Sun, Kai-Lung; Spahn, Frank

    2015-01-01

    A kinky and clumpy ringlet shares orbit with the moon Pan in the center of the 320-km wide Encke gap in Saturn's rings (Porco et al., 2005). The ringlet is mainly composed of micron-sized particles (Showalter, 1991, Hedman et al., 2011), implying that these particles may be significantly perturbed by non-gravitational forces, which can limit their lifetimes. We establish a kinetic model considering the birth, evolution, and death of dust in the Encke central ringlet allowing to evaluate the ringlet optical depth. First, we investigate the generation of dust by micrometeorite impacts (the `impact-ejecta' process) on putative, yet undetected embedded moonlets. Taking into account the orbital evolution under the influence of the relevant perturbation forces, the dominant loss mechanisms are collisions with ring particles in the gap edges, the putative moonlets in the gap, or erosion by sputtering in Saturn's plasma environment. However, our results show that this impact-ejecta process alone can only sustain a ri...

  11. SEPS comet rendezvous performance assessment. [Solar Electric Propulsion System

    Science.gov (United States)

    Sauer, C. G., Jr.

    1980-01-01

    This paper presents an assessment of delivered payload capability for a number of selected rendezvous missions to periodic comets with launch opportunities through the years 1986-1996. These missions are chosen using a selection criteria that considers both expected scientific interest and earth-based sighting considerations. Some 22 mission opportunities are found that satisfies the selection criteria. Spacecraft performance is presented for each mission opportunity based on use of a space shuttle, a twin stage inertial-upper-stage, and a conceptual solar-electric-propulsion-system with a nominal rendezvous 50 days before comet perihelion. Additional trajectory and propulsion enhancements are investigated for several comet rendezvous missions in order to improve spacecraft performance. An indirect transfer trajectory for an Encke mission is shown to offer substantial delivered payload. In addition the use of concentrator solar arrays is considered for several of the more interesting comet missions.

  12. Reconstructing the orbit of the Chelyabinsk meteor using satellite observations

    DEFF Research Database (Denmark)

    Proud, Simon Richard

    2013-01-01

    The large number of objects in a range of orbits around the Sun means that some will inevitably intersect the Earth, becoming a meteor. These objects are commonly comet fragments or asteroids. To determine the type of a particular meteor requires knowledge of its trajectory and orbital path...... that is typically estimated by using ground-based observations such as images or radar measurements. A lack of data can, however, make this difficult and create large uncertainties in the reconstructed orbit. Here I show a new method for estimating a meteor's trajectory, and hence allowing computation of the orbit......, based upon measurements from satellite sensors. The meteor that fell on 15 February 2013 is used as an example and the resulting orbit is in broad agreement with estimates from other observations. This new technique represents an alternative method for trajectory determination that may be particularly...

  13. The Newcastle meteor radar

    Science.gov (United States)

    Keay, Colin

    1987-01-01

    A brief history and development of the Newcastle Meteor Radar system is given. Also described are its geographical coordinates and its method of operation. The initial objective when the project was commenced was to develop an entirely digital analyzer capable of recognizing meteor echo signals and recording as many of their parameters as possible. This objective was achieved.

  14. Meteors and meteorites spectra

    Science.gov (United States)

    Koukal, J.; Srba, J.; Gorková, S.; Lenža, L.; Ferus, M.; Civiš, S.; Knížek, A.; Kubelík, P.; Kaiserová, T.; Váňa, P.

    2016-01-01

    The main goal of our meteor spectroscopy project is to better understand the physical and chemical properties of meteoroids. Astrometric and spectral observations of real meteors are obtained via spectroscopic CCD video systems. Processed meteor data are inserted to the EDMOND database (European viDeo MeteOr Network Database) together with spectral information. The fully analyzed atmospheric trajectory, orbit and also spectra of a Leonid meteor/meteoroid captured in November 2015 are presented as an example. At the same time, our target is the systematization of spectroscopic emission lines for the comparative analysis of meteor spectra. Meteoroid plasma was simulated in a laboratory by laser ablation of meteorites samples using an (ArF) excimer laser and the LIDB (Laser Induced Dielectric Breakdown) in a low pressure atmosphere and various gases. The induced plasma emissions were simultaneously observed with the Echelle Spectrograph and the same CCD video spectral camera as used for real meteor registration. Measurements and analysis results for few selected meteorite samples are presented and discussed.

  15. Simulating Meteor Shower Observations In The Martian Atmosphere

    Science.gov (United States)

    McAuliffe, J. P.; Christou, A. A.

    2005-08-01

    It is known that fast meteoroids entering the martian atmosphere give rise to bright, detectable meteors (Adolfsson et al, Icarus 119, 144, 1996). Although single meteors have already been detected at Mars (Selsis et al., Nature 435, 581, 2005), the characterisation of the martian meteor year will require a large number of detections. Experience at the Earth suggests that data storage and bandwidth resources to conduct such surveys will be substantial, and may be prohibitive. In an attempt to quantify the problem in detail, we have simulated meteor shower detection in the martian and terrestrial atmospheres. For a given shower, we assume a meteoroid stream flux, size distribution and velocity based on current knowledge of Earth streams as well as the proximity of certain comets' orbits to that of Mars. A numerical code is used to simulate meteoroid ablation in a model martian and terrestrial atmosphere. Finally, using the same baseline detector characteristics (limiting magnitude, sky coverage) we generate detection statistics for the two planets. We will present results for different types of showers, including strong annual activity and episodic outbursts from Halley-type and Jupiter family comets. We will show how detection efficiency at Mars compares to the Earth for these showers and discuss optimum strategies for monitoring the martian atmosphere for meteor activity. Astronomy research at Armagh Observatory is funded by the Northern Ireland Department of Culture, Arts and Leisure (DCAL).

  16. Comet and Meteorite Traditions of Aboriginal Australians

    CERN Document Server

    Hamacher, Duane W

    2014-01-01

    Of the hundreds of distinct Aboriginal cultures of Australia, many have oral traditions rich in descriptions and explanations of comets, meteors, meteorites, airbursts, impact events, and impact craters. These views generally attribute these phenomena to spirits, death, and bad omens. There are also many traditions that describe the formation of meteorite craters as well as impact events that are not known to Western science.

  17. Meteor Stream Membership Criteria

    CERN Document Server

    Klacka, J

    2000-01-01

    Criteria for the membership of individual meteors in meteor streams are discussed from the point of view of their mathematical and also physical properties. Discussion is also devoted to the motivation. It is shown that standardly used criteria (mainly D-criterion of Southworth and Hawkins, 1963) have unusual mathematical properties in the sense of a term ``distance'', between points in a phase space, and, physical motivation and realization for the purpose of obtaining their final form is not natural and correct, and, moreover, they lead also to at least surprising astrophysical results. General properties of possible criteria are discussed. A new criterion for the membership in meteor streams is suggested. It is based on probability theory. Finally, a problem of meteor orbit determination for known parent body is discussed.

  18. Atlas of Great Comets

    Science.gov (United States)

    Stoyan, Ronald; Dunlop, Storm

    2015-01-01

    Foreword; Using this book; Part I. Introduction: Cometary beliefs and fears; Comets in art; Comets in literature and poetry; Comets in science; Cometary science today; Great comets in antiquity; Great comets of the Middle Ages; Part II. The 30 Greatest Comets of Modern Times: The Great Comet of 1471; Comet Halley 1531; The Great Comet of 1556; The Great Comet of 1577; Comet Halley, 1607; The Great Comet of 1618; The Great Comet of 1664; Comet Kirch, 1680; Comet Halley, 1682; The Great Comet of 1744; Comet Halley, 1759; Comet Messier, 1769; Comet Flaugergues, 1811; Comet Halley, 1835; The Great March Comet of 1843; Comet Donati, 1858; Comet Tebbutt, 1861; The Great September Comet of 1882; The Great January Comet of 1910; Comet Halley, 1910; Comet Arend-Roland, 1956; Comet Ikeya-Seki, 1965; Comet Bennett, 1970; Comet Kohoutek, 1973-4; Comet West, 1976; Comet Halley, 1986; Comet Shoemaker-Levy 9, 1994; Comet Hyakutake, 1996; Comet Hale-Bopp, 1997; Comet McNaught, 2007; Part III. Appendices; Table of comet data; Glossary; References; Photo credits; Index.

  19. A low cost meteor observation system using radio forward scattering and the interferometry technique

    Science.gov (United States)

    Madkour, Waleed; Yamamoto, Masa-yuki; Kakinami, Yoshihiro; Mizumoto, Satoshi

    2016-02-01

    We present a low cost meteor observation system based on the radio forward scattering and interferometry technique at Kochi University of Technology (KUT). The system can be a suitable model for low budget educational institutes that target practical learning of astronomical objects and upper atmospheric characteristics. The system methodology for the automatic counting of meteor echoes, filtering noise and detecting meteor echo directions is described. Detection of the meteor echo directions, which is the basic element for determining the meteor trajectories and the orbital parameters of parent comets, is based on a software system developed for analysis of phase differences detected by interferometry. Randomly selected observation samples measured by the radio interferometer are compared to simultaneous optical observations by video cameras to verify the system accuracy. Preliminary error analysis revealed that the system accuracy is directly related to the duration of observed meteor echoes. Eighty percent of meteor echo samples with durations longer than 3 s showed agreement in azimuth and elevation angles measurements to within a 10° error range, while meteor echo samples with shorter durations showed lower agreement levels probably due to the low system sampling resolution of 0.1 s. The reasonable agreement level of meteor echoes with duration longer than 3 s demonstrated the applicability of the system methodology. Accurate observation of shorter duration meteor echoes could possibly be achieved by improving the system resolution.

  20. The return of the Andromedids meteor shower

    CERN Document Server

    Wiegert, Paul A; Weryk, Robert J; Wong, Daniel K

    2012-01-01

    The Andromedid meteor shower underwent spectacular outbursts in 1872 and 1885, producing thousands of visual meteors per hour and described as `stars fell like rain' in Chinese records of the time. The shower originates from comet 3D/Biela whose disintegration in the mid-1800's is linked to the outbursts, but the shower has been weak or absent since the late 19th Century. This shower returned in December 2011 with a zenithal hourly rate of approximately 50, the strongest return in over a hundred years. Some 122 probable Andromedid orbits were detected by the Canadian Meteor Orbit Radar. The shower outburst occurred during 2011 Dec 3-5. The radiant at RA +$18\\degree$ and Dec +$56\\degree$ is typical of the `classical' Andromedids of the early 1800's, whose radiant was actually in Cassiopeia. The orbital elements indicate that the material involved was released before 3D/Biela's breakup prior to 1846. The observed shower in 2011 had a slow geocentric speed (16 km s$^{-1}$) and was comprised of small particles: t...

  1. Meteor Beliefs Project: meteors in the poems of John Donne

    Science.gov (United States)

    McBeath, A.; Gheorghe, A. D.

    2004-07-01

    An examination of the uses of meteor imagery in the poems of Englishman John Donne (1572-1631) is made, revealing a set of beliefs reflecting the period when ideas about astronomy, including meteors, were beginning to undergo radical change.

  2. Photoacoustic Sounds from Meteors

    Science.gov (United States)

    Spalding, Richard; Tencer, John; Sweatt, William; Conley, Benjamin; Hogan, Roy; Boslough, Mark; Gonzales, GiGi; Spurný, Pavel

    2017-01-01

    Concurrent sound associated with very bright meteors manifests as popping, hissing, and faint rustling sounds occurring simultaneously with the arrival of light from meteors. Numerous instances have been documented with −11 to −13 brightness. These sounds cannot be attributed to direct acoustic propagation from the upper atmosphere for which travel time would be several minutes. Concurrent sounds must be associated with some form of electromagnetic energy generated by the meteor, propagated to the vicinity of the observer, and transduced into acoustic waves. Previously, energy propagated from meteors was assumed to be RF emissions. This has not been well validated experimentally. Herein we describe experimental results and numerical models in support of photoacoustic coupling as the mechanism. Recent photometric measurements of fireballs reveal strong millisecond flares and significant brightness oscillations at frequencies ≥40 Hz. Strongly modulated light at these frequencies with sufficient intensity can create concurrent sounds through radiative heating of common dielectric materials like hair, clothing, and leaves. This heating produces small pressure oscillations in the air contacting the absorbers. Calculations show that −12 brightness meteors can generate audible sound at ~25 dB SPL. The photoacoustic hypothesis provides an alternative explanation for this longstanding mystery about generation of concurrent sounds by fireballs. PMID:28145486

  3. Great Comets

    Science.gov (United States)

    Burnham, Robert

    2000-05-01

    Spectacular and mysterious objects that come and go in the night sky, comets have dwelt in our popular culture for untold ages. As remnants from the formation of the Solar system, they are objects of key scientific research and space missions. As one of nature's most potent and dramatic dangers, they pose a threat to our safety--and yet they were the origin of our oceans and perhaps even life itself. This beautifully illustrated book tells the story of the biggest and most awe-inspiring of all comets: those that have earned the title "Great." Robert Burnham focuses on the Great comets Hyakutake in 1996 and Hale-Bopp in 1997, which gripped attention worldwide because, for many, they were the first comets ever seen. He places these two recent comets in the context of their predecessors from past ages, among them the famous Comet Halley. Great Comets explains the exciting new discoveries that have come from these magnificent objects and profiles the spaceprobes to comets due for launch in the next few years. The book even takes a peek behind Hollywood's science-fiction fantasies to assess the real risks humanity faces from potential impacts of both comets and asteroids. For everyone interested in astronomy, this exciting book reveals the secrets of the Great Comets and provides essential tools for keeping up to date with comet discoveries in the future. Robert Burnham has been an amateur astronomer since the mid-1950s. He has been a senior editor of Astronomy magazine (1986-88) and is the author of many books and CD-ROMS, including Comet Hale-Bopp: Find and Enjoy the Great Comet and Comet Explorer.

  4. Meteor layers in the Martian ionosphere: Observations and Modelling

    Science.gov (United States)

    Peter, Kerstin; Molina Cuberos, Gregorio J.; Witasse, Olivier; Paetzold, Martin

    Observations by the radio science experiments MaRS on Mars Express and VeRa on Venus Express revealed the appearance of additional electron density layers in the Martian and Venu-sian ionosphere below the common secondary layers in some of the ionospheric profiles. This may be an indicator for the signature of meteoric particles in the Martian atmosphere. There are two main sources of meteoric flux into planetary atmospheres: the meteoroid stream com-ponent whose origin is related to comets, and the sporadic meteoroid component which has its source in body collisions i.e. in the Kuiper belt or the asteoroid belt. This paper will present the detection status for the Martian meteor layers in MaRS electron density profiles and the first steps towards modelling this feature. The presented meteor layer model will show the influence of the sporadic meteoric component on the Martian ionosphere. Input param-eters to this model are the ablation profiles of atomic Magnesium and Iron in the Martian atmosphere caused by sporadic meteoric influx, the neutral atmosphere which is taken from the Mars Climate Database and electron density profiles for an undisturbed ionosphere from a simple photochemical model. The meteor layer model includes the effects of molecular and eddy diffusion processes of metallic species and contains chemical reaction schemes for atomic Magnesium and Iron. It calculates the altitude-density-profiles for several metallic species on the basis of Mg and Fe in chemical equilibrium by analytical solution of the reaction equations. A first comparison of model and observed meteoric structures in the Martian ionosphere will be presented.

  5. Meteoroids and Meteors - Observations and Connection to Parent Bodies

    Science.gov (United States)

    Abe, Shinsuke

    2009-05-01

    Meteoroid are a small rocky bodies traveling through interplanetary space. Meteors are phenomena caused by the interaction of meteoroids with the Earth's upper atmosphere. In this chapter the author, will briefly discuss observational methods and then concentrate on optical observations of meteors. First, the basic properties of meteor phenomenon in the atmosphere and classification of meteoroids are introduced and then coincidental phenomena, e.g., wake, jets, and train, are mentioned. Scientific observations (imaging and spectroscopy) carried out using various observational techniques allow measuring characteristics of meteoroids, e.g., orbits, density, strength, compositions. All information are potentially useful for investigating parent bodies of meteoroids, such as comets and asteroids. Searching for organics-related CHON and water in meteoroids is of particular interest for astrobiology.

  6. Martian Meteor Crater

    Science.gov (United States)

    2004-01-01

    20 February 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a fairly young meteor impact crater on Mars that is about the same size ( 1 kilometer; 0.62 miles) as the famous Meteor Crater in northern Arizona, U.S.A. Like the Arizona crater, boulders of ejected bedrock can be seen on the crater's ejecta blanket and in the crater itself. This crater is located in the Aethiopis region of Mars near 4.7oN, 224.1oW. Sunlight illuminates the scene from the lower left.

  7. Precise Trajectories and Orbits of Meteoroids from the 1999 Leonid Meteor Storm

    Science.gov (United States)

    Betlem, Hans; Jenniskens, Peter; Spurny, Pavel; VanLeeuwen, Guus Docters; Miskotte, Koen; TerKuile, Casper R.; Zerubin, Peter; Angelos, Chris; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    Photographic multi-station observations of 47 Leonid meteors are presented that were obtained from two ground locations in Spain during the 1999 meteor storm. We find an unresolved compact cluster of radiants at alpha = 153.67 +/- 0.05 and delta = 21.70 +/- 0.05 for a mean solar longitude of 235.282 (J2000). The position is identical to that of the November 17/18 outburst of 1998, which implies that both are due to comet 55P/Tempel-Tuttle's ejecta from 1899. We also find a halo which contains about 28% of all meteors. The spatial distribution of radiant positions appears to be Lorentzian, with a similar fraction of meteors in the profile wings as the meteor storm activity curve.

  8. Meteors as a Delivery Vehicle for Organic Matter to the Early Earth

    Science.gov (United States)

    Jenniskens, Peter; DeVincenzi, D. (Technical Monitor)

    2001-01-01

    Only in recent years has a concerted effort been made to study the circumstances under which extraterrestrial organic matter is accreted on Earth by way of meteors. Meteors are the luminous phenomena associated with the (partial) ablation of meteoric matter and represent the dominant pathway from space to Earth, with the possible exception of rare giant impacts of asteroids and comets. Meteors dominated the supply of organics to the early Earth if organic matter survived this pathway efficiently. Moreover, meteors are a source of kinetic energy that can convert inert atmospheric gases such as CO, N, and H2O into useful compounds, such as HCN and NO. Understanding these processes relies heavily on empirical evidence that is still very limited. Here I report on the observations in hand and discuss their relevance in the context of the origin of life.

  9. Infrasound detection of meteors

    Science.gov (United States)

    ElGabry, M. N.; Korrat, I. M.; Hussein, H. M.; Hamama, I. H.

    2017-06-01

    Meteorites that penetrate the atmosphere generate infrasound waves of very low frequency content. These waves can be detected even at large distances. In this study, we analyzed the infrasound waves produced by three meteors. The October 7, 2008 TC3 meteor fell over the north Sudan Nubian Desert, the February 15, 2013 Russian fireball, and the February 6, 2016 Atlantic meteor near to the Brazil coast. The signals of these three meteors were detected by the infrasound sensors of the International Monitoring System (IMS) of the Comprehensive Test Ban Treaty Organization (CTBTO). The progressive Multi Channel Technique is applied to the signals in order to locate these infrasound sources. Correlation of the recorded signals in the collocated elements of each array enables to calculate the delays at the different array element relative to a reference one as a way to estimate the azimuth and velocity of the coming infrasound signals. The meteorite infrasound signals show a sudden change in pressure with azimuth due to its track variation at different heights in the atmosphere. Due to movement of the source, a change in azimuth with time occurs. Our deduced locations correlate well with those obtained from the catalogues of the IDC of the CTBTO.

  10. Meteor showers in review

    Science.gov (United States)

    Jenniskens, Peter

    2017-09-01

    Recent work on meteor showers is reviewed. New data is presented on the long duration showers that wander in sun-centered ecliptic coordinates. Since the early days of meteor photography, much progress has been made in mapping visual meteor showers, using low-light video cameras instead. Now, some 820,000 meteoroid orbits have been measured by four orbit surveys during 2007-2015. Mapped in sun-centered ecliptic coordinates in 5° intervals of solar longitude, the data show a number of long duration (>15 days) meteor showers that have drifting radiants and speeds with solar longitude. 18 showers emerge from the antihelion source and follow a drift pattern towards high ecliptic latitudes. 27 Halley-type showers in the apex source move mostly towards lower ecliptic longitudes, but those at high ecliptic latitudes move backwards. Also, 5 low-speed showers appear between the toroidal ring and the apex source, moving towards the antihelion source. Most other showers do not last long, or do not move much in sun-centered ecliptic coordinates. The surveys also detected episodic showers, which mostly document the early stages of meteoroid stream formation. New data on the sporadic background have shed light on the dynamical evolution of the zodiacal cloud.

  11. Video Meteor Fluxes

    Science.gov (United States)

    Campbell-Brown, M. D.; Braid, D.

    2011-01-01

    The flux of meteoroids, or number of meteoroids per unit area per unit time, is critical for calibrating models of meteoroid stream formation and for estimating the hazard to spacecraft from shower and sporadic meteors. Although observations of meteors in the millimetre to centimetre size range are common, flux measurements (particularly for sporadic meteors, which make up the majority of meteoroid flux) are less so. It is necessary to know the collecting area and collection time for a given set of observations, and to correct for observing biases and the sensitivity of the system. Previous measurements of sporadic fluxes are summarized in Figure 1; the values are given as a total number of meteoroids striking the earth in one year to a given limiting mass. The Gr n et al. (1985) flux model is included in the figure for reference. Fluxes for sporadic meteoroids impacting the Earth have been calculated for objects in the centimeter size range using Super-Schmidt observations (Hawkins & Upton, 1958); this study used about 300 meteors, and used only the physical area of overlap of the cameras at 90 km to calculate the flux, corrected for angular speed of meteors, since a large angular speed reduces the maximum brightness of the meteor on the film, and radiant elevation, which takes into account the geometric reduction in flux when the meteors are not perpendicular to the horizontal. They bring up corrections for both partial trails (which tends to increase the collecting area) and incomplete overlap at heights other than 90 km (which tends to decrease it) as effects that will affect the flux, but estimated that the two effects cancelled one another. Halliday et al. (1984) calculated the flux of meteorite-dropping fireballs with fragment masses greater than 50 g, over the physical area of sky accessible to the MORP fireball cameras, counting only observations in clear weather. In the micron size range, LDEF measurements of small craters on spacecraft have been used to

  12. Perspectives on Comets, Comet-like Asteroids, and Their Predisposition to Provide an Environment That Is Friendly to Life.

    Science.gov (United States)

    Bosiek, Katharina; Hausmann, Michael; Hildenbrand, Georg

    2016-04-01

    In recent years, studies have shown that there are many similarities between comets and asteroids. In some cases, it cannot even be determined to which of these groups an object belongs. This is especially true for objects found beyond the main asteroid belt. Because of the lack of comet fragments, more progress has been made concerning the chemical composition of asteroids. In particular, the SMASSII classification establishes a link between the reflecting spectra and chemical composition of asteroids and meteorites. To find clues for the chemical structure of comets, the parameters of all known asteroids of the SMASSII classification were compared to those of comet groups like the Encke-type comets, the Jupiter-family comets, and the Halley-type comets, as well as comet-like objects like the damocloids and the centaurs. Fifty-six SMASSII objects similar to comets were found and are categorized as comet-like asteroids in this work. Aside from the chemistry, it is assumed that the available energy on these celestial bodies plays an important role concerning habitability. For the determination of the available energy, the effective temperature was calculated. Additionally, the size of these objects was considered in order to evaluate the possibility of a liquid water core, which provides an environment that is more likely to support processes necessary to create the building blocks of life. Further study of such objects could be notable for the period of the Late Heavy Bombardment and could therefore provide important implications for our understanding of the inner workings of the prebiotic evolution within the Solar System since the beginning.

  13. Perspectives on Comets, Comet-like Asteroids, and Their Predisposition to Provide an Environment That Is Friendly to Life

    Science.gov (United States)

    Bosiek, Katharina; Hausmann, Michael; Hildenbrand, Georg

    2016-04-01

    In recent years, studies have shown that there are many similarities between comets and asteroids. In some cases, it cannot even be determined to which of these groups an object belongs. This is especially true for objects found beyond the main asteroid belt. Because of the lack of comet fragments, more progress has been made concerning the chemical composition of asteroids. In particular, the SMASSII classification establishes a link between the reflecting spectra and chemical composition of asteroids and meteorites. To find clues for the chemical structure of comets, the parameters of all known asteroids of the SMASSII classification were compared to those of comet groups like the Encke-type comets, the Jupiter-family comets, and the Halley-type comets, as well as comet-like objects like the damocloids and the centaurs. Fifty-six SMASSII objects similar to comets were found and are categorized as comet-like asteroids in this work. Aside from the chemistry, it is assumed that the available energy on these celestial bodies plays an important role concerning habitability. For the determination of the available energy, the effective temperature was calculated. Additionally, the size of these objects was considered in order to evaluate the possibility of a liquid water core, which provides an environment that is more likely to support processes necessary to create the building blocks of life. Further study of such objects could be notable for the period of the Late Heavy Bombardment and could therefore provide important implications for our understanding of the inner workings of the prebiotic evolution within the Solar System since the beginning.

  14. The World of Comets

    Science.gov (United States)

    Guillemin, Amédée; Glaisher, James

    2010-10-01

    1. Beliefs and superstitions relative to comets; 2. Cometary astronomy up to the time of Newton; 3. The motions and orbits of comets; 4. Periodical comets; 5. Periodical comets; 6. The world of comets and cometary systems; 7. Physical and chemical constitution of comets; 8. Physical transformations of comets; 9. Mass and density of comets; 10. The light of comets; 11. Theory of cometary phenomena; 12. Comets and shooting stars; 13. Comets and the earth; 14. Physical influences of comets; 15. Some questions about comets; Tables.

  15. Zhamanshin meteor crater

    Science.gov (United States)

    Florenskiy, P. V.; Dabizha, A. I.

    1987-01-01

    A historical survey and geographic, geologic and geophysical characteristics, the results of many years of study of the Zhamanshin meteor crater in the Northern Aral region, are reported. From this data the likely initial configuration and cause of formation of the crater are reconstructed. Petrographic and mineralogical analyses are given of the brecciated and remelted rocks, of the zhamanshinites and irgizite tektites in particular. The impact melting, dispersion and quenching processes resulting in tektite formation are discussed.

  16. 2P/Encke, the Taurid complex NEOs and the Maribo and Sutter’s Mill meteorites

    DEFF Research Database (Denmark)

    Tubiana, C.; Snodgrass, C.; Michelsen, Rene;

    2015-01-01

    filter, used to investigate the possible presence of cometary activity around the nucleus of 2P/Encke and the NEOs, show that no resolved coma is present. None of the FORS spectra show the 700 nm absorption feature due to hydrated minerals that is seen in the CM chondrite meteorites. All objects show......, which is not seen in 2P/Encke, which suggests that they are not related. Conclusions. Despite similar orbits, we find no spectroscopic evidence for a link between 2P/Encke, the Taurid complex NEOs and the Maribo and Sutter’s Mill meteorites. However, we cannot rule out a connection to the meteorites...

  17. Meteors and how to observe them

    CERN Document Server

    Lunsford, Robert

    2009-01-01

    No two meteor showers are alike, and their variation depends on current conditions and the observer's location. This introduction to the art of meteor observing explains how best to view meteor activity under all conditions and from all locations.

  18. The EISCAT meteor code

    Directory of Open Access Journals (Sweden)

    G. Wannberg

    2008-08-01

    Full Text Available The EISCAT UHF system has the unique capability to determine meteor vector velocities from the head echo Doppler shifts measured at the three sites. Since even meteors spending a very short time in the common volume produce analysable events, the technique lends itself ideally to mapping the orbits of meteors arriving from arbitrary directions over most of the upper hemisphere.

    A radar mode optimised for this application was developed in 2001/2002. A specially selected low-sidelobe 32-bit pseudo-random binary sequence is used to binary phase shift key (BPSK the transmitted carrier. The baud-length is 2.4 μs and the receiver bandwidth is 1.6 MHz to accommodate both the resulting modulation bandwidth and the target Doppler shift. Sampling is at 0.6 μs, corresponding to 90-m range resolution. Target range and Doppler velocity are extracted from the raw data in a multi-step matched-filter procedure. For strong (SNR>5 events the Doppler velocity standard deviation is 100–150 m/s. The effective range resolution is about 30 m, allowing very accurate time-of-flight velocity estimates. On average, Doppler and time-of-flight (TOF velocities agree to within about one part in 103. Two or more targets simultaneously present in the beam can be resolved down to a range separation <300 m as long as their Doppler shifts differ by more than a few km/s.

  19. Coded continuous wave meteor radar

    OpenAIRE

    2015-01-01

    The concept of coded continuous wave meteor radar is introduced. The radar uses a continuously transmitted pseudo-random waveform, which has several advantages: coding avoids range aliased echoes, which are often seen with commonly used pulsed specular meteor radars (SMRs); continuous transmissions maximize pulse compression gain, allowing operation with significantly lower peak transmit power; the temporal resolution can be changed after ...

  20. Dynamical model for the toroidal sporadic meteors

    Energy Technology Data Exchange (ETDEWEB)

    Pokorný, Petr; Vokrouhlický, David [Institute of Astronomy, Charles University, V Holešovičkách 2, CZ-18000 Prague 8 (Czech Republic); Nesvorný, David [Department of Space Studies, Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302 (United States); Campbell-Brown, Margaret; Brown, Peter, E-mail: petr.pokorny@volny.cz, E-mail: vokrouhl@cesnet.cz, E-mail: davidn@boulder.swri.edu, E-mail: margaret.campbell@uwo.ca, E-mail: pbrown@uwo.ca [Department of Physics and Astronomy, University of Western Ontario, London, ON N6A 3K7 (Canada)

    2014-07-01

    More than a decade of radar operations by the Canadian Meteor Orbit Radar have allowed both young and moderately old streams to be distinguished from the dispersed sporadic background component. The latter has been categorized according to broad radiant regions visible to Earth-based observers into three broad classes: the helion and anti-helion source, the north and south apex sources, and the north and south toroidal sources (and a related arc structure). The first two are populated mainly by dust released from Jupiter-family comets and new comets. Proper modeling of the toroidal sources has not to date been accomplished. Here, we develop a steady-state model for the toroidal source of the sporadic meteoroid complex, compare our model with the available radar measurements, and investigate a contribution of dust particles from our model to the whole population of sporadic meteoroids. We find that the long-term stable part of the toroidal particles is mainly fed by dust released by Halley type (long period) comets (HTCs). Our synthetic model reproduces most of the observed features of the toroidal particles, including the most troublesome low-eccentricity component, which is due to a combination of two effects: particles' ability to decouple from Jupiter and circularize by the Poynting-Robertson effect, and large collision probability for orbits similar to that of the Earth. Our calibrated model also allows us to estimate the total mass of the HTC-released dust in space and check the flux necessary to maintain the cloud in a steady state.

  1. Meteor fireball sounds identified

    Science.gov (United States)

    Keay, Colin

    1992-01-01

    Sounds heard simultaneously with the flight of large meteor fireballs are electrical in origin. Confirmation that Extra/Very Low Frequency (ELF/VLF) electromagnetic radiation is produced by the fireball was obtained by Japanese researchers. Although the generation mechanism is not fully understood, studies of the Meteorite Observation and Recovery Project (MORP) and other fireball data indicate that interaction with the atmosphere is definitely responsible and the cut-off magnitude of -9 found for sustained electrophonic sounds is supported by theory. Brief bursts of ELF/VLF radiation may accompany flares or explosions of smaller fireballs, producing transient sounds near favorably placed observers. Laboratory studies show that mundane physical objects can respond to electrical excitation and produce audible sounds. Reports of electrophonic sounds should no longer be discarded. A catalog of over 300 reports relating to electrophonic phenomena associated with meteor fireballs, aurorae, and lightning was assembled. Many other reports have been cataloged in Russian. These may assist the full solution of the similar long-standing and contentious mystery of audible auroral displays.

  2. Tabulation of comet observations.

    Science.gov (United States)

    1991-07-01

    Concerning comets: 1957 III Arend-Roland, 1957 V Mrkos, 1958 III Burnham, 1959 III Bester-Hoffmeister, 1959 VI Alcock, 1959 VIII P/Giacobini-Zinner, 1960 I P/Wild 1, 1960 II Burnham, 1960 III P/Schaumasse, 1960 VIII P/Finlay, 1961 V Wilson-Hubbard, 1961 VIII Seki, 1962 III Seki-Lines, 1962 VIII Humason, 1963 I Ikeya, 1963 III Alcock, 1963 V Pereyra, 1964 VI Tomita-Gerber-Honda, 1964 VIII Ikeya, 1964 IX Everhart, 1979 X Bradfield, 1980 X P/Stephan-Oterma, 1980 XII Meier, 1980 XIII P/Tuttle, 1981 II Panther, 1982 I Bowell, 1982 IV P/Grigg-Skjellerup, 1982 VII P/d'Arrest, 1986 III P/Halley, 1987 IV Shoemaker, 1987 XII P/Hartley 3, 1987 XIX P/Schwassmann-Wachmann 2, 1987 XXIX Bradfield, 1987 XXX Levy, 1987 XXXII McNaught, 1987 XXXIII P/Borrelly, 1987 XXXVI P/Parker-Hartley, 1987 XXXVII P/Helin- Roman-Alu 1, 1988 III Shoemaker-Holt, 1988 V Liller, 1988 VIII P/Ge-Wang, 1988 XI P/Shoemaker-Holt 2, 1988 XIV P/Tempel 2, 1988 XV Machholz, 1988 XX Yanaka, 1988 XXI Shoemaker, 1988 XXIV Yanaka, 1989 III Shoemaker, 1989 V Shoemaker-Holt-Rodriquez, 1989 VIII P/Pons-Winnecke, 1989 X P/Brorsen-Metcalf, 1989 XI P/Gunn, 1989 XIII P/Lovas 1, 1989 XVIII McKenzie-Russell, 1989 XIX Okazaki-Levy-Rudenko, 1989 XX P/Clark, 1989 XXI Helin-Ronan-Alu, 1989 XXII Aarseth-Brewington, 1989h P/Van Biesbroeck, 1989t P/Wild 2, 1989u P/Kearns-Kwee, 1989c1 Austin, 1989e1 Skorichenko-George, 1990a P/Wild 4, 1990b Černis-Kiuchi-Nakamura, 1990c Levy, 1990e P/Wolf-Harrington, 1990f P/Honda-Mrkos-Pajdušáková, 1990g McNaught-Hughes, 1990i Tsuchiya-Kiuchi, 1990n P/Taylor, 1990ο P/Shoemaker-Levy 1, 1991a P/Metcalf-Brewington, 1991b Arai, 1991c P/Swift-Gehrels, 1991d Shoemaker-Levy, 1991e P/Shoemaker-Levy 3, 1991h P/Takamizawa, 1991j P/Hartley 1, 1991k P/Mrkos, 1991l Helin-Lawrence, 1991n P/Faye, 1991q P/Levy, 1991t P/Hartley 2, P/Encke, P/Schwassmann-Wachmann 1.

  3. Infrasound detection of meteors

    Directory of Open Access Journals (Sweden)

    M.N. ElGabry

    2017-06-01

    The signals of these three meteors were detected by the infrasound sensors of the International Monitoring System (IMS of the Comprehensive Test Ban Treaty Organization (CTBTO. The progressive Multi Channel Technique is applied to the signals in order to locate these infrasound sources. Correlation of the recorded signals in the collocated elements of each array enables to calculate the delays at the different array element relative to a reference one as a way to estimate the azimuth and velocity of the coming infrasound signals. The meteorite infrasound signals show a sudden change in pressure with azimuth due to its track variation at different heights in the atmosphere. Due to movement of the source, a change in azimuth with time occurs. Our deduced locations correlate well with those obtained from the catalogues of the IDC of the CTBTO.

  4. Astrophotography Basics: Meteors, Comets, Eclipses, Aurorae, Star Trails. Revised.

    Science.gov (United States)

    Eastman Kodak Co., Rochester, NY.

    This pamphlet gives an introduction to the principles of astronomical picture-taking. Chapters included are: (1) "Getting Started" (describing stationary cameras, sky charts and mapping, guided cameras, telescopes, brightness of astronomical subjects, estimating exposure, film selection, camera filters, film processing, and exposure for…

  5. Meteors do not break exogenous organic molecules into high yields of diatomics.

    Science.gov (United States)

    Jenniskens, Peter; Schaller, Emily L; Laux, Christophe O; Wilson, Michael A; Schmidt, Greg; Rairden, Rick L

    2004-01-01

    Meteoroids that dominate the Earth's extraterrestrial mass influx (50-300 microm size range) may have contributed a unique blend of exogenous organic molecules at the time of the origin of life. Such meteoroids are so large that most of their mass is ablated in the Earth's atmosphere. In the process, organic molecules are decomposed and chemically altered to molecules differently from those delivered to the Earth's surface by smaller (10 cm) meteorites. The question addressed here is whether the organic matter in these meteoroids is fully decomposed into atoms or diatomic compounds during ablation. If not, then the ablation products made available for prebiotic organic chemistry, and perhaps early biology, might have retained some memory of their astrophysical nature. To test this hypothesis we searched for CN emission in meteor spectra in an airborne experiment during the 2001 Leonid meteor storm. We found that the meteor's light-emitting air plasma, which included products of meteor ablation, contained less than 1 CN molecule for every 30 meteoric iron atoms. This contrasts sharply with the nitrogen/iron ratio of 1:1.2 in the solid matter of comet 1P/Halley. Unless the nitrogen content or the abundance of complex organic matter in the Leonid parent body, comet 55P/Tempel-Tuttle, differs from that in comet 1P/Halley, it appears that very little of that organic nitrogen decomposes into CN molecules during meteor ablation in the rarefied flow conditions that characterize the atmospheric entry of meteoroids approximately 50 microm-10 cm in size. We propose that the organics of such meteoroids survive instead as larger compounds.

  6. Meteor Beliefs Project: Seven years and counting

    Science.gov (United States)

    McBeath, A.; Drobnock, G. J.; Gheorghe, A. D.

    2010-04-01

    The Meteor Beliefs Project's seventh anniversary is celebrated with an eclectic mixture of meteor beliefs from the 1799 Leonids in Britain, the folkloric link between meteors and wishing in some Anglo-American sources, how a meteoric omen came to feature in Nathaniel Hawthorne's 1850 novel The Scarlet Letter, and a humorous item from the satirical magazine Punch in 1861, all helping to show how meteor beliefs can be transformed by different parts of society.

  7. Review of amateur meteor research

    Science.gov (United States)

    Rendtel, Jürgen

    2017-09-01

    Significant amounts of meteor astronomical data are provided by amateurs worldwide, using various methods. This review concentrates on optical data. Long-term meteor shower analyses based on consistent data are possible over decades (Orionids, Geminids, κ-Cygnids) and allow combination with modelling results. Small and weak structures related to individual stream filaments of cometary dust have been analysed in both major and minor showers (Quadrantids, September ε-Perseids), providing feedback to meteoroid ejection and stream evolution processes. Meteoroid orbit determination from video meteor networks contributes to the improvement of the IAU meteor data base. Professional-amateur cooperation also concerns observations and detailed analysis of fireball data, including meteorite ground searches.

  8. On the interaction meteor complex

    Science.gov (United States)

    Rajchl, J.

    An approach to the problem of a meteoric complex called the interaction meteor complex (IMC) is applied and discussed, generalizing the idea of the interaction layer (Rajchl 1969). The role of an extended interaction of meteoroids is emphasized, both with planet surfaces and/or their satellites and with planet atmospheres, elastic or inelastic in form. The dissipation and related formative aspect are joined in one complex and compared with a topological compact. Examples of these types of interaction are presented.

  9. Meteor showers an annotated catalog

    CERN Document Server

    Kronk, Gary W

    2014-01-01

    Meteor showers are among the most spectacular celestial events that may be observed by the naked eye, and have been the object of fascination throughout human history. In “Meteor Showers: An Annotated Catalog,” the interested observer can access detailed research on over 100 annual and periodic meteor streams in order to capitalize on these majestic spectacles. Each meteor shower entry includes details of their discovery, important observations and orbits, and gives a full picture of duration, location in the sky, and expected hourly rates. Armed with a fuller understanding, the amateur observer can better view and appreciate the shower of their choice. The original book, published in 1988, has been updated with over 25 years of research in this new and improved edition. Almost every meteor shower study is expanded, with some original minor showers being dropped while new ones are added. The book also includes breakthroughs in the study of meteor showers, such as accurate predictions of outbursts as well ...

  10. Coded continuous wave meteor radar

    Science.gov (United States)

    Vierinen, Juha; Chau, Jorge L.; Pfeffer, Nico; Clahsen, Matthias; Stober, Gunter

    2016-03-01

    The concept of a coded continuous wave specular meteor radar (SMR) is described. The radar uses a continuously transmitted pseudorandom phase-modulated waveform, which has several advantages compared to conventional pulsed SMRs. The coding avoids range and Doppler aliasing, which are in some cases problematic with pulsed radars. Continuous transmissions maximize pulse compression gain, allowing operation at lower peak power than a pulsed system. With continuous coding, the temporal and spectral resolution are not dependent on the transmit waveform and they can be fairly flexibly changed after performing a measurement. The low signal-to-noise ratio before pulse compression, combined with independent pseudorandom transmit waveforms, allows multiple geographically separated transmitters to be used in the same frequency band simultaneously without significantly interfering with each other. Because the same frequency band can be used by multiple transmitters, the same interferometric receiver antennas can be used to receive multiple transmitters at the same time. The principles of the signal processing are discussed, in addition to discussion of several practical ways to increase computation speed, and how to optimally detect meteor echoes. Measurements from a campaign performed with a coded continuous wave SMR are shown and compared with two standard pulsed SMR measurements. The type of meteor radar described in this paper would be suited for use in a large-scale multi-static network of meteor radar transmitters and receivers. Such a system would be useful for increasing the number of meteor detections to obtain improved meteor radar data products.

  11. Barringer Meteor Crater, Arizona

    Science.gov (United States)

    2001-01-01

    Barringer Crater, also known as 'Meteor Crater,' is a 1,300-meter (0.8 mile) diameter, 174-meter (570-feet) deep hole in the flat-lying desert sandstones 30 kilometers (18.6 miles) west of Winslow, Arizona. Since the 1890s geologic studies here played a leading role in developing an understanding of impact processes on the Earth, the moon and elsewhere in the solar system.This view was acquired by the Landsat 4 satellite on December 14, 1982. It shows the crater much as a lunar crater might appear through a telescope. Morning sun illumination is from the southeast (lower right). The prominent gully meandering across the scene is known as Canyon Diablo. It drains northward toward the Little Colorado River and eventually to the Grand Canyon. The Interstate 40 highway crosses and nearly parallels the northern edge of the scene.The ejecta blanket around the crater appears somewhat lighter than the surrounding terrain, perhaps in part due to its altered mineralogic content. However, foot traffic at this interesting site may have scarred and lightened the terrain too. Also, the roughened surface here catches the sunlight on the southerly slopes and protects a highly reflective patchy snow cover in shaded northerly slopes, further lightening the terrain as viewed from space on this date.

  12. DYNAMICAL MODEL FOR THE ZODIACAL CLOUD AND SPORADIC METEORS

    Energy Technology Data Exchange (ETDEWEB)

    Nesvorny, David; Vokrouhlicky, David; Pokorny, Petr; Bottke, William F. [Department of Space Studies, Southwest Research Institute, 1050 Walnut St., Suite 300, Boulder, CO 80302 (United States); Janches, Diego [Space Weather Laboratory, Code 674, GSFC/NASA, Greenbelt, MD 20771 (United States); Jenniskens, Peter [Carl Sagan Center, SETI Institute, 515 N. Whisman Road, Mountain View, CA 94043 (United States)

    2011-12-20

    The solar system is dusty, and would become dustier over time as asteroids collide and comets disintegrate, except that small debris particles in interplanetary space do not last long. They can be ejected from the solar system by Jupiter, thermally destroyed near the Sun, or physically disrupted by collisions. Also, some are swept by the Earth (and other planets), producing meteors. Here we develop a dynamical model for the solar system meteoroids and use it to explain meteor radar observations. We find that the Jupiter Family Comets (JFCs) are the main source of the prominent concentrations of meteors arriving at the Earth from the helion and antihelion directions. To match the radiant and orbit distributions, as measured by the Canadian Meteor Orbit Radar (CMOR) and Advanced Meteor Orbit Radar (AMOR), our model implies that comets, and JFCs in particular, must frequently disintegrate when reaching orbits with low perihelion distance. Also, the collisional lifetimes of millimeter particles may be longer ({approx}> 10{sup 5} yr at 1 AU) than postulated in the standard collisional models ({approx}10{sup 4} yr at 1 AU), perhaps because these chondrule-sized meteoroids are stronger than thought before. Using observations of the Infrared Astronomical Satellite to calibrate the model, we find that the total cross section and mass of small meteoroids in the inner solar system are (1.7-3.5) Multiplication-Sign 10{sup 11} km{sup 2} and {approx}4 Multiplication-Sign 10{sup 19} g, respectively, in a good agreement with previous studies. The mass input required to keep the zodiacal cloud in a steady state is estimated to be {approx}10{sup 4}-10{sup 5} kg s{sup -1}. The input is up to {approx}10 times larger than found previously, mainly because particles released closer to the Sun have shorter collisional lifetimes and need to be supplied at a faster rate. The total mass accreted by the Earth in particles between diameters D = 5 {mu}m and 1 cm is found to be {approx}15

  13. Meteor Showers in the Ancient Maya Hieroglyphic Codices

    Science.gov (United States)

    Kinsman, J. H.

    2014-07-01

    Researchers of the ancient Maya culture have long been fascinated with the Maya obsession concerning cyclical calendars and precise visual observations of astronomical bodies and phenomena, in particular the Sun, Moon, visible planets, and solar and lunar eclipses. Although considered possible, heretofore no record of specific sightings of comets or meteor showers in the Maya inscriptions has been firmly established by scholars. Besides difficulties with decipherment of the hieroglyphic script, investigators have had to grapple with an ancient Maya calendar that has not been accurately correlated to the European calendar. Recent examination by this researcher has found that it may be possible to recognize written accounts of meteor showers embedded in the hieroglyphic corpus, especially the codices, the screen-fold books that were the tools of the astronomer-priests of that day. By proposing an alternative decipherment of an astronomical sign and using the accompanying hieroglyphic texts and illustrations with appropriate dates, this researcher believes it is possible to demonstrate that the Maya may have recorded meteor showers occurring in the seventh through the tenth centuries AD.

  14. A Persistent Meteoric Ion Layer in the Martian Atmosphere

    Science.gov (United States)

    Crismani, Matteo; Schneider, Nicholas M.; Jain, Sonal Kumar; Plane, John; Deigo Carrillo Sanchez, Juan; Deighan, Justin; Stevens, Michael H.; Evans, Scott; Chaffin, Michael S.; Jacosky, Bruce; IUVS Team

    2016-10-01

    We report on a persistent metal ion layer at Mars produced by meteoric ablation in the upper atmosphere, observed by the Imaging Ultraviolet Spectrograph (IUVS) on MAVEN. The response of the Martian atmosphere to meteoroid influx constrains cometary activity, dust dynamics, ionospheric production at Mars and meteoric smoke may represent a site of nucleation for high altitude clouds. Using observations that span more than an Earth year, we find this layer is global and steady state, contrary to previous observations, but in accordance with predictions. IUVS observations cover a range of observation conditions, which allows us to determine the variability of the Mg+ layer seasonally and geographically. Mars has passed through several predicted meteor showers, though the fluences of these events have hitherto been unconstrained. Analysis of these events will determine whether Mars' atmosphere responds to such events dramatically, as was the case with comet Siding Spring, or more similarly to Earth. Mg is also detected, but the ratio of Mg to Mg+ is less than predicted, indicative of undetermined chemical processes in the Martian atmosphere.

  15. Bolidozor - Distributed radio meteor detection system

    CERN Document Server

    Kakona, Jakub; Kakona, Martin

    2016-01-01

    Most of the meteor radioastronomical radars are backscatter radars which cover only a small area of the atmosphere. Therefore a daytime meteor flux models are based on sparse data collected by only a few radar systems. To solve this issue, a radar system with a wide coverage is required. We present a new approach of open-source multi-static radio meteor detection system which could be distributed over a large area. This feature allows us to detect meteor events taking place over a larger area as well and gather more uniform data about meteor flux and possibly about meteor trajectories.

  16. Meteor forward scattering at multiple frequencies

    Science.gov (United States)

    Nedeljkovic, Sasa

    2006-08-01

    Meteor forward scattering is a well known method of detecting meteors using a radio telescope to receive signals from distant transmitters scattered from a meteor trail. The traditional way of performing the meteor forward scattering is to tune the receiver to some particular frequency to match a distant transmitter and wait for reflected signals. In this paper I will show how new technologies can be used to make a simpler digital radio telescope capable of analyzing broadband spectra from 0 to 250 MHz. Such spectra contain information about several reflections on a single meteor, which can be enough to calculate the meteor's kinetic parameters.

  17. Coded continuous wave meteor radar

    Directory of Open Access Journals (Sweden)

    J. Vierinen

    2015-07-01

    Full Text Available The concept of coded continuous wave meteor radar is introduced. The radar uses a continuously transmitted pseudo-random waveform, which has several advantages: coding avoids range aliased echoes, which are often seen with commonly used pulsed specular meteor radars (SMRs; continuous transmissions maximize pulse compression gain, allowing operation with significantly lower peak transmit power; the temporal resolution can be changed after performing a measurement, as it does not depend on pulse spacing; and the low signal to noise ratio allows multiple geographically separated transmitters to be used in the same frequency band without significantly interfering with each other. The latter allows the same receiver antennas to be used to receive multiple transmitters. The principles of the signal processing are discussed, in addition to discussion of several practical ways to increase computation speed, and how to optimally detect meteor echoes. Measurements from a campaign performed with a coded continuous wave SMR are shown and compared with two standard pulsed SMR measurements. The type of meteor radar described in this paper would be suited for use in a large scale multi-static network of meteor radar transmitters and receivers. This would, for example, provide higher spatio-temporal resolution for mesospheric wind field measurements.

  18. Coded continuous wave meteor radar

    Science.gov (United States)

    Vierinen, J.; Chau, J. L.; Pfeffer, N.; Clahsen, M.; Stober, G.

    2015-07-01

    The concept of coded continuous wave meteor radar is introduced. The radar uses a continuously transmitted pseudo-random waveform, which has several advantages: coding avoids range aliased echoes, which are often seen with commonly used pulsed specular meteor radars (SMRs); continuous transmissions maximize pulse compression gain, allowing operation with significantly lower peak transmit power; the temporal resolution can be changed after performing a measurement, as it does not depend on pulse spacing; and the low signal to noise ratio allows multiple geographically separated transmitters to be used in the same frequency band without significantly interfering with each other. The latter allows the same receiver antennas to be used to receive multiple transmitters. The principles of the signal processing are discussed, in addition to discussion of several practical ways to increase computation speed, and how to optimally detect meteor echoes. Measurements from a campaign performed with a coded continuous wave SMR are shown and compared with two standard pulsed SMR measurements. The type of meteor radar described in this paper would be suited for use in a large scale multi-static network of meteor radar transmitters and receivers. This would, for example, provide higher spatio-temporal resolution for mesospheric wind field measurements.

  19. A fast meteor detection algorithm

    Science.gov (United States)

    Gural, P.

    2016-01-01

    A low latency meteor detection algorithm for use with fast steering mirrors had been previously developed to track and telescopically follow meteors in real-time (Gural, 2007). It has been rewritten as a generic clustering and tracking software module for meteor detection that meets both the demanding throughput requirements of a Raspberry Pi while also maintaining a high probability of detection. The software interface is generalized to work with various forms of front-end video pre-processing approaches and provides a rich product set of parameterized line detection metrics. Discussion will include the Maximum Temporal Pixel (MTP) compression technique as a fast thresholding option for feeding the detection module, the detection algorithm trade for maximum processing throughput, details on the clustering and tracking methodology, processing products, performance metrics, and a general interface description.

  20. Urania in the Marketplace: The Blue Comet (A Railroad’s Astronomical Heritage)

    Science.gov (United States)

    Rumstay, Kenneth S.

    2017-01-01

    Between 1929 February 21 and 1941 September 27 the Central New Jersey Railroad operated a luxury passenger train between Jersey City and Atlantic City. Named The Blue Comet, the locomotive, tender, and coaches sported a unique royal blue paint scheme designed to evoke images of celestial bodies speeding through space. Inside each car were etched window panes and lampshades featuring stars and comets. Each coach sported the name of a famous comet on its side; these comets were of course named for their discoverers. Some of the astronomers honored in this unique fashion remain famous to this day, or at least their comets do. The names D’Arrest, Barnard, Encke, Faye, Giacobini, Halley, Olbers, Temple, Tuttle, and Westphal are familiar ones. But Biela, Brorsen, deVico, Spitaler, and Winnecke have now largely faded into obscurity; their stories are recounted here.Although more than seventy years have elapsed since its last run, The Blue Comet, perhaps the most famous passenger train in American history, lives on in the memories of millions of passengers and railfans. This famous train returned to the attention of millions of television viewers on the evening of 2007 June 3, in an episode of the HBO series The Sopranos.This work was supported by a faculty development grant from Valdosta State University.

  1. Coded continuous wave meteor radar

    Science.gov (United States)

    Chau, J. L.; Vierinen, J.; Pfeffer, N.; Clahsen, M.; Stober, G.

    2016-12-01

    The concept of a coded continuous wave specular meteor radar (SMR) is described. The radar uses a continuously transmitted pseudorandom phase-modulated waveform, which has several advantages compared to conventional pulsed SMRs. The coding avoids range and Doppler aliasing, which are in some cases problematic with pulsed radars. Continuous transmissions maximize pulse compression gain, allowing operation at lower peak power than a pulsed system. With continuous coding, the temporal and spectral resolution are not dependent on the transmit waveform and they can be fairly flexibly changed after performing a measurement. The low signal-to-noise ratio before pulse compression, combined with independent pseudorandom transmit waveforms, allows multiple geographically separated transmitters to be used in the same frequency band simultaneously without significantly interfering with each other. Because the same frequency band can be used by multiple transmitters, the same interferometric receiver antennas can be used to receive multiple transmitters at the same time. The principles of the signal processing are discussed, in addition to discussion of several practical ways to increase computation speed, and how to optimally detect meteor echoes. Measurements from a campaign performed with a coded continuous wave SMR are shown and compared with two standard pulsed SMR measurements. The type of meteor radar described in this paper would be suited for use in a large-scale multi-static network of meteor radar transmitters and receivers. Such a system would be useful for increasing the number of meteor detections to obtain improved meteor radar data products, such as wind fields. This type of a radar would also be useful for over-the-horizon radar, ionosondes, and observations of field-aligned-irregularities.

  2. Do comets C/1861 G1 (Thatcher) and C/1861 J1 (Great comet) have a common origin?

    Science.gov (United States)

    Branham, R. L.

    2015-10-01

    A new orbit is calculated for Comet C/1861 G1 (Thatcher), associated with the Lyrid meteor shower, to replace Oppolzer's orbit of 1864. The new orbit is based upon 649 observations, 326 in right ascension and 323 in declination, made between 11 April 1861 and 7 Sept. 1861. The final orbit uses residuals calculated with the Welsch weighting function. The comet's period of 416.87 ± 0.56 yr agrees with Oppolzer's period of 415 yr athough other elements such as the inclination differ. Although the post-perihelion residuals are relatively random, 52.1% probability of randomness, pre-perihelion residuals lack randomness indicating possible deviations from Keplerian motion caused by ejection of meteoritic material. Comet Thatcher is unrelated to the Great comet of 1861.

  3. New trends in meteor radio receivers

    Science.gov (United States)

    Rault, Jean-Louis

    2014-01-01

    Recent progresses in low cost—but performing—SDR (software defined radio) technology presents a major breakthrough in the domain of meteor radio observations. Their performances are now good enough for meteor work and should therefore encourage newcomers to join the meteor radio community.

  4. Meteor Crater, AZ

    Science.gov (United States)

    2002-01-01

    The Barringer Meteorite Crater (also known as 'Meteor Crater') is a gigantic hole in the middle of the arid sandstone of the Arizona desert. A rim of smashed and jumbled boulders, some of them the size of small houses, rises 50 m above the level of the surrounding plain. The crater itself is nearly a 1500 m wide, and 180 m deep. When Europeans first discovered the crater, the plain around it was covered with chunks of meteoritic iron - over 30 tons of it, scattered over an area 12 to 15 km in diameter. Scientists now believe that the crater was created approximately 50,000 years ago. The meteorite which made it was composed almost entirely of nickel-iron, suggesting that it may have originated in the interior of a small planet. It was 50 m across, weighed roughly 300,000 tons, and was traveling at a speed of 65,000 km per hour. This ASTER 3-D perspective view was created by draping an ASTER bands 3-2-1image over a digital elevation model from the US Geological Survey National Elevation Dataset.This image was acquired on May 17, 2001 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet.ASTER is one of five Earth-observing instruments launched December 18,1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. Science team leader; Bjorn Eng of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The Terra mission is part of NASA's Earth Science Enterprise, along

  5. Mars Methane highs unrelated to comets

    Science.gov (United States)

    Roos-Serote, Maarten; Atreya, Sushil K.; Webster, Chris; Mahaffy, Paul

    2016-10-01

    Until the Curiosity Rover arrived at Mars, all measurements of methane were done by remote sensing, either from Earth or from orbiting spacecraft, using a variety of different instruments and under different observing conditions. The Curiosity Rover's Sample Analysis at Mars (SAM) / Tunable Laser Spectrometer (TLS) has carried out systematic measurements of martian methane from Gale crater for two consecutive martian years (31 - 33, starting in October 2012). Meteoric material interacts with the martian atmosphere when Mars passes through a meteoroid stream left behind by cometary bodies orbiting the Sun. Predictions show that 33 such events are likely to occur during the martian year. It has been suggested that the organics present in this material trigger the formation of methane in the atmosphere, and thus these events could possibly be an explanation for the observed variations in the methane abundance. In a recent paper, Fries et al. [2016] argued that all measurements of high methane concentrations are within 16 days of a predicted meteor shower event, and that as such there is a correlation. We present a new analysis including seven new data points that were not available previously. All these new measurements show low methane values. Some of the new measurements were deliberately taken at the same Ls when high values of methane were measured in the previous martian year, showing that the high methane measurements are likely not seasonal, as would be expected if they were connected to meteor shower events. In our analysis we take into account all the predicted meteor events and search for any correlation drawn between these events and the level of methane in the atmosphere. We conclude that whether we consider individual data points, apply statistical analysis, or consider different time spans between measurements and the occurrence of meteor events, or possible supply of organic material from comets, there is no evidence for such a correlation in the

  6. Giant comets and mass extinctions of life

    Science.gov (United States)

    Napier, W. M.

    2015-03-01

    I find evidence for clustering in age of well-dated impact craters over the last 500 Myr. At least nine impact episodes are identified, with durations whose upper limits are set by the dating accuracy of the craters. Their amplitudes and frequency are inconsistent with an origin in asteroid breakups or Oort cloud disturbances, but are consistent with the arrival and disintegration in near-Earth orbits of rare, giant comets, mainly in transit from the Centaur population into the Jupiter family and Encke regions. About 1 in 10 Centaurs in Chiron-like orbits enter Earth-crossing epochs, usually repeatedly, each such epoch being generally of a few thousand years' duration. On time-scales of geological interest, debris from their breakup may increase the mass of the near-Earth interplanetary environment by two or three orders of magnitude, yielding repeated episodes of bombardment and stratospheric dusting. I find a strong correlation between these bombardment episodes and major biostratigraphic and geological boundaries, and propose that episodes of extinction are most effectively driven by prolonged encounters with meteoroid streams during bombardment episodes. Possible mechanisms are discussed.

  7. Giant comets and mass extinctions of life

    CERN Document Server

    Napier, W M

    2015-01-01

    I find evidence for clustering in age of well-dated impact craters over the last 500 Myr. At least nine impact episodes are identified, with durations whose upper limits are set by the dating accuracy of the craters. Their amplitudes and frequency are inconsistent with an origin in asteroid breakups or Oort cloud disturbances, but are consistent with the arrival and disintegration in near-Earth orbits of rare, giant comets, mainly in transit from the Centaur population into the Jupiter family and Encke regions. About 1 in 10 Centaurs in Chiron-like orbits enter Earth-crossing epochs, usually repeatedly, each such epoch being generally of a few thousand years duration. On time-scales of geological interest, debris from their breakup may increase the mass of the near-Earth interplanetary environment by two or three orders of magnitude, yielding repeated episodes of bombardment and stratospheric dusting. I find a strong correlation between these bombardment episodes and major biostratigraphic and geological boun...

  8. Meteors Without Borders: a global campaign

    Science.gov (United States)

    Heenatigala, T.

    2012-01-01

    "Meteors Without Borders" is a global project, organized by Astronomers Without Borders and launched during the Global Astronomy Month in 2010 for the Lyrid meteor shower. The project focused on encouraging amateur astronomy groups to hold public outreach events for major meteor showers, conduct meteor-related classroom activities, photography, poetry and art work. It also uses social-media platforms to connect groups around the world to share their observations and photography, live during the events. At the International Meteor Conference 2011, the progress of the project was presented along with an extended invitation for collaborations for further improvements of the project.

  9. Determination of the meteor limiting magnitude

    Science.gov (United States)

    Kingery, A.; Blaauw, R. C.

    2017-09-01

    We present our method to calculate the meteor limiting magnitude. The limiting meteor magnitude defines the faintest magnitude at which all meteors are still detected by a given system. An accurate measurement of the limiting magnitude is important in order to calculate the meteoroid flux from a meteor shower or sporadic source. Since meteor brightness is linked to meteor mass, the limiting magnitude is needed to calculate the limiting mass of the meteor flux measurement. The mass distribution of meteoroids is thought to follow a power law, thus being slightly off in the limiting magnitude can have a significant effect on the measured flux. Sky conditions can change on fairly short timescales; therefore one must monitor the meteor limiting magnitude at regular intervals throughout the night, rather than just measuring it once. We use the stellar limiting magnitude as a proxy of the meteor limiting magnitude. Our method for determining the stellar limiting magnitude and how we transform it into the meteor limiting magnitude is presented. These methods are currently applied to NASA's wide-field meteor camera network to determine nightly fluxes, but are applicable to other camera networks.

  10. Comet of the Century

    Science.gov (United States)

    Schaaf, Fred; Ottewell, G.

    The present century has been a disappointing one for comets, but past centuries often featured spectacular, unforgettable comet shows that dominated the night (and even daytime) sky for months: comets that outshone Venus or even the Moon, whose spectacular tails stretched more than halfway across the sky or were weirdly split, and whose apparition was held responsible for everything from wars to unusually good wine vintages. Published to coincide with the first naked-eye appearance of Comet Hale-Bopp, perhaps our own comet of the century, this book is an irresistible guide to comet facts and lore throughout history.

  11. Canadian Meteor Orbit Radar (CMOR

    Directory of Open Access Journals (Sweden)

    A. R. Webster

    2004-01-01

    Full Text Available The radar system described here (CMOR comprises a basic 5-element receiving system, co-located with a pulsed transmitter, specifically designed to observe meteor echoes and to determine their position in space with an angular resolution of ~1° and a radial resolution of ~3 km. Two secondary receiving sites, a few km distant and arranged to form approximately a right angle with the base station, allow the determination of the velocity (speed and direction of the meteor that, together with the time of occurrence, lead to an estimate of the orbit of the original meteoroid. Some equipment details are presented along with a method used to determine the orbits. Representative echoes are shown and observations on the 2002 Leonid shower presented.

  12. Kharkiv Meteor Radar System (the XX Age)

    Science.gov (United States)

    Kolomiyets, S. V.

    2012-09-01

    Kharkiv meteor radar research are of historic value (Kolomiyets and Sidorov 2007). Kharkiv radar observations of meteors proved internationally as the best in the world, it was noted at the IAU General Assembly in 1958. In the 1970s Kharkiv meteor automated radar system (MARS) was recommended at the international level as a successful prototype for wide distribution. Until now, this radar system is one of the most sensitive instruments of meteor radars in the world for astronomical observations. In 2004 Kharkiv meteor radar system is included in the list of objects which compose the national property of Ukraine. Kharkiv meteor radar system has acquired the status of the important historical astronomical instrument in world history. Meteor Centre for researching meteors in Kharkiv is a analogue of the observatory and performs the same functions of a generator and a battery of special knowledge and skills (the world-famous studio). Kharkiv and the location of the instrument were brand points on the globe, as the place where the world-class meteor radar studies were carried out. They are inscribed in the history of meteor astronomy, in large letters and should be immortalized on a world-wide level.

  13. Meteor Streams and Parent Bodies

    OpenAIRE

    Klacka, Jozef

    1999-01-01

    Problem of meteor orbit determination for a given parent body is discussed. Some of the published methods for obtaining meteoroid's orbital elements at the moment of intersecting Earth's orbit on the basis of geometrical variation of parent body's orbital elements are discussed. The main result concerns the following two facts: i) in real situations physical quantities for the change of orbital elements of the parent body must be used, and, ii) the usage of Southworth and Hawkins (1963) D-cri...

  14. Big data era in meteor science

    Science.gov (United States)

    Vinković, D.; Gritsevich, M.; Srećković, V.; Pečnik, B.; Szabó, G.; Debattista, V.; Škoda, P.; Mahabal, A.; Peltoniemi, J.; Mönkölä, S.; Mickaelian, A.; Turunen, E.; Kákona, J.; Koskinen, J.; Grokhovsky, V.

    2016-01-01

    Over the last couple of decades technological advancements in observational techniques in meteor science have yielded drastic improvements in the quality, quantity and diversity of meteor data, while even more ambitious instruments are about to become operational. This empowers meteor science to boost its experimental and theoretical horizons and seek more advanced science goals. We review some of the developments that push meteor science into the big data era that requires more complex methodological approaches through interdisciplinary collaborations with other branches of physics and computer science. We argue that meteor science should become an integral part of large surveys in astronomy, aeronomy and space physics, and tackle the complexity of micro-physics of meteor plasma and its interaction with the atmosphere.

  15. The 25th International Meteor Conference

    Science.gov (United States)

    Roggemans, Paul

    2006-08-01

    Since the founding of the International Meteor Organization, the International Meteor Conferences guaranteed the vital personal contacts between its members. In recent years IMCs were sometimes assumed to have started with IMO. However, the IMCs grew out of a much older initiative, the Meteor Seminars that started in 1979, later also called International Meteor Weekends. These events played a crucial role in the making of the IMO. The 2006 IMC in Roden, the Netherlands later this year is in fact a jubilee edition as it is the 25th edition since the very beginning in 1979!

  16. Physics of comets

    CERN Document Server

    Krishna Swamy, K S

    1997-01-01

    The study of Comet Halley in 1986 was a tremendous success for cometary science. In March of that year, six spacecrafts passed through Comet Halley as close as 600 km from the nucleus and made the in situ measurements of various kinds. These space missions to Comet Halley and that of the ICE spacecraft to Comet Giacobini-Zinner combined with studies, both ground-based and above the atmosphere, have increased our knowledge of cometary science in a dramatic way.This new edition of Physics of Comets incorporates these new and exciting findings. The emphasis of the book is on the physical processe

  17. Visibility of comet nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Ney, E.P.

    1982-01-22

    Photography of the nucleus of comet Halley is the goal of several planned space missions. The nucleus of a comet is surrounded by a cloud of dust particles. If this cloud is optically thick, it will prevent observation of the nuclear surface. Broadband photometry of nine comets has been analyzed to determine the visibility of their nuclei. Only in the case of comet West near perihelion was the dust dense enough to interfere with imaging. Comparison of the visual brightness of the well-observed comets with that of Halley in 1910 leads to the conclusion that the nucleus of Halley can be imaged without significant obscuration by the dust.

  18. Visually observing comets

    CERN Document Server

    Seargent, David A J

    2017-01-01

    In these days of computers and CCD cameras, visual comet observers can still contribute scientifically useful data with the help of this handy reference for use in the field. Comets are one of the principal areas for productive pro-amateur collaboration in astronomy, but finding comets requires a different approach than the observing of more predictable targets. Principally directed toward amateur astronomers who prefer visual observing or who are interested in discovering a new comet or visually monitoring the behavior of known comets, it includes all the advice needed to thrive as a comet observer. After presenting a brief overview of the nature of comets and how we came to the modern understanding of comets, this book details the various types of observations that can usefully be carried out at the eyepiece of a telescope. Subjects range from how to search for new comets to visually estimating the brightness of comets and the length and orientation of tails, in addition to what to look for in comet heads a...

  19. Meteor Streams and Parent Bodies

    CERN Document Server

    Klacka, J

    1999-01-01

    Problem of meteor orbit determination for a given parent body is discussed. Some of the published methods for obtaining meteoroid's orbital elements at the moment of intersecting Earth's orbit on the basis of geometrical variation of parent body's orbital elements are discussed. The main result concerns the following two facts: i) in real situations physical quantities for the change of orbital elements of the parent body must be used, and, ii) the usage of Southworth and Hawkins (1963) D-criterion yields results not corresponding to observations.

  20. Global variation of meteor trail plasma turbulence

    Directory of Open Access Journals (Sweden)

    L. P. Dyrud

    2011-12-01

    Full Text Available We present the first global simulations on the occurrence of meteor trail plasma irregularities. These results seek to answer the following questions: when a meteoroid disintegrates in the atmosphere, will the resulting trail become plasma turbulent? What are the factors influencing the development of turbulence? and how do these trails vary on a global scale? Understanding meteor trail plasma turbulence is important because turbulent meteor trails are visible as non-specular trails to coherent radars. Turbulence also influences the evolution of specular radar meteor trails; this fact is important for the inference of mesospheric temperatures from the trail diffusion rates, and their usage for meteor burst communication. We provide evidence of the significant effect that neutral atmospheric winds and ionospheric plasma density have on the variability of meteor trail evolution and on the observation of non-specular meteor trails. We demonstrate that trails are far less likely to become and remain turbulent in daylight, explaining several observational trends for non-specular and specular meteor trails.

  1. Sporadic E-Layers and Meteor Activity

    Science.gov (United States)

    Alimov, Obid

    2016-07-01

    In average width it is difficult to explain variety of particularities of the behavior sporadic layer Es ionospheres without attraction long-lived metallic ion of the meteoric origin. Mass spectrometric measurements of ion composition using rockets indicate the presence of metal ions Fe+, Mg+, Si+, Na+, Ca+, K+, Al+ and others in the E-region of the ionosphere. The most common are the ions Fe+, Mg+, Si+, which are primarily concentrated in the narrow sporadic layers of the ionosphere at altitudes of 90-130 km. The entry of meteoric matter into the Earth's atmosphere is a source of meteor atoms (M) and ions (M +) that later, together with wind shear, produce midlatitude sporadic Es layer of the ionosphere. To establish the link between sporadic Es layer and meteoroid streams, we proceeded from the dependence of the ionization coefficient of meteors b on the velocity of meteor particles in different meteoroid streams. We investigated the dependence of the critical frequency f0Es of sporadic E on the particle velocity V of meteor streams and associations. It was established that the average values of f0Es are directly proportional to the velocity V of meteor streams and associations, with the correlation coefficient of 0.53 ions M+ of meteoric origin.

  2. Forward scattering of meteors at multiple frequencies

    Science.gov (United States)

    Nedeljkovic, S.; Netterfield, C. B.

    2006-05-01

    Forward scattering of meteors is a method of meteor detection using a radio receiver to detect signals coming from the transmitters not in line-of-sight. When a meteoroid enters the atmosphere an ionized trail which can reflect radio waves is created. If the meteor, the transmitter and the receiver are in "good" geometrical alignment such that coherent scattering is possible, the receiver will be able to detect a signal reflected from the meteor. A digital radio spectrometer working between 50 and 150MHz and connected to a small wide-frequency, wide-beam antenna can be used as a detector. Its spectral resolution is better than 50kHz and able to resolve individual FM radio and TV stations. In this paper we shall give an overview of the apparatus used to detect meteors at FM frequencies. We will also explain how we can extract the kinetic parameters of the meteoroid. Some preliminary results will be presented.

  3. Stratospheric Sampling and In Situ Atmospheric Chemical Element Analysis During Meteor Showers: A Resource Study

    Science.gov (United States)

    Noever, David A.

    2000-01-01

    Resources studies for asteroidal mining evaluation have depended historically on remote sensing analysis for chemical elements. During the November 1998 Leonids meteor shower, a stratospheric balloon and various low-density capture media were used to sample fragments from Comet Tempel-Tuttle debris during a peak Earth crossing. The analysis not only demonstrates how potential sampling strategies may improve the projections for metals or rare elements in astromining, but also benchmarks materials during low temperature (-60 F), high dessication environments as seen during atmospheric exposure. The results indicate high aluminum, magnesium and iron content for various sampled particles recovered, but generalization to the sporadic meteors expected from asteroidal sources will require future improvements in larger sampling volumes before a broad-use strategy for chemical analysis can be described. A repeat of the experimental procedure is planned for the November 1999 Leonids' shower, and various improvements for atmospheric sampling will be discussed.

  4. Letter - Reply: Meteors in Australian Aboriginal Dreamings

    Science.gov (United States)

    Hamacher, Duane W.

    2011-06-01

    In response to the letter by Gorelli (2010) about Hamacher & Norris (2010), he is quite right about Aboriginal people witnessing impact events in Australia. There are several oral traditions regarding impact sites, some of which were probably witnessed, as Gorelli pointed out. The Henbury craters he mentions, with a young age of only ∼ 4200 years, have oral traditions that seem to describe a cosmic impact, including an aversion to drinking water that collects in the craters in fear that the fire-devil (which came from the sun, according to an Elder) would rain iron in them again. Other impact sites, such as Gosse's Bluff crater (Tnorala in the Arrernte language) and Wolfe Creek crater (Kandimalal in the Djaru language) have associated impact stories, despite their old ages (142 Ma and ∼0.3 Ma, respectively). In addition, many fireball and airburst events are described in Aboriginal oral traditions, a number of which seem to indicate impact events that are unknown to Western science. I have published a full treatise of meteorite falls and impact events in Australian Aboriginal culture that I would like to bring to the attention of Gorelli and WGN readers (Hamacher & Norris, 2009). Although our paper was published in the 2009 volume of Archaeoastronomy, it did not appear in print until just recently, which is probably why it has gone unnoticed. Recent papers describing the association between meteorites and Aboriginal cosmology (Hamacher, 2011) and comets in Aboriginal culture (Hamacher & Norris, 2011) have also been published, and would likely be of interest to WGN readers. I heartily agree with Gorelli that oral traditions are fast disappearing, taking with them a wealth of information about not only that peoples' culture, but also about past geologic and astronomical events, such as meteorite falls and cosmic impacts (a branch of the growing field of Geomythology). There is an old saying that "when a man dies, a library goes with him". This is certainly the

  5. The Zodiacal Cloud Model applied to the Martian atmosphere. Diurnal variations in Meteoric ion layers

    Science.gov (United States)

    Diego Carrillo-Sánchez, Juan; Plane, John M. C.; Withers, Paul; Fallows, Kathryn; Nesvorný, David; Pokorný, Petr; Feng, Wuhu

    2016-04-01

    Sporadic metal layers have been detected in the Martian atmosphere by radio occultation measurements using the Mars Express Orbiter and Mars Global Surveyor spacecraft. More recently, metallic ion layers produced by the meteor storm event following the close encounter between Comet Siding Spring (C/2013 A1) and Mars were identified by the Imaging UltraViolet Spectrograph (IUVS) aboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft. However, the background metal layers produced by the influx of sporadic meteors have not yet been detected at Mars (contrary to the permanent metal layers identified in the Earth's atmosphere). The Zodiacal Dust Cloud (ZDC) model for particle populations released by asteroids (AST), and dust grains from Jupiter Family Comets (JFC) and Halley-Type Comets (HTC) has been combined with a Monte Carlo sampling method and the Chemical ABlation MODel (CABMOD) to predict the ablation rates of Na, K, Fe, Si, Mg, Ca and Al above 40 km altitude in the Martian atmosphere. CABMOD considers the standard treatment of meteor physics, including the balance of frictional heating by radiative losses and the absorption of heat energy through temperature increases, melting phase transitions and vaporization, as well as sputtering by inelastic collisions with the air molecules. These vertical profiles are input into the Leeds 1-D Mars atmospheric model which includes photo-ionization, and gas-phase ion-molecule and neutral chemistry, in order to explore the evolution of the resulting metallic ions and atoms. We conclude that the formation of the sporadic ion layers observed below 100 km with a plasma density exceeding 104 cm-3 requires the combination of the three different influx sources considered by the ZDC model, with a significant asteroidal contribution. Finally, we explore the changes of the neutral and ionized Mg and Fe layers over a diurnal cycle.

  6. I Spy a Comet!

    Science.gov (United States)

    2005-01-01

    This image shows comet Tempel 1 as seen through the clear filter of the medium resolution imager camera on Deep Impact. It was taken on June 25, 2005, when the spacecraft was 8,007,845.1 kilometers (4,976,075 miles) away from the comet. Ten images were combined to create this picture, and a logarithmic stretch was applied to enhance the coma of the comet.

  7. A meteor stream study of 1966

    Science.gov (United States)

    Terentjeva, Alexandra

    2017-03-01

    3600 individual photographic orbits of meteor bodies and about 2000 visual meteor radiants with corresponding velocities were compiled and carefully studied in detail. 154 minor meteor streams were detected in the Solar System, their basic orbital and other data are given. Firstly some remarkable shower and stream properties are established: examples of the large elliptic radiation areas with semi-major axes perpendicular to the Ecliptic; the existence of the Northern (N) , Southern (S) and Ecliptical (Q) branches of some streams; stream-antipodes and radiant-antipodes (symmetrically arranged relatively to the Ecliptic) with angular distances from the Ecliptic to 40-80°; a number of short-perihelion streams (q 0.05-0.07 A.U.); some meteor streams perpendicular to the Ecliptic's plane. There are also some unique meteor bodies with their orbits enclosed within the limits of the Earth's one, or having the clockwise and anticlockwise direction in two similar orbits. Hyperbolic photographic velocities vh = 57-88 km /sec are treated as real ones according to the best radar and visual observations. A "bunch" of ecliptical streams, discovered in the USSR in 1950, is a complex of orbits of the mostly massive meteor particles of the Zodiacal Cloud. The stream evolution rate is comparatively high. The total complex of sporadic meteor bodies is not totally chaotic and accidental.

  8. Research on artificial meteor trail emergency communication

    Science.gov (United States)

    Juntao, Liu; Xijun, Yan; Li, Jia

    As the particles known as meteors enter the earth's atmosphere, a small fraction of which can form ionized cloud, this ionized cloud has property useful for reflecting electromagnetic wave. Meteor burst communication is a point to point communication technology base on the above principle. Similarly, artificial meteor trail communication establishes “ionized cloud” signal channel by alkali metal ionizing at high-altitude ionosphere to reflect electromagnetic waves. Currently, Meteor burst communication is a mature communication technology with many advantages. However, as a completely uncontrollable natural phenomena, the communication time, duration time, the amount of information transmitted and antenna alignment direction are all uncontrollable. We can only figure out key parameters such as throughput and waiting time within a certain time relying on statistical regularities. Information transmission between specified sites in certain time is impossible to predict accurately. These disadvantages greatly reduce the dependability of meteor trail communication and cannot meet emergency communication’s requirements for real-time, controllable and uninterrupted. Artificial meteor trail emergency communication technology solves the above problems, it’s a reliable emergency telecommunication method. This paper focuses on the necessity and feasibility of artificial meteor trail emergency communication technology, as well as its future application.

  9. Listening to FM and Chasing Meteors

    Science.gov (United States)

    Nedeljkovic, Sasa; Barth Netterfield, C.

    2005-08-01

    This poster will show how a digital radio spectrometer working between 50 and 150 MHz can be used for meteor detection. The spectrometer is connected to a small wide-frequency, wide-beam antenna. With better than 50 kHz spectral resolution, the instrument can resolve individual FM radio and TV stations. Existing commercial transmitters over the horizon will be used as transmitters for the forward scattering method of meteor detection. Given the frequency, directivity, and power of transmitters, and time evolution of the reflection, we can extract dynamical parameters of the meteor using only one receiver.

  10. Meteor shower activity derived from meteor watching public campaign in Japan

    Science.gov (United States)

    Ishizaki, Masaharu; Watanabe, Jun-ichi; Sato, Mikiya

    2017-09-01

    We have carried out a meteor watching public campaigns from 2004 for major meteor showers in the case of appropriate observing condition as one of the outreach programs conducted by National Astronomical Observatory of Japan. We received a huge number of the reports on meteor counts from the general public participants. The results sometimes show similar time variation of the hourly rates derived from the data collected by skilled observers. In this paper, some of the results are presented showing that such campaigns have a potential to extract scientific result related to the meteor showers mainly due to the large number of the data collected by unskilled observers.

  11. The KUT meteor radar: An educational low cost meteor observation system by radio forward scattering

    Science.gov (United States)

    Madkour, W.; Yamamoto, M.

    2016-01-01

    The Kochi University of Technology (KUT) meteor radar is an educational low cost observation system built at Kochi, Japan by successive graduate students since 2004. The system takes advantage of the continuous VHF- band beacon signal emitted from Fukui National College of Technology (FNCT) for scientific usage all over Japan by receiving the forward scattered signals. The system uses the classical forward scattering setup similar to the setup described by the international meteor organization (IMO), gradually developed from the most basic single antenna setup to the multi-site meteor path determination setup. The primary objective is to automate the observation of the meteor parameters continuously to provide amounts of data sufficient for statistical analysis. The developed software system automates the observation of the astronomical meteor parameters such as meteor direction, velocity and trajectory. Also, automated counting of meteor echoes and their durations are used to observe mesospheric ozone concentration by analyzing the duration distribution of different meteor showers. The meteor parameters observed and the methodology used for each are briefly summarized.

  12. An emerging chemical classifications of comets: implications for the early Solar System

    Science.gov (United States)

    Mumma, M. J.

    Cometary nuclei are messengers from the early solar system; they contain key information from the time when planets were forming, and even earlier - some contain material from the natal interstellar cloud. During the first 500 million years of Earth's existence, comets likely delivered vast quantities of pre-biotic organic material along with water for its oceans. The most easily modified forms of matter -the ices, low-temperature-refractory organics, and refractory minerals - hold special significance for understanding these processes. More than two dozen parent volatile species can be characterized directly from Earth-based observatories. Hyakutake and Hale-Bopp were the first bright comets to be studied with powerful new astronomical facilities. A wealth of new information on cometary organic composition was obtained, including the discovery of symmetric hydrocarbons (methane, ethane, acetylene) by infrared spectroscopy and the detection of six new parent volatiles at radio wavelengths. Since then, larger telescopes and even more powerful instruments have become available, permitting in-depth investigation of much fainter comets. With the powerful cross-dispersed cryogenic infrared echelle spectrometer (NIRSPEC, at the 10-m Keck-2 telescope), ten parent volatile species can be characterized in about two hours, eliminating many sources of systematic error. Six Oort cloud comets have been studied with it since 1999. The apparition of two bright comets in spring 2004 doubled the number of comets in which more than a dozen parent volatiles were quantified. The compositions of eleven Oort-cloud comets (including comet Halley and the deceased comet C/1999 S4 LINEAR) and two Jupiter-family comets (Encke, G-Z) will be compared and discussed in the context of chemical diversity in the giant-planets' nebular region. Implications for the delivery of water and pre-biotic organics to the early Earth will be mentioned. Mumma, M. J. et al. (2001), Ap. J. 546, 1183-1193. Mumma

  13. Comparison with Russian analyses of meteor impact

    Energy Technology Data Exchange (ETDEWEB)

    Canavan, G.H.

    1997-06-01

    The inversion model for meteor impacts is used to discuss Russian analyses and compare principal results. For common input parameters, the models produce consistent estimates of impactor parameters. Directions for future research are discussed and prioritized.

  14. Meteor Shower Forecasting for Spacecraft Operations

    Science.gov (United States)

    Moorhead, Althea V.; Cooke, William J.; Campbell-Brown, Margaret D.

    2017-01-01

    Although sporadic meteoroids are a much greater hazard to spacecraft than shower meteoroids in general, meteor showers can significantly increase the risk of damage over short time periods. Because showers are brief, it is sometimes possible to mitigate the risk operationally, which requires accurate predictions of shower activity. NASA's Meteoroid Environment Office generates an annual meteor shower forecast that describes the variations in the near-Earth meteoroid flux produced by meteor showers, which presents the shower flux both in absolute terms and relative to the sporadic ux. The shower forecast incorporates model predictions of annual variations in shower activity and quotes fluxes to several limiting particle kinetic energies. In this work, we describe our forecasting methods, compare them to actual observations, and highlight recent improvements to the temporal pro les based on flux measurements from the Canadian Meteor Orbit Radar (CMOR).

  15. Analysis of ALTAIR 1998 Meteor Radar Data

    Science.gov (United States)

    Zinn, J.; Close, S.; Colestock, P. L.; MacDonell, A.; Loveland, R.

    2011-01-01

    We describe a new analysis of a set of 32 UHF meteor radar traces recorded with the 422 MHz ALTAIR radar facility in November 1998. Emphasis is on the velocity measurements, and on inferences that can be drawn from them regarding the meteor masses and mass densities. We find that the velocity vs altitude data can be fitted as quadratic functions of the path integrals of the atmospheric densities vs distance, and deceleration rates derived from those fits all show the expected behavior of increasing with decreasing altitude. We also describe a computer model of the coupled processes of collisional heating, radiative cooling, evaporative cooling and ablation, and deceleration - for meteors composed of defined mixtures of mineral constituents. For each of the cases in the data set we ran the model starting with the measured initial velocity and trajectory inclination, and with various trial values of the quantity mPs 2 (the initial mass times the mass density squared), and then compared the computed deceleration vs altitude curves vs the measured ones. In this way we arrived at the best-fit values of the mPs 2 for each of the measured meteor traces. Then further, assuming various trial values of the density Ps, we compared the computed mass vs altitude curves with similar curves for the same set of meteors determined previously from the measured radar cross sections and an electrostatic scattering model. In this way we arrived at estimates of the best-fit mass densities Ps for each of the cases. Keywords meteor ALTAIR radar analysis 1 Introduction This paper describes a new analysis of a set of 422 MHz meteor scatter radar data recorded with the ALTAIR High-Power-Large-Aperture radar facility at Kwajalein Atoll on 18 November 1998. The exceptional accuracy/precision of the ALTAIR tracking data allow us to determine quite accurate meteor trajectories, velocities and deceleration rates. The measurements and velocity/deceleration data analysis are described in Sections

  16. The Southern Argentine Agile Meteor Radar (SAAMER)

    Science.gov (United States)

    Janches, Diego

    2014-11-01

    The Southern Argentina Agile Meteor Radar (SAAMER) is a new generation system deployed in Rio Grande, Tierra del Fuego, Argentina (53 S) in May 2008. SAAMER transmits 10 times more power than regular meteor radars, and uses a newly developed transmitting array, which focuses power upward instead of the traditional single-antenna-all-sky configuration. The system is configured such that the transmitter array can also be utilized as a receiver. The new design greatly increases the sensitivity of the radar enabling the detection of large number of particles at low zenith angles. The more concentrated transmitted power enables additional meteor studies besides those typical of these systems based on the detection of specular reflections, such as routine detections of head echoes and non-specular trails, previously only possible with High Power and Large Aperture radars. In August 2010, SAAMER was upgraded to a system capable to determine meteoroid orbital parameters. This was achieved by adding two remote receiving stations approximately 10 km away from the main site in near perpendicular directions. The upgrade significantly expands the science that is achieved with this new radar enabling us to study the orbital properties of the interplanetary dust environment. Because of the unique geographical location, SAAMER allows for additional inter-hemispheric comparison with measurements from Canadian Meteor Orbit Radar, which is geographically conjugate. Initial surveys show, for example, that SAAMER observes a very strong contribution of the South Toroidal Sporadic meteor source, of which limited observational data is available. In addition, SAAMER offers similar unique capabilities for meteor showers and streams studies given the range of ecliptic latitudes that the system enables detailed study of showers at high southern latitudes (e.g July Phoenicids or Puppids complex). Finally, SAAMER is ideal for the deployment of complementary instrumentation in both, permanent

  17. A Comet's Missing Light

    Science.gov (United States)

    Kohler, Susanna

    2016-05-01

    On 28 November 2013, comet C/2012 S1 better known as comet ISON should have passed within two solar radii of the Suns surface as it reached perihelion in its orbit. But instead of shining in extreme ultraviolet (EUV) wavelengths as it grazed the solar surface, the comet was never detected by EUV instruments. What happened to comet ISON?Missing EmissionWhen a sungrazing comet passes through the solar corona, it leaves behind a trail of molecules evaporated from its surface. Some of these molecules emit EUV light, which can be detected by instruments on telescopes like the space-based Solar Dynamics Observatory (SDO).Comet ISON, a comet that arrived from deep space and was predicted to graze the Suns corona in November 2013, was expected to cause EUV emission during its close passage. But analysis of the data from multiple telescopes that tracked ISON in EUV including SDO reveals no sign of it at perihelion.In a recent study, Paul Bryans and DeanPesnell, scientists from NCARs High Altitude Observatory and NASA Goddard Space Flight Center, try to determine why ISON didnt display this expected emission.Comparing ISON and LovejoyIn December 2011, another comet dipped into the Suns corona: comet Lovejoy. This image, showingthe orbit Lovejoy took around the Sun, is a composite of SDO images of the pre- and post-perihelion phases of the orbit. Click for a closer look! The dashed part of the curve represents where Lovejoy passed out of view behind the Sun. [Bryans Pesnell 2016]This is not the first time weve watched a sungrazing comet with EUV-detecting telescopes: Comet Lovejoy passed similarly close to the Sun in December 2011. But when Lovejoy grazed the solar corona, it emitted brightly in EUV. So why didnt ISON? Bryans and Pesnell argue that there are two possibilities:the coronal conditions experienced by the two comets were not similar, orthe two comets themselves were not similar.To establish which factor is the most relevant, the authors first demonstrate that both

  18. Regular and transitory showers of comet C/1979 Y1 (Bradfield)

    Science.gov (United States)

    Hajduková, M.; Neslušan, L.

    2017-09-01

    Aims: We intend to map the whole meteor complex of the long-period comet C/1979 Y1 (Bradfield), which is a proposed parent body of the July Pegasids, No. 175 in the list of meteor showers established by the Meteor Data Center (MDC) of the International Astronomical Union (IAU). Methods: For five perihelion passages of the parent comet in the past, we model associated theoretical stream, its parts, each consisting of 10 000 test particles, and follow the dynamical evolution of these parts up to the present. Subsequently, we analyze the mean orbital characteristics of those particles of the parts that approach the Earth's orbit and, thus, create a shower or showers. The showers are compared with their observed counterparts separated from photographic, radio, and several video databases. Results: The modeled stream of C/1979 Y1 approaches the Earth's orbit in two filaments that correspond to two regular (annual) showers. We confirm the generic relationship between the studied parent comet and 175 July Pegasids. The other predicted shower is a daytime shower with the mean radiant situated symmetrically to the July Pegasids with respect to the apex of the Earth's motion. This shower is not in the IAU MDC list, but we separated it from the Cameras-for-Allsky-Meteor-Surveillance (CAMS) and SonotaCo video data as a new shower. We suggest naming it α-Microscopiids. The stronger influence of the Poynting-Robertson drag deflects the stream away from the Earth's orbit in those sections that correspond to the July Pegasids and the predicted daytime shower, but it makes the stream cross the Earth's orbit in other sections. Corresponding showers are, however, only expected to survive during a limited period and to consist of particles of sizes in a narrow interval. We identified one of these "transitory" filaments to the 104 γ-Bootids in the IAU MDC list of meteor showers.

  19. Meteor-Shower on Mars Indicates Cometary Activity Far Away From the Sun

    Science.gov (United States)

    Sekhar, Aswin; ASHER, DAVID

    2015-08-01

    Introduction: The close encounter of Comet C/2013 A1 (Siding Spring) with Mars on 2014 Oct 19 at 1830h (UT) generated a lot of interest and modelling work [1] [2] [3] in the solar system community. A recent (on 2014 Nov 7) press release from NASA implied that a meteor shower was detected on Mars by their space instruments some hours after the comet-Mars close encounter. Various work [4] [5] [6] has suggested that very specific meteoroid sizes and ejection conditions may be required to produce meteor phenomena at Mars at the given times.Stream dynamics: Meteoroid stream modelling and their orbital geometry calculations have gained high precision over the years. In this work, we compute in detail the structure of the cloud of meteoroids released by C/2013 A1, showing its dependence on heliocentric ejection distances, 3-dimensional ejection velocities, and particle sizes. Our calculations using numerical integrator MERCURY, [7], incorporating radiation pressure, [8], show that ejection of particles at large heliocentric distances (about 7 au to 13 au) from C/2013 A1 could lead to evolution of a dense meteoroid cloud which intersects Mars a few hours after the comet-Mars close encounter. Hence this detection of a meteor shower on Mars by space instruments is an indirect confirmation of cometary activity at large distances which has rarely been observed directly by telescopes so far. Furthermore it shows that comprehensive threat estimation needs to be done for satellites orbiting the Earth when dynamically new comets come very close to the Earth in future.References:[1] Vaubaillon J., Macquet L., Soja R. 2014. MNRAS. 439: 3294.[2] Moorhead A. V., Wiegert P. A., Cooke W. J. 2014. Icarus. 231:13.[3] Ye Q.-Z., Hui M.-T., 2014, ApJ, 787: 115.[4] Farnocchia D. et al. 2014. ApJL. 790: 114.[5] Kelley M. S. P. et al. 2014, ApJL, 792: 16.[6] Tricarico P. et al., 2014, ApJL, 787: 35.[7] Chambers J. E. 1999. MNRAS. 304: 793.[8] Burns J. A, Lamy P. L., Soter S. 1979. Icarus. 40: 1.

  20. Meteor burst in the post 2000 era

    Science.gov (United States)

    Marriott, C.; Oduol, V.; Ghosh, A.; Tailor, B.

    In recent years a renewed interest has been shown in the possibility of using meteor burst links in tactical communications, both for networking and covert operations. Some of the applications that recent performance improvements would permit are evaluated. In evaluating the feasibility of a meteor burst implementation, certain technical and physical limitations are addressed. For the success of these applications, interoperability with other communication systems is necessary. The level of interoperability with other media, and the standards necessary to assure this interoperability are examined. Methods of minimizing and combating jamming are proposed. Meteor burst systems can be used in a large number of applications within a tactical environment. The principal disadvantage of the meteor burst medium is the problem of interference to other spectrum users from the probe end, and the interference from other users at the receiver end. The low throughput characteristic of meteor burst compares with some of the channel capacities used in other systems. Interoperability with other networks or communications links is relatively easy if certain straightforward protocols and standards are established.

  1. Comet composition and Lab

    Science.gov (United States)

    Bockelée-Morvan, Dominique; Biver, Nicolas

    2016-10-01

    Comet composition and properties provide information on chemical and physical processes that occurred in the early Solar system, 4.6 Gyr ago. The study of comets and of star-forming regions both help for a better understanding of the formation of planetary systems. A review of our present knowledge of cometary composition is presented. We also discuss laboratory studies that would be helpful for data analysis.

  2. IAU Meteor Data Center | the shower database: a status report

    CERN Document Server

    Jopek, Tadeusz Jan

    2016-01-01

    Currently, the meteor shower part of Meteor Data Center database includes: 112 established showers, 563 in the working list, among them 36 have pro tempore status and 23 will be removed from the list. The list of shower complexes contains 25 groups, 3 have established status and 1 has pro tempore status. In the past three years, new meteor showers submitted to the MDC database were detected amongst meteors observed by CAMS stations (Cameras for Allsky Meteor Surveillance), meteors included in the EDMOND (European viDeo MeteOr Network Database), meteors collected by Japanese SonotaCo Network, meteors recorded in IMO (International Meteor Organization) database, amongst meteors observed by Croatian Meteor Network and meteors observed on the Southern Hemisphere by the SAAMER radar. During the XXIXth General Assembly of the IAU in Honolulu, Hawaii in 2015, the names of 18 showers were o?cially accepted and moved to the list of established showers. Also, one shower already o?cially named (3/SIA the Southern iota A...

  3. Encke's special perturbation technique associated with the KS regularized variables. I - Satellite motions in the earth's gravitational field with axial symmetry

    Science.gov (United States)

    Awad, Mervat El-Sayed

    1988-10-01

    A special perturbation technique of Encke type associated with the Kustaanheimo-Stiefel (KS) regularized variables is developed for satellite motions in the earth's gravitational field with axial symmetry. Its computational algorithm is of recursive nature and could be applied to any perturbed conic motion, whatever the number of the zonal harmonic coefficients may be. Applications of the algorithm are also included.

  4. Determination of Parameters of Meteor Bodies from Observational Data with High Accuracy of Estimate

    Science.gov (United States)

    Gritsevich, Maria

    A great volume of data has been accumulated thus far related to the photoregistration of the paths of meteor bodies in the terrestrial atmosphere. Most images have been obtained by four fireball networks, which operate in the USA, Canada, Europe, and Spain in different time periods. The approximation of the actual data using theoretical models makes it possible to achieve additional estimates, which do not directly follow from the observations. For example, the correct mathematical modeling of meteor events in the atmosphere is necessary for further estimates of the key parameters, including the extra-atmospheric mass, the ablation coefficient, and the effective enthalpy of evaporation of entering bodies. In turn, this information is needed by some applications, namely, those aimed at studying the problems of asteroid and comet security, to develop measures of planetary defense, and to determine the bodies that can reach Earth's surface. In the report, the mathematical technique to find basic dynamic parameters of the theoretical relationship between the height and the velocity of the meteor body motion that help to fit observations along the luminous part of the trajectories in the best way is suggested. The main difference from previous studies is that the given observations are approximated using the analytical solution of the equations of meteor physics. Note that, for the limited values of the mass loss parameter, analytical solution is usually replaced by the simpler expression (e.g., Stulov et al., 1995). In particular, this approximate solution was earlier used as a trial function during the implementation of the least-squares method. New model presented in the report was applied to a number of bright meteors observed by the Canadian camera network and by the US Prairie network. Results of such calculation are partly presented. During our data processing we discovered several sufficiently thermostable meteor bodies whose mass loss parameters were almost

  5. Advances in Meteoroid and Meteor Science

    CERN Document Server

    Trigo-Rodríguez, J. M; Llorca, J; Janches, D

    2008-01-01

    This volume is a compilation of articles that summarize the most recent results in meteor, meteoroid and related fields presented at the Meteoroids 2007 conference held at the impressive CosmoCaixa Science Museum in Barcelona, Spain. The conference took place between the 11th and the 15th of June and was organized by the Institute of Space Sciences (Consejo Superior de Investigaciones Científicas, CSIC) and the Institut d'Estudis Espacials de Catalunya (IEEC). Researchers in meteor science and supporting fields representing more than 20 countries participated at this international conference. The papers contained in this volume underwent the rigorous refereeing process, and they are good examples of the continuous progress being made in this research field. Technological advances in meteor and metoroid detection, the ever-increasing sophistication of computer modeling, and the proliferation of autonomous monitoring stations continue to create new niches for exciting research on meteoroids and their parent bo...

  6. Independent identification of meteor showers in EDMOND database

    CERN Document Server

    Rudawska, R; Tóth, J; Kornoš, L

    2014-01-01

    Cooperation and data sharing among national networks and International Meteor Organization Video Meteor Database (IMO VMDB) resulted in European viDeo MeteOr Network Database (EDMOND). The current version of the database (EDMOND 5.0) contains 144 751 orbits collected from 2001 to 2014. In our survey we used EDMOND database in order to identify existing and new meteor showers in the database. In the first step of the survey, using Dsh criterion we found groups around each meteor within similarity threshold. Mean parameters of the groups were calculated and compared using a new function based on geocentric parameters (solar longitude, right ascension, declination, and geocentric velocity). Similar groups were merged into final clusters (representing meteor showers), and compared with IAU Meteor Data Center list of meteor showers. This paper presents the results obtained by the proposed methodology.

  7. The Radio Meteor Zoo: a citizen science project

    Science.gov (United States)

    Calders, S.; Verbeeck, C.; Lamy, H.; Martínez Picar, A.

    2016-01-01

    Scientists from the BRAMS radio meteor network have started a citizen science project called Radio Meteor Zoo in collaboration with Zooniverse in order to identify meteor reflections in BRAMS spectrograms. First, a small-scale version of the Radio Meteor Zoo was carried out with a sample of meteor identifications in 12 spectrograms by 35 volunteers. Results are presented here and allowed us to define a method that reliably detects meteor reflections based on the identifications by the volunteers. It turns out that, if each spectrogram is inspected by 10 volunteers, hit and false detection percentages of 95% respectively 6% are expected. The Radio Meteor Zoo is online at https://www.zooniverse.org/projects/zooniverse/radio-meteor-zoo. Citizen scientists are kindly invited to inspect spectrograms.

  8. Comets in Australian Aboriginal Astronomy

    CERN Document Server

    Hamacher, Duane W

    2010-01-01

    We present 25 accounts of comets from 40 Australian Aboriginal communities, citing both supernatural perceptions of comets and historical accounts of bright comets. Historical and ethnographic descriptions include the Great Comets of 1843, 1861, 1901, 1910, and 1927. We describe the perceptions of comets in Aboriginal societies and show that they are typically associated with fear, death, omens, malevolent spirits, and evil magic, consistent with many cultures around the world. We also provide a list of words for comets in 16 different Aboriginal languages.

  9. Comets in Australian Aboriginal Astronomy

    Science.gov (United States)

    Hamacher, Duane W.; Norris, Ray P.

    2011-03-01

    We present 25 accounts of comets from 40 Australian Aboriginal communities, citing both supernatural perceptions of comets and historical accounts of historically bright comets. Historical and ethnographic descriptions include the Great Comets of 1843, 1861, 1901, 1910, and 1927. We describe the perceptions of comets in Aboriginal societies and show that they are typically associated with fear, death, omens, malevolent spirits, and evil magic, consistent with many cultures around the world. We also provide a list of words for comets in 16 different Aboriginal languages.

  10. Infrasonic Tracking of the Chelyabinsk Meteor

    Science.gov (United States)

    Garces, M. A.; Smirnov, A.; Liszka, L.

    2013-12-01

    The Infrasonic Energy, Nth Octave (INFERNO) energy estimator of Garces (2013) is used in conjunction with the PMCC4 array processing algorithm to refine the chronology and energetics of infrasonic signals from the Chelyabinsk Meteor. We concentrate on infrasound array data from the closest stations: I31KZ (Aktyubinsk, Kazakhstan), I43RU (Dubna, Russia), and KURK (Kurchatov, Kazakhstan), using the published satellite trajectory as a starting point. This study systematically applies standardized, self-similar, logarithmic time-frequency multiresolution algorithms to infrasonic data with the aim of improving the temporal and spatial resolution of the arrivals associated with the meteor's impact.

  11. Modern Meteor Science An Interdisciplinary View

    CERN Document Server

    Hawkes, Robert; Brown, Peter

    2005-01-01

    This volume represents a blend of leading edge research and authoritative reviews in meteor science. It provides a comprehensive view of meteoroid research including the dynamics, sources and distribution of these bodies, and their chemistry and physical processes in the interplanetary medium and the Earth’s atmosphere. Techniques for investigation of meteor phenomena in the book include conventional and large aperture radar systems, spacecraft detection, optical systems, spectral measurements, and laboratory based interplanetary dust particle studies. The book will be of interest to researchers and students in astronomy, astrophysics, cosmochemistry, space engineering and space science. Cover photograph was taken by Masayuki Toda.

  12. Are There Meteors Originated from Near Earth Asteroid (25143) Itokawa?

    CERN Document Server

    Ohtsuka, K; Abe, M; Yano, H; Watanabe, J

    2008-01-01

    As a result of a survey of Itokawid meteors (i.e., meteors originated from Near Earth Asteroid (25143) Itokawa = 1998SF36), from among the multi-station optical meteor orbit data of ~15000 orbits, and applying the D-criteria, we could find five Itokawid meteor candidates. We also analyzed corresponding mineral materials of the Itokawid candidates through their trajectory and atmospheric data. We conclude, on the basis of our investigation, that the fireball, MORP172, is the strongest Itokawid candidate.

  13. Jupiter Laser Facility - COMET Laser

    Data.gov (United States)

    Federal Laboratory Consortium — COMET has 4 beam configurations with uncompressed pulse lengths from 500 ps to 6 ns, compressed pulses to 0.5 ps, and beam energies up to 20 J. COMET can fire every...

  14. Automated Meteor Fluxes with a Wide-Field Meteor Camera Network

    Science.gov (United States)

    Blaauw, R. C.; Campbell-Brown, M. D.; Cooke, W.; Weryk, R. J.; Gill, J.; Musci, R.

    2013-01-01

    Within NASA, the Meteoroid Environment Office (MEO) is charged to monitor the meteoroid environment in near ]earth space for the protection of satellites and spacecraft. The MEO has recently established a two ]station system to calculate automated meteor fluxes in the millimeter ]size ]range. The cameras each consist of a 17 mm focal length Schneider lens on a Watec 902H2 Ultimate CCD video camera, producing a 21.7 x 16.3 degree field of view. This configuration has a red ]sensitive limiting meteor magnitude of about +5. The stations are located in the South Eastern USA, 31.8 kilometers apart, and are aimed at a location 90 km above a point 50 km equidistant from each station, which optimizes the common volume. Both single station and double station fluxes are found, each having benefits; more meteors will be detected in a single camera than will be seen in both cameras, producing a better determined flux, but double station detections allow for non ]ambiguous shower associations and permit speed/orbit determinations. Video from the cameras are fed into Linux computers running the ASGARD (All Sky and Guided Automatic Real ]time Detection) software, created by Rob Weryk of the University of Western Ontario Meteor Physics Group. ASGARD performs the meteor detection/photometry, and invokes the MILIG and MORB codes to determine the trajectory, speed, and orbit of the meteor. A subroutine in ASGARD allows for the approximate shower identification in single station meteors. The ASGARD output is used in routines to calculate the flux in units of #/sq km/hour. The flux algorithm employed here differs from others currently in use in that it does not assume a single height for all meteors observed in the common camera volume. In the MEO system, the volume is broken up into a set of height intervals, with the collecting areas determined by the radiant of active shower or sporadic source. The flux per height interval is summed to obtain the total meteor flux. As ASGARD also

  15. Luceafarul: a Romanian meteor-inspired poem.

    Science.gov (United States)

    McBeath, A.; Ghoerghe, A. D.

    1999-10-01

    The poem Luceafarul, written by Mihai Eminescu and first published in 1883, is considered as being the greatest Romanian poetic masterpiece. In commemorating the 110th anniversary of the author's death in 1999, the authors present here a short discussion of the poem's astronomical imagery, which includes the re-using of long-held beliefs about meteors from old Romanian myths and folklore.

  16. CONTENUTO DI URANIO E TORIO NELLE METEORITI

    Directory of Open Access Journals (Sweden)

    M. SANTANGELO

    1955-06-01

    Full Text Available Molti ricercatori in questi ultimi anni si sono interessati al problema
    della composizione delle meteoriti; dai risultati sperimentali si
    è cercato trarre elementi circa la genesi di questi materiali, questione
    ancora aperta, ed avere informazioni sui processi chimici e termodinamici
    cui le meteoriti furono soggette prima della loro caduta sulla
    terra.
    Uno degli aspetti del problema è quello dell'abbondanza percentuale
    degli elementi chimici e della loro composizione isotopica nella
    materia meteorica dei diversi tipi : ciò perché esso è connesso con
    quello piii generale dell'origine e distribuzione degli elementi nel cosmo
    e nella terra, nonché con quello dell'età delle meteoriti (l .
    In un recente lavoro Urey e collaboratori (-, esaminando un gran
    numero di analisi chimiche effettuate su questi materiali, sono pervenuti
    alla formulazione di alcuni criteri di classificazione in base alla
    percentuale dei componenti più abbondanti ed alla presenza o meno
    di disomogeneità strutturali nella massa fondamentale. Fra gli elementi
    meno abbondanti presentano particolare interesse quelli delle due famiglie
    radioattive naturali Torio e Uranio; le loro concentrazioni sono
    state determinate per alcune meteoriti siliciche (stonv ineteorites e
    per qualcuna ferrica (iron meteorites

  17. The Makings of Meteor Astronomy: Part IX

    Science.gov (United States)

    Beech, M.

    1995-04-01

    Chladni's ideas on the origin of fireballs, shooting stars and meteorites were not fully formed when he first published his thesis in 1794. Below we discuss some of the initial debate concerning the origin of Chladni's cosmic masses. We also discuss a couple of hybrid meteor models.

  18. The makings of meteor astronomy: Part VIII.

    Science.gov (United States)

    Beech, M.

    1994-12-01

    Ernst Chladni (1756 - 1827) is often considered to be the father of modern meteor astronomy. While his thesis of 1794 offered no essentially new or innovative ideas it did break important ground in showing the clear inadequacies of the then accepted model of fireball origins.

  19. Comets in ancient India

    CERN Document Server

    Gupta, Patrick Das

    2014-01-01

    The Indo-aryans of ancient India observed stars and constellations for ascertaining auspicious times for sacrificial rites ordained by vedas. It is but natural that they would have recounted in the vedic texts about comets. In Rigveda ($\\sim $ 1700 - 1500 BC) and Atharvaveda ($\\sim $ 1150 BC), there are references to dhumaketus and ketus, which stand for comets in Sanskrit. Varahamihira in 550 AD and Ballala Sena ($\\sim $ 1100 - 1200 AD) have described a large number of comets recorded by ancient seers such as Parashara, Vriddha Garga, Narada, Garga, etc. In this article, I conjecture that an episode narrated in Mahabharata of a radiant king, Nahusha, ruling the heavens, and later turning into a serpent after he had kicked the seer Agastya (also the star Canopus), is a mythological retelling of a cometary event.

  20. Infrared observations of comets

    Science.gov (United States)

    Hanner, Martha S.

    1991-01-01

    Selected comets are observed in the near infrared (1 to 2.2 micron) and thermal infrared (3.5 to 20 micron) with the NASA Infrared Telescope Facility (IRTF) and other telescopes as appropriate, in order to characterize the physical properties of the dust grains; their composition, size distribution, emissivity, and albedo. Systematic variations in these properties among comets are looked for, in order to understand the heterogeneity of comet nuclei. Spectrophotometry of the 10 micron silicate emission feature is particularly emphasized. The rate of dust production from the nucleus and its temporal variability are also determined. Knowledge of the dust environment is essential to S/C design and mission planning for NASA's CRAF mission.

  1. Astrobiology of Comets

    Science.gov (United States)

    Hoover, Richard B.; Wickramasinghe, Nalin C.; Wallis, Max K.; Sheldon, Robert B.

    2004-01-01

    We review the current state of knowledge concerning microbial extremophiles and comets and the potential significance of comets to Astrobiology. We model the thermal history of a cometary body, regarded as an assemblage of boulders, dust, ices and organics, as it approaches a perihelion distance of - IAU. The transfer of incident energy from sunlight into the interior leads to the melting of near surface ices, some under stable porous crust, providing possible habitats for a wide range of microorganisms. We provide data concerning new evidence for indigenous microfossils in CI meteorites, which may be the remains of extinct cometary cores. We discuss the dominant microbial communities of polar sea-ice, Antarctic ice sheet, and cryoconite environments as possible analogs for microbial ecosystems that may grow in sub-crustal pools or in ice/water films in comets.

  2. Analysis of historical meteor and meteor shower records: Korea, China, and Japan

    CERN Document Server

    Yang, H J; Park, M G; Yang, Hong-Jin; Park, Changbom; Park, Myeong-Gu

    2005-01-01

    We have compiled and analyzed historical Korean meteor and meteor shower records in three Korean official history books, Samguksagi which covers the three Kingdoms period (57 B.C -- A.D. 935), Goryeosa of Goryeo dynasty (A.D. 918 -- 1392), and Joseonwangjosillok of Joseon dynasty (A.D. 1392 -- 1910). We have found 3861 meteor and 31 meteor shower records. We have confirmed the peaks of Perseids and an excess due to the mixture of Orionids, north-Taurids, or Leonids through the Monte-Carlo test. The peaks persist from the period of Goryeo dynasty to that of Joseon dynasty, for almost one thousand years. Korean records show a decrease of Perseids activity and an increase of Orionids/north-Taurids/Leonids activity. We have also analyzed seasonal variation of sporadic meteors from Korean records. We confirm the seasonal variation of sporadic meteors from the records of Joseon dynasty with the maximum number of events being roughly 1.7 times the minimum. The Korean records are compared with Chinese and Japanese re...

  3. Discovering the Nature of Comets.

    Science.gov (United States)

    Whipple, Fred L.

    1986-01-01

    "The Mystery of Comets" by Dr. Fred Whipple provides an introduction to the modern picture of comets and his personal reminiscences of how his model of comets came to be. An adaptation of several sections of the book is presented. (JN)

  4. Look--It's a Comet!

    Science.gov (United States)

    Berglund, Kay

    1997-01-01

    Describes a classroom lesson on comets that uses modeling and guided imagery to spark students' curiosity. Comet models are built using chunks of rock salt, polystyrene balls, and tinsel. Abstract ideas are made more concrete with a guided imagery story called Comet Ride! Includes an introduction to the use of parallax to measure the distance of…

  5. Comet LINEAR Splits Further

    Science.gov (United States)

    2001-05-01

    Third Nucleus Observed with the VLT Summary New images from the VLT show that one of the two nuclei of Comet LINEAR (C/2001 A2), now about 100 million km from the Earth, has just split into at least two pieces . The three fragments are now moving through space in nearly parallel orbits while they slowly drift apart. This comet will pass through its perihelion (nearest point to the Sun) on May 25, 2001, at a distance of about 116 million kilometres. It has brightened considerably due to the splitting of its "dirty snowball" nucleus and can now be seen with the unaided eye by observers in the southern hemisphere as a faint object in the southern constellation of Lepus (The Hare). PR Photo 18a/01 : Three nuclei of Comet LINEAR . PR Photo 18b/01 : The break-up of Comet LINEAR (false-colour). Comet LINEAR splits and brightens ESO PR Photo 18a/01 ESO PR Photo 18a/01 [Preview - JPEG: 400 x 438 pix - 55k] [Normal - JPEG: 800 x 875 pix - 136k] ESO PR Photo 18b/01 ESO PR Photo 18b/01 [Preview - JPEG: 367 x 400 pix - 112k] [Normal - JPEG: 734 x 800 pix - 272k] Caption : ESO PR Photo 18a/01 shows the three nuclei of Comet LINEAR (C/2001 A2). It is a reproduction of a 1-min exposure in red light, obtained in the early evening of May 16, 2001, with the 8.2-m VLT YEPUN (UT4) telescope at Paranal. ESO PR Photo 18b/01 shows the same image, but in a false-colour rendering for more clarity. The cometary fragment "B" (right) has split into "B1" and "B2" (separation about 1 arcsec, or 500 km) while fragment "A" (upper left) is considerably fainter. Technical information about these photos is available below. Comet LINEAR was discovered on January 3, 2001, and designated by the International Astronomical Union (IAU) as C/2001 A2 (see IAU Circular 7564 [1]). Six weeks ago, it was suddenly observed to brighten (IAUC 7605 [1]). Amateurs all over the world saw the comparatively faint comet reaching naked-eye magnitude and soon thereafter, observations with professional telescopes indicated

  6. What do comets 252P/LINEAR and P2016 BA14 have in common?

    Science.gov (United States)

    Rudawska, Regina; Vaubaillon, Jeremie; Tóth, Juraj; Raetz, Stefanie

    2016-10-01

    Automated surveys of NEOs continue to discover objects in cometary-like orbits that are likely candidate parent bodies [1]. Some of them unexpectedly produce a comet-like comae and tails [2, 3]. Here, we study one such case, namely asteroid 2016 BA14 recently discovered by the Pan-STARRS survey, which shows cometary appearance and has a Tisserand parameter of 2.8. Moreover, the orbital similarly between P/2016 BA14 and comet 252P/LINEAR was pointed. If those JFCs split in the past, significant dust would have been released. We present a survey of results dealing with investigating the association of comets P/2016 BA14 and 252P/LINEAR with meteor showers observed on Earth. We carry out a further search to investigate the possible genetic relationship between the comets themselves too. To confirm the reality of the relation between a comet and a meteoroid stream it is necessary to investigate the evolution of their orbits. The model of generation and evolution of meteoroid stream in the solar system is taken from Vaubaillon et al. [4]. The ejections of meteoroids from the possible parent body surface took place when it was passing its perihelion between 1700 A.D. and 2016 A.D. Next, the orbits of ejected meteoroids were integrated to year 2079. We will show the similarities and differences of the two streams, and will conclude regarding the possible relationship between P/2016 BA14 and 252P/LINEAR.[1] Jenniskens, P., Meteor Showers and their Parent Comets (Cambridge University Press), 2006[2] Jewitt, D., AJ, 143, 66, 2012[3] Jewitt, D. and Li, J., AJ, 140, 1519, 2010[4] Vaubaillon, J., Colas, F. Jorda, L., A&A, 439, 751, 2005

  7. Death of a comet

    CERN Multimedia

    Hawkes, N

    2000-01-01

    The comet Linear dissolved as it made its closest approach to the sun on July 25th. The first stages of its breakup had been witnessed by the Hubble telescope when it threw off a piece of its crust (3 paragraphs).

  8. Comets in Indian Scriptures

    Science.gov (United States)

    Das Gupta, P.

    2016-01-01

    The Indo-Aryans of ancient India observed stars and constellations for ascertaining auspicious times in order to conduct sacrificial rites ordained by the Vedas. Naturally, they would have sighted comets and referred to them in the Vedic texts. In Rigveda (circa 1700-1500 BC) and Atharvaveda (circa 1150 BC), there are references to dhumaketus and ketus, which stand for comets in Sanskrit. Rigveda speaks of a fig tree whose aerial roots spread out in the sky (Parpola 2010). Had this imagery been inspired by the resemblance of a comet's tail with long and linear roots of a banyan tree (ficus benghalensis)? Varahamihira (AD 550) and Ballal Sena (circa AD 1100-1200) described a large number of comets recorded by ancient seers, such as Parashara, Vriddha Garga, Narada, and Garga, to name a few. In this article, we propose that an episode in Mahabharata in which a radiant king, Nahusha, who rules the heavens and later turns into a serpent after he kicked the seer Agastya (also the star Canopus), is a mythological retelling of a cometary event.

  9. Asteroids, meteorites, and comets

    CERN Document Server

    Elkins-Tanton, Linda T

    2010-01-01

    Asteroids, Comets, and Meteorites provides students, researchers, and general readers with the most up-to-date information on this fascinating field. From the days of the dinosaurs to our modern environment, this book explores all aspects of these cosmic invaders.

  10. The Composition of Comets

    CERN Document Server

    Cochran, Anita L; Cordiner, Martin; Hadamcik, Edith; Lasue, Jeremie; Gicquel, Adeline; Schleicher, David G; Charnley, Steven B; Mumma, Michael J; Paganini, Lucas; Bockelee-Morvan, Dominique; Biver, Nicolas; Kuan, Yi-Jehng

    2015-01-01

    This paper is the result of the International Cometary Workshop, held in Toulouse, France in April 2014, where the participants came together to assess our knowledge of comets prior to the ESA Rosetta Mission. In this paper, we look at the composition of the gas and dust from the comae of comets. With the gas, we cover the various taxonomic studies that have broken comets into groups and compare what is seen at all wavelengths. We also discuss what has been learned from mass spectrometers during flybys. A few caveats for our interpretation are discussed. With dust, much of our information comes from flybys. They include {\\it in situ} analyses as well as samples returned to Earth for laboratory measurements. Remote sensing IR observations and polarimetry are also discussed. For both gas and dust, we discuss what instruments the Rosetta spacecraft and Philae lander will bring to bear to improve our understanding of comet 67P/Churyumov-Gerasimenko as "ground-truth" for our previous comprehensive studies. Finally...

  11. A Search of Reactivated Comets

    Science.gov (United States)

    Ye, Quan-Zhi

    2017-05-01

    Dormant or near-dormant short-period comets can unexpectedly regain the ability to eject dust. In many known cases, the resurrection is short-lived and lasts less than one orbit. However, it is possible that some resurrected comets can remain active in later perihelion passages. We search the archival images of various facilities to look for these “reactivated” comets. We identify two candidates, 297P/Beshore and 332P/Ikeya-Murakami, both of which were found to be inactive or weakly active in the previous orbit before their discovery. We derive a reactivation rate of ˜ 0.007 {{comet}}-1 {{orbit}}-1, which implies that typical short-period comets only become temporarily dormant a few times or less. Smaller comets are prone to rotational instability and may undergo temporary dormancy more frequently. Next generation high-cadence surveys may find more reactivation events of these comets.

  12. The Swedish Allsky Meteor Network: first results

    Science.gov (United States)

    Stempels, E.; Kero, E.

    2016-01-01

    The Swedish Allsky Meteor Network started operations with two cameras in early 2014 and has since grown steadily. Currently, seven stations are active and several more will come online in the near future. The network to a large degree relies on low-cost stations run by private individuals or small societies of amateur astronomers. Originally based on the Danish meteor network Stjerneskud, the central node of Uppsala University provides the network with the necessary infrastructure, such as a continually updated software distribution and automatic processing of data from all stations. Although covering a very large land mass with relatively low resources is challenging, there have up to now been several well-observed events, often in collaboration with observations from neighboring countries. We give a short overview of the network's current status, chosen technical solutions, and some results.

  13. A Global Atmospheric Model of Meteoric Iron

    Science.gov (United States)

    Feng, Wuhu; Marsh, Daniel R.; Chipperfield, Martyn P.; Janches, Diego; Hoffner, Josef; Yi, Fan; Plane, John M. C.

    2013-01-01

    The first global model of meteoric iron in the atmosphere (WACCM-Fe) has been developed by combining three components: the Whole Atmosphere Community Climate Model (WACCM), a description of the neutral and ion-molecule chemistry of iron in the mesosphere and lower thermosphere (MLT), and a treatment of the injection of meteoric constituents into the atmosphere. The iron chemistry treats seven neutral and four ionized iron containing species with 30 neutral and ion-molecule reactions. The meteoric input function (MIF), which describes the injection of Fe as a function of height, latitude, and day, is precalculated from an astronomical model coupled to a chemical meteoric ablation model (CABMOD). This newly developed WACCM-Fe model has been evaluated against a number of available ground-based lidar observations and performs well in simulating the mesospheric atomic Fe layer. The model reproduces the strong positive correlation of temperature and Fe density around the Fe layer peak and the large anticorrelation around 100 km. The diurnal tide has a significant effect in the middle of the layer, and the model also captures well the observed seasonal variations. However, the model overestimates the peak Fe+ concentration compared with the limited rocket-borne mass spectrometer data available, although good agreement on the ion layer underside can be obtained by adjusting the rate coefficients for dissociative recombination of Fe-molecular ions with electrons. Sensitivity experiments with the same chemistry in a 1-D model are used to highlight significant remaining uncertainties in reaction rate coefficients, and to explore the dependence of the total Fe abundance on the MIF and rate of vertical transport.

  14. Meteors, space aliens, and other exotic encounters

    Science.gov (United States)

    Tom. Hofacker

    1998-01-01

    Exotics have had a big impact on our environment. If you do not think so, just look at how many people believe that humans would not exist on this planet were it not for exotics. This belief centers on two main theories: (1) that humans could not have evolved were it not for a huge meteor from outer space striking the earth resulting in extinction of the dinasours, the...

  15. Hyperbolic meteors: interstellar or generated locally via the gravitational slingshot effect?

    CERN Document Server

    Wiegert, Paul A

    2014-01-01

    The arrival of solid particles from outside our solar system would present us with an invaluable source of scientific information. Attempts to detect such interstellar particles among the meteors observed in Earth's atmosphere have almost exclusively assumed that those particles moving above the Solar System's escape speed -- particles on orbits hyperbolic with respect to the Sun-- were precisely the extrasolar particles being searched for. Here we show that hyperbolic particles can be generated entirely within the Solar System by gravitational scattering of interplanetary dust and meteoroids by the planets. These particles have necessarily short lifetimes as they quickly escape our star system; nonetheless some may arrive at Earth at speeds comparable to those expected of interstellar meteoroids. Some of these are associated with the encounter of planets with the debris streams of individual comets; however, such encounters are relatively rare. The rates of occurrence of hyperbolically-scattered sporadic met...

  16. Physical and Chemical Properties of Meteoric Smoke

    Science.gov (United States)

    Plane, J. M.; Saunders, R. E.

    2005-12-01

    Somewhere between 10 and 100 tonnes (the current range of estimates) of interplanetary dust enters the earth's atmosphere each day. At least 60 percent of this ablates completely into atoms and ions, mostly between 70 and 110 km. This paper is concerned with the subsequent fate of the ablated metals and silicon. These species form a variety of oxides and hydroxides below 90 km, and it is widely believed that these species condense into nanometer-sized dust particles, known as "meteoric smoke". Here we will report laboratory experiments to simulate the production of meteoric smoke particles. Several chemical systems were investigated using a photochemical reactor: pure iron, iron-oxygen, silicon-oxygen and mixed iron-silicon-oxygen nano-particles. The particles were analysed for size distribution (diameter greater than 3 nm), chemical and physical structure and optical extinction. The kinetics of particle growth through condensation and coagulation were also measured in a novel aerosol flow tube. The results are used to refine aerosol growth models, and then to speculate on the likely form and size distribution of meteoric smoke in the mesosphere. Finally, we will consider how changes in the interplanetary dust flux could have affected the evolution of the earth's atmosphere.

  17. On meteor stream spatial structure theory

    Science.gov (United States)

    Andreev, G. V.

    1987-01-01

    The classical spatial representation of meteor streams is an elliptical torus with variable cross section. The position of this torus in space is determined by the mean orbit elements that may be obtained directly from observations of individual meteor stream particles when crossed by the Earth. Since the orbits of individual particles of a stream differ from each other, the distance between them on a plane normal to the mean orbit of elliptical torus forms some area, i.e., a cross section. The size and form of these cross sections change with the change of the direction among the mean orbit and are completely defined by the dispersion values of the orbit elements in a stream. An attempt was made to create an analytical method that would permit description of the spatial and time parameters of meteor streams, i.e., the form and size of their cross section, density of incident flux and their variations along the mean orbit and in time. In this case, the stream is considered as a continuous flux rather than a set of individual particles.

  18. 67P, Singing Comet

    Science.gov (United States)

    Smirnova, Ekaterina

    2017-04-01

    I would like to propose to present a short science-art-music collaboration film called "67P, Singing Comet" (5:27 min). If time of the session will allow, prior to the film I would like to make a slide show introduction to this project, highlighting the inspiration - the mission Rosetta by the European Space Agency (ESA) - and the artistic collaboration that took place in creating this piece. 
 Inspired by the ESA Rosetta mission to the comet 67P, Ekaterina Smirnova (artist and project director, New York), Lee Mottram (clarinetist, Wales), Takuto Fukuda (composer, Japan) and Brian Hekker (video editor, New York) collaborated to create a unique atmospheric piece.
 Water and the origins of life throughout the Universe (specifically the Earth) is an element of the mission and the focus of Ekaterina's artistic vision. Ekaterina literally and figuratively paints a sensory assemblage using a combination of synthetic and natural elements to shape this artistic creation. To paint her watercolor works she is using a replica of the water found on the comet and implementing her own heartbeat into the music to create a recognizable inward sound of life.
 The Electro-Acoustic composition by Takuto Fukuda features an electronically manipulated performance by clarinetist Lee Mottram. The piece ceremoniously begins with reverberant bursts of low-register atonal bells transporting the listener to their ethereal inner origins of body and mind. The imagination takes the experience to an unknown destination as it gains speed gliding through the visual and audible textures of space and time. 
The comet's water similarly reacts with an ebb and flow thawing ice to potentially give life a chance as it is thrust along an orbit around the Sun. Near then far from the heat the comet forms frozen particles from vapors as it reaches it's furthest stretches creating an aerodynamic tail of icicles that slowly dissipate in a cycle that repeats itself until the comet's ultimate collision

  19. Interferometric meteor head echo observations using the Southern Argentina Agile Meteor Radar

    Science.gov (United States)

    Janches, D.; Hocking, W.; Pifko, S.; Hormaechea, J. L.; Fritts, D. C.; Brunini, C.; Michell, R.; Samara, M.

    2014-03-01

    A radar meteor echo is the radar scattering signature from the free electrons generated by the entry of extraterrestrial particles into the atmosphere. Three categories of scattering mechanisms exist: specular, nonspecular trails, and head echoes. Generally, there are two types of radars utilized to detect meteors. Traditional VHF all-sky meteor radars primarily detect the specular trails, while high-power, large-aperture (HPLA) radars efficiently detect meteor head echoes and, in some cases, nonspecular trails. The fact that head echo measurements can be performed only with HPLA radars limits these studies in several ways. HPLA radars are sensitive instruments constraining the studies to the lower masses, and these observations cannot be performed continuously because they take place at national observatories with limited allocated observing time. These drawbacks can be addressed by developing head echo observing techniques with modified all-sky meteor radars. Such systems would also permit simultaneous detection of all different scattering mechanisms using the same instrument, rather than requiring assorted different classes of radars, which can help clarify observed differences between the different methodologies. In this study, we demonstrate that such concurrent observations are now possible, enabled by the enhanced design of the Southern Argentina Agile Meteor Radar (SAAMER). The results presented here are derived from observations performed over a period of 12 days in August 2011 and include meteoroid dynamical parameter distributions, radiants, and estimated masses. Overall, the SAAMER's head echo detections appear to be produced by larger particles than those which have been studied thus far using this technique.

  20. Comets and their origin the tools to decipher a comet

    CERN Document Server

    Meierhenrich, Uwe

    2014-01-01

    Divided into two parts, the first four chapters of Comets and their Origin refer to comets and their formation in general, describing cometary missions, comet remote observations, astrochemistry, artificial comets, and the chirality phenomenon.The second part covers the cometary Rosetta mission, its launch, journey, scientific objectives, and instrumentations, as well as the landing scenario on a cometary nucleus. Along the way, the author presents general questions concerning the origin of terrestrial water and the molecular beginnings of lifeon Earth, as well as how the instruments used on

  1. CINE: Comet INfrared Excitation

    Science.gov (United States)

    de Val-Borro, Miguel; Cordiner, Martin A.; Milam, Stefanie N.; Charnley, Steven B.

    2017-08-01

    CINE calculates infrared pumping efficiencies that can be applied to the most common molecules found in cometary comae such as water, hydrogen cyanide or methanol. One of the main mechanisms for molecular excitation in comets is the fluorescence by the solar radiation followed by radiative decay to the ground vibrational state. This command-line tool calculates the effective pumping rates for rotational levels in the ground vibrational state scaled by the heliocentric distance of the comet. Fluorescence coefficients are useful for modeling rotational emission lines observed in cometary spectra at sub-millimeter wavelengths. Combined with computational methods to solve the radiative transfer equations based, e.g., on the Monte Carlo algorithm, this model can retrieve production rates and rotational temperatures from the observed emission spectrum.

  2. Comets at radio wavelengths

    CERN Document Server

    Crovisier, Jacques; Colom, Pierre; Biver, Nicolas

    2016-01-01

    Comets are considered as the most primitive objects in the Solar System. Their composition provides information on the composition of the primitive solar nebula, 4.6 Gyr ago. The radio domain is a privileged tool to study the composition of cometary ices. Observations of the OH radical at 18 cm wavelength allow us to measure the water production rate. A wealth of molecules (and some of their isotopologues) coming from the sublimation of ices in the nucleus have been identified by observations in the millimetre and submillimetre domains. We present an historical review on radio observations of comets, focusing on the results from our group, and including recent observations with the Nan\\c{c}ay radio telescope, the IRAM antennas, the Odin satellite, the Herschel space observatory, ALMA, and the MIRO instrument aboard the Rosetta space probe.

  3. Chemistry of comets

    Energy Technology Data Exchange (ETDEWEB)

    Delsemme, A.H.

    1988-07-29

    In comets, most elements seem to be present in their cosmic abundances. This includes the metals whose abundances are the same as in chondrites, but also the light elements C, N, O, S that are the same as in the Sun; only hydrogen (and presumably helium and neon) is depleted by a factor close to 1000. In the bright comets of the 1970s, three-quarters of the cosmic abundance of carbon was found to be missing from the gaseous fraction. The missing carbon has now been found in Comet Halley: it was in the large organic fraction representing 33% of the cometary dust. A part of this fraction vaporizes slowly out of the dust grains: it is the origin of an extended source of gas discovered around the nucleus of Comet Halley. Water remains the major constituent being 80% of the volatile ices. Formic acid, formaldehyde, carbon dioxide and carbon monoxide explain together more than 13% of the rest of the volatiles. The last 7% include the parent molecules of the radicals excited by fluorescence and observed in the traditional spectra, like hydrogen cyanide HCN (for CN), probably acetylene C/sub 2/C/sub 2/ (for C/sub 2/) and cyclopropadiene C/sub 3/H/sub 2/ (for C/sub 3/). The inorganic fraction of the dust contains mainly silicates and some iron sulphide, whereas the organic fraction also contains unsaturated hydrocarbons and probably hydrogen cyanide, acetonitrile, aminoethylene, pyrrole, pyridine, pyrimidine and possibly purines including adenine. Some prebiotic precursors of the nucleic bases are present, but no traces of any amino acids have been found.

  4. SOFTWARE AND HARDWARE SYSTEMS FOR SOUNDING METEOR TRAILS

    Directory of Open Access Journals (Sweden)

    Lebedeva, A.A.

    2016-06-01

    Full Text Available The article describes the basic physical principles of meteor radio. A block diagram of hardware and software for sensing meteor trails. The principles of software-defined radio system lies at the heart of the complex. The paper presents a functional diagram of a digital oscillator, as well as software description with an example of the received data. This complex allows eliminating a number of shortcomings meteor radio, as well as increasing its range and security.

  5. Mesospheric observations by a forward scattering meteor radar basic setup

    Science.gov (United States)

    Madkour, Waleed; Yamamoto, Masa-yuki

    2016-08-01

    The durations of radio echo signals scattered from meteor ionized trails might not show a consistent increase corresponding to higher density trails due to the rapid removal of meteor ions at certain heights. Several studies have concluded the dominant role of the secondary ozone layer over diffusion in the removal of the meteor trails below 95 km through chemical oxidization of the meteor ions. Using a basic setup configuration of a forward scattering receiver, a trial to observe the mesospheric ozone concentration was performed by analyzing the meteor echo duration distributions. The forward scattered meteor echoes have the advantage of long durations that can enable observing the transition from the diffusion-removal regime to the chemistry-removal regime. The cumulative meteor echo duration distribution of two meteor showers, the Perseids and the Geminids, were analyzed over 10 years and the chemistry-removal regime in each shower was observed. The knee duration position at which a drop in the number of long overdense meteor echoes starts differed by around 30 seconds between the two showers. As the secondary ozone concentration is inversely related to the solar activity level, the Geminids 2011 corresponding to a high solar activity level showed a significant higher counts of long duration echoes compared to the Geminids 2006 during a low activity level, with the knee position shifted to longer duration. The knee positions obtained during the two distinct meteor showers and the two half solar cycle points are generally in agreement with the mesospheric ozone conditions expected in each case. However, continuous data record is required for the other meteor showers and the sporadic meteors at different heights to observe the mesospheric ozone concentration vertically and the full 11-years solar cycle.

  6. An Introduction to Comets and Their Origin.

    Science.gov (United States)

    Chapman, Robert D.; Brandt, John C.

    1985-01-01

    Presents excerpts from "The Comet Book," a nontechnical primer on comets. Various topics discusses in these excerpts include such basic information about comets as their components, paths, and origins. (DH)

  7. PAHs in Comets: An Overview

    CERN Document Server

    Li, Aigen

    2008-01-01

    Polycyclic aromatic hydrocarbon (PAH) molecules, ubiquitously seen in the interstellar medium (ISM) of our own and external galaxies, might have been incorporated into comets if they are formed from relatively unprocessed interstellar matter. The detection of PAHs in comets would be an important link between the ISM and comets. This review compiles our current knowledge on cometary PAHs, based on ground-based and space-borne observations of infrared vibrational and ultraviolet fluorescence spectra of comets, and laboratory analysis of interplanetary dust particles possibly of cometary origin and cometary samples returned to Earth by the Stardust spacecraft. The latter provided the most unambiguous evidence for the presence of PAHs in cometary nuclei.

  8. The TRAPPIST comet survey

    Science.gov (United States)

    Jehin, E.; Opitom, C.; Manfroid, J.; Hutsemékers, D.; Gillon, M.

    2014-07-01

    TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope) is a 60-cm robotic telescope that has been installed in June 2010 at the ESO La Silla Observatory [1]. Operated from Liège (Belgium) it is devoted to the detection and characterisation of exoplanets and to the study of comets and other small bodies in the Solar System. We describe here the hardware and the goals of the project and give an overview of the comet production rates monitoring after three years of operations. The telescope and observatory --- TRAPPIST's optical tube unit is a Ritchey-Chretien 0.6 meter telescope with a focal length of 4.8 meter. It is associated with a German equatorial mount that is, thanks to its direct drive system, extremely fast (up to 50 deg/s), accurate (tracking accuracy without autoguider better than 2'' in 10 min), and free of periodic error. The instrument is a Peltier cooled commercial camera equipped with a Fairchild 3041 back-illuminated 2k×2k chip. The pixel scale is 0.64''/pixel. Three read-out modes are available, the shortest read-out time being 2s. The total field of view of the camera is 22'×22'. It is associated to a custom-made dual filter wheel. One of the filter wheel contains broad band filters (Johnson B, V, R, Cousins Ic, Sloan z, and a special I+z filter), while the other contains the narrow-band NASA HB cometary filters (OH, NH, CN, CO+, C3, and C2 gaseous species; UC, BC, GC and RC solar continuum windows and a NaI D filter) [2]. The telescope is protected by a 5 meter diameter dome that was totally refurbished and automatized. The observatory is fully robotic and equipped with a weather station, an UPS and webcams. The la Silla site is excellent with more than 300 clear nights per year and the telescope has proven to be very reliable with a small amount of technical downtime. Comet monitoring --- For relatively bright comets (V alert is given and can bring important information on the nature of comets. In addition to providing the

  9. A new method of discovering new meteor showers from the IMO single-station video meteor database

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    It has been found that unknown meteor showers could be efficiently discovered from the single station video meteor database of the International Meteor Organization(IMO) by assuming the geocentric velocity and adjusting it within the dynamically permitted range. The mean geocentric velocities of new meteor showers can be obtained,as well as the coordinates of the radiants. The activity period and maximum time can also be obtained if there are sufficient shower meteors. All single station video meteor observations between February 13 and 17(from 2000 to 2005) in IMO’s database are processed with this method. As a result,two new meteor showers,one near RA=245.10°,Dec=41.82° in Hercules and the other near RA=233.03°,Dec=17.04° in Serpenids,are discovered. Some dynamical characteristics of the new meteor showers are also determined. Considering the random nature on the selection of period in this work,it is expected that there are some more potential new meteor showers in IMO’s video database.

  10. A new method of discovering new meteor showers from the IMO single-station video meteor database

    Institute of Scientific and Technical Information of China (English)

    LI Jun; ZHU Jin

    2008-01-01

    It has been found that unknown meteor showers could be efficiently discovered from the single station video meteor database of the International Meteor Organi-zation (IMO) by assuming the geocentric velocity and adjusting it within the dy-namically permitted range. The mean geocentric velocities of new meteor showers can be obtained, as well as the coordinates of the radiants. The activity period and maximum time can also be obtained if there are sufficient shower meteors. All sin-gle station video meteor observations between February 13 and 17 (from 2000 to 2005) in IMO's database are processed with this method. As a result, two new me-teor showers, one near RA=245.10°, Dec:41.82° in Hercules and the other near RA=233.03°, Dec:17.04° in Serpenids, are discovered. Some dynamical character-istics of the new meteor showers are also determined. Considering the random nature on the selection of period in this work, it is expected that there are some more potential new meteor showers in IMO's video database.

  11. Meteor Beliefs Project: Meteoric imagery associated with the death of John Brown in 1859

    Science.gov (United States)

    Drobnock, G. J.; McBeath, A.; Gheorghe, A. D.

    2009-12-01

    An examination is made of metaphorical meteor imagery used in conjunction with the death of American anti-slavery activist John Brown, who was executed in December 1859. Such imagery continues to be used in this regard into the 21st century.

  12. Meteor Beliefs Project: some meteoric imagery in the works of William Shakespeare

    Science.gov (United States)

    McBeath, A.; Gheorghe, A. D.

    2003-08-01

    Passages from three of William Shakespeare's plays are presented, illustrating some of the beliefs in meteors in 16th-17th century England. They also reflect earlier beliefs and information which it is known Shakespeare drew on in constructing his works.

  13. A Global Model of Meteoric Sodium

    Science.gov (United States)

    Marsh, Daniel R.; Janches, Diego; Feng, Wuhu; Plane, John M. C.

    2013-01-01

    A global model of sodium in the mesosphere and lower thermosphere has been developed within the framework of the National Center for Atmospheric Research's Whole Atmosphere Community Climate Model (WACCM). The standard fully interactive WACCM chemistry module has been augmented with a chemistry scheme that includes nine neutral and ionized sodium species. Meteoric ablation provides the source of sodium in the model and is represented as a combination of a meteoroid input function (MIF) and a parameterized ablation model. The MIF provides the seasonally and latitudinally varying meteoric flux which is modeled taking into consideration the astronomical origins of sporadic meteors and considers variations in particle entry angle, velocity, mass, and the differential ablation of the chemical constituents. WACCM simulations show large variations in the sodium constituents over time scales from days to months. Seasonality of sodium constituents is strongly affected by variations in the MIF and transport via the mean meridional wind. In particular, the summer to winter hemisphere flow leads to the highest sodium species concentrations and loss rates occurring over the winter pole. In the Northern Hemisphere, this winter maximum can be dramatically affected by stratospheric sudden warmings. Simulations of the January 2009 major warming event show that it caused a short-term decrease in the sodium column over the polar cap that was followed by a factor of 3 increase in the following weeks. Overall, the modeled distribution of atomic sodium in WACCM agrees well with both ground-based and satellite observations. Given the strong sensitivity of the sodium layer to dynamical motions, reproducing its variability provides a stringent test of global models and should help to constrain key atmospheric variables in this poorly sampled region of the atmosphere.

  14. The Southern Argentina Agile Meteor Radar (SAAMER): Platform for comprehensive meteor radar observations and studies

    Science.gov (United States)

    Janches, D.; Hormaechea, J.; Pifko, S.; Hocking, W.; Fritts, D.; Brunini, C.; Close, S.; Michell, R.; Samara, M.

    2014-07-01

    The Southern Argentina Agile Meteor Radar (SAAMER) is a new generation system deployed in Rio Grande, Tierra del Fuego, Argentina (53^oS) in May 2008 (Janches et al., 2013,2014). SAAMER transmits 10 times more power than regular meteor radars, and uses a newly developed transmitting array, which focuses power upward instead of the traditional single-antenna-all-sky configuration. The system is configured such that the transmitter array can also be utilized as a receiver. The new design greatly increases the sensitivity of the radar enabling the detection of large numbers of particles at low zenith angles. The more concentrated transmitted power enables additional meteor studies besides those typical of these systems based on the detection of specular reflections, such as routine detections of head echoes and non-specular trails, previously only possible with High Power and Large Aperture radars (Janches et al., 2014). In August 2010, SAAMER was upgraded to a system capable to determine meteoroid orbital parameters. This was achieved by adding two remote receiving stations approximately 10 km away from the main site in near perpendicular directions (Pifko et al., 2014). The upgrade significantly expands the science that is achieved with this new radar enabling us to study the orbital properties of the interplanetary dust environment. Because of the unique geographical location, the SAAMER allows for additional inter-hemispheric comparison with measurements from Canadian Meteor Orbit Radar, which is geographically conjugate. Initial surveys show, for example, that SAAMER observes a very strong contribution of the South Toroidal Sporadic meteor source (Pifko et al., 2014), of which limited observational data is available. In addition, SAAMER offers similar unique capabilities for meteor showers and streams studies given the range of ecliptic latitudes that the system enables to survey (Janches et al., 2013). It can effectively observe radiants from the ecliptic south

  15. Detecting active comets with SDSS

    Energy Technology Data Exchange (ETDEWEB)

    Solontoi, Michael; Ivezic, Zeljko; /Washington U., Seattle, Astron. Dept.; West, Andrew A.; /MIT, MKI; Claire, Mark; /Washington U., Seattle, Astron. Dept.; Juric, Mario; /Princeton U. Observ.; Becker, Andrew; Jones, Lynne; /Washington U., Seattle, Astron. Dept.; Hall, Patrick B.; /York U., Canada; Kent, Steve; /Fermilab; Lupton, Robert H.; /Princeton U. Observ.; Quinn, Tom; /Washington U., Seattle, Astron. Dept. /Princeton U. Observ.

    2010-12-01

    Using a sample of serendipitously discovered active comets in the Sloan Digital Sky Survey (SDSS), we develop well-controlled selection criteria for greatly increasing the efficiency of comet identification in the SDSS catalogs. After follow-up visual inspection of images to reject remaining false positives, the total sample of SDSS comets presented here contains 19 objects, roughly one comet per 10 million other SDSS objects. The good understanding of selection effects allows a study of the population statistics, and we estimate the apparent magnitude distribution to r {approx} 18, the ecliptic latitude distribution, and the comet distribution in SDSS color space. The most surprising results are the extremely narrow range of colors for comets in our sample (e.g. root-mean-square scatter of only {approx}0.06 mag for the g-r color), and the similarity of comet colors to those of jovian Trojans. We discuss the relevance of our results for upcoming deep multi-epoch optical surveys such as the Dark Energy Survey, Pan-STARRS, and the Large Synoptic Survey Telescope (LSST), and estimate that LSST may produce a sample of about 10,000 comets over its 10-year lifetime.

  16. Asteroids and Comets

    CERN Document Server

    Fernandez, Yanga R; Howell, Ellen S; Woodney, Laura M

    2015-01-01

    Asteroids and comets are remnants from the era of Solar System formation over 4.5 billion years ago, and therefore allow us to address two fundamental questions in astronomy: what was the nature of our protoplanetary disk, and how did the process of planetary accretion occur? The objects we see today have suffered many geophysically-relevant processes in the intervening eons that have altered their surfaces, interiors, and compositions. In this chapter we review our understanding of the origins and evolution of these bodies, discuss the wealth of science returned from spacecraft missions, and motivate important questions to be addressed in the future.

  17. Fully correcting the meteor speed distribution for radar observing biases

    Science.gov (United States)

    Moorhead, Althea V.; Brown, Peter G.; Campbell-Brown, Margaret D.; Heynen, Denis; Cooke, William J.

    2017-09-01

    Meteor radars such as the Canadian Meteor Orbit Radar (CMOR) have the ability to detect millions of meteors, making it possible to study the meteoroid environment in great detail. However, meteor radars also suffer from a number of detection biases; these biases must be fully corrected for in order to derive an accurate description of the meteoroid population. We present a bias correction method for patrol radars that accounts for the full form of ionization efficiency and mass distribution. This is an improvement over previous methods such as that of Taylor (1995), which requires power-law distributions for ionization efficiency and a single mass index. We apply this method to the meteor speed distribution observed by CMOR and find a significant enhancement of slow meteors compared to earlier treatments. However, when the data set is severely restricted to include only meteors with very small uncertainties in speed, the fraction of slow meteors is substantially reduced, indicating that speed uncertainties must be carefully handled.

  18. Goals, technique and equipment of meteor study in Russia

    Science.gov (United States)

    Kartashova, A.; Bagrov, A. V.; Bolgova, G. T.; Kruchkov, S. V.; Leonov, V. A.; Mazurov, V. A.

    2013-09-01

    Institute of Astronomy RAS is one of the science institutes in the Russian Federation providing systematic optical meteor observations and supervises several meteor groups in our country. The main tasks of our investigations are dedicated to study meteoroid nature as well as meteoroid streams and meteoroid population in the Solar System. In the XXI century we in Russia carry out the reconstruction of our meteor astronomy due to possibilities of new meteor observation equipment (more powerful than were used before as visual and photographic methods) had made possible to select more interesting goals. First of our task is investigation of meteoroid streams crossing the Earth's orbit, and character of meteoroid distributions along of them. The multi stations meteor monitoring from located in the both hemispheres of the Earth can help in this study. According to the analysis of the evolution of meteor orbits, the compact and long lived meteoroid streams consist mainly from large particles. The observation equipment (cheap TV-cameras) with low limiting magnitude we use for gathering observational data. On the other hand, the observations of weak meteors are needed for new meteor shower indication (or confirmation of known meteor shower). The more effective way to do it is comparison of individual meteor orbits parameters (then calculation of radiants of meteor showers). The observations of space debris (as the meteors with low velocity - less 11.2 km/s) can be taking up within this task. The combination of high sensitive TV-cameras WATEC and super-fast lenses COMPUTAR are widely used for meteor TV-monitoring. The TVsystems for round-year meteor observations are fixed and are permanently oriented to the zenith area (the patrol camera - PatrolCa). The mobile TV-cameras (MobileCa) are used for double station observations (if it is possible) and located not far from main cameras PatrolCa (20-30 km). The mobile TVcameras observe 90% of main PatrolCa cameras FOV at altitudes

  19. Approximation of the observed motion of bolides by the analytical solution of the equations of meteor physics

    Science.gov (United States)

    Gritsevich, M. I.

    2007-12-01

    A great volume of data has been accumulated thus far related to the photoregistration of the paths of meteor bodies in the terrestrial atmosphere. Most images have been obtained by four bolide networks, which operate in the USA, Canada, Europe, and Spain in different time periods. The approximation of the actual data using theoretical models makes it possible to achieve additional estimates, which do not directly follow from the observations. In the present study, we suggest an algorithm to find such parameters of the theoretical relationship between the height and the velocity of the bolide motion that help to fit observations along the luminous part of the trajectories in the best way. The main difference from previous studies is that the given observations are approximated using the analytical solution of the equations of meteor physics. The model presented in this study was applied to a number of bright meteors observed by the Canadian camera network and by the US Prairie network and to the Benésov bolide, which is one of the largest fireballs registered by the European network. The correct mathematical modeling of meteor events in the atmosphere is necessary for further estimates of the key parameters, including the extra-atmospheric mass, the ablation coefficient, and the effective enthalpy of evaporation of entering bodies. In turn, this information is needed by some applications, namely, those aimed at studying the problems of asteroid and comet security, to develop measures of planetary defense, and to determine the bodies that can reach Earth’s surface.

  20. Study of the Dynamics of Meteoroids Through the Earth's Atmosphere and Retrieval of Meteorites: The Mexican Meteor Network

    Science.gov (United States)

    Cordero Tercero, M. G.; Farah Simon, A.; Velazquez-Villegas, F.

    2016-12-01

    When a comet , asteroid or meteoroid impact with a planet several things can happen depending on the mass, velocity and composition of the impactor, if the planet or moon has an atmosphere or not, and the angle of impact. On bodies without an atmosphere like Mercury or the Moon, every object that strikes their surfaces produces impact craters with sizes ranging from centimeters to hundreds and even thousands of kilometers across. On bodies with an atmosphere, this encounter can produce impact craters, meteorites, meteors and fragmentation. Each one of these phenomena is interesting because they provide information about the surfaces and the geological evolution of solar system bodies. Meteors are luminous wakes on the sky due to the interaction between the meteoroid and the Earth's atmosphere. A meteoroid is asteroidal or cometary material ranging in size from 2 mm to a few tens of meters. The smallest tend to evaporate at heights between 80 and 120 km. Objects of less than 2 mm are called micrometeorites. If the meteor brightness exceeds the brightness of Venus, the phenomenon is called a bolide or fireball. If a meteoroid, or a fragment of it, survives atmospheric ablation and it can be recovered on the ground, that piece is called a meteorite. Most meteoroids 2 meters long fragment suddenly into the atmosphere, it produces a shock wave that can affect humans and their environment like the Chelyabinsk event occurred on February 15, 2013 an two less energetic events in Mexico in 2010 and 2011. To understand the whole phenomenon, we proposed a video camera network for observing meteors. The objectives of this network are to: a) contribute to the study of the fragmentation of meteoroids in the Earth's atmosphere, b) determine values of important physical parameters; c) study seismic waves produced by atmospheric shock waves, d) study the dynamics of meteoroids and f) recover and study meteorites. During this meeting, the progress of the project will be presented.

  1. Anatomy of a Busted Comet

    Science.gov (United States)

    2008-01-01

    [figure removed for brevity, see original site] Poster Version (Figure 1) NASA's Spitzer Space Telescope captured the picture on the left of comet Holmes in March 2008, five months after the comet suddenly erupted and brightened a millionfold overnight. The contrast of the picture has been enhanced on the right to show the anatomy of the comet. Every six years, comet 17P/Holmes speeds away from Jupiter and heads inward toward the sun, traveling the same route typically without incident. However, twice in the last 116 years, in November 1892 and October 2007, comet Holmes mysteriously exploded as it approached the asteroid belt. Astronomers still do not know the cause of these eruptions. Spitzer's infrared picture at left hand side of figure 1, reveals fine dust particles that make up the outer shell, or coma, of the comet. The nucleus of the comet is within the bright whitish spot in the center, while the yellow area shows solid particles that were blown from the comet in the explosion. The comet is headed away from the sun, which lies beyond the right-hand side of figure 1. The contrast-enhanced picture on the right shows the comet's outer shell, and strange filaments, or streamers, of dust. The streamers and shell are a yet another mystery surrounding comet Holmes. Scientists had initially suspected that the streamers were small dust particles ejected from fragments of the nucleus, or from hyerpactive jets on the nucleus, during the October 2007 explosion. If so, both the streamers and the shell should have shifted their orientation as the comet followed its orbit around the sun. Radiation pressure from the sun should have swept the material back and away from it. But pictures of comet Holmes taken by Spitzer over time show the streamers and shell in the same configuration, and not pointing away from the sun. The observations have left astronomers stumped. The horizontal line seen in the contrast-enhanced picture is a trail of debris that travels along with the

  2. The Taurid complex meteor showers and asteroids

    CERN Document Server

    Porubčan, V; Williams, I P

    2009-01-01

    The structure of the Taurid meteor complex based on photographic orbits available in the IAU Meteor database is studied. We have searched for potential sub-streams or filaments to be associated with the complex utilizing the Southworth-Hawkins D-criterion. Applying a strict limiting value for D=0.10, fifteen sub-streams or filaments, consisting of more than three members, could be separated out from the general complex. To confirm their mutual consistence as filaments, rather than fortuitous clumping at the present time, the orbital evolution over 5000 years of each member is studied. Utilizing the D-criterion we also searched for NEOs that might be associated with the streams and filaments of the complex and investigated the orbital evolution of potential members. Possible associations between 7 Taurid filaments and 9 NEOs were found. The most probable are for S Psc(b) -- 2003QC10, N Tau(a) -- 2004TG10, o Ori -- 2003UL3 and N Tau(b) -- 2002XM35. Some of the potential parent objects could be either dormant co...

  3. Erosion of ejecta at Meteor Crater, Arizona

    Science.gov (United States)

    Grant, John A.; Schultz, Peter H.

    1993-01-01

    New methods for estimating erosion at Meteor Crater, Arizona, indicate that continuous ejecta deposits beyond 1/4-1/2 crater radii from the rim have been lowered less than 1 m on the average. This conclusion is based on the results of two approaches: coarsening of unweathered ejecta into surface lag deposits and calculation of the sediment budget within a drainage basin on the ejecta. Preserved ejecta morphologies beneath thin alluvium revealed by ground-penetrating radar provide qualitative support for the derived estimates. Although slightly greater erosion of less resistant ejecta locally has occurred, such deposits were limited in extent, particularly beyond 0.25R-0.5R from the present rim. Subtle but preserved primary ejecta features further support our estimate of minimal erosion of ejecta since the crater formed about 50,000 years ago. Unconsolidated deposits formed during other sudden extreme events exhibit similarly low erosion over the same time frame; the common factor is the presence of large fragments or large fragments in a matrix of finer debris. At Meteor Crater, fluvial and eolian processes remove surrounding fines leaving behind a surface lag of coarse-grained ejecta fragments that armor surfaces and slow vertical lowering.

  4. Sungrazing Comets: Snowballs in Hell

    Science.gov (United States)

    Battams, K.

    2012-12-01

    Experiencing the most extreme environment our solar system has to offer, so-called "Sungrazing" comets approach, penetrate, and on rare occasion survive passage through, the several million degree solar corona on a surprisingly routine basis. Discoveries of such comets occur on average every 3-days in data recorded by the ESA/NASA SOHO and NASA STEREO satellites, with 17-years of near-continuous observations by SOHO having led to the discovery of over 2,300 new comets to date. In this talk I will provide a brief introduction and status update for the "Sungrazing Comets" project that enables the discovery and recording of these objects. I will then present an overview of the instruments that discover these "Sungrazing comets", explaining how their unique design gives us a window into an otherwise unobservable world, and finally will discuss the tremendous scientific value that they bring to both the solar and cometary communities.

  5. Multiwavelength Observations of Recent Comets

    Science.gov (United States)

    Milam, Stefanie N.; Charnley, Steven B.; Gicquel, Adeline; Cordiner, Martin; Kuan, Yi-Jehng; Chuang, Yo-Ling; Villanueva, Geronimo; DiSanti, Michael A.; Bonev, Boncho P.; Remijan, Anthony J.; Coulson, Iain

    2013-01-01

    Comets provide important clues to the physical and chemical processes that occurred during the formation and early evolution of the Solar System, and could also have been important for initiating prebiotic chemistry on the early Earth. Comets are comprised of molecular ices, that may be pristine inter-stellar remnants of Solar System formation, along with high-temperature crystalline silicate dust that is indicative of a more thermally varied history in the protosolar nebula. Comparing abundances of cometary parent volatiles, and isotopic fractionation ratios, to those found in the interstellar medium, in disks around young stars, and between cometary families, is vital to understanding planetary system formation and the processing history experienced by organic matter in the so-called interstellar-comet connection. We will present a comparison of molecular abundances in these comets to those observed in others, supporting a long-term effort of building a comet taxonomy based on composition.

  6. The chemical diversity of comets

    CERN Document Server

    Crovisier, J; Bockelée-Morvan, D; Boissier, J; Colom, P; Lis, D C

    2009-01-01

    A fundamental question in cometary science is whether the different dynamical classes of comets have different chemical compositions, which would reflect different initial conditions. From the ground or Earth orbit, radio and infrared spectroscopic observations of a now significant sample of comets indeed reveal deep differences in the relative abundances of cometary ices. However, no obvious correlation with dynamical classes is found. Further results come, or are expected, from space exploration. Such investigations, by nature limited to a small number of objects, are unfortunately focussed on short-period comets (mainly Jupiter-family). But these in situ studies provide "ground truth" for remote sensing. We discuss the chemical differences in comets from our database of spectroscopic radio observations, which has been recently enriched by several Jupiter-family and Halley-type comets.

  7. Comet or Asteroid?

    Science.gov (United States)

    1997-11-01

    When is a minor object in the solar system a comet? And when is it an asteroid? Until recently, there was little doubt. Any object that was found to display a tail or appeared diffuse was a comet of ice and dust grains, and any that didn't, was an asteroid of solid rock. Moreover, comets normally move in rather elongated orbits, while most asteroids follow near-circular orbits close to the main plane of the solar system in which the major planets move. However, astronomers have recently discovered some `intermediate' objects which seem to possess properties that are typical for both categories. For instance, a strange object (P/1996 N2 - Elst-Pizarro) was found last year at ESO ( ESO Press Photo 36/96 ) which showed a cometary tail, while moving in a typical asteroidal orbit. At about the same time, American scientists found another (1996 PW) that moved in a very elongated comet-type orbit but was completely devoid of a tail. Now, a group of European scientists, by means of observations carried out at the ESO La Silla observatory, have found yet another object that at first appeared to be one more comet/asteroid example. However, continued and more detailed observations aimed at revealing its true nature have shown that it is most probably a comet . Consequently, it has received the provisional cometary designation P/1997 T3 . The Uppsala-DLR Trojan Survey Some time ago, Claes-Ingvar Lagerkvist (Astronomical Observatory, Uppsala, Sweden), in collaboration with Gerhard Hahn, Stefano Mottola, Magnus Lundström and Uri Carsenty (DLR, Institute of Planetary Exploration, Berlin, Germany), started to study the distribution of asteroids near Jupiter. They were particularly interested in those that move in orbits similar to that of Jupiter and which are located `ahead' of Jupiter in the so-called `Jovian L4 Lagrangian point'. Together with those `behind' Jupiter, these asteroids have been given the names of Greek and Trojan Heroes who participated in the famous Trojan war

  8. Spectral, photometric, and dynamic analysis of eight Draconid meteors

    CERN Document Server

    Borovička, Jiř\\'ı; Shrbený, Lukáš; Štork, Rostislav; Hornoch, Kamil

    2014-01-01

    We analyzed spectra, trajectories, orbits, light curves, and decelerations of eight Draconid meteors observed from Northern Italy on October 8, 2011. Meteor morphologies of two of the meteors are also presented, one of them obtained with a high resolution camera. Meteor radiants agree with theoretical predictions, with a hint that some meteors may belong to the pre-1900 meteoroid trails. The spectra confirm that Draconids have normal chondritic composition of main elements (Mg, Fe, Na). There are, nevertheless, differences in the temporal evolution of Na line emission. The differences are correlated with the shapes of the light curves and the deceleration rates. Our data confirm that Draconids are porous conglomerates of grains, nevertheless, significant differences in the atmospheric fragmentation of cm-sized Draconids were found. Various textures with various resistance to fragmentation exist among Draconid meteoroids and even within single meteoroids.

  9. A processing method and results of meteor shower radar observations

    Science.gov (United States)

    Belkovich, O. I.; Suleimanov, N. I.; Tokhtasjev, V. S.

    1987-01-01

    Studies of meteor showers permit the solving of some principal problems of meteor astronomy: to obtain the structure of a stream in cross section and along its orbits; to retrace the evolution of particle orbits of the stream taking into account gravitational and nongravitational forces and to discover the orbital elements of its parent body; to find out the total mass of solid particles ejected from the parent body taking into account physical and chemical evolution of meteor bodies; and to use meteor streams as natural probes for investigation of the average characteristics of the meteor complex in the solar system. A simple and effective method of determining the flux density and mass exponent parameter was worked out. This method and its results are discussed.

  10. Devolatilization or melting of carbonates at Meteor Crater, AZ?

    Science.gov (United States)

    Hörz, F.; Archer, P. D.; Niles, P. B.; Zolensky, M. E.; Evans, M.

    2015-06-01

    We have investigated the carbonates in the impact melts and in a monolithic clast of highly shocked Coconino sandstone of Meteor Crater, AZ to evaluate whether melting or devolatilization is the dominant response of carbonates during high-speed meteorite impact. Both melt- and clast-carbonates are calcites that have identical crystal habits and that contain anomalously high SiO2 and Al2O3. Also, both calcite occurrences lack any meteoritic contamination, such as Fe or Ni, which is otherwise abundantly observed in all other impact melts and their crystallization products at Meteor Crater. The carbon and oxygen isotope systematics for both calcite deposits suggest a low temperature environment (Meteor Crater. Although confined to Meteor Crater, these findings are in stark contrast to Osinski et al. (2008) who proposed that melting of carbonates, rather than devolatilization, is the dominant process during hypervelocity impact into carbonate-bearing targets, including Meteor Crater.

  11. First results on video meteors from Crete, Greece

    Science.gov (United States)

    Maravelias, G.

    2012-01-01

    This work presents the first systematic video meteor observations from a, forthcoming permanent, station in Crete, Greece, operating as the first official node within the International Meteor Organization's Video Network. It consists of a Watec 902 H2 Ultimate camera equipped with a Panasonic WV-LA1208 (focal length 12mm, f/0.8) lens running MetRec. The system operated for 42 nights during 2011 (August 19-December 30, 2011) recording 1905 meteors. It is significantly more performant than a previous system used by the author during the Perseids 2010 (DMK camera 21AF04.AS by The Imaging Source, CCTV lens of focal length 2.8 mm, UFO Capture v2.22), which operated for 17 nights (August 4-22, 2010) recording 32 meteors. Differences - according to the author's experience - between the two softwares (MetRec, UFO Capture) are discussed along with a small guide to video meteor hardware.

  12. The Updated IAU MDC Catalogue of Photographic Meteor Orbits

    Science.gov (United States)

    Porubcan, V.; Svoren, J.; Neslusan, L.; Schunova, E.

    2011-01-01

    The database of photographic meteor orbits of the IAU Meteor Data Center at the Astronomical Institute SAS has gradually been updated. To the 2003 version of 4581 photographic orbits compiled from 17 different stations and obtained in the period 1936-1996, additional new 211 orbits compiled from 7 sources have been added. Thus, the updated version of the catalogue contains 4792 photographic orbits (equinox J2000.0) available either in two separate orbital and geophysical data files or a file with the merged data. All the updated files with relevant documentation are available at the web of the IAU Meteor Data Center. Keywords astronomical databases photographic meteor orbits 1 Introduction Meteoroid orbits are a basic tool for investigation of distribution and spatial structure of the meteoroid population in the close surroundings of the Earth s orbit. However, information about them is usually widely scattered in literature and often in publications with limited circulation. Therefore, the IAU Comm. 22 during the 1976 IAU General Assembly proposed to establish a meteor data center for collection of meteor orbits recorded by photographic and radio techniques. The decision was confirmed by the next IAU GA in 1982 and the data center was established (Lindblad, 1987). The purpose of the data center was to acquire, format, check and disseminate information on precise meteoroid orbits obtained by multi-station techniques and the database gradually extended as documented in previous reports on the activity of the Meteor Data Center by Lindblad (1987, 1995, 1999 and 2001) or Lindblad and Steel (1993). Up to present, the database consists of 4581 photographic meteor orbits (Lindblad et al., 2005), 63.330 radar determined orbit: Harvard Meteor Project (1961-1965, 1968-1969), Adelaide (1960-1961, 1968-1969), Kharkov (1975), Obninsk (1967-1968), Mogadish (1969-1970) and 1425 video-recordings (Lindblad, 1999) to which additional 817 video meteors orbits published by Koten el

  13. Temperature tides determined with meteor radar

    Science.gov (United States)

    Hocking, W. K.; Hocking, A.

    2002-09-01

    A new analysis method for producing tidal temperature parameters using meteor radar measurements is presented, and is demonstrated with data from one polar and two mid-latitude sites. The technique further develops the temperature algorithm originally introduced by Hocking (1999). That earlier method was used to produce temperature measurements over time scales of days and months, but required an empirical model for the mean temperature gradient in the mesopause region. However, when tides are present, this temperature gradient is modulated by the presence of the tides, complicating extraction of diurnal variations. Nevertheless, if the vertical wavelengths of the tides are known from wind measurements, the effects of the gradient variations can be compensated for, permitting determination of temperature tidal amplitudes and phases by meteor techniques. The basic theory is described, and results from meteor radars at Resolute Bay (Canada), London (Canada) and Albuquerque (New Mexico, USA) are shown. Our results are compared with other lidar data, computer models, fundamental tidal theory and rocket data. Phase measurements at two mid-latitude sites (Albuquerque, New Mexico, and London, Canada) show times of maximum for the diurnal temperature tide to change modestly throughout most of the year, varying generally between 0 h and 6 h, with an excursion to 12 h in June at London. The semidiurnal tide shows a larger annual variation in time of maximum, being at 2 4 h in the winter months but increasing to 9 h during the late summer and early fall. We also find that, at least at mid-latitudes, the phase of the temperature tide matches closely the phase of the meridional tide, and theoretical justification for this statement is given. We also demonstrate that this is true using the Global Scale Wave Model (Hagan et al., 1999). Median values for the temperature amplitudes for each site are in the range 5 to 6 Kelvin. Results from a more northern site (Resolute Bay) show

  14. The MAGIC meteoric smoke particle sampler

    Science.gov (United States)

    Hedin, Jonas; Giovane, Frank; Waldemarsson, Tomas; Gumbel, Jörg; Blum, Jürgen; Stroud, Rhonda M.; Marlin, Layne; Moser, John; Siskind, David E.; Jansson, Kjell; Saunders, Russell W.; Summers, Michael E.; Reissaus, Philipp; Stegman, Jacek; Plane, John M. C.; Horányi, Mihály

    2014-10-01

    Between a few tons to several hundred tons of meteoric material enters the Earth's atmosphere each day, and most of this material is ablated and vaporized in the 70-120 km altitude region. The subsequent chemical conversion, re-condensation and coagulation of this evaporated material are thought to form nanometre sized meteoric smoke particles (MSPs). These smoke particles are then subject to further coagulation, sedimentation and global transport by the mesospheric circulation. MSPs have been proposed as a key player in the formation and evolution of ice particle layers around the mesopause region, i.e. noctilucent clouds (NLC) and polar mesosphere summer echoes (PMSE). MSPs have also been implicated in mesospheric heterogeneous chemistry to influence the mesospheric odd oxygen/odd hydrogen (Ox/HOx) chemistry, to play an important role in the mesospheric charge balance, and to be a significant component of stratospheric aerosol and enhance the depletion of O3. Despite their apparent importance, little is known about the properties of MSPs and none of the hypotheses can be verified without direct evidence of the existence, altitude and size distribution, shape and elemental composition. The aim of the MAGIC project (Mesospheric Aerosol - Genesis, Interaction and Composition) was to develop an instrument and analysis techniques to sample for the first time MSPs in the mesosphere and return them to the ground for detailed analysis in the laboratory. MAGIC meteoric smoke particle samplers have been flown on several sounding rocket payloads between 2005 and 2011. Several of these flights concerned non-summer mesosphere conditions when pure MSP populations can be expected. Other flights concerned high latitude summer conditions when MSPs are expected to be contained in ice particles in the upper mesosphere. In this paper we present the MAGIC project and describe the MAGIC MSP sampler, the measurement procedure and laboratory analysis. We also present the attempts to

  15. A Creaking and Cracking Comet

    Science.gov (United States)

    Faurschou Hviid, Stubbe; Hüttig, Christian; Groussin, Olivier; Mottola, Stefano; Keller, Horst Uwe; OSIRIS Team

    2016-10-01

    Since the middle of 2014 the OSIRIS cameras on the ESA Rosetta mission have been monitoring the evolution of the comet 67P/Churyumov-Gerasimenko as it passed through perihelion. During the perihelion passage several change events have been observed on the nucleus surface. For example existing large scale cracks have expanded and new large scale cracks have been created. Also several large scale "wave pattern" like change events have been observed in the Imhotep and Hapi regions. These are events not directly correlated with any normal visible cometary activity. One interpretation is that these are events likely caused by "seismic" activity. The seismic activity is created by the self-gravity stress of the non-spherical comet nucleus and stress created by the non-gravitational forces acting on the comet. The non-gravitational forces are changing the rotation period of the comet (~20min/perihelion passage) which induces a changing mechanical stress pattern through the perihelion passage. Also the diurnal cycle with its changing activity pattern is causing a periodic wobble in the stress pattern that can act as a trigger for a comet quake. The stress pattern has been modeled using a finite element model that includes self-gravity, the comet spin and the non-gravitational forces based on a cometary activity model. This paper will discuss what can be learned about the comet nucleus structure and about the cometary material properties from these events and from the FEM model.

  16. Rosetta following a living comet

    Science.gov (United States)

    Accomazzo, Andrea; Ferri, Paolo; Lodiot, Sylvain; Pellon-Bailon, Jose-Luis; Hubault, Armelle; Porta, Roberto; Urbanek, Jakub; Kay, Ritchie; Eiblmaier, Matthias; Francisco, Tiago

    2016-09-01

    The International Rosetta Mission was launched on 2nd March 2004 on its 10 year journey to rendezvous with comet 67P Churyumov-Gerasimenko. Rosetta performed comet orbit insertion on the 6th of August 2014, after which it characterised the nucleus and orbited it at altitudes as low as a few kilometres. In November 2014 Rosetta delivered the lander Philae to perform the first soft landing ever on the surface of a comet. The critical landing operations have been conducted with remarkable accuracy and will constitute one of the most important achievements in the history of spaceflight. After this critical operation, Rosetta began the escort phase of the comet in its journey in the Solar System heading to the perihelion, reached in August 2015. Throughout this period, the comet environment kept changing with increasing gas and dust emissions. A first phase of bound orbits was followed by a sequence of complex flyby segments which allowed the scientific instruments to perform in depth investigation of the comet environment and nucleus. The unpredictable nature of the comet activity forced the mission control team to implement unplanned changes to the flight plan prepared for this mission phase and to plan the whole mission in a more dynamic way than originally conceived. This paper describes the details of the landing operations and of the main comet escort phase. It also includes the mission status as achieved after perihelion and the findings about the evolution of the comet and its environment from a mission operations point of view. The lessons learned from this unique and complex operations phase and the plans for the next mission phases, which include a mission extension into 2016, are also described.

  17. Tabulation of comet observations.

    Science.gov (United States)

    1998-04-01

    Concerning comets: C/1940 R2 (Cunningham), C/1941 B2 (de Kock-Paraskevopoulos), C/1941 K1 (van Gent), C/1942 X1 (Whipple-Fedtke-Tevzadze), C/1946 C1 (Timmers), C/1946 K1 (Pajdušáková-Rotbart-Weber), C/1946 P1 (Jones), C/1946 U1 (Bester), C/1947 S1 (Bester), C/1947 X1 (Southern comet), C/1947 Y1 (Mrkos), C/1948 E1 (Pajdušáková-Mrkos), C/1948 L1 (Honda-Bernasconi), C/1948 V1 (Eclipse comet), C/1949 N1 (Bappu-Bok-Newkirk), C/1950 K1 (Minkowski), C/1951 C1 (Pajdušáková), C/1952 H1 (Mrkos), C/1952 M1 (Peltier), C/1952 Q1 (Harrington), C/1953 G1 (Mrkos-Honda), C/1953 T1 (Abell), C/1954 O1 (Vozárová), C/1955 L1 (Mrkos), C/1955 N1 (Bakharev-Macfarlane-Krienke), C/1955 O1 (Honda), C/1956 E1 (Mrkos), C/1956 R1 (Arend-Roland), C/1957 P1 (Mrkos), C/1957 U1 (Latyshev-Wild-Burnham), C/1959 Q1 (Alcock), C/1959 Q2 (Alcock), C/1959 Y1 (Burnham), C/1995 O1 (Hale-Bopp), C/1996 J1 (Evans-Drinkwater), C/1996 P2 (Russell-Watson), C/1997 BA6 (Spacewatch), C/1997 D1 (Mueller), C/1997 J1 (Mueller), C/1997 J2 (Meunier-Dupouy), C/1997 N1 (Tabur), C/1997 T1 (Utsunomiya), 10P/Tempel 2, 21P/Giacobini-Zinner, 29P/Schwassmann-Wachmann 1, 43P/Wolf-Harrington, 55P/Tempel-Tuttle, 62P/Tsuchinshan 1, 69P/Taylor, 78P/Gehrels 2, 81P/Wild 2, 88P/Howell, 95P/Chiron, 103P/Hartley 2, 104P/Kowal 2, 111P/Helin-Roman-Crockett, 118P/Shoemaker-Levy 4, 121P/Shoemaker-Holt 2, 129P/Shoemaker-Levy 3, 134P/Kowal-Vavrova, P/1997 C1 (Gehrels), P/1997 G1 (Montani).

  18. Crowdsourcing, the great meteor storm of 1833, and the founding of meteor science.

    Science.gov (United States)

    Littmann, Mark; Suomela, Todd

    2014-06-01

    Yale science professor Denison Olmsted used crowdsourcing to gather observations from across the United States of the unexpected deluge of meteors on 13 November 1833--more than 72,000/h. He used these observations (and newspaper accounts and correspondence from scientists) to make a commendably accurate interpretation of the meteor storm, overturning 2100 years of erroneous teachings about shooting stars and establishing meteor science as a new branch of astronomy. Olmsted's success was substantially based on his use of newspapers and their practice of news pooling to solicit observations from throughout the country by lay and expert observers professionally unaffiliated with Yale College and him. In today's parlance, Olmsted was a remarkably successful early practitioner of scientific crowdsourcing, also known as citizen science. He may have been the first to use mass media for crowdsourcing in science. He pioneered many of the citizen-science crowdsourcing practices that are still in use today: an open call for citizen participation, a clearly defined task, a large geographical distribution for gathering data and a rapid response to opportunistic events. Olmsted's achievement is not just that he used crowdsourcing in 1833 but that crowdsourcing helped him to advance science significantly.

  19. Diurnal variation of non-specular meteor trails

    Directory of Open Access Journals (Sweden)

    J. Hinrichs

    2009-05-01

    Full Text Available We present results of simulated radar observations of meteor trails in an effort to show how non-specular meteor trails are expected to vary as a function of a number of key atmospheric, ionospheric and meteoroid parameters. This paper identifies which geophysical sources effect the variability in non-specular trail radar observations, and provides an approach that uses some of these parameter dependencies to determine meteoroid and atmospheric properties based upon the radar meteor observations. The numerical model used follows meteor evolution from ablation and ionization to head echo plasma generation and through formation of field aligned irregularities (FAI. Our main finding is that non-specular meteor trail duration is highly sensitive to the presence of lower thermospheric winds or electric fields and the background ionospheric electron density. In an effort to make key predictions we present the first results of how the same meteoroid is expected to produce dramatically different meteor trails as a function of location and local time. For example, we show that mid-latitude trail durations are often shorter lasting than equatorial trail observations because of the difference in mid-latitude wind speed and equatorial drift speed. The simulated trails also account for observations showing that equatorial nighttime non-specular meteor trails last significantly longer and are observed more often than daytime trails.

  20. Detecting Forward-Scattered Radio Signals from Atmospheric Meteors Using Low-Cost Software Defined Radio

    Science.gov (United States)

    Snjegota, Ana; Rattenbury, Nicholas James

    2017-01-01

    The forward scattering of radio signals from atmospheric meteors is a known technique used to detect meteor trails. This article outlines the project that used the forward-scattering technique to observe the 2015 August, September, and October meteor showers, as well as sporadic meteors, in the Southern Hemisphere. This project can easily be…

  1. Main characteristics of the COMET/COMRADE experiments

    Science.gov (United States)

    Borg, J.; Bibring, J.-P.; Maag, Carl R.

    1994-01-01

    Both the COMET (Collection en Orbite de Matiere Extra Terrestre) and the COMRADE (Collection of Micrometeorites, Residue and Debris Ejecta) programs are developed to the collection and analysis of the particles of various origins orbiting around the Earth at low altitudes (between approx. 300 and approx. 500 km). The COMET experiment is more specifically designed to be flown for a short period of time (a few days), in concordance with a meteor stream crossing the Earth. Thus, it results in a considerable enrichment in the collection of grains related to a given comet. The COMRADE experiment has been selected as a proposal for long-duration flights (a few months), in order to gain information on all sizes of particles present on low Earth orbits, including submicrometer grains. It has been accepted by ESA authorities for use on the EURECA 2 platform. The objectives of these studies are multiple. The use of passive detectors gives access to the chemical and isotopical properties of the grains in the micrometer size range, by analyzing either the particle remnant mixed with the target material, or the intact particle captured in a specific low-density material. The particle remnants of the micrometer-sized extraterrestrial grains, having impacted on purposely designed metallic collectors, are identified for complete and detailed chemical, isotopic, and organic analysis, thereby determining grain composition as well as the existence of organic and inorganic molecules, to be related with the possible cometary origin of the grains. Micrometer/submicrometer dust grains are also captured in a manner that ensures minimal particle degradation. The captured intact particles are returned to Earth for complete and detailed chemical, isotopic, spectral, mineralogical, and organic analysis.

  2. Diuble Station Observation of Telescopic Meteors in Mykolaiv

    Directory of Open Access Journals (Sweden)

    Kulichenko, M.O.

    2017-01-01

    Full Text Available Meteor research using TV CCD unintensified techniques was started in 2011 in Nikolaev astronomical observatory (RI «NAO». The method of meteor registration is based on the combined observation method developed at RI «NAO». The main accent of the research is made on the precise astrometry and meteoroid orbits calculation. In 2013 first double station meteors with low baseline were observed. Estimation of uncertainties of visible radiant equatorial coordinates, geocentric velocity and heliocentric meteoroid orbit parameters was carried out.

  3. METEOR v1.0 - A usage example; METEOR v1.0 - Un ejemplo de uso

    Energy Technology Data Exchange (ETDEWEB)

    Palomo, E.

    1994-07-01

    This script describes a detailed example of the use of the software package METEOR for statistical analysis of meteorological data series. A real spanish meteorological data set is chosen to show the capabilities of METEOR. Output files and resultant plots provided of their interpretations are compiled in three appendixes. The original version of METEOR have been developed by Ph. D.Elena Palomo, CIEMAT-IER, GIASE. It is built by linking programs and routines written in FORTRAN 77 and it adds the graphical capabilities of GNUPLOT. The shape of this toolbox was designed following the criteria of modularity, flexibility and agility criteria. All the input, output and analysis options are structured in three main menus: i) the first is aimed to evaluate the quality of the data set; ii) the second is aimed for pre-processing of the data; and iii) the third is aimed towards the statistical analyses and for creating the graphical outputs. Actually the information about METEOR is constituted by three documents written is spanish: 1) METEOR v1.0: User's guide; 2) METEOR v1.0: A usage example; 3) METEOR v1 .0: Design and structure of the software package. (Author)

  4. Comets and Asteroids with FIRST

    Science.gov (United States)

    Bockelée-Morvan, D.; Crovisier, J.

    2001-07-01

    The infrared and microwave domains have proved to be privileged tools to study the physical and chemical properties of small bodies of the Solar System. After a review of the recent results obtained on comets and asteroids in these wavelength ranges, we forecast the major outcomes that can be expected from their observations with the Herschel Space Observatory (hereafter referred as to FIRST, the former denomination). This prospect is focussed on: 1) observations of water rotational lines in comets to measure water outgassing and study water excitation in the coma and its kinematics; 2) observations of HDO in comets to constrain solar nebula models and formation scenarii of comets; 3) the study of surface properties of asteroids.

  5. The Geminid meteor shower during the ECOMA sounding rocket campaign: specular and head echo radar observations

    Directory of Open Access Journals (Sweden)

    G. Stober

    2013-03-01

    Full Text Available The ECOMA (Existence of Charge state Of meteoric smoke particles in the Middle Atmosphere sounding rocket campaign was conducted during the Geminid meteor shower in December 2010 in order to explore whether there is a change of the properties of meteoric smoke particles due to the stream. In parallel to the rocket flights, three radars monitored the Geminid activity located at the launch site in Northern Norway and in Northern Germany to gain information about the meteor flux into the atmosphere. The results presented here are based on specular meteor radar observations measuring the radiant position, the velocity and the meteor flux into the atmosphere during the Geminids. Further, the MAARSY (Middle Atmosphere Alomar Radar System radar was operated to conduct meteor head echo experiments. The interferometric capabilities of MAARSY permit measuring the meteor trajectories within the radar beam and to determine the source radiant and geocentric meteor velocity, as well as to compute the meteor orbit.

  6. An early look of comet C/2013 A1 (Siding Spring): Breathtaker or nightmare?

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Quan-Zhi [Department of Physics and Astronomy, The University of Western Ontario, London, Ontario N6A 3K7 (Canada); Hui, Man-To, E-mail: qye22@uwo.ca [Nhut Thung Pau Observatory, Guangzhou (China)

    2014-06-01

    The dynamically new comet, C/2013 A1 (Siding Spring), is to make a close approach to Mars on 2014 October 19 at 18:30 UT at a distance of 40 ± 1 Martian radii. Such an extremely rare event offers a precious opportunity for the spacecrafts on Mars to closely study a dynamically new comet itself as well as the planet-comet interaction. Meanwhile, the high-speed meteoroids released from C/Siding Spring also pose a threat to physically damage the spacecrafts. Here we present our observations and modeling results of C/Siding Spring to characterize the comet and assess the risk posed to the spacecrafts on Mars. We find that the optical tail of C/Siding Spring is dominated by larger particles at the time of the observation. Synchrone simulation suggests that the comet was already active in late 2012 when it was more than 7 AU from the Sun. By parameterizing the dust activity with a semi-analytic model, we find that the ejection speed of C/Siding Spring is comparable to comets such as the target of the Rosetta mission, 67P/Churyumov-Gerasimenko. Under a nominal situation, the simulated dust cone will miss the planet by about 20 Martian radii. At the extreme ends of uncertainties, the simulated dust cone will engulf Mars, but the meteoric influx at Mars is still comparable to the nominal sporadic influx, seemly indicating that an intense and enduring meteoroid bombardment due to C/Siding Spring is unlikely. Further simulation also suggests that gravitational disruption of the dust tail may be significant enough to be observable at Earth.

  7. TURBULENCE IN THE SOLAR WIND MEASURED WITH COMET TAIL TEST PARTICLES

    Energy Technology Data Exchange (ETDEWEB)

    DeForest, C. E.; Howard, T. A. [Southwest Research Institute, 1050 Walnut Street Suite 300, Boulder, CO 80302 (United States); Matthaeus, W. H. [Department of Physics and Astronomy, University of Delaware, 217 Sharp Laboratory, Newark, DE 19711 (United States); Rice, D. R. [Northwestern University, 633 Clark St., Evanston, IL 60208 (United States)

    2015-10-20

    By analyzing the motions of test particles observed remotely in the tail of Comet Encke, we demonstrate that the solar wind undergoes turbulent processing enroute from the Sun to the Earth and that the kinetic energy entrained in the large-scale turbulence is sufficient to explain the well-known anomalous heating of the solar wind. Using the heliospheric imaging (HI-1) camera on board NASA's STEREO-A spacecraft, we have observed an ensemble of compact features in the comet tail as they became entrained in the solar wind near 0.4 AU. We find that the features are useful as test particles, via mean-motion analysis and a forward model of pickup dynamics. Using population analysis of the ensemble's relative motion, we find a regime of random-walk diffusion in the solar wind, followed, on larger scales, by a surprising regime of semiconfinement that we attribute to turbulent eddies in the solar wind. The entrained kinetic energy of the turbulent motions represents a sufficient energy reservoir to heat the solar wind to observed temperatures at 1 AU. We determine the Lagrangian-frame diffusion coefficient in the diffusive regime, derive upper limits for the small scale coherence length of solar wind turbulence, compare our results to existing Eulerian-frame measurements, and compare the turbulent velocity with the size of the observed eddies extrapolated to 1 AU. We conclude that the slow solar wind is fully mixed by turbulence on scales corresponding to a 1–2 hr crossing time at Earth; and that solar wind variability on timescales shorter than 1–2 hr is therefore dominated by turbulent processing rather than by direct solar effects.

  8. CO in distantly active comets

    CERN Document Server

    Womack, Maria; Wierzchos, Kacper

    2016-01-01

    Activity of most comets near the Sun is dominated by sublimation of frozen water, the most abundant ice in comets. Some comets, however, are active well beyond the water-ice sublimation limit of ~3 AU. Three bodies dominate the observational record and modeling efforts for distantly active comets: the long-period comet C/1995 O1 Hale-Bopp and the short-period comets (with Centaur orbits) 29P/Schwassmann Wachmann 1 and 2060 Chiron. We summarize what is known about these three objects emphasizing their gaseous comae. We calculate their CN/CO and CO2/CO production rate ratios from the literature and discuss implications. Using our own data we derive CO production rates for all three objects, in order to examine a correlation between gas production and different orbital histories and/or size. We find that orbital history does not appear to play a significant role in explaining 29P's CO production rates. 29P outproduces Hale-Bopp at the same heliocentric distance, even though it has been subjected to much more sol...

  9. Helium and Neon in Comets

    Science.gov (United States)

    Jewitt, David

    1996-01-01

    Two comets were observed with EUVE in late 1994. Both comet Mueller and comet Borrelly are short-period comets having well established orbital elements and accurate ephemerides. Spectra of 40 ksec were taken of each. No evidence for emission lines from either Helium or Neon was detected. We calculated limits on the production rates of these atoms (relative to solar) assuming a standard isotropic outflow model, with a gas streaming speed of 1 km/s. The 3-sigma (99.7% confidence) limits (1/100,000 for He, 0.8 for Ne) are based on a conservative estimate of the noise in the EUVE spectra. They are also weakly dependent on the precise pointing and tracking of the EUVE field of view relative to the comet during the integrations. These limits are consistent with ice formation temperatures T greater than or equal to 30 K, as judged from the gas trapping experiments of Bar-Nun. For comparison, the solar abundances of these elements are He/O = 110, Ne/O = 1/16. Neither limit was as constraining as we had initially hoped, mainly because comets Mueller and Borrelly were intrinsically less active than anticipated.

  10. THE SPLITTING OF COMET HALLEY

    Institute of Scientific and Technical Information of China (English)

    Chen Daohan; Liu Linzhong; Alan Gilmore

    2000-01-01

    In combination with the authors previous obsewation about the splitting of Comet Halley in March 1986, the events involving the sharp, straight feature in the antisolar direction observed in the head of Comet Halley in 1910 (such as those occurring on May 14, 25 and 31, and June 2) are rediscussed The analysis leads to the following scenario: When Comet Halley explodes and splits, a fragment jettisoned or thrown off from the nucleus will, after moving in the direction of its tail, develop into a mini-comet. Although not well developed or permanent, it has its own plasma tail and, sometimes, a dust tail. If Bobrovnikoffs definition of a secondary nucleus is assumed, then the fragment should be considered as a real secondary nucleus. It seems that the current idea of a tailward jet suggested by Sekanina and Larson is a wrong explanation for the plasma tail of a mini-comet and hence the rotation period of 52-53h for Comet Halley is doubtful

  11. The splitting of Comet Halley

    Institute of Scientific and Technical Information of China (English)

    陈道汉; 刘麟仲; Alan Gilmore

    1995-01-01

    In combination with the authors’ previous observation about the splitting of Comet Halley in March 1986, the events involving the sharp, straight feature in the antisolar direction observed in the bead of Comet Halley in 1910 (such as those occurring on May 14, 25 and 31, and June 2) are rediscussed. The analysis leads to the following scenario: When Comet Halley explodes and splits, a fragment jettisoned or thrown off from the nucleus will, after moving in the direction of its tail, develop into a mini-comet. Although not well developed or permanent, it has its own plasma tail and, sometimes, a dust tail. If Bobrovnikoff’s definition of a secondary nucleus is assumed, then the fragment should be considered as a real secondary nucleus. It seems that the current idea of a tailward jet suggested by Sekanina and Larson is a wrong explanation for the plasma tail of a mini-comet and hence the rotation period of 52- 53 h for Comet Halley is doubtful.

  12. A passive FPAA based RF scatter meteor detector

    CERN Document Server

    Popowicz, Adam; Bernacki, Krzysztof; Fietkiewicz, Karol

    2015-01-01

    In the article we present a hardware meteor detector. The detection principle is based on the electromagnetic wave reflection from the ionized meteor trail in the atmosphere. The detector uses the ANADIGM field programmable analogue array (FPAA), which is an attractive alternative for a typically used detecting equipment - a PC computer with dedicated software. We implement an analog signal path using most of available FPAA resources to obtain precise audio signal detection. Our new detector was verified in collaboration with the Polish Fireball Network - the organization which monitors meteor activity in Poland. When compared with currently used signal processing PC software employing real radio meteor scatter signals, our low-cost detector proved to be more precise and reliable. Due to its cost and efficiency superiority over the current solution, the presented module is going to be implemented in the planned distributed detectors system.

  13. Improving Photometric Calibration of Meteor Video Camera Systems

    Science.gov (United States)

    Ehlert, Steven; Kingery, Aaron; Cooke, William

    2016-01-01

    Current optical observations of meteors are commonly limited by systematic uncertainties in photometric calibration at the level of approximately 0.5 mag or higher. Future improvements to meteor ablation models, luminous efficiency models, or emission spectra will hinge on new camera systems and techniques that significantly reduce calibration uncertainties and can reliably perform absolute photometric measurements of meteors. In this talk we discuss the algorithms and tests that NASA's Meteoroid Environment Office (MEO) has developed to better calibrate photometric measurements for the existing All-Sky and Wide-Field video camera networks as well as for a newly deployed four-camera system for measuring meteor colors in Johnson-Cousins BV RI filters. In particular we will emphasize how the MEO has been able to address two long-standing concerns with the traditional procedure, discussed in more detail below.

  14. A confidence index for forecasting of meteor showers

    Science.gov (United States)

    Vaubaillon, Jeremie

    2017-09-01

    The forecasting of meteor showers is currently very good at predicting the timing of meteor outbursts, but still needs further work regarding the level of a given shower. Moreover, uncertainties are rarely provided, leaving the end user (scientist, space agency or the public) with no way to evaluate how much the prediction is trustworthy. A confidence index for the forecasting of meteor showers is presented. It allows one to better understand how a specific forecasting has been performed. In particular, it underlines the role of our current knowledge of the parent body, its past orbit and past activity. The role of close encounters with planets for the time period considered is quantified as well. This confidence index is a first step towards better constrained forecasting of future meteor showers.

  15. The investigation of multiplet structures in meteor spectra

    Science.gov (United States)

    Mozgova, Alona; Churyumov, Klim

    2016-07-01

    The structures of the iron multiplets and some other elements observed in spectra of meteor comas were considered. The catalog of iron multiplets lines was made. For each term there are indicated energy levels and wavelengths of spectral lines. For clearly explaining the transitions that accompany the radiation in given multiplets the complete Grotrian diagrams were constructed. Spectral analysis has an important role in understanding the physical processes which occur in meteor comas. Each meteor spectrum contains a large number of spectral lines belonging to atoms of different chemical elements and has a multiplet structures. The multiplets are usually spaced pairs or triples of lines but the multiplet may consist of one or more lines than three. The studying of multiplet structures in meteor spectra makes it possible to investigate the properties and a behavior of atoms of the meteor body matter. It can be used for creating models of physical and chemical processes which occur during the meteor flight in the Earth's atmosphere. For some tasks of meteor physics it needs to know not only the wavelength of a line and its belonging to some multiplet, but also both the excitation potentials of the upper and lower levels. This is useful, for example, for the study of the atoms distribution over the levels and how it differs from the Boltzmann distribution, as well as for the construction of curves growth and for determining the temperature excitation in the meteor coma, etc. For this purpose, the Walt Grotrian diagrams or chart of terms are built. They show the allowed transitions between the energy levels of the atoms. These diagrams can be used for one or more electrons (multielectrons) in the atom. The specific selection rules are taken into account in their construction. These rules are related to the change in angular momentum of the electron.

  16. A chemical model of meteoric ablation

    Directory of Open Access Journals (Sweden)

    T. Vondrak

    2008-12-01

    Full Text Available Most of the extraterrestrial dust entering the Earth's atmosphere ablates to produce metal vapours, which have significant effects on the aeronomy of the upper mesosphere and lower thermosphere. A new Chemical Ablation Model (CAMOD is described which treats the physics and chemistry of ablation, by including the following processes: sputtering by inelastic collisions with air molecules before the meteoroid melts; evaporation of atoms and oxides from the molten particle; diffusion-controlled migration of the volatile constituents (Na and K through the molten particle; and impact ionization of the ablated fragments by hyperthermal collisions with air molecules. Evaporation is based on thermodynamic equilibrium in the molten meteoroid (treated as a melt of metal oxides, and between the particle and surrounding vapour phase. The loss rate of each element is then determined assuming Langmuir evaporation. CAMOD successfully predicts the meteor head echo appearance heights, observed from incoherent scatter radars, over a wide range of meteoroid velocities. The model also confirms that differential ablation explains common-volume lidar observations of K, Ca and Ca+ in fresh meteor trails. CAMOD is then used to calculate the injection rates into the atmosphere of a variety of elements as a function of altitude, integrated over the meteoroid mass and velocity distributions. The most abundant elements (Fe, Mg and Si have peak injection rates around 85 km, with Na and K about 8 km higher. The more refractory element Ca ablates around 82 km with a Na:Ca ratio of 4:1, which does therefore not explain the depletion of atomic Ca to Na, by more than 2 orders of magnitude, in the upper mesosphere. Diffusion of the most volatile elements (Na and K does not appear to be rate-limiting except in the fastest meteoroids. Non-thermal sputtering causes ~35% mass loss from the fastest (~60–70 km s−1 and smallest (10−17–10

  17. A chemical model of meteoric ablation

    Directory of Open Access Journals (Sweden)

    T. Vondrak

    2008-07-01

    Full Text Available Most of the extraterrestrial dust entering the Earth's atmosphere ablates to produce metal vapours, which have significant effects on the aeronomy of the upper mesosphere and lower thermosphere. A new Chemical Ablation Model (CAMOD is described which treats the physics and chemistry of ablation, by including the following processes: sputtering by inelastic collisions with air molecules before the meteoroid melts; evaporation of atoms and oxides from the molten particle; diffusion-controlled migration of the volatile constituents (Na and K through the molten particle; and impact ionization of the ablated fragments by hyperthermal collisions with air molecules. Evaporation is based on thermodynamic equilibrium in the molten meteoroid (treated as a melt of metal oxides, and between the particle and surrounding vapour phase. The loss rate of each element is then determined assuming Langmuir evaporation. CAMOD successfully predicts the meteor head echo appearance heights, observed from incoherent scatter radars, over a wide range of meteoroid velocities. The model also confirms that differential ablation explains common-volume lidar observations of K, Ca and Ca+ in fresh meteor trails. CAMOD is then used to calculate the injection rates into the atmosphere of a variety of elements as a function of altitude, integrated over the meteoroid mass and velocity distributions. The most abundant elements (Fe, Mg and Si have peak injection rates around 85 km, with Na and K about 8 km higher. The more refractory element Ca ablates around 82 km with a Na:Ca ratio of 4:1, which does therefore not explain the depletion of atomic Ca to Na, by more than 2 orders of magnitude, in the upper mesosphere. Diffusion of the most volatile elements (Na and K does not appear to be rate-limiting except in the fastest meteoroids. Non-thermal sputtering causes ~35% mass loss from the fastest (~60–70 km s−1 and smallest (10−17–10

  18. The 2014 KCG Meteor Outburst: Clues to a Parent Body

    Science.gov (United States)

    Moorhead, Althea V.; Brown, Peter G.; Spurny, Pavel; Cooke, William J.

    2015-01-01

    The Kappa Cygnid (KCG) meteor shower exhibited unusually high activity in 2014, producing ten times the typical number of meteors. The shower was detected in both radar and optical systems and meteoroids associated with the outburst spanned at least five decades in mass. In total, the Canadian Meteor Orbit Radar, European Network, and NASA All Sky and Southern Ontario Meteor Network produced thousands of KCG meteor trajectories. Using these data, we have undertaken a new and improved characterization of the dynamics of this little-studied, variable meteor shower. The Cygnids have a di use radiant and a significant spread in orbital characteristics, with multiple resonances appearing to play a role in the shower dynamics. We conducted a new search for parent bodies and found that several known asteroids are orbitally similar to the KCGs. N-body simulations show that the two best parent body candidates readily transfer meteoroids to the Earth in recent centuries, but neither produces an exact match to the KCG radiant, velocity, and solar longitude. We nevertheless identify asteroid 2001 MG1 as a promising parent body candidate.

  19. STONE 6: Sedimentary meteors from Mars

    Science.gov (United States)

    Westall, F.; Demets, R.; Brandstetter, F.; Edwards, H. G. M.; Cockell, C. S.; Parnell, J.; Foucher, F.; Kurat, G.; Brack, A.

    2008-09-01

    STONE 6 is a space experiment to test the potential for survival of sedimentary meteors from Mars surviving entry into the Earth's atmosphere. Two sediments and a basalt (as the control) were embedded close to the ablation point of the heat shield of a FOTON M3 capsule for atmospheric entry from lower Earth orbit in September 2007. The sediments included (1) an ~3.5 billion year (Ga) old volcanic sand containing carbonaceous microfossils and (2) an ~370 million year (Ma) old lacustrine rock containing chemical biomarkers. The backs of the samples were smeared with a living endolithic microorganism, Chroococcidiopsis. The sediments survived reentry, as did some of the chemical biomarkers in the lacustrine sediment and the carbonaceous microfossils in the 3.5 Ga-old sediment survived (away from the fusion crust). An increase in the crystallinity of the carbon in both sediments was noted. The Chroococcidiopsis did not survive but their carbonised remains did. Thus sedimentary meteorites from Mars could reach the surface of the Earth and, if they contain traces of fossil life, these traces could be preserved. However, living organisms may need more than 2cm of rock protection.

  20. METEOR v1.0 - User's Guide; METEOR v1.0 - Guia de Usuarios

    Energy Technology Data Exchange (ETDEWEB)

    Palomo, E.

    1994-07-01

    This script is a User's Guide for the software package METEOR for statistical analysis of meteorological data series. The original version of METEOR have been developed by Ph.D. Elena Palomo, CIEMAT-IER, GIMASE. It is built by linking programs and routines written in FORTRAN 77 and it adds the graphical capabilities of GNUPLOT. The shape of this toolbox was designed following the criteria of modularity, flexibility and agility criteria. All the input, output and analysis options are structured in three main menus: i) the first is aimed to evaluate the quality of the data set; ii) the second is aimed for pre-processing of the data; and iii) the third is aimed towards the statistical analyses and for creating the graphical outputs. Actually the information about METEOR is constituted by three documents written in spanish: 1) METEOR v1.0: User's guide; 2) METEOR v1.0: A usage example; 3) METEOR v1.0: Design and structure of the software package. (Author)

  1. Upward-moving low-light meteor. I: Observation results

    Science.gov (United States)

    Kozak, P. M.; Watanabe, J.

    2017-01-01

    The results of TV-detecting an earth-atmosphere-grazing low-light meteor are presented. The meteor was registered near Kyiv, Ukraine, on 23 September 2003 at UT = 20:55:52 during the Autumn Equinox observations. It was registered with both observational cameras within the altitude range H ≈ 115.6 div 117.9 km (Δ {H} ≈ - 2.3 km), the zenith distance of its radiant varying within the bounds of {Z_R} ≈ 93.7° div 94.0°. After 3D reconstruction of the trajectory, the perigee distance of the meteor was found {R_P} ≈ {{6467}}{{.4}} km, while the altitude of the minimal encounter with earth above sea level was{H_P} = 101.7 km. Traveling with the velocity of {υ}_{∞} ≈ 62.9 km/s, the meteor reached the view fields of the cameras ˜426 km after the perigee (˜6.8 s), and left them at the height of ˜461 km, practically not changing its absolute magnitude which varied in the range of {2.9^m} div {4.1^m} . Thus, the meteor remained inside the view fields of the cameras for ˜0.5 s, passing the distance of ˜35˜ km during this time. The right ascension and declination of geocentric radiant of the meteor before perigee were {α _G} ≈ 79.3°, {δ _G} ≈ - 4.2° accordingly, and the geocentric velocity {υ_G} ≈ 61.9 km/s, while after the perigee {α _G} ≈ 78.1°, {δ _G} ≈ - 2.8°, and {υ_G} ≈ 61.9 km/s (the atmosphere deceleration was neglected). The computations of heliocentric orbit elements of the meteor led to the conclusion that the meteoroid does not belong to any known meteor streams. While traveling through the view fields of the cameras, the meteor lost the mass of ˜ 5 × 10-3 g. Since the meteor was registered at the heights where ablation must become lower and eventually stop, one can assert that the meteoroid left the earth atmosphere saving part of its mass.

  2. Gaseous activity of distant comets

    Science.gov (United States)

    Womack, Maria; Sarid, Gal; Wierzchos, Kacper

    2016-10-01

    The activity of most comets within 3AU of the Sun is dominated by the sublimation of frozen water, the most abundant ice in comets. Some comets, however, are active well beyond the water-ice sublimation limit. Studying distantly active comets provides valuable opportunities to explore primitive bodies when water-ice sublimation is largely dormant, which is the case for most of a comet's lifetime. Beyond 4 AU, super-volatiles such as CO or CO2 are thought to play a major role in driving observed activity. Carbon monoxide is of special interest because it is a major contributor to comae and has a very low sublimation temperature. Three bodies dominate the observational record and modeling efforts for distantly active small bodies: the long-period comet C/1995 O1 Hale-Bopp and the short-period comets (with centaur orbits) 29P/Schwassmann Wachmann 1 and 2060 Chiron. Hale-Bopp's long-period orbit means it has experienced very little solar heating in its lifetime and is analogous to dynamically new comets making their first approach to the Sun. Because Chiron and 29P have much smaller orbits closer to the Sun, they have experienced much more thermal processing than Hale-Bopp and this is expected to have changed their chemical composition from their original state. We point out that the observed CO production rates and line-widths in these three distantly active objects are consistent with each other when adjusted for heliocentric distance. This is particularly interesting for Hale-Bopp and 29P, which have approximately the same radius. The consistent CO production rates may point to a similar CO release mechanism in these objects. We also discuss how observed radio line profiles support that the development and sublimation of icy grains in the coma at about 5-6 AU is probably a common feature in distantly active comets, and an important source of other volatiles within 6 AU, including H2O, HCN, CH3OH, and H2CO.

  3. The Phosphorous Inventory of Comets

    Science.gov (United States)

    Boice, Daniel; De Almeida, Amaury

    2012-07-01

    Phosphorus is a key element in all known forms of life but its role in life's origin is not known. Phosphorus-bearing compounds have been observed in space, are ubiquitous in meteorites, albeit in small quantities, and have been detected as part of the dust component in comet Halley. However, searches for P-bearing species in the gas phase in cometary comae have been unsuccessful. We present results of the first quantitative study of phosphorus-bearing molecules in comets to identify likely species containing phosphorus and to aid in future searches for this important element, possibly shedding light on issues of comet formation (time and place) and understanding prebiotic to biotic evolution of life.

  4. Catastrophic Disruption of Comet ISON

    Science.gov (United States)

    Keane, Jacqueline V.; Milam, Stefanie N.; Coulson, Iain M.; Kleyna, Jan T.; Sekanina, Zdenek; Kracht, Rainer; Riesen, Timm-Emmanuel; Meech, Karen J.; Charnley, Steven B.

    2016-01-01

    We report submillimeter 450 and 850 microns dust continuum observations for comet C/2012 S1 (ISON) obtained at heliocentric distances 0.31-0.08 au prior to perihelion on 2013 November 28 (rh?=?0.0125 au). These observations reveal a rapidly varying dust environment in which the dust emission was initially point-like. As ISON approached perihelion, the continuum emission became an elongated dust column spread out over as much as 60? (greater than 10(exp 5) km in the anti-solar direction. Deconvolution of the November 28.04 850 microns image reveals numerous distinct clumps consistent with the catastrophic disruption of comet ISON, producing approximately 5.2?×?10(exp 10) kg of submillimeter-sized dust. Orbital computations suggest that the SCUBA-2 emission peak coincides with the comet's residual nucleus.

  5. Comets 169P/NEAT and P/2003 T12 (SOHO): Two possible fragments of a common ancestor?

    Science.gov (United States)

    Sosa, Andrea; Fernández, Julio Angel

    2015-08-01

    In a recent work we analyzed the orbit evolution of Jupiter family comets in near-Earth orbits, and found some comets moving on highly stable orbits, like the near-Earth asteroids (Fernández & Sosa 2015). Two of them actually show almost identical orbits; they are the comets 169P/NEAT and P/2003 T12 (SOHO). Comet 169P seems to be a few km-sized, almost inactive body, while P/2003 T12 would be a very small comet, with a sub-km radius nucleus. We performed extended orbital integrations for the past 100,000 yr to further study their dynamical evolution. We found that the orbital parameters remain stable for several thousand years, with a well defined absolute minimum of their relative spatial distance around 2900 yr in the past, coincident with a low value of the relative velocity. This spatial minimum is in a remarkable good agreement with the results obtained by means of other methods to study common origins between pairs of asteroids (Vokrouhlicky & Nesvorny 2008, Southworth & Hawkins 1963), and to test a comet-meteor shower association (Drummond 1981). Our results support the hypothesis of a breakup of a parent body, that ocurred about 2900 yr ago, as the most probable origin for the studied pair of comets. Possible fragmentation mechanisms, like thermal stress, rotational instability, or colisions, are briefly discussed.References:Drumond J.D. 1981. Icarus 45, 545-553.Fernández J.A., & Sosa A. 2015. Submitted to Planetary & Space Science.Southworth R.B., & Hawkins, G.S. 1963. Smithson. Contrib. Astrophys. 7, 261-285Vokrouhlicky D., & Nesvorny D. 2008. Astron. J. 136, 280-290.

  6. Comets. [and solar system evolution

    Science.gov (United States)

    Neugebauer, M.

    1986-01-01

    The nature, history, and evolution of comets are considered. Cometary ions, formed by photoionization and other processes, are forced into a highly structured ion tail by the interaction with the solar wind. The importance of comets to solar-system studies lies in the possibilities that they are well-preserved samples of either the interstellar cloud which collapsed to form the solar system or the planetesimals from which the outer planets accumulated, and that they provided either the prebiotic complex molecules from which life evolved or some volatiles necessary for the evolution of these molecules.

  7. EUV observations of comet Halley

    Science.gov (United States)

    Ripken, H. W.; Fahr, H. J.; Lay, G.

    The use of spaceborne or sounding-rocket EUV observations to determine the He/H abundance ratio, the shape of the Lyman-alpha emission line, and the H velocity distribution in comet Halley is discussed. The resonance-absorption-cell spectrophotometers of the payloads proposed by Fahr et al. (1984) for the Ultra-Halley experiment are briefly characterized and shown to be capable of obtaining quantitative measurements of the 58.4-nm line of He for comet He/H ratios in excess of 0.0004, successfully eliminating or accounting for geocoronal and cosmic contamination.

  8. American Meteor Society Fireball reporting system and mobile application

    Science.gov (United States)

    Hankey, M.

    2014-07-01

    The American Meteor Society (AMS) founded in 1911 pioneered the visual study of meteors and has collected data relating to meteor observations and bright fireballs for over 100 years. In December 2010, the online fireball reporting system was upgraded to an interactive application that utilizes Google Maps and other programmatic methods to pinpoint the observer's location, azimuth and elevation values with a high degree of precision. The AMS has collected 10s of 1000s of witness reports relating to 100s of events each year since the new application was released. Three dimensional triangulation methods that average the data collected from witnesses have been developed that can determine the start and end points of the meteor with an accuracy of saw the fireball. This process is designed to require no button click or user interaction to start and stop the time recording. A count down initiates the process and once the user's phone crosses the plane of azimuth for the end point of the fireball the velocity timer automatically stops. Users are asked to log the recording three times in an effort to minimize error. The three values are then averaged into a final score. Once enough witnesses have filed reports, elapsed time data collected from the mobile phone can be used to determine the velocity of the fireball. With the velocity, trajectory solution and RA/DEC the AMS can plot orbital estimates for significant fireball events reported to the society. Our hope is that overtime this catalog of events will reveal patterns relating to the origins of bright fireballs at certain times of year. The AMS also hopes to be able to associate fireball events reported to the society with known meteor showers when RA/DEC radiant estimates fall close enough to those of known showers. In addition to the enhanced fireball reporting application, the AMS Mobile App provides a meteor shower calendar with information, radiant maps and moon conditions for all upcoming showers. There is also

  9. Division F Commission 22: Meteors, Meteorites, and Interplanetary Dust

    Science.gov (United States)

    Jenniskens, Peter; Borovička, Jiří; Watanabe, Jun-Ichi; Jopek, Tadeusz; Abe, Shinsuke; Consolmagno, Guy J.; Ishiguro, Masateru; Janches, Diego; Ryabova, Galina O.; Vaubaillon, Jérémie; Zhu, Jin

    2016-04-01

    Commission 22 (Meteors, Meteorites and Interplanetary Dust) was established at the first IAU General Assembly held in Rome in 1922, with William Frederick Denning as its first President. Denning was an accountant by profession, but as an amateur astronomer he contributed extensively to meteor science. Commission 22 thus established a pattern that has continued to this day that non-professional astronomers were welcomed and valued and could play a significant role in its affairs. The field of meteors, meteorites and interplanetary dust has played a disproportional role in the astronomical perception of the general public through the majestic displays of our annual meteor showers. Those in the field deployed many techniques uncommon in other fields of astronomy, studying the ``vermin of space'', the small solid bodies that pervade interplanetary space and impact Earth's atmosphere, the surface of the Moon, and that of our satellites in orbit. Over time, the field has tackled a wide array of problems, from predicting the encounter with meteoroid streams, to the origin of our meteorites and the nature of the zodiacal cloud. Commission 22 has played an important role in organizing the field through dedicated meetings, a data centre, and working groups that developed professional-amateur relationships and that organized the nomenclature of meteor showers. The contribution of Commission 22 to the field is perhaps most readily seen in the work of the presidents that followed in the footsteps of Denning.

  10. Charles Olivier and the rise of meteor science

    CERN Document Server

    Taibi, Richard

    2017-01-01

    This fascinating portrait of an amateur astronomy movement tells the story of how Charles Olivier recruited a hard-working cadre of citizen scientists to rehabilitate the study of meteors. By 1936, Olivier and members of his American Meteor Society had succeeded in disproving an erroneous idea about meteor showers. Using careful observations, they restored the public’s trust in predictions about periodic showers and renewed respect for meteor astronomy among professional astronomers in the United States. Charles Olivier and his society of observers who were passionate about watching for meteors in the night sky left a major impact on the field. In addition to describing Olivier’s career and describing his struggles with competitive colleagues in a hostile scientific climate, the author provides biographies of some of the scores of women and men of all ages who aided Olivier in making shower observations, from the Leonids and Perseids and others. Half of these amateur volunteers were from 13 to 25 years of...

  11. SuprimeCam Observation of Sporadic Meteors during Perseids 2004

    CERN Document Server

    Iye, M; Yanagisawa, M; Ebizuka, N; Ohnishi, K; Hirose, C; Asami, N; Komiyama, Yu; Furusawa, H

    2007-01-01

    We report the serendipitous findings of 13 faint meteors and 44 artificial space objects by Subaru SuprimeCam imaging observations during 11-16 August 2004. The meteors, at about 100km altitude, and artificial satellites/debris in orbit, at 500km altitude or higher, were clearly discriminated by their apparent defocused image sizes. CCD photometry of the 13 meteors, including 1 Perseid, 1 Aquarid, and 11 sporadic meteors, was performed. We defined a peak video-rate magnitude by comparing the integrated photon counts from the brightest portion of the track traversed within 33ms to those from a 0-mag star during the same time duration. This definition gives magnitudes in the range 4.0< V_{vr} <6.4 and 4.1< I_{vr}<5.9 for these 13 meteors. The corresponding magnitude for virtual naked-eye observers could be somewhat fainter especially for the V-band observation, in which the [OI] 5577 line lasting about 1 sec as an afterglow could contribute to the integrated flux of the present 5-10 min CCD exposure...

  12. Meteoric 10Be in soil profiles - A global meta-analysis

    Science.gov (United States)

    Graly, Joseph A.; Bierman, Paul R.; Reusser, Lucas J.; Pavich, Milan J.

    2010-12-01

    In order to assess current understanding of meteoric 10Be dynamics and distribution in terrestrial soils, we assembled a database of all published meteoric 10Be soil depth profiles, including 104 profiles from 27 studies in globally diverse locations, collectively containing 679 individual measurements. This allows for the systematic comparison of meteoric 10Be concentration to other soil characteristics and the comparison of profile depth distributions between geologic settings. Percent clay, 9Be, and dithionite-citrate extracted Al positively correlate to meteoric 10Be in more than half of the soils where they were measured, but the lack of significant correlation in other soils suggests that no one soil factor controls meteoric 10Be distribution with depth. Dithionite-citrate extracted Fe and cation exchange capacity are only weakly correlated to meteoric 10Be. Percent organic carbon and pH are not significantly related to meteoric 10Be concentration when all data are complied. The compilation shows that meteoric 10Be concentration is seldom uniform with depth in a soil profile. In young or rapidly eroding soils, maximum meteoric 10Be concentrations are typically found in the uppermost 20 cm. In older, more slowly eroding soils, the highest meteoric 10Be concentrations are found at depth, usually between 50 and 200 cm. We find that the highest measured meteoric 10Be concentration in a soil profile is an important metric, as both the value and the depth of the maximum meteoric 10Be concentration correlate with the total measured meteoric 10Be inventory of the soil profile. In order to refine the use of meteoric 10Be as an estimator of soil erosion rate, we compare near-surface meteoric 10Be concentrations to total meteoric 10Be soil inventories. These trends are used to calibrate models of meteoric 10Be loss by soil erosion. Erosion rates calculated using this method vary based on the assumed depth and timing of erosional events and on the reference data selected.

  13. Meteoric 10Be in soil profiles - A global meta-analysis

    Science.gov (United States)

    Graly, Joseph A.; Bierman, Paul R.; Reusser, Lucas J.; Pavich, Milan J.

    2010-01-01

    In order to assess current understanding of meteoric 10Be dynamics and distribution in terrestrial soils, we assembled a database of all published meteoric 10Be soil depth profiles, including 104 profiles from 27 studies in globally diverse locations, collectively containing 679 individual measurements. This allows for the systematic comparison of meteoric 10Be concentration to other soil characteristics and the comparison of profile depth distributions between geologic settings. Percent clay, 9Be, and dithionite-citrate extracted Al positively correlate to meteoric 10Be in more than half of the soils where they were measured, but the lack of significant correlation in other soils suggests that no one soil factor controls meteoric 10Be distribution with depth. Dithionite-citrate extracted Fe and cation exchange capacity are only weakly correlated to meteoric 10Be. Percent organic carbon and pH are not significantly related to meteoric 10Be concentration when all data are complied.The compilation shows that meteoric 10Be concentration is seldom uniform with depth in a soil profile. In young or rapidly eroding soils, maximum meteoric 10Be concentrations are typically found in the uppermost 20 cm. In older, more slowly eroding soils, the highest meteoric 10Be concentrations are found at depth, usually between 50 and 200 cm. We find that the highest measured meteoric 10Be concentration in a soil profile is an important metric, as both the value and the depth of the maximum meteoric 10Be concentration correlate with the total measured meteoric 10Be inventory of the soil profile.In order to refine the use of meteoric 10Be as an estimator of soil erosion rate, we compare near-surface meteoric 10Be concentrations to total meteoric 10Be soil inventories. These trends are used to calibrate models of meteoric 10Be loss by soil erosion. Erosion rates calculated using this method vary based on the assumed depth and timing of erosional events and on the reference data selected.

  14. Featured Image: A Comet's Coma

    Science.gov (United States)

    Kohler, Susanna

    2016-11-01

    This series of images (click for the full view!) features the nucleus of comet 67P/Churymov-Gerasimenko. The images were taken with the Wide Angle Camera of RosettasOSIRIS instrument asRosetta orbited comet 67P. Each column represents a different narrow-band filter that allows us to examine the emission of a specific fragment species, and the images progress in time from January 2015 (top) to June 2015 (bottom). In a recent study, Dennis Bodewits (University of Maryland) and collaborators used these images to analyze the comets inner coma, the cloud of gas and dust produced around the nucleus as ices sublime. OSIRISs images allowed the team to explore how the 67Ps inner coma changed over time as the comet approached the Sun marking the first time weve been able to study such an environment at this level of detail. To read more about what Bodewits and collaborators learned, you can check out their paper below!CitationD. Bodewits et al 2016 AJ 152 130. doi:10.3847/0004-6256/152/5/130

  15. Altitudinal dependence of meteor radio afterglows measured via optical counterparts

    CERN Document Server

    Obenberger, K S; Dowell, J D; Schinzel, F K; Stovall, K; Sutton, E K; Taylor, G B

    2016-01-01

    Utilizing the all-sky imaging capabilities of the LWA1 radio telescope along with a host of all-sky optical cameras, we have now observed 44 optical meteor counterparts to radio afterglows. Combining these observations we have determined the geographic positions of all 44 afterglows. Comparing the number of radio detections as a function of altitude above sea level to the number of expected bright meteors we find a strong altitudinal dependence characterized by a cutoff below $\\sim$ 90 km, below which no radio emission occurs, despite the fact that many of the observed optical meteors penetrated well below this altitude. This cutoff suggests that wave damping from electron collisions is an important factor for the evolution of radio afterglows, which agrees with the hypothesis that the emission is the result of electron plasma wave emission.

  16. Meteoric sphaerosiderite lines and their use for paleohydrology and paleoclimatology

    Science.gov (United States)

    Ludvigson, Greg A.; Gonzalez, Luis A.; Metzger, R.A.; Witzke, B.J.; Brenner, Richard L.; Murillo, A.P.; White, T.S.

    1998-01-01

    Sphaerosiderite, a morphologically distinct millimeter-scale spherulitic siderite (FeCO3), forms predominantly in wetland soils and sediments, and is common in the geologic record. Ancient sphaerosiderites are found in paleosol horizons within coal-bearing stratigraphic intervals and, like their modern counterparts, are interpreted as having formed in water-saturated environments. Here we report on sphaerosiderites from four different stratigraphic units, each of which has highly variable 13C and relatively stable 18O compositions. The unique isotopic trends are analogous to well-documented meteoric calcite lines, which we define here as meteoric sphaerosiderite lines. Meteoric sphaerosiderite lines provide a new means of constraining ground-water ??18O and thus allow evaluation of paleohydrology and paleoclimate in humid continental settings.

  17. French Meteor Network for High Precision Orbits of Meteoroids

    Science.gov (United States)

    Atreya, P.; Vaubaillon, J.; Colas, F.; Bouley, S.; Gaillard, B.; Sauli, I.; Kwon, M. K.

    2011-01-01

    There is a lack of precise meteoroids orbit from video observations as most of the meteor stations use off-the-shelf CCD cameras. Few meteoroids orbit with precise semi-major axis are available using film photographic method. Precise orbits are necessary to compute the dust flux in the Earth s vicinity, and to estimate the ejection time of the meteoroids accurately by comparing them with the theoretical evolution model. We investigate the use of large CCD sensors to observe multi-station meteors and to compute precise orbit of these meteoroids. An ideal spatial and temporal resolution to get an accuracy to those similar of photographic plates are discussed. Various problems faced due to the use of large CCD, such as increasing the spatial and the temporal resolution at the same time and computational problems in finding the meteor position are illustrated.

  18. Landslides and impacts on comets.

    Science.gov (United States)

    Czechowski, Leszek

    2016-07-01

    The recent landing of Philae on the comet 67P/Czuriumow-Gierasimienko indicates that elastic properties of comet's nuclei could be similar to elastic properties of dry snow, namely Young modulus is assumed to be 106 - 108 Pa. We considered a simple model of two spheres (with radius 1400 m each) connected by cylinder (with radius of 200 m and length of 200 m). Density is 470 kg m-3. This shape corresponds approximately to shape of some comets. A few vibration modes are possible. In present research we consider 3 modes: bending, lengthening-shortening along axis of symmetry, and torsion. Let assume that comets are hit by small meteoroid of the mass of 1 kg and velocity 20 km s-1. The maximum values of acceleration of the surface resulting from this impact are given in Table 1. Note that these values are higher than acceleration of the gravity of the comet. Consequently, these vibrations could be an important factor of surface evolution, e.g. they could trigger landslides. It could be alternative mechanism to that presented in [4] (i.e. fluidization). Acknowledgement: The research is partly supported by Polish National Science Centre (decision 2014/15/B/ST 10/02117) References [1] T. Spohn, J. Knollenberg, A. J. Ball, M. Ba-naszkiewicz, J. Benkhoff, M. Grott, J. Gry-gorczuk, C. Hüttig, A. Hagermann, G. Kargl, E. Kaufmann, N. Kömle, E. Kührt, K. J. Kossacki, W. Marczewski, I. Pelivan, R. Schrödter, K. Seiferlin. (2015) Thermal and mechanical properties of the near-surface layers of comet 67P/Churyumov- Gera-simenko Science 31 July 2015: Vol. 349 no. 6247 DOI: 10.1126/science.aab0464 [2] Reuter B. (2013) On how to measure snow mechanical properties relevant to slab avalanche release. International Snow Science Workshop Grenoble - Chamonix Mont-Blanc - 2013 007 [3] Ball A.J. (1997) Ph. D. Thesis: Measuring Physical Properties at the Surface of a Comet Nu-cleus, Univ.of Kent U.K. [4] Belton M. J.S., Melosh J. (2009). Fluidization and multiphase transport of

  19. The Low Albedo of Comets

    Science.gov (United States)

    Buratti, B. J.; Choukroun, M.; Bauer, J. M.

    2016-12-01

    Comets are among the handful of objects with very low albedos, in the 0.02-0.06 range. Dark material is common in the outer Solar System, but analysis of the spectra and albedo of this material by spacecraft including Cassini and New Horizons shows that it is diverse, covering a range of compositions. Some is neutral-colored in the visible, such as that found on Phoebe, while some is very red, such as that on the surfaces of D-type asteroids or the low-albedo side of Iapetus. The different types of low-albedo material may reflect both compositional diversity, including contamination by volatiles or darkening agents, and divergent alteration histories. The key question is whether a particular sub-type of low albedo material is pristine - an unprocessed accumulation of interstellar dust - or an end product of polymerization and photolysis into ever more complex materials. Comets have albedos similar to the leading hemisphere of Iapetus, the surface of Titan, and the lowest-albedo C-type and D-type asteroids. Observations by the WISE and NEOWISE cameras show that comets have consistently low albedos (1). The first quantitative measurement of low-albedo material in the Kuiper Belt, from which comets such as Jupiter Family Comets including 67P/Churyumov-Gerasimenko come, shows that even this material is not as dark as that found on comets (2). Results from both Stardust (3) and more recently Rosetta (4, 5) show that cometary surfaces contain prebiotic molecules, including the amino acid glycine. Other very low albedo objects have also been connected to complex organic molecules: on Iapetus, PAHs have been detected (6), and Titan's surface is believed to be covered with hydrocarbons produced in its haze layer (7). The presence of organic molecules, including complex ones, could be the unique characteristic of the very darkest material. The delivery of pre-biotic material from comets to the young Earth could represent a key link in the origins of terrestrial life. (1

  20. Radio observations of Jupiter-family comets

    CERN Document Server

    Crovisier, J; Bockelée-Morvan, D; Colom, P

    2008-01-01

    Radio observations from decimetric to submillimetric wavelengths are now a basic tool for the investigation of comets. Spectroscopic observations allow us i) to monitor the gas production rate of the comets, by directly observing the water molecule, or by observing secondary products (e.g., the OH radical) or minor species (e.g., HCN); ii) to investigate the chemical composition of comets; iii) to probe the physical conditions of cometary atmospheres: kinetic temperature and expansion velocity. Continuum observations probe large-size dust particles and (for the largest objects) cometary nuclei. Comets are classified from their orbital characteristics into two separate classes: i) nearly-isotropic, mainly long-period comets and ii) ecliptic, short-period comets, the so-called Jupiter-family comets. These two classes apparently come from two different reservoirs, respectively the Oort cloud and the trans-Neptunian scattered disc. Due to their different history and - possibly - their different origin, they may h...

  1. CO in Distantly Active Comets

    Science.gov (United States)

    Womack, M.; Sarid, G.; Wierzchos, K.

    2017-03-01

    The activity of most comets near the Sun is dominated by the sublimation of frozen water, the most abundant ice in comets. Some comets, however, are active well beyond the water-ice sublimation limit of ∼3 au. Three bodies dominate the observational record and modeling efforts for distantly active comets: the long-period comet C/1995 O1 (Hale-Bopp), and the short-period comets (with Centaur orbits) 29P/Schwassmann-Wachmann 1 and 2060 Chiron. We summarize what is known about these three objects with an emphasis on their gaseous comae. We calculate their CN/CO and CO2/CO production rate ratios from the literature and discuss implications, such as HCN and CO2 outgassing are not significant contributors to their comae. Using our own data we derive CO production rates, Q(CO), for all three objects to examine whether there is a correlation between gas production and different orbital histories and/or size. The CO measurements of Hale-Bopp (4–11 AU) and 29P are consistent with a nominal production rate of Q(CO) = 3.5 × 1029 r‑2 superimposed with sporadic outbursts. The similarity of Hale-Bopp CO production rates for pre- and post-perihelion suggests that thermal inertia was not very important and therefore most of the activity is at or near the surface of the comet. We further examine the applicability of existing models in explaining the systematic behavior of our small sample. We find that orbital history does not appear to play a significant role in explaining 29P’s CO production rates. 29P outproduces Hale-Bopp at the same heliocentric distance, even though it has been subjected to much more solar heating. Previous modeling work on such objects predicts that 29P should have been devolatilized over a fresher comet like Hale-Bopp. This may point to 29P having a different orbital history than current models predict, with its current orbit acquired more recently. On the other hand, Chiron’s CO measurements are consistent with it being significantly depleted

  2. An Automatic Video Meteor Observation Using UFO Capture at the Showa Station

    Science.gov (United States)

    Fujiwara, Y.; Nakamura, T.; Ejiri, M.; Suzuki, H.

    2012-05-01

    The goal of our study is to clarify meteor activities in the southern hemi-sphere by continuous optical observations with video cameras with automatic meteor detection and recording at Syowa station, Antarctica.

  3. Physics-Based Modeling of Meteor Entry and Breakup

    Science.gov (United States)

    Prabhu, Dinesh K.; Agrawal, Parul; Allen, Gary A., Jr.; Bauschlicher, Charles W., Jr.; Brandis, Aaron M.; Chen, Yih-Kang; Jaffe, Richard L.; Palmer, Grant E.; Saunders, David A.; Stern, Eric C.; Tauber, Michael E.; Venkatapathy, Ethiraj

    2015-01-01

    A new research effort at NASA Ames Research Center has been initiated in Planetary Defense, which integrates the disciplines of planetary science, atmospheric entry physics, and physics-based risk assessment. This paper describes work within the new program and is focused on meteor entry and breakup.Over the last six decades significant effort was expended in the US and in Europe to understand meteor entry including ablation, fragmentation and airburst (if any) for various types of meteors ranging from stony to iron spectral types. These efforts have produced primarily empirical mathematical models based on observations. Weaknesses of these models, apart from their empiricism, are reliance on idealized shapes (spheres, cylinders, etc.) and simplified models for thermal response of meteoritic materials to aerodynamic and radiative heating. Furthermore, the fragmentation and energy release of meteors (airburst) is poorly understood.On the other hand, flight of human-made atmospheric entry capsules is well understood. The capsules and their requisite heatshields are designed and margined to survive entry. However, the highest speed Earth entry for capsules is 13 kms (Stardust). Furthermore, Earth entry capsules have never exceeded diameters of 5 m, nor have their peak aerothermal environments exceeded 0.3 atm and 1 kW/sq cm. The aims of the current work are: (i) to define the aerothermal environments for objects with entry velocities from 13 to 20 kms; (ii) to explore various hypotheses of fragmentation and airburst of stony meteors in the near term; (iii) to explore the possibility of performing relevant ground-based tests to verify candidate hypotheses; and (iv) to quantify the energy released in airbursts. The results of the new simulations will be used to anchor said risk assessment analyses. With these aims in mind, state-of-the-art entry capsule design tools are being extended for meteor entries. We describe: (i) applications of current simulation tools to

  4. Performance of Watec 910 HX camera for meteor observing

    Science.gov (United States)

    Ocaña, Francisco; Zamorano, Jaime; Tapia Ayuga, Carlos E.

    2014-01-01

    The new Watec 910 HX model is a 0.5 MPix multipurpose video camera with up to ×256 frames integration capability. We present a sensitivity and spectral characterization done at Universidad Complutense de Madrid Instrument Laboratory (LICA). In addition, we have carried out a field test to show the performance of this camera for meteor observing. With respect to the similar model 902 H2 Ultimate, the new camera has additional set-up controls that are important for the scientific use of the recordings. However the overall performance does not justify the extra cost for most of the meteor observers.

  5. Optical Observations of Meteors Generating Infrasound - I: Acoustic Signal Identification and Phenomenology

    OpenAIRE

    Silber, Elizabeth A.; Brown, Peter G.

    2014-01-01

    We analyze infrasound signals from 71 bright meteors simultaneously detected by video to investigate the phenomenology and characteristics of meteor-generated near-field infrasound and shock production. A taxonomy for meteor generated infrasound signal classification has been developed using the time-pressure signal of the infrasound arrivals. Based on the location along the meteor trail where the infrasound signal originates, we find most signals are associated with cylindrical shocks, with ...

  6. Detecting Forward-Scattered Radio Signals from Atmospheric Meteors Using Low-Cost Software Defined Radio

    Science.gov (United States)

    Snjegota, Ana; Rattenbury, Nicholas James

    2017-02-01

    The forward scattering of radio signals from atmospheric meteors is a known technique used to detect meteor trails. This article outlines the project that used the forward-scattering technique to observe the 2015 August, September, and October meteor showers, as well as sporadic meteors, in the Southern Hemisphere. This project can easily be replicated in any part of the world and is a suitable, low-cost project designed for students who are interested in astronomy.

  7. The location of Asteroidal Belt Comets (ABCs), in a comet's evolutionary diagram: The Lazarus Comets

    Science.gov (United States)

    Ferrín, Ignacio; Zuluaga, Jorge; Cuartas, Pablo

    2013-09-01

    There is a group of newly recognized asteroids in the main belt that are exhibiting cometary characteristics. We will call them Asteroidal Belt Comets or ABCs for short. The surprising property of these objects is that their orbits are entirely asteroidal while their behaviour is entirely cometary, with Tisserand invariants larger than 3.0, while all Jupiter family comets have Tisserand invariants smaller than 3.0. An analysis of their orbital and physical properties has resulted in the following conclusion. (1) We define the `detached group (DG)' as those objects that exhibit cometary characteristics (sublimating water) and have aphelion distances Q < 4.5 au. The DG contains all the ABCs traditionally recognized, plus a few other members not traditionally recognized like 2P and 107P. With the above definition there are 11 members of the ABC group: 2P, 107P, 133P, 176P, 233P, 238P, C/2008 R1, C/2010 R2, 2011 CR42, 3200 and 300163 = 2006 VW139. And there are three members of the collisioned asteroids, CA, P/2010 A2, 596 Scheila and P/2012 F5 Gibbs. (2) In the literature a common reason for activity is interplanetary collisions. Active objects sublimate ices except for the CA that have exhibited dust tails due to collisions and 3200 Phaethon activated by solar wind sputtering. In this work, we will trace the origin of activity to a diminution of their perihelion distances, a hypothesis that has not been previously explored in the literature. (3) We have calibrated the blackbody (colour) temperature of comets versus perihelion distance, R, regardless of class. We find T = 325 ± 5 K/√R. (4) Using a mathematical model of the thermal wave we calculate the thickness of the crust or dust layer on comet nuclei. We find a thickness of 2.0 ± 0.5 m for comet 107P, 4.7 ± 1.2 m for comet 133P and 1.9 ± 0.5 m for a sample of nine comets. Note the small errors. (5) We have located three ABCs in an evolutionary diagram of Remaining Revolutions (RR) versus Water-Budget Age (WB

  8. Determination of the velocity of meteors based on sinodial modulation and frequency analysis

    NARCIS (Netherlands)

    Bettonvil, F.C.M.

    2008-01-01

    In meteor photography the velocity of meteors is generally obtained from a chopper which blocks periodically the incident light beam in front of the camera lens. In this paper I examine modulation of the meteor trail instead with a sinodial function and use frequency analysis to compute accurately t

  9. Anomalous meteors from the observations with super-isocon TV systems

    Science.gov (United States)

    Kozak, P.; Watanabe, J.; Sato, M.

    2014-07-01

    There is a range of both optical and radar observations of meteors the behavior of which essentially differs from the behavior of most meteors. In some cases such meteors cannot be explained in the frame of the classic physical theory of meteors, in other cases the meteors are just of rare type. First of all these are the meteors with true hyperbolic velocities. In spite of the fact that most of hyperbolic orbits are the results of calculation errors, the meteors with extremely high velocities appreciably exceeding the hyperbolic limit of 73 km/s exist and can be of interstellar origin [1--3]. Another very rare phenomenon describes the possible cluster structure of meteor streams, which could be connected with the ejection of the substance from the cometary nucleus shortly before collision of the particles with the Earth [4]. Among anomalies connected with the meteor motion in the atmosphere one can note, first of all, the ultra-high altitudes of meteor beginnings exceeding 130--140 km [5--7]. Some other observations point to the beginning heights of bright meteors from Leonid shower on altitudes near 200 km [8]. The classic physical theory of meteors cannot explain their radiation on such high altitudes because of low air density [9]. Recently the results of TV observations of meteors with diffusive and cloudy structure appeared [9,10]. The results of observations in which, according to author's opinion, the meteors have a few kilometers transverse jets [9--11] were presented as well. There are video frames with bright meteor obtained with high temporal resolution, where authors declared the radiation, which could be an effect of a spread directly of the shock wave [12]. During many years' double-station observations of meteors which have been carrying out at Astronomical Observatory of Kyiv National Taras Shevchenko University the ultra-sensitive TV transmitting tubes of super-isocon type were used [7]. Given type of the tube is one of the most sensitive in the

  10. ISO's analysis of Comet Hale-Bopp

    Science.gov (United States)

    1997-03-01

    The European Space Agency's Infrared Space Observatory ISO inspected Comet Hall-Bopp during the spring and autumn of 1996. The need to keep ISO's telescope extremely cold restricts the spacecraft's pointing in relation to the Sun and the Earth and it ruled out observations at other times. The analyses of the 1996 observations are not yet complete, but already they give new insight into the nature of comets. Comet Hale-Bopp is believed to be a large comet with a nucleus up to 40 kilometres wide. It was discovered in July 1995 by two American astronomers working independently, Alan Hale and Thomas Bopp. At that time, the comet was a billion kilometres away from the Sun, but 200 times brighter than Halley's Comet was, when at a comparable distance. Comet Hale-Bopp will make its closest approach to the Earth on 22 March, and its closest approach to the Sun (perihelion) on 1 April 1997. Some scientific results from ISO The discovery of Comet Hale-Bopp occurred before ISO's launch in November 1995. When first observed by ISO in March and April 1996, the comet was still 700 million kilometres from the Sun, and almost as far from the Earth and ISO. With its privileged view of infrared wavebands inaccessible from the Earth's surface, ISO's photometer ISOPHOT discovered that carbon dioxide was an important constituent of the comet's emissions of vapour.ISOPHOT measured the temperature of the dust cloud around Comet Hale-Bopp. In March 1996, when the comet was still more than 700 million kilometres from the Sun, the dust cloud was at minus 120 degrees C. When ISOPHOT made similar observations in October 1996, the comet was 420 million kilometres from the Sun, and the dust cloud had warmed to about minus 50 degrees C. Intensive observations of Comet Hale-Bopp were also made by ISO's Short-Wave Spectrometer SWS, the Long-Wave Spectrometer LWS, and the ISOPHOT spectrometer PHOT-S. Results are due for publication at the end of March. They will give details about the composition

  11. Building single-page web apps with meteor

    CERN Document Server

    Vogelsteller, Fabian

    2015-01-01

    If you are a web developer with basic knowledge of JavaScript and want to take on Web 2.0, build real-time applications, or simply want to write a complete application using only JavaScript and HTML/CSS, this is the book for you.This book is based on Meteor 1.0.

  12. Improving Photometric Calibration of Meteor Video Camera Systems

    Science.gov (United States)

    Ehlert, Steven; Kingery, Aaron; Suggs, Robert

    2016-01-01

    We present the results of new calibration tests performed by the NASA Meteoroid Environment Oce (MEO) designed to help quantify and minimize systematic uncertainties in meteor photometry from video camera observations. These systematic uncertainties can be categorized by two main sources: an imperfect understanding of the linearity correction for the MEO's Watec 902H2 Ultimate video cameras and uncertainties in meteor magnitudes arising from transformations between the Watec camera's Sony EX-View HAD bandpass and the bandpasses used to determine reference star magnitudes. To address the rst point, we have measured the linearity response of the MEO's standard meteor video cameras using two independent laboratory tests on eight cameras. Our empirically determined linearity correction is critical for performing accurate photometry at low camera intensity levels. With regards to the second point, we have calculated synthetic magnitudes in the EX bandpass for reference stars. These synthetic magnitudes enable direct calculations of the meteor's photometric ux within the camera band-pass without requiring any assumptions of its spectral energy distribution. Systematic uncertainties in the synthetic magnitudes of individual reference stars are estimated at 0:20 mag, and are limited by the available spectral information in the reference catalogs. These two improvements allow for zero-points accurate to 0:05 ?? 0:10 mag in both ltered and un ltered camera observations with no evidence for lingering systematics.

  13. Airborne observation of 2011 Draconids meteor outburst: the Italian mission

    CERN Document Server

    Sigismondi, Costantino

    2011-01-01

    The outburst of 8 October 2011 of Draconids meteors has been observed visually onboard of Alitalia AZ790 flight. The enhanced zenithal hourly rate around ZHR=300 from 19 UT to 21:50 UT has been observed over central Asia. The data and the method of analysis are described and compared with other observations made worldwide.

  14. The 2017 Meteor Shower Activity Forecast for Earth Orbit

    Science.gov (United States)

    Moorehead, Althea; Cooke, Bill; Moser, Danielle

    2017-01-01

    Most meteor showers will display typical activity levels in 2017. Perseid activity is expected to be higher than normal but less than in 2016; rates may reach 80% of the peak ZHR in 2016. Despite this enhancement, the Perseids rank 4th in flux for 0.04-cm-equivalent meteoroids: the Geminids (GEM), Daytime Arietids (ARI), and Southern delta Aquariids (SDA) all produce higher fluxes. Aside from heightened Perseid activity, the 2017 forecast includes a number of changes. In 2016, the Meteoroid Environment Office used 14 years of shower flux data to revisit the activity profiles of meteor showers included in the annual forecast. Both the list of showers and the shape of certain major showers have been revised. The names and three-letter shower codes were updated to match those in the International Astronomical Union (IAU) Meteor Data Center, and a number of defunct or insignificant showers were removed. The most significant of these changes are the increased durations of the Daytime Arietid (ARI) and Geminid (GEM) meteor showers. This document is designed to supplement spacecraft risk assessments that incorporate an annual averaged meteor shower flux (as is the case with all NASA meteor models). Results are presented relative to this baseline and are weighted to a constant kinetic energy. Two showers - the Daytime Arietids (ARI) and the Geminids (GEM) - attain flux levels approaching that of the baseline meteoroid environment for 0.1-cm-equivalent meteoroids. This size is the threshold for structural damage. These two showers, along with the Quadrantids (QUA) and Perseids (PER), exceed the baseline flux for 0.3-cm-equivalent particles, which is near the limit for pressure vessel penetration. Please note, however, that meteor shower fluxes drop dramatically with increasing particle size. As an example, the Arietids contribute a flux of about 5x10(exp -6) meteoroids m(exp -2) hr-1 in the 0.04-cm-equivalent range, but only 1x10(exp -8) meteoroids m(sub -2) hr-1 for the 0

  15. Comet Assay in Cancer Chemoprevention.

    Science.gov (United States)

    Santoro, Raffaela; Ferraiuolo, Maria; Morgano, Gian Paolo; Muti, Paola; Strano, Sabrina

    2016-01-01

    The comet assay can be useful in monitoring DNA damage in single cells caused by exposure to genotoxic agents, such as those causing air, water, and soil pollution (e.g., pesticides, dioxins, electromagnetic fields) and chemo- and radiotherapy in cancer patients, or in the assessment of genoprotective effects of chemopreventive molecules. Therefore, it has particular importance in the fields of pharmacology and toxicology, and in both environmental and human biomonitoring. It allows the detection of single strand breaks as well as double-strand breaks and can be used in both normal and cancer cells. Here we describe the alkali method for comet assay, which allows to detect both single- and double-strand DNA breaks.

  16. Dynamical Behavior of Meteor in AN Atmosphere: Theory vs Observations

    Science.gov (United States)

    Gritsevich, Maria

    Up to now the only quantities which directly follow from the available meteor observations are its brightness, the height above sea level, the length along the trajectory, and as a consequence its velocity as a function of time. Other important parameters like meteoroid's mass, its shape, bulk and grain density, temperature remain unknown and should be found based on physical theories and special experiments. In this study I will consider modern methods for evaluating meteoroid parameters from observational data, and some of their applications. The study in particular takes an approach in modelling the meteoroids' mass and other properties from the aerodynamical point of view, e.g. from the rate of body deceleration in the atmosphere as opposed to conventionally used luminosity [1]. An analytical model of the atmospheric entry is calculated for registered meteors using published observational data and evaluating parameters describing drag, ablation and rotation rate of meteoroid along the luminous segment of the trajectory. One of the special features of this approach is the possibility of considering a change in body shape during its motion in the atmosphere. The correct mathematical modelling of meteor events is necessary for further studies of consequences for collisions of cosmic bodies with the Earth [2]. It also helps us to estimate the key parameters of the meteoroids, including deceleration, pre-entry mass, terminal mass, ablation coefficient, effective destruction enthalpy, and heat-transfer coefficient. With this information, one can use models for the dust influx onto Earth to estimate the number of meteors detected by a camera of a given sensitivity. References 1. Gritsevich M. I. Determination of Parameters of Meteor Bodies based on Flight Obser-vational Data // Advances in Space Research, 44, p. 323-334, 2009. 2. Gritsevich M. I., Stulov V. P. and Turchak L. I. Classification of Consequences for Col-lisions of Natural Cosmic Bodies with the Earth

  17. Anomalous photometrical displays in faint meteors from TV observations in Kyiv

    Science.gov (United States)

    Kozak, P. M.

    2016-10-01

    Analysis of a large range of results of modern TV meteor observations for searching presence their of the meteors with highly displayed anomalies in kinematic and photometrical characteristics has been carried out. In parallel, the results of Kyiv meteor group observations obtained with the help of observational systems equipped by high sensitive transmitting TV tubes of superisocon type, which have a range of highly displayed anomalies in a meteor development are presented. Comparative qualitative analysis of the observational data containing anomalous displays in meteor photometrical parameters, in part in their light curves is carried out, and the conclusions about physical reality of technical artifacts of the selected anomalies are done.

  18. Realistic Detectability of Close Interstellar Comets

    CERN Document Server

    Cook, Nathaniel V; Granvik, Mikael; Stephens, Denise C

    2016-01-01

    During the planet formation process, billions of comets are created and ejected into interstellar space. The detection and characterization of such interstellar comets (also known as extra-solar planetesimals or extra-solar comets) would give us in situ information about the efficiency and properties of planet formation throughout the galaxy. However, no interstellar comets have ever been detected, despite the fact that their hyperbolic orbits would make them readily identifiable as unrelated to the solar system. Moro-Mart\\'in et al. 2009 have made a detailed and reasonable estimate of the properties of the interstellar comet population. We extend their estimates of detectability with a numerical model that allows us to consider "close" interstellar comets, e.g., those that come within the orbit of Jupiter. We include several constraints on a "detectable" object that allow for realistic estimates of the frequency of detections expected from the Large Synoptic Survey Telescope (LSST) and other surveys. The inf...

  19. The Toroidal Sporadic Sources: Looking for parent bodies of meteor streams

    Science.gov (United States)

    Pokorny, Petr; Brown, Peter G.; Moorhead, Althea V.; Wiegert, Paul; Janches, Diego

    2016-10-01

    The origin and characteristics of the North toroidal (NT) and South toroidal (ST) sporadic meteoroid sources remain poorly known. The NT was first noted in radar measurements in the late 1950s, however, its origin has puzzled astronomers for more than 50 years. The ST started being more thoroughly observed in recent years. The NT and ST meteoroid population shows orbital elements unlike any known contemporary parent population in the Solar System, dominated by particles with very high inclinations, modest semi-major axis values and low eccentricities. Recently, several dynamical models have suggested that the parent bodies of the NT source may be linked to the population of Halley-type comets. However, no model to date has been able to reproduce in detail the significant temporal variations in activity seen throughout the year.In this work we present observations of the NT meteoroid source made by the Canadian Meteor Orbit Radar (CMOR) between 2011 - 2015 and of the ST source obtained with the South Argentina Agile Meteor Radar (SAAMER) between 2011 - 2015. We use these results to define in detail the temporal and orbital element variations in the activity of both sources. We also present preliminary results from a model, in which we have identified 169 near-Earth objects that are potential contributors to the NT/ST meteoroid population at the current time. Furthermore, we integrate their orbits backward in time 25,000 years. For each potential parent body, we simulate 5 clones to span the range of possible parent body orbits as a function of time. From our initial epoch 25 ka, we eject 2000 test meteoroids per 100 years of sizes 30 μm to 1 mm per potential parent clone and examine the resulting dust trail intersecting the Earth to match the various temporally distinct portions of the NT/ST meteoroid complex. We find that while some of the observed features of both sources can be modeled as distinct past contributions from individual parent bodies, many major

  20. Video and photometric observations of a sprite in coincidence with a meteor-triggered jet event

    Energy Technology Data Exchange (ETDEWEB)

    Suszcynsky, D. M. [Space and Atmospheric Sciences Group, Los Alamos National Laboratory, Los Alamos, New Mexico (United States); Strabley, R. [Space and Atmospheric Sciences Group, Los Alamos National Laboratory, Los Alamos, New Mexico (United States); Roussel-Dupre, R. [Atmospheric and Climate Sciences Group, Los Alamos National Laboratory, Los Alamos, New Mexico (United States); Symbalisty, E. M. D. [Atmospheric and Climate Sciences Group, Los Alamos National Laboratory, Los Alamos, New Mexico (United States); Armstrong, R. A. [Mission Research Corporation, Nashua, New Hampshire (United States); Lyons, W. A. [FMA Research Inc., Fort Collins, Colorado (United States); Taylor, M. [Space Dynamics Laboratory, Utah State University, Logan (United States)

    1999-12-27

    Video and photometric observations of a meteor-triggered ''jet'' event in association with the occurrence of a sprite were collected during the SPRITES '98 campaign. The event raises interest in the question of possible meteoric triggering of upper atmospheric transients as originally suggested by Muller [1995]. The event consisted of three stages: (1) the observation of a moderately bright meteor, (2) the development of a sprite in the immediate vicinity of the meteor as the meteor reached no lower than {approx}70 km altitude, and (3) a slower-forming jet of luminosity that appeared during the late stages of the sprite and propagated back up the ionization trail of the meteor. The event is analyzed in terms of its geometry, its relevance to the meteor, and the implications to existing theories for sprite formation. (c) 1999 American Geophysical Union.

  1. Cometary Volatiles and the Origin of Comets

    Science.gov (United States)

    A'Hearn, Michael F.; Feaga, Lori M.; Keller, H. Uwe; Kawakita, Hideyo; Hampton, Donald L.; Kissel, Jochen; Klaasen, Kenneth P.; McFadden, Lucy A.; Meech, Karen J.; Schultz, Peter H.; Sunshine, Jessica M.; Thomas, Peter C.; Veverka, Joseph; Yeomans, Donald K.; Besse, Sebastien; Bodewits, Dennis; Farnham, Tony L.; Groussin, Olivier; Kelley, Michael S.; Lisse, Carey M.; Merlin, Frederic; Protopapa, Silvia; Wellnitz, Dennis D.

    2012-01-01

    We describe recent results on the CO/C02/H2O composition of comets and compare these with models of the protoplanetary disk. We argue that the cometary observations require reactions on grain surfaces to convert CO to CO2 and also require formation between the CO and CO2 snow lines. This then requires very early mixing of cometesimals in the protoplanetary disk analogous to the mixing described for the asteroid belt by Walsh and Morbidelli. We suggest that most comets formed in the region of the giant planets. the traditional source of the Oort-cloud comets but not of the Jupiter-family comets

  2. X-ray emission from comets.

    Science.gov (United States)

    Cravens, T E

    2002-05-10

    The discovery of x-ray emission from comet Hyakutake was surprising given that comets are known to be cold. Observations by x-ray satellites such as the Röntgen Satellite (ROSAT) indicate that x-rays are produced by almost all comets. Theoretical and observational work has demonstrated that charge-exchange collisions of highly charged solar wind ions with cometary neutral species can explain this emission. X-ray observations of comets and other solar system objects may be used to determine the structure and dynamics of the solar wind.

  3. The MAGIC Meteoric Smoke Particle Sampler - Description and Results

    Science.gov (United States)

    Hedin, J.

    2013-12-01

    Between a few to several hundred tons of meteoric material enters the Earth's atmosphere each day, and much of this material ablates in the 70 -130 km region of the atmosphere. Already in the early 1960's it was suggested that meteoroid ablation products could recondense and form solid nanometer-scale smoke particles in the altitude range of the mesosphere and lower thermosphere (MLT). These so-called meteoric smoke particles (MSPs) are then subject to further coagulation, sedimentation, and transport by the mesospheric meridional circulation which in turn determines the latitudinal and seasonal variation of the MSP distribution. MSPs have been suggested to be important for a variety of atmospheric phenomena: 1. they are the most likely candidate for the nuclei of mesospheric ice particles (NLC and PMSE); 2. they provide surface area on which heterogeneous chemical reactions take place and may influence, for example, the water vapor distribution and Ox/HOx chemistry in the mesosphere; 3. they act as ultimate sink in mesospheric metal chemistry by scavenging various gas-phase products of meteoric ablation; 4. they can significantly influence the ionospheric D-region charge balance by scavenging free electrons and positive ions; and 5. they may be involved in the formation of NAT particles in polar stratospheric clouds and the destruction of ozone. Given the above points, it is obvious that there is a large scientific interest in the properties and global distribution of MSPs. Basic information about MSP properties is today available from optical occultation measurements (AIM/SOFIE) and, more indirectly, from in-situ measurements of the charged particle population. In order to understand the role of meteoric smoke particles in the mesosphere and their impact on that environment their presence must be certified and their physical characterization (number density, size distribution, shape, composition etc.) determined. A way to obtain maximum information about particle

  4. Rosetta: Comet-Chaser, Comet-Lander, and Comet-Hopper All In One Mission! (Presentation Recording)

    Science.gov (United States)

    Chmielewski, Artur B.

    2015-09-01

    Mission to Catch a Comet! Comets have inspired awe and wonder since the dawn of history. Many scientists today believe that comets crashed into Earth in its formative period spewing organic molecules that were crucial to the growth of life. Comets may have formed about the same time as the giant planets of our solar system (Jupiter, Saturn, Uranus, and Neptune) - about 4.6 billion years ago. Some scientists think that comets and planets were both made from the same clumps of dust and ice that spewed from our Sun's birth; others think that these roving time capsules are even older than that, and that they may contain grains of interstellar stuff that is even older than our solar system.

  5. Spectrophotometry of 25 comets - Post-Halley updates for 17 comets plus new observations for eight additional comets

    Science.gov (United States)

    Newburn, Ray L., Jr.; Spinrad, Hyron

    1989-01-01

    The best possible production figures within the current post-Halley framework and available observations are given for H2O, O(1D), CN, C3, C2 and dust in 25 comets. Of these, the three objects with the smallest mixing ratios of all minor species have moderate to little or no dust and appear 'old'. Comets with large amounts of CN are very dusty, and there is a clear correlation of CN with dust, although comets with little or no dust still have some CN. Thus, CN appears to have at least two sources, dust and one or more parent gases. Also, the C2/CN production ratio changes continuously with heliocentric distance in every comet considered, suggesting that C2 production may be a function of coma density as well as parental abundance. Dust production ranges from essentially zero in Comet Sugano-Saigusa-Fujikawa up to 67,000 kg/s for Halley on March 14, 1986.

  6. Constraining the Drag Coefficients of Meteors in Dark Flight

    Science.gov (United States)

    Carter, R. T.; Jandir, P. S.; Kress, M. E.

    2011-01-01

    Based on data in the aeronautics literature, we have derived functions for the drag coefficients of spheres and cubes as a function of Mach number. Experiments have shown that spheres and cubes exhibit an abrupt factor-of-two decrease in the drag coefficient as the object slows through the transonic regime. Irregularly shaped objects such as meteorites likely exhibit a similar trend. These functions are implemented in an otherwise simple projectile motion model, which is applicable to the non-ablative dark flight of meteors (speeds less than .+3 km/s). We demonstrate how these functions may be used as upper and lower limits on the drag coefficient of meteors whose shape is unknown. A Mach-dependent drag coefficient is potentially important in other planetary and astrophysical situations, for instance, in the core accretion scenario for giant planet formation.

  7. Planetary science: Meteor Crater formed by low-velocity impact

    Science.gov (United States)

    Melosh, H. J.; Collins, G. S.

    2005-03-01

    Meteor Crater in Arizona was the first terrestrial structure to be widely recognized as a meteorite impact scar and has probably been more intensively studied than any other impact crater on Earth. We have discovered something surprising about its mode of formation - namely that the surface-impact velocity of the iron meteorite that created Meteor Crater was only about 12 km s-1. This is close to the 9.4 km s-1 minimum originally proposed but far short of the 15-20 km s-1 that has been widely assumed - a realization that clears up a long-standing puzzle about why the crater does not contain large volumes of rock melted by the impact.

  8. Planetary science: Meteor Crater formed by low-velocity impact.

    Science.gov (United States)

    Melosh, H J; Collins, G S

    2005-03-10

    Meteor Crater in Arizona was the first terrestrial structure to be widely recognized as a meteorite impact scar and has probably been more intensively studied than any other impact crater on Earth. We have discovered something surprising about its mode of formation--namely that the surface-impact velocity of the iron meteorite that created Meteor Crater was only about 12 km s(-1). This is close to the 9.4 km s(-1) minimum originally proposed but far short of the 15-20 km s(-1) that has been widely assumed--a realization that clears up a long-standing puzzle about why the crater does not contain large volumes of rock melted by the impact.

  9. The Universidad Complutense of Madrid meteor and fireball patrol station

    Science.gov (United States)

    Zamorano, J.; Gallego, J.; Ocaña, F.; Sanchez de Miguel, A.; Izquierdo, J.; Manjavacas, E.; Ponce, R.; Garcia, L.; Saez, G.; Ramirez, P.

    2011-11-01

    The Universidad Complutense of Madrid (UCM) has recently installed a high sensitivity video system to detect meteors. It is intended to study the entry in our atmosphere of interplanetary particles of mass greater than a gram. The station, not fully equipped yet, is a node of the national Spanish Fireball Network (SPMN) and includes cameras located at the Astronomical Observatory (Physics building) and others distributed around. The system has been automated to detect and record meteors only when the atmospheric conditions are good enough. Undergraduate and graduate physics students have collaborated to develop, install and test the system. Detections which are bright enough to drop a meteorite are analyzed using double station observations with the cameras of the SPMN nodes around Spain to determine their atmospheric paths, origin and landing area.

  10. Pulse-level interference and meteor processing of Arecibo ISR data

    Science.gov (United States)

    Wen, C.-H.; Briczinski, S. J.; Livneh, D. J.; Doherty, J. F.; Mathews, J. D.

    2007-07-01

    We introduce a simple but effective order statistics filter for the pulse-level interference and meteor processing of Arecibo ionosphere observation data. Using this filter and the techniques introduced by Wen et al. [2005. Adaptive filtering for the separation of incoherent scatter and meteor signals for Arecibo Observation Data. Journal of Atmospheric and Solar-Terrestrial Physics 67, 1190 1195] we effectively remove/separate the unwanted signals, such as impulsive interference and meteor returns, encountered during incoherent scatter radar (ISR) observations of the ionosphere. We further analyze the separated signals to obtain uniquely “cleaned” incoherent scatter power data and scientifically valuable meteor parameters. We present the processed incoherent scatter results from 22/23 March 2004 observations and the altitude and the speed distributions of the separated meteor signals. The nighttime photochemical E-region is clearly revealed for the first time as a result of meteor and interference removal. Additionally, these results reveal the first major bias in large aperture radar meteor headecho results—the meteor speed distribution is flattened by the absence of at least 50% of the events with duration less than 10 ms revealed by meteor-specific observations. Meteor data derived from standard incoherent scatter data always displays this bias.

  11. Variations of the meteor echo heights at Beijing and Mohe, China

    Science.gov (United States)

    Liu, Libo; Liu, Huixin; Chen, Yiding; Le, Huijun; Sun, Yang-Yi; Ning, Baiqi; Hu, Lianhuan; Wan, Weixing

    2017-01-01

    Detecting the changing of the upper atmosphere is an important and challenging issue. The change in the meteor peak heights observed by a meteor radar should contain information of the neutral density in the meteoroid ablation region. In this work, observations from the VHF all-sky meteor radars operated at Beijing (40.3°N, 116.2°E) and Mohe (53.5°N, 122.3°E), China, are collected to explore the temporal patterns of the meteor peak heights. The daily meteor peak height is determined through a least squares fitting of the height profile of meteor radar echoes under a normal distribution assumption. There are considerable seasonal variations in the meteor peak heights, being dominated by an annual component at Beijing and a semiannual one at Mohe. Moreover, the Ensemble Empirical Mode Decomposition (EEMD) is employed to determine the overall trends in the series of the meteor peak heights. The EEMD analysis reveals an overall decrease in the meteor peak heights at both stations, indicating the descending trend in neutral density near 90 km altitude at middle latitudes. The meteor peak heights show a rather weak solar activity effect at Beijing, which is different from the positive effects reported at some other sites.

  12. Color Systematics of Comets and Related Bodies

    CERN Document Server

    Jewitt, Dave

    2015-01-01

    Most comets are volatile-rich bodies that have recently entered the inner solar system following long-term storage in the Kuiper belt and the Oort cloud reservoirs. These reservoirs feed several distinct, short-lived "small body" populations. Here, we present new measurements of the optical colors of cometary and comet-related bodies including long-period (Oort cloud) comets, Damocloids (probable inactive nuclei of long-period comets) and Centaurs (recent escapees from the Kuiper belt and precursors to the Jupiter family comets). We combine the new measurements with published data on short-period comets, Jovian Trojans and Kuiper belt objects to examine the color systematics of the comet-related populations. We find that the mean optical colors of the dust in short-period and long-period comets are identical within the uncertainties of measurement, as are the colors of the dust and of the underlying nuclei. These populations show no evidence for scattering by optically-small particles or for compositional gra...

  13. Episodic Aging and End States of Comets

    Science.gov (United States)

    Sekanina, Zdenek

    2008-01-01

    It is known that comets are aging very rapidly on cosmic scales, because they rapidly shed mass. The processes involved are (i) normal activity - sublimation of ices and expulsion of dust from discrete emission sources on and/or below the surface of a comet's nucleus, and (ii) nuclear fragmentation. Both modes are episodic in nature, the latter includes major steps in the comet's life cycle. The role and history of dynamical techniques used are described and results on mass losses due to sublimation and dust expulsion are reviewed. Studies of split comets, Holmes-like exploding comets, and cataclysmically fragmenting comets show that masses of 10 to 100 million tons are involved in the fragmentation process. This and other information is used to investigate the nature of comets' episodic aging. Based on recent advances in understanding the surface morphology of cometary nuclei by close-up imaging, a possible mechanism for large-scale fragmentation events is proposed and shown to be consistent with evidence available from observations. Strongly flattened pancake-like shapes appear to be required for comet fragments by conceptual constraints. Possible end states are briefly examined.

  14. RFP for the Comet Nuclei Tour (CONTOUR)

    DEFF Research Database (Denmark)

    Jørgensen, John Leif; Madsen, Peter Buch; Betto, Maurizio

    1999-01-01

    This document describes the ASC Star Tracker (performance, functionality, requirements etc.) to The Johns Hopkins University - Applied Physics Laboratory for their Comet Nuclei TOUR (CONTOUR) Program.......This document describes the ASC Star Tracker (performance, functionality, requirements etc.) to The Johns Hopkins University - Applied Physics Laboratory for their Comet Nuclei TOUR (CONTOUR) Program....

  15. Episodic Aging and End States of Comets

    Science.gov (United States)

    Sekanina, Zdenek

    2008-01-01

    It is known that comets are aging very rapidly on cosmic scales, because they rapidly shed mass. The processes involved are (i) normal activity - sublimation of ices and expulsion of dust from discrete emission sources on and/or below the surface of a comet's nucleus, and (ii) nuclear fragmentation. Both modes are episodic in nature, the latter includes major steps in the comet's life cycle. The role and history of dynamical techniques used are described and results on mass losses due to sublimation and dust expulsion are reviewed. Studies of split comets, Holmes-like exploding comets, and cataclysmically fragmenting comets show that masses of 10 to 100 million tons are involved in the fragmentation process. This and other information is used to investigate the nature of comets' episodic aging. Based on recent advances in understanding the surface morphology of cometary nuclei by close-up imaging, a possible mechanism for large-scale fragmentation events is proposed and shown to be consistent with evidence available from observations. Strongly flattened pancake-like shapes appear to be required for comet fragments by conceptual constraints. Possible end states are briefly examined.

  16. Comet mission hopes to uncover Earth's origins

    CERN Multimedia

    Henderson, M

    2004-01-01

    "A European spacecraft that will hunt down a comet in search of clues to the origin of life on Earth will blast off tomorrow from the Kourou spaceport in French Guiana. The Rosetta probe will take 12 years to catch up with Churyumov-Gerasimenko before becoming the first spacecraft to make a soft, controlled landing on a comet's nucleus" (1 page).

  17. Amino Acids from a Comet

    Science.gov (United States)

    Cook, Jamie Elisla

    2009-01-01

    NASA's Stardust spacecraft returned samples from comet 81P/Wild 2 to Earth in January 2006. Examinations of the organic compounds in cometary samples can reveal information about the prebiotic organic inventory present on the early Earth and within the early Solar System, which may have contributed to the origin of life. Preliminary studies of Stardust material revealed the presence of a suite of organic compounds including several amines and amino acids, but the origin of these compounds (cometary- vs. terrestrial contamination) could not be identified. We have recently measured the carbon isotopic ratios of these amino acids to determine their origin, leading to the first detection of a coetary amino acid.

  18. Development of the mesospheric Na layer at 69° N during the Geminids meteor shower 2010

    Directory of Open Access Journals (Sweden)

    T. Dunker

    2013-01-01

    Full Text Available The ECOMA sounding rocket campaign in 2010 was performed to investigate the charge state and number density of meteoric smoke particles during the Geminids meteor shower in December 2010. The ALOMAR Na lidar contributed to the campaign with measurements of sodium number density, temperature and line-of-sight wind between 80 and 110 km altitude over Andøya in northern Norway. This paper investigates a possible connection between the Geminids meteor shower and the mesospheric sodium layer. We compare with data from a meteor radar and from a rocket-borne in situ particle instrument on three days. Our main result is that the sodium column density is smaller during the Geminids meteor shower than the winter average at the same latitude. Moreover, during two of the three years considered, the sodium column density decreased steadily during these three weeks of the year. Both the observed decrease of Na column density by 30% and of meteoric smoke particle column density correlate well with a corresponding decrease of sporadic meteor echoes. We found no correlation between Geminids meteor flux rates and sodium column density, nor between sporadic meteors and Na column density (R = 0.25. In general, we found the Na column density to be at very low values for winter, between 1.8 and 2.6 × 1013 m−2. We detected two meteor trails containing sodium, on 13 December 2010 at 87.1 km and on 19 December 2010 at 84 km. From these meteor trails, we estimate a global meteoric Na flux of 121 kg d−1 and a global total meteoric influx of 20.2 t d−1.

  19. Development of the mesospheric Na layer at 69° N during the Geminids meteor shower 2010

    Science.gov (United States)

    Dunker, T.; Hoppe, U.-P.; Stober, G.; Rapp, M.

    2013-01-01

    The ECOMA sounding rocket campaign in 2010 was performed to investigate the charge state and number density of meteoric smoke particles during the Geminids meteor shower in December 2010. The ALOMAR Na lidar contributed to the campaign with measurements of sodium number density, temperature and line-of-sight wind between 80 and 110 km altitude over Andøya in northern Norway. This paper investigates a possible connection between the Geminids meteor shower and the mesospheric sodium layer. We compare with data from a meteor radar and from a rocket-borne in situ particle instrument on three days. Our main result is that the sodium column density is smaller during the Geminids meteor shower than the winter average at the same latitude. Moreover, during two of the three years considered, the sodium column density decreased steadily during these three weeks of the year. Both the observed decrease of Na column density by 30% and of meteoric smoke particle column density correlate well with a corresponding decrease of sporadic meteor echoes. We found no correlation between Geminids meteor flux rates and sodium column density, nor between sporadic meteors and Na column density (R = 0.25). In general, we found the Na column density to be at very low values for winter, between 1.8 and 2.6 × 1013 m-2. We detected two meteor trails containing sodium, on 13 December 2010 at 87.1 km and on 19 December 2010 at 84 km. From these meteor trails, we estimate a global meteoric Na flux of 121 kg d-1 and a global total meteoric influx of 20.2 t d-1.

  20. Advanced Meteor radar at Tirupati: System details and first results

    Science.gov (United States)

    Sunkara, Eswaraiah; Gurubaran, Subramanian; Sundararaman, Sathishkumar; Venkat Ratnam, Madineni; Karanam, Kishore Kumar; Eethamakula, Kosalendra; Vijaya Bhaskara Rao, S.

    An advanced meteor radar viz., Enhanced Meteor Detection Radar (EMDR) operating at 35.25 MHz is installed at Sri Venkateswara University (SVU), Tirupati (13.63oN, 79.4oE), India, in the month of August 2013. Present communication describes the need for the meteor radar at present location, system description, its measurement techniques, its variables and comparison of measured mean winds with contemporary radars over the Indian region. The present radar site is selected to fill the blind region of Gadanki (13.5oN, 79.2oE) MST radar, which covers mesosphere and lower thermosphere (MLT) region (70-110 km). By modifying the receiving antenna structure and elements, this radar is capable of providing accurate wind information between 70 and 110 km unlike other similar radars. Height covering region is extended by increasing the meteor counting capacity by modifying the receiving antenna structure and elements and hence its wind estimation limits extended below and above of 80 and 100 km, respectively. In the present study, we also made comparison of horizontal winds in the MLT region with those measured by similar and different (MST and MF radars) techniques over the Indian region including the model (HWM 07) data sets. The comparison showed a very good agreement between the overlapping altitudes (82-98 km) of different radars. Zonal winds compared very well as that of meridional winds. The observed discrepancies and limitations in the wind measurement are discussed. This new radar is expected to play important role in understanding the vertical and lateral coupling by forming a unique local network.

  1. VLF observation during Leonid Meteor Shower-2002 from Kolkata

    CERN Document Server

    Chakrabarti, S K; Acharyya, K; Mandal, S; Chakrabarti, S; Khan, R; Bose, B; Chakrabarti, Sandip K.

    2002-01-01

    Using a Gyrator-II Loop antenna tuned at 19.0Khz, we monitored the meteor shower during 17-24th November, 2002. We observe the primary peak at 3h58m (UT) on the 19th of November, 2002. We distinctly observed several `beadlike' and `exponentially dropping' signals. The `beadlike' signals were more in abundance on the 18th of November, 2002, one day prior to the actual encounter.

  2. Detection and analysis of rock cracks in meteor crater

    OpenAIRE

    Wang, Min

    2010-01-01

    In 2000, a geologist Fridtjof Riis discovered a meteor crater in Ritland, Hjelmelan municipality in Rogland. This crater was formed by meteorite impact. The crater has areas with a lot of cracks in the rocks, and geologists think these cracks are very valuable information for them. By making photos with an ordinary camera, they want to get binary pictures where the cracks are shown as white lines on a black background. They can measure and quantify the length and direction of t...

  3. Photographic fireball networks. [for global recording of meteor trails

    Science.gov (United States)

    Halliday, I.

    1973-01-01

    Three networks for the photography of bright fireballs are now in operation; in the central United States, central Europe and western Canada. A detailed comparison is made of the parameters which describe the three networks. Although only two meteorites for which photographic orbital data are available have been recovered, the networks are contributing valuable data on fireball orbits, influx rates and problems of meteor physics.

  4. Organic matter in comets and cometary dust.

    Science.gov (United States)

    Llorca, Jordi

    2005-03-01

    Comets are primitive conglomerates of the solar system containing a mixture of frozen gases, refractory grains, and carbonaceous particles rich in biogenic elements. The dramatic display of comets is mostly caused by a cloud of micrometer-sized dust particles that leave the comet nucleus when frozen gases sublimate as they approach the Sun. Analyses of cometary dust captured in the stratosphere together with data obtained from space missions to comets have revealed the presence of a great variety of organic molecules. Since substantial amounts of cometary dust were gently deposited on Earth, their organic content could have played a major role in prebiotic processes prior to the appearance of microorganisms. This review discusses the description and implications for life of the organic content of comets and cometary dust.

  5. Comets and How to Observe Them

    CERN Document Server

    Schmude, Richard

    2010-01-01

    Comets have inspired wonder, excitement and even fear ever since they were first observed. They contain material from early in the life of the Solar System, held in deep-freeze. This makes them key in our understanding of the formation and evolution of many Solar System bodies. Recent ground- and space-based observations have changed much in our understanding of comets. Comets and How to Observe Them gives a summary of our current knowledge and describes how amateur astronomers can contribute to the body of scientific knowledge of comets. This book contains many practical examples of how to construct comet light-curves, measure how fast a comet’s coma expands, and determine the rotation period of the nucleus. All these examples are illustrated with drawings and photographs.

  6. Rates, Flux Densities, and Spectral Indices of Meteor Radio Afterglows

    CERN Document Server

    Obenberger, K S; Hancock, P J; Holmes, J M; Pedersen, T R; Schinzel, F K; Taylor, G B

    2016-01-01

    Using the narrowband all-sky imager mode of the LWA1 we have now detected 30 transients at 25.6 MHz, 1 at 34 MHz, and 93 at 38.0 MHz. While we have only optically confirmed that 37 of these events are radio afterglows from meteors, evidence suggests that most, if not all, are. Using the beam-forming mode of the LWA1 we have also captured the broadband spectra between 22.0 and 55.0 MHz of four events. We compare the smooth, spectral components of these four events and fit the frequency dependent flux density to a power law, and find that the spectral index is time variable, with the spectrum steepening over time for each meteor afterglow. Using these spectral indices along with the narrow band flux density measurements of the 123 events at 25.6 and 38 MHz, we predict the expected flux densities and rates for meteor afterglows potentially observable by other low frequency radio telescopes.

  7. SPA Meteor Section Results: April-June 2004

    Science.gov (United States)

    McBeath, Alastair

    2007-06-01

    Results presented to the SPA Meteor Section from the second quarter of 2004 are analyzed and discussed, along with some relevant items that generated correspondence from Society members and others. A very approximate radio confirmation was possible of a Lyrid peak in the early hours UT of April 22, before the anticipated ideal maximum time, along with an eta Aquarid peak around May 5. Some notes are given on a brilliant fireball over the Franco-Belgian border at 21h57m +- 1m UT on May 20, together with an unusual fireball-like, though actually non-meteoric, event or events over or near Spain and Portugal in the late evening hours UT of June 1/2, plus a meteorite fall in Auckland, New Zealand, on June 11, reported as hot to the touch on arrival. Maxima from the June daytime streams were recorded by radio on June 6, 8 and 10-12, much as found in the Forward Scatter Meteor Year analyses previously. The June Booetid visual outburst on June 23 was not detected in the radio results, although moderate maxima probably due to the beta Taurids were, on June 22, 25 and 28, again largely as recorded before.

  8. Impact Vaporization as a Possible Source of Mercury's Calcium Exosphere

    Science.gov (United States)

    Killen, Rosemary M.; Hahn, Joseph M.

    2015-01-01

    Mercury's calcium exosphere varies in a periodic way with that planet's true anomaly. We show that this pattern can be explained by impact vaporization from interplanetary dust with variations being due to Mercury's radial and vertical excursions through an interplanetary dust disk having an inclination within 5 degrees of the plane of Mercury's orbit. Both a highly inclined dust disk and a two-disk model (where the two disks have a mutual inclination) fail to reproduce the observed variation in calcium exospheric abundance with Mercury true anomaly angle. However, an additional source of impacting dust beyond the nominal dust disk is required near Mercury's true anomaly (?) 25deg +/-5deg. This is close to but not coincident with Mercury's true anomaly (?=45deg) when it crosses comet 2P/Encke's present day orbital plane. Interestingly, the Taurid meteor storms at Earth, which are also due to Comet Encke, are observed to occur when Earth's true anomaly is +/-20 or so degrees before and after the position where Earth and Encke orbital planes cross. The lack of exact correspondence with the present day orbit of Encke may indicate the width of the potential stream along Mercury's orbit or a previous cometary orbit. The extreme energy of the escaping calcium, estimated to have a temperature greater than 50000 K if the source is thermal, cannot be due to the impact process itself but must be imparted by an additional mechanism such as dissociation of a calcium-bearing molecule or ionization followed by recombination.

  9. Hydrogen cyanide polymers on comets.

    Science.gov (United States)

    Matthews, C N; Ludicky, R

    1992-01-01

    The original presence on cometary nuclei of frozen volatiles such as methane, ammonia and water makes them ideal sites for the formation and condensed-phase polymerization of hydrogen cyanide. We propose that the non-volatile black crust of comet Halley consists largely of such polymers. Dust emanating from Halley's nucleus, contributing to the coma and tail, would also arise partly from these solids. Indeed, secondary species such as CN have been widely detected, as well as HCN itself and particles consisting only of H, C and N. Our continuing investigations suggest that the yellow-orange-brown-black polymers are of two types: ladder structures with conjugated -C=N- bonds, and polyamidines readily converted by water to polypeptides. These easily formed macromolecules could be major components of the dark matter observed on the giant planets Jupiter and Saturn, as well as on outer solar system bodies such as asteroids, moons and other comets. Implications for prebiotic chemistry are profound. Primitive Earth may have been covered by HCN polymers either through cometary bombardment or by terrestrial happenings of the kind that brought about the black crust of Halley. The resulting proteinaceous matrix could have promoted the molecular interactions leading to the emergence of life.

  10. Fractal Fragmentation triggered by meteor impact: The Ries Crater (Germany)

    Science.gov (United States)

    Paredes Marino, Joali; Perugini, Diego; Rossi, Stefano; Kueppers, Ulrich

    2015-04-01

    FRACTAL FRAGMENTATION TRIGGERED BY METEOR IMPACT: THE RIES CRATER (GERMANY) Joali Paredes (1), Stefano Rossi (1), Diego Perugini (1), Ulrich Kueppers (2) 1. Department of Physics and Geology, University of Perugia, Italy 2. Department of Earth and Environmental Sciences, University of Munich, Germany The Nördlinger Ries is a large circular depression in western Bavaria, Germany. The depression was caused by a meteor impact, which occurred about 14.3 million-14.5 million years ago. The original crater rim had an estimated diameter of 24 kilometers. Computer modeling of the impact event indicates that the impact or probably had diameters of about 1.5 kilometers and impacted the target area at an angle around 30 to 50 degrees from the surface in a west- southwest to east-northeast direction. The impact velocity is thought to have been about 20 km/s. The meteor impact generated extensive fragmentation of preexisting rocks. In addition, melting of these rocks also occurred. The impact melt was ejected at high speed provoking its extensive fragmentation. Quenched melt fragments are ubiquitous in the outcrops. Here we study melt fragment size distributions with the aim of understanding the style of melt fragmentation during ejection and to constrain the rheological properties of such melts. Digital images of suevite (i.e. the rock generated after deposition and diagenesis of ash and fragments produced by the meteor impact) were obtained using a high-resolution optical scanner. Successively, melt fragments were traced by image analysis and the images segmented in order to obtain binary images on which impact melt fragments are in black color, embedded on a white background. Hence, the size of fragments was determined by image analysis. Fractal fragmentation theory has been applied to fragment size distributions of melt fragments in the Ries crater. Results indicate that melt fragments follow fractal distributions indicating that fragmentation of melt generated by the

  11. Assessing the Main-Belt Comet Population with Comet Hunters

    Science.gov (United States)

    Schwamb, Megan E.; Hsieh, Henry H.; Zhang, Zhi-Wei; Chen, Ying-Tung; Lintott, Chris; Wang, Shiang-Yu; Mishra, Ishan

    2017-01-01

    Cometary activity in the asteroid belt is a recent discovery. Evidence suggests recent collisions play a role excavating subsurface water ice in these Main Belt Comets (MBCs). MBCs may be an alternative source of Earth’s water. The properties and origins of the MBCs remain elusive. To date ~15 MBCs are known, but only with many tens to 100s of MBCs can we fully explore this new reservoir and its implications for the early Earth.Automated routines identify cometary objects by comparing the point spread functions (PSFs) of moving objects to background stars. This approach may miss cometary activity with low-level dust comae or trails that are too weak or extended to affect an object's near-nucleus PSF profile. Direct visual inspection of moving objects by survey team members can often catch such unusual objects, but such an approach is impractical for the largest surveys to date, and will only become more intractable with the next generation wide-field surveys.With the Internet, tens of thousands of people can be engaged in the scientific process. With this citizen science approach, the combined assessment of many non-experts often equals or rivals that of a trained expert and in many cases outperforms automated algorithms. The Comet Hunters (http://www.comethunters.org) project enlists the public to search for MBCs in data from the Hyper Suprime-Cam (HSC) wide survey. HSC is to date the largest field-of-view camera (covering a 1.5 degree diameter circle on sky) on a 8-10-m class telescope. The HSC wide survey provides the sensitivity to detect cometary activity at lower levels than have been possible for previous surveys.We will give an overview of the Comet Hunters project. We will present the results from the first ~10,000 HSC asteroids searched and provide an estimate on the frequency of cometary activity in the Main Asteroid beltAcknowledgements: This work uses data generated via the Zooniverse.org platform, development of which was supported by a Global

  12. OpenComet: an automated tool for comet assay image analysis.

    Science.gov (United States)

    Gyori, Benjamin M; Venkatachalam, Gireedhar; Thiagarajan, P S; Hsu, David; Clement, Marie-Veronique

    2014-01-01

    Reactive species such as free radicals are constantly generated in vivo and DNA is the most important target of oxidative stress. Oxidative DNA damage is used as a predictive biomarker to monitor the risk of development of many diseases. The comet assay is widely used for measuring oxidative DNA damage at a single cell level. The analysis of comet assay output images, however, poses considerable challenges. Commercial software is costly and restrictive, while free software generally requires laborious manual tagging of cells. This paper presents OpenComet, an open-source software tool providing automated analysis of comet assay images. It uses a novel and robust method for finding comets based on geometric shape attributes and segmenting the comet heads through image intensity profile analysis. Due to automation, OpenComet is more accurate, less prone to human bias, and faster than manual analysis. A live analysis functionality also allows users to analyze images captured directly from a microscope. We have validated OpenComet on both alkaline and neutral comet assay images as well as sample images from existing software packages. Our results show that OpenComet achieves high accuracy with significantly reduced analysis time.

  13. OpenComet: An automated tool for comet assay image analysis

    Directory of Open Access Journals (Sweden)

    Benjamin M. Gyori

    2014-01-01

    Full Text Available Reactive species such as free radicals are constantly generated in vivo and DNA is the most important target of oxidative stress. Oxidative DNA damage is used as a predictive biomarker to monitor the risk of development of many diseases. The comet assay is widely used for measuring oxidative DNA damage at a single cell level. The analysis of comet assay output images, however, poses considerable challenges. Commercial software is costly and restrictive, while free software generally requires laborious manual tagging of cells. This paper presents OpenComet, an open-source software tool providing automated analysis of comet assay images. It uses a novel and robust method for finding comets based on geometric shape attributes and segmenting the comet heads through image intensity profile analysis. Due to automation, OpenComet is more accurate, less prone to human bias, and faster than manual analysis. A live analysis functionality also allows users to analyze images captured directly from a microscope. We have validated OpenComet on both alkaline and neutral comet assay images as well as sample images from existing software packages. Our results show that OpenComet achieves high accuracy with significantly reduced analysis time.

  14. Meteor observations with Mini-Mega-TORTORA wide-field monitoring system

    Science.gov (United States)

    Karpov, S.; Orekhova, N.; Beskin, G.; Biryukov, A.; Bondar, S.; Ivanov, E.; Katkova, E.; Perkov, A.; Sasyuk, V.

    2016-12-01

    Here we report on the results of meteor observations with 9-channel Mini-Mega-TORTORA (MMT-9) optical monitoring system with the wide field and high temporal resolution. During the first 1.5 years of operation more than 90 thousands of meteors have been detected, at a rate of 300-350 per night, with durations from 0.1 to 2.5 seconds and angular velocities up to 38 degrees per second. The faintest detected meteors have peak brightnesses about 10 mag, while the majority have them ranging from 4 to 8 mag. Some of the meteors have been observed in BVR filters simultaneously. Color variations along the trail for them have been determined. The parameters of the detected meteors have been published online. The database also includes data from 10 thousands of meteors detected by our previous FAVOR camera during 2006-2009.

  15. Determination of meteor-head echo trajectories using the interferometric capabilities of MAARSY

    Directory of Open Access Journals (Sweden)

    C. Schult

    2013-10-01

    Full Text Available During the flight of a meteoroid through the neutral atmosphere, the high kinetic energy is sufficient to ionize the meteoric constituents. Radar echoes coming from plasma irregularities surrounding the meteoroids are called meteor-head echoes, and can be detected by HPLA radar systems. Measurements of these echoes were conducted with MAARSY (Middle Atmosphere Alomar Radar System in December 2010. The interferometric capabilities of the radar system permit the determination of the meteor trajectories within the radar beam with high accuracy. The received data are used to gain information about entry velocities, source radiants, observation heights and other meteoroid parameters. Our preliminary results indicate that the majority of meteors have masses between 10−10 and 10−3 kg and the mean masses of the sporadic meteors and Gemenids meteors are ∼10−8 kg.

  16. A Numerical Model to Assess Soil Fluxes from Meteoric 10Be Data

    Science.gov (United States)

    Campforts, B.; Govers, G.; Vanacker, V.; Vanderborght, J.; Smolders, E.; Baken, S.

    2015-12-01

    Meteoric 10Be may be mobile in the soil system. The latter hampers a direct translation of meteoric 10Be inventories into spatial variations in erosion and deposition rates. Here, we present a spatially explicit 2D model that allows us to simulate the behaviour of meteoric 10Be in the soil system. The Be2D model is then used to analyse the potential impact of human-accelerated soil fluxes on meteoric 10Be inventories. The model consists of two parts. A first component deals with advective and diffusive mobility of meteoric 10Be within the soil profile including particle migration, chemical leaching and bioturbation, whereas a second component describes lateral soil (and meteoric 10Be) fluxes over the hillslope. Soil depth is calculated dynamically, accounting for soil production through weathering and lateral soil fluxes from creep, water and tillage erosion. Model simulations show that meteoric 10Be inventories can indeed be related to erosion and deposition, across a wide range of geomorphological and pedological settings. However, quantification of the effects of vertical mobility is essential for a correct interpretation of the observed spatial patterns in 10Be data. Moreover, our simulations suggest that meteoric 10Be can be used as a tracer to unravel human impact on soil fluxes when soils have a high retention capacity for meteoric meteoric 10Be. Application of the Be2D model to existing data sets shows that model parameters can reliably be constrained, resulting in a good agreement between simulated and observed meteoric 10Be concentrations and inventories. This confirms the suitability of the Be2D model as a robust tool to underpin quantitative interpretations of spatial variability in meteoric 10Be data for eroding landscapes.

  17. Short and long-term delivery rates of meteoric 10Be to terrestrial soils

    Science.gov (United States)

    Graly, Joseph A.; Reusser, Lucas J.; Bierman, Paul R.

    2011-02-01

    Well-constrained, long-term average meteoric 10Be deposition rates are important when meteoric 10Be is used as a chronometer or tracer of Earth surface processes. To constrain meteoric 10Be delivery to terrestrial soils, we estimate time-integrated 10Be deposition rates from meteoric 10Be inventories measured in dated soils and compare these results to a new synthesis of short-term measurements of 10Be in precipitation. Comparison of these long-term rates to short-term measurements suggests that short-term measurements likely predict long-term meteoric 10Be deposition rates within uncertainties of ~ 20%. In precipitation measurements, it is possible to deconvolve the contribution of atmospherically-produced "primary" meteoric 10Be from "recycled" meteoric 10Be delivered by terrestrial dust if a second isotope is measured that quantifies either the recycled or primary components of meteoric 10Be deposition. We use dust-concentration dependent differences between 7Be and 10Be measurements to make new estimates of the recycled contribution to total meteoric 10Be flux delivered to the Earth's surface. These dust-corrected data show a strong linear dependence between precipitation amount and primary meteoric 10Be flux. Concentrations of primary meteoric 10Be in mid- and low-latitude precipitation vary predictably by latitude between 0.63 · 10 4 and 2.05 · 10 4 atoms/cm 3 of precipitation, providing a first-order estimate of primary meteoric 10Be deposition for a given latitude and precipitation rate.

  18. Meteor detections at the Metsähovi Fundamental Geodetic Research Station (Finland)

    Science.gov (United States)

    Raja-Halli, A.; Gritsevich, M.; Näränen, J.; Moreno-Ibáñez, M.; Lyytinen, E.; Virtanen, J.; Zubko, N.; Peltoniemi, J.; Poutanen, M.

    2016-01-01

    We provide an overview and present some spectacular examples of the recent meteor observations at the Metsähovi Geodetic Research Station. In conjunction with the Finnish Fireball Network the all-sky images are used to reconstruct atmospheric trajectories and to calculate the pre-impact meteor orbits in the Solar System. In addition, intensive collaborative work is pursued with the meteor research groups worldwide. We foresee great potential of this activity also for educational and outreach purposes.

  19. Bloody rain again! Red rain and meteors in history and myth

    Science.gov (United States)

    McCafferty, P.

    2008-01-01

    In July 2001, red rain fell over Kerala in India shortly after reports of a meteor. When analysed, this red rain appeared to contain red cells, apparently demonstrating that such cells must exist in space and that the theory of panspermia is correct. However, doubts have been expressed about whether reports of a meteor were merely a coincidence. This paper examines historical and mythical accounts of red rain, to establish if these, too, show a connection with meteors.

  20. The location of Asteroidal Belt Comets (ABCs), in a comets' evolutionary diagram: The Lazarus Comets

    CERN Document Server

    Ferrin, Ignacio; Cuartas, Pablo

    2013-01-01

    There is a group of newly recognized asteroids in the main belt that are exhibiting cometary characteristics. We will call them Asteroidal Belt Comets or ABCs. An analysis of their orbital and physical properties has resulted in the following conclusion: (1) We define the detached group, DG, as objects sublimating water that have aphelion distances Q < 4.5 AU. The detached group contains all the ABCs traditionally recognized, plus a few other members like 2P and 107P. With the above definition there are 11 members of the ABC group: 2P, 107P, 133P, 176P, 233P, 238P, C/2008 R1, C/2010 R2, 2011 CR42, 3200, and 300163 = 2006 VW139. (2) Active objects sublimate ices except collisioned asteroids, CA, P/2010 A2, 596 Scheila, and P/2012 F5 Gibbs, and 3200 Phaethon who was active due to sputtering. (3)We have calibrated the black body (color) temperature of comets vs perihelion distance, R. We find T = 325+-5 K/SQRT(R). (4) Using a mathematical model of the thermal wave we calculate the thickness of the dust layer ...

  1. A Post-Stardust Mission View of Jupiter Family Comets

    Science.gov (United States)

    Zolensky, M.

    2011-01-01

    Before the Stardust Mission, many persons (including the mission team) believed that comet nuclei would be geologically boring objects. Most believed that comet nucleus mineralogy would be close or identical to the chondritic interplanetary dust particles (IDPs), or perhaps contain mainly amorphous nebular condensates or that comets might even be composed mainly of preserved presolar material [1]. Amazingly, the results for Comet Wild 2 (a Jupiter class comet) were entirely different. Whether this particular comet will ultimately be shown to be typical or atypical will not be known for a rather long time, so we describe our new view of comets from the rather limited perspective of this single mission.

  2. How to estimate the effect of an intense meteor shower on human space activities

    Institute of Scientific and Technical Information of China (English)

    WU GuangJie

    2009-01-01

    In the present age, the potential threat to space projects oming from some intense meteor storms has been noticed. Especially, the increasing activities of mankind in space for scientific, commercial and military purposes have led to an increase in safety-related problems about the satellites, space stations and astronauts. Several new techniques for observing meteors end meteor showers have been devel-oped. However, how to estimate even predict the effect of an intense meteor shower should be further studied. The initial definition about a meteor storm based on visual observations with a Zenithal Hourly Rate of over one thousand seems insufficient, since it only means a storm or burst of meteors in numbers. In 2006 the author suggested a synthetical index of the potential threats about intense aotivi-ties of meteors; however, it is too complex to determine several parameters. In this paper, the author suggests a Special True Number Flux Density (STNFD). Set a certain energy-limit, or a certain elec-tric-charge-limit, end then calculate the number flux density. Through the comparison between two of the 10 strong meteor showers in recent years it is found that the important factor affecting the space flight security is not only the number of meteoroids, but also their velocities, their average energy and the population index r. Calculations show that Giacobinids, even June Bootids, should be one of the most hazardous meteor showers.

  3. How to estimate the effect of an intense meteor shower on human space activities

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In the present age,the potential threat to space projects coming from some intense meteor storms has been noticed.Especially,the increasing activities of mankind in space for scientific,commercial and military purposes have led to an increase in safety-related problems about the satellites,space stations and astronauts.Several new techniques for observing meteors and meteor showers have been developed.However,how to estimate even predict the effect of an intense meteor shower should be further studied.The initial definition about a meteor storm based on visual observations with a Zenithal Hourly Rate of over one thousand seems insufficient,since it only means a storm or burst of meteors in numbers.In 2006 the author suggested a synthetical index of the potential threats about intense activities of meteors;however,it is too complex to determine several parameters.In this paper,the author suggests a Special True Number Flux Density(STNFD).Set a certain energy-limit,or a certain electric-charge-limit,and then calculate the number flux density.Through the comparison between two of the 10 strong meteor showers in recent years it is found that the important factor affecting the space flight security is not only the number of meteoroids,but also their velocities,their average energy and the population index r.Calculations show that Giacobinids,even June Bootids,should be one of the most hazardous meteor showers.

  4. TV Observations of Meteors in INASAN: Equipment, Methods and First Results

    Science.gov (United States)

    Kartashova, Anna P.; Bagrov, A. V.; Leonov, V. A.

    2007-08-01

    For the analysis the risk from particles of meteor streams, we must have proved information about masses and densities of meteors. The prime task is to select minor streams from sporadic meteors. Very few astronomers tried to do it, when others only mark observed meteor “Sporadic” without registering its track. So very few previous observations cannot be used for streams detection, and we had to do it from special observations. As a width of meteoroid stream may be very narrow, the Earth will cross it in few hours and it is necessary to observe meteor events 24 hour a day. This is why we provide meteor monitoring and catch every ray of light in night skies and ask other observers to join our program. The current goal of our investigation is continuous monitoring of meteor events by two ways: from nearby sites (about 20-60 km distance) for triangle observations and simultaneously from some observation sites separated by approximately thousand kilometers for detection of minor streams. The last one will reveal spatial heterogeneity's of strong meteor showers also. Since July 2002 at the Arkhyz Space Tracking Station (North Caucasus) and near Moscow hybrid TV-cameras with CCD (“PatrolCa”) are used for meteor observations. Limiting magnitude of the first camera is about +5 magn in the 52-degrees field under frame rate 25 f/sec, the second camera has limiting magnitude 11,5m in field 18x22 degrees with rate 7,5 f/sec. Since June 2006 four extra PatrolCa begin stereo (basis) TV-observation near Moscow with the aims of determination of individual orbits of observed meteors and their physical densities. Observed by meteor monitoring data show that at least 40% of sporadic meteors may be referred to catalogued weak meteor streams. In this paper we present the method of definition of celestial coordinates of objects in the single frame of the wide-angle system. The method allows definition of celestial coordinates of a meteor at the restrictions of absents of enough

  5. LCOGT Network observations of spacecraft target comets

    Science.gov (United States)

    Lister, Tim; Knight, Matthew M.; Snodgrass, Colin; Samarasinha, Nalin H.

    2015-01-01

    Las Cumbres Observatory Global Telescope (LCOGT) network currently has 12 telescopes at 6 locations in the northern and southern hemispheres with expansion plans for more. This network is versatile and can respond rapidly to target of opportunity events and also perform long term monitoring of slowly changing astronomical phenomena.We have been using the LCOGT Network to perform photometric monitoring of comet 67P/Churyumov-Gerasimenko to support the ESA Rosetta comet mission and of C/2013 A1 (Siding Spring) as part of the ground-based observation teams for these important comets. This broadband photometry will allow a vital link between the detailed in-situ measurements made by the spacecraft and the global properties of the coma, at a time when the comet is only visible for short periods from single sites. The science we can extract includes the rotational state of the nucleus, characterization of the nucleus' activity, gas and dust properties in the coma (e.g., outflow velocities), chemical origin of gas species in the coma, and temporal behavior of the coma structure when the comet is close to the sun. Comet Siding Spring is a dynamically new comet on its first approach to the Sun that will pass close to Mars, so we can directly sample the composition of an original unaltered remnant of the protoplanetary disc. We will also be making use of specialized comet filters available at LCOGT's 2-m Faulkes Telescope North (FTN) to obtain a unique data set on comet C/2013 A1 (Siding Spring), as part of a large worldwide campaign. As one of only two robotic telescope equipped with cometary narrowband filters in the Northern hemisphere and having the largest aperture plus a high quality site, FTN can provide critical regular monitoring that cannot be achieved by any other single facility in the campaign.

  6. COLOR SYSTEMATICS OF COMETS AND RELATED BODIES

    Energy Technology Data Exchange (ETDEWEB)

    Jewitt, David, E-mail: jewitt@ucla.edu [Department of Earth, Planetary and Space Sciences, UCLA, 595 Charles Young Drive East, Los Angeles, CA 90095-1567 (United States)

    2015-12-15

    Most comets are volatile-rich bodies that have recently entered the inner solar system following long-term storage in the Kuiper belt and the Oort cloud reservoirs. These reservoirs feed several distinct, short-lived “small body” populations. Here, we present new measurements of the optical colors of cometary and comet-related bodies including long-period (Oort cloud) comets, Damocloids (probable inactive nuclei of long-period comets) and Centaurs (recent escapees from the Kuiper belt and precursors to the Jupiter family comets). We combine the new measurements with published data on short-period comets, Jovian Trojans and Kuiper belt objects to examine the color systematics of the comet-related populations. We find that the mean optical colors of the dust in short-period and long-period comets are identical within the uncertainties of measurement, as are the colors of the dust and of the underlying nuclei. These populations show no evidence for scattering by optically small particles or for compositional gradients, even at the largest distances from the Sun, and no evidence for ultrared matter. Consistent with earlier work, ultrared surfaces are common in the Kuiper belt and on the Centaurs, but not in other small body populations, suggesting that this material is hidden or destroyed upon entry to the inner solar system. The onset of activity in the Centaurs and the disappearance of the ultrared matter in this population begin at about the same perihelion distance (∼10 AU), suggesting that the two are related. Blanketing of primordial surface materials by the fallback of sub-orbital ejecta, for which we calculate a very short timescale, is the likely mechanism. The same process should operate on any mass-losing body, explaining the absence of ultrared surface material in the entire comet population.

  7. Simulations of directed energy comet deflection

    Science.gov (United States)

    Zhang, Qicheng; Lubin, Philip M.; Hughes, Gary B.

    2016-09-01

    Earth-crossing asteroids and comets pose a long-term hazard to life and property on Earth. Schemes to mitigate the impact threat have been studied extensively but tend to focus on asteroid diversion while neglecting the possibility of a comet threat. Such schemes often demand physically intercepting the target by spacecraft, a task feasible only for targets identified decades in advance in a restricted range of orbits. A threatening comet is unlikely to satisfy these criteria and so necessitates a fundamentally different approach for diversion. Comets are naturally perturbed from purely gravitational trajectories through solar heating of their surfaces which activates sublimation-driven jets. Artificial heating of a comet, such as by a high-powered laser array in Earth orbit, may supplement natural heating by the Sun to purposefully manipulate its path to avoid an impact. The effectiveness of any particular laser array for a given comet depends on the comet's heating response which varies dramatically depending on factors including nucleus size, orbit and dynamical history. These factors are incorporated into a numerical orbital model using established models of nongravitational perturbations to evaluate the effectiveness and feasibility of using high-powered laser arrays in Earth orbit or on the ground to deflect a variety of comets. Simulation results suggest that orbital arrays of 500m and 10GW operating for 10 min=d over 1 yr may be adequate for mitigating impacts by comets up to 500m in diameter. Continuously operating ground-based arrays of 100m and 10GW may be similarly effective when appropriately located.

  8. METEOR v1.0 - Design and structure of the software package; METEOR v1.0 - Estructura y modulos informaticos

    Energy Technology Data Exchange (ETDEWEB)

    Palomo, E.

    1994-07-01

    This script describes the structure and the separated modules of the software package METEOR for the statistical analysis of meteorological data series. It contains a systematic description of the subroutines of METEOR and, also, of the required shape for input and output files. The original version of METEOR have been developed by Ph.D. Elena Palomo, CIEMAT-IER, GIMASE. It is built by linking programs and routines written in FORTRAN 77 and it adds thc graphical capabilities of GNUPLOT. The shape of this toolbox was designed following the criteria of modularity, flexibility and agility criteria. All the input, output and analysis options are structured in three main menus: i) the first is aimed to evaluate the quality of the data set; ii) the second is aimed for pre-processing of the data; and iii) the third is aimed towards the statistical analyses and for creating the graphical outputs. Actually the information about METEOR is constituted by three documents written in spanish: 1) METEOR v1.0: User's guide; 2) METEOR v1.0: A usage example; 3) METEOR v 1.0: Design and structure of the software package. (Author)

  9. A Comet Engulfs Mars: MAVEN Observations of Comet Siding Spring's Influence on the Martian Magnetosphere

    Science.gov (United States)

    Espley, Jared R.; Dibraccio, Gina A.; Connerney, John E. P.; Brain, David; Gruesbeck, Jacob; Soobiah, Yasir; Halekas, Jasper S.; Combi, Michael; Luhmann, Janet; Ma, Yingjuan

    2015-01-01

    The nucleus of comet C/2013 A1 (Siding Spring) passed within 141,000?km of Mars on 19 October 2014. Thus, the cometary coma and the plasma it produces washed over Mars for several hours producing significant effects in the Martian magnetosphere and upper atmosphere. We present observations from Mars Atmosphere and Volatile EvolutioN's (MAVEN's) particles and field's instruments that show the Martian magnetosphere was severely distorted during the comet's passage. We note four specific major effects: (1) a variable induced magnetospheric boundary, (2) a strong rotation of the magnetic field as the comet approached, (3) severely distorted and disordered ionospheric magnetic fields during the comet's closest approach, and (4) unusually strong magnetosheath turbulence lasting hours after the comet left. We argue that the comet produced effects comparable to that of a large solar storm (in terms of incident energy) and that our results are therefore important for future studies of atmospheric escape, MAVEN's primary science objective.

  10. Comet Lesions in Patients with Pseudoxanthoma Elasticum

    Directory of Open Access Journals (Sweden)

    Sinan Tatlıpınar

    2015-12-01

    Full Text Available Pseudoxanthoma elasticum (PXE is a genetic multisystemic disorder affecting the skin, eyes and cardiovascular system. Basic fundoscopic findings in PXE result from Bruch’s membrane involvement. The most important fundoscopic findings are angioid streaks. Other significant ocular findings are peau d’orange appearance, optic disc drusen, pattern dystrophy-like macular appearance, comet lesions, and choroidal neovascularization. Comet lesions are a pathognomonic ocular finding for PXE. The presence of both angioid streaks in the fundus and typical skin lesions should alert clinicians to PXE. Herein, we present two PXE cases with comet lesions.

  11. Kinematic Characteristics of Meteor Showers by Results of the Combined Radio-Television Observations

    Science.gov (United States)

    Narziev, Mirhusen

    2016-07-01

    One of the most important tasks of meteor astronomy is the study of the distribution of meteoroid matter in the solar system. The most important component to address this issue presents the results of measurements of the velocities, radiants, and orbits of both showers and sporadic meteors. Radiant's and orbits of meteors for different sets of data obtained as a result of photographic, television, electro-optical, video, Fireball Network and radar observations have been measured repeatedly. However, radiants, velocities and orbits of shower meteors based on the results of combined radar-optical observations have not been sufficiently studied. In this paper, we present a methods for computing the radiants, velocities, and orbits of the combined radar-TV meteor observations carried out at HisAO in 1978-1980. As a result of the two-year cycle of simultaneous TV-radar observations 57 simultaneous meteors have been identified. Analysis of the TV images has shown that some meteor trails appeared as dashed lines. Among the simultaneous meteors of d-Aquariids 10 produced such dashed images, and among the Perseids there were only 7. Using a known method, for such fragmented images of simultaneous meteors - together with the measured radar distance, trace length, and time interval between the segments - allowed to determine meteor velocity using combined method. In addition, velocity of the same meteors was measured using diffraction and radar range-time methods based on the results of radar observation. It has been determined that the mean values of meteoroid velocity based on the combined radar-TV observations are greater in 1 ÷ 3 km / c than the averaged velocity values measured using only radar methods. Orbits of the simultaneously observed meteors with segmented photographic images were calculated on the basis of the average velocity observed using the combined radar-TV method. The measured results of radiants velocities and orbital elements of individual meteors

  12. IAU Meteor Data Center-the shower database: A status report

    Science.gov (United States)

    Jopek, Tadeusz Jan; Kaňuchová, Zuzana

    2017-09-01

    Currently, the meteor shower part of Meteor Data Center database includes: 112 established showers, 563 in the working list, among them 36 have the pro tempore status. The list of shower complexes contains 25 groups, 3 have established status and 1 has the pro tempore status. In the past three years, new meteor showers submitted to the MDC database were detected amongst the meteors observed by CAMS stations (Cameras for Allsky Meteor Surveillance), those included in the EDMOND (European viDeo MeteOr Network Database), those collected by the Japanese SonotaCo Network, recorded in the IMO (International Meteor Organization) database, observed by the Croatian Meteor Network and on the Southern Hemisphere by the SAAMER radar. At the XXIX General Assembly of the IAU in Honolulu, Hawaii in 2015, the names of 18 showers were officially accepted and moved to the list of established ones. Also, one shower already officially named (3/SIA the Southern iota Aquariids) was moved back to the working list of meteor showers. At the XXIX GA IAU the basic shower nomenclature rule was modified, the new formulation predicates ;The general rule is that a meteor shower (and a meteoroid stream) should be named after the constellation that contains the nearest star to the radiant point, using the possessive Latin form;. Over the last three years the MDC database was supplemented with the earlier published original data on meteor showers, which permitted verification of the correctness of the MDC data and extension of bibliographic information. Slowly but surely new database software options are implemented, and software bugs are corrected.

  13. Forward-scattering of meteors: a digital way

    Science.gov (United States)

    Nedeljkovic, Saša; Miovic, Vjera

    2005-02-01

    The new cutting edge technologies have opened the possibility of using digital spectrometers to probe the sky. With the sampling rate of ˜400 Msamples/s and the capability to digitally process data in real-time it is possible to get wideband spectra covering the frequencies in the range 0-200 MHz with the resolution of a few kHz. This presentation will show how such a spectrometer can be applied to the forward-scattering method of meteor detection.

  14. A Comet Surface Sample Return System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed Phase II investigation will focus on the development of spacecraft systems required to obtain a sample from the nucleus of a comet, hermetically seal...

  15. A Comet Surface Sample Return System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed Phase I investigation will focus on the development of spacecraft systems required to obtain a sample from the nucleus of a comet, hermetically seal the...

  16. Spacecraft fleet to comet Halley - an introduction

    Energy Technology Data Exchange (ETDEWEB)

    Tsurutani, B.T.

    1985-01-01

    Questions related to the formation and the characteristics of comets are discussed, and it is suggested that an evolutionary link exists between comets, prebiotic organic synthesis, and the origin of life as it is known. Fundamental questions about the solar wind interaction with comets, are considered, giving attention to the ionization mechanisms in the different cometary regions, the presence of field-aligned currents, and the cometary plasma tail. It is pointed out that some of the questions will soon be answered when the NASA-ESA International Cometary Explorer (ICE) goes through the tail of Giacobini-Zinner in September 1985, and when a five spacecraft fleet arrives at comet Halley in March 1986. 14 references.

  17. The seeding of life by comets

    Science.gov (United States)

    Greenberg, J. M.; Mendoza-Gomez, Celia X.

    1992-01-01

    The chemical and morphological structures of comets and interstellar dust are reviewed to demonstrate the feasibility of comets providing the necessary prebiotic molecules for the formation of life on the early earth. The chemical evolution of interstellar dust is shown to be the source of organics in comets, and the molecules observed in the grains are listed as are the products resulting from grain photolysis. It is emphasized that comets could only transfer prebiotic molecules to the earth if they are fluffy aggregates that break up into fine fragments. The contributions to the early earth are considered in terms of the competition between the evolution of the living organisms and the destructive effects of impacts. It is considered that life began as the bombardment during the first 5 x 10 exp 8 years began to tail off.

  18. The seeding of life by comets.

    Science.gov (United States)

    Greenberg, J M; Mendoza-Gomez, C X

    1992-01-01

    The evidence that living organisms were already extant on the earth almost 4 Gyr ago and that early bombardment by comets and asteroids created a hostile environment up to about this time has revived the question of how it was possible for prebiotic chemical evolution to have provided the necessary ingredients for life to have developed in the short intervening time. The actual bracketed available temporal space is no more than 0.5 Gyr and probably much less. Was this sufficient time for an earth-based source of the first simple organic precursor molecules to have led to the level of the prokaryotic cell? If not, then the difficulty would be resolved if the ancient earth was impregnated by organic molecular seed from outer space. Curiously, it seems that the most likely source of such seeds was the same a one of the sources of the hostile enviroment, namely the comets which bombarded the earth. With the knowledge of comets gained by the space missions it has become clear that a very large fraction of the chemical composition of comet nuclei consists of quite complex organic molecules. Furthermore it has been demonstrated that comets consist of very fluffy aggregates of interstellar dust whose chemistry derives from photoprocessing of simple ice mixtures in space. Thus, the ultimate source of organics in comets comes from the chemical evolution of interstellar dust. An important and critical justification for assuming that interstellar dust is the ultimate source of prebiotic molecular insertion on the earth is the proof that comets are extremely fluffy aggregates, which have the possibility of breaking up into finely divided fragments when the comet impacts the earth's atmosphere. In the following we will summarize the properties of interstellar dust and the chemical and morphological structure of comets indicated by the most recent interpretations of comet observations. It will be shown that the suitable condition for comets having provided abundant prebiotic

  19. Triggering Comet-Like Activity of Main Belt Comets

    Science.gov (United States)

    Haghighipour, Nader; Maindl, Thomas I.; Schaefer, Christoph; Speith, Roland; Dvorak, Rudolf

    2016-10-01

    Main-belt comets (MBCs) have attracted a great deal of interest since their identification as activated asteroids by Hsieh and Jewitt in 2006. It has been suggested that the comet-like activity of these objects are due to the sublimation of sub-surface water-ice that has been exposed as a result of their surfaces being impacted by small (e.g, m-sized) bodies. We have examined the viability of this scenario by simulating impacts between m-sized impactors and km-sized targets using a smooth particle hydrodynamics (SPH) approach. We have carried out simulations for a range of impact velocities and angles, material type and strength, and water content of the target allowing m-sized impactors to erode enough of an MBC's surface to trigger its activation. Results indicate that for the range of impact velocities corresponding to those in the asteroid belt, the depth of an impact crater is slightly larger than 10 m suggesting that if the activation of MBCs is due to the sublimation of sub-surface water-ice, this ice has to exist no deeper than a few meters from the surface. Our simulations point to a clearly notable spread in the aggregated crater depths due to different impact energy, impact angles, and MBC's water contents showing deeper craters due to less overall material strength. Results also show that ice-exposure occurs in the bottom and on the interior surface of impact craters as well as the surface of the target where some of the ejected icy inclusions are re-accreted. Our results, in addition to demonstrating that the impact scenario is indeed a viable mechanism to expose ice and trigger the activity of MBCs, indicate that the activity of the current MBCs is likely due to ice sublimation from multiple impact sites and/or the water contents of these objects (and other asteroids in the outer asteroid belt) is larger than the 5% that is traditionally considered in models of terrestrial planet formation. We present details of our simulations and discuss their

  20. The comet assay: a heavenly method!

    Science.gov (United States)

    Collins, Andrew R

    2015-01-01

    The contributions to this special issue of Mutagenesis have been selected to cover the main research areas served by the comet assay, namely genotoxicology, environmental toxicology, human biomonitoring and fundamental investigations into mechanisms of DNA damage and repair. Innovative methods are described, technical issues are explored, and guidelines are given for venturing into relatively new or unexploited areas of research. The popularity of the comet assay in a historical context is illustrated by a bibliometric survey.

  1. Atlas of Secular Light Curves of Comets

    Science.gov (United States)

    Ferrin, Ignacio

    2007-12-01

    We have completed work on the secular light curves of 30 periodic and non-periodic comets. The objectives and approach of this project has been explained in Ferrin (Icarus, 178, 493-516, 2005). Each comet requires 2 plots. The time plot shows the reduced (to Δ = 1 AU) magnitude of the comet as a function of time, thus displaying the brightness history of the object. The log plot is a reflected double log plot. The reflection takes place at R=1 AU, to allow the determination of the absolute magnitude by extrapolation. 22 photometric parameters are measured from the plots, most of them new. The plots have been collected in a document that constitutes "The Atlas". We have defined a photometric age, P-AGE, that attempts to measure the age of a comet based on its activity. P-AGE has been scaled to human ages to help in its interpretation. We find that comets Hale-Bopp and 29P/SW 1, are baby comets (P-AGE 100 cy). The secular light curve of 9P/Tempel 1 exhibits sublimation due to H2O and due to CO. Comet 67P/Churyumov-Gerasimento to be visited by the Rossetta spacecraft in 2014 exhibits a photometric anomaly. Comet 65P/Gunn exhibits a lag in maximum brightness of LAG = + 254 days after perihelion. We suggest that the pole is pointing to the sun at that time. The secular light curves will be presented and a preliminary interpretation will be advanced. The secular light curves present complexity beyond current understanding. The observations described in this work were carried out at the National Observatory of Venezuela (ONV), managed by the Center for Research in Astronomy (CIDA), for the Ministry of Science and Technology (MinCyT).

  2. On the classification of comet plasma tails

    Science.gov (United States)

    Mozhenkov, E. R.; Vaisberg, O. L.

    2017-07-01

    The investigation of plasma tails of comets is an important part of comet research. Different classifications of plasma tails of comets are proposed. Plasma acceleration in the tails is investigated in sufficient detail. Several cometary forms are explained. Plasma tails of Mars and Venus were observed during the first studies of these planets. They are associated with the capture of ionized atoms and exosphere molecules by the solar wind magnetized plasma flow. Distinct plasma tails of Mars and Venus are caused by the mass loading of the solar wind with heavy ions. It was shown that the transverse dimension of the tails of Mars, Venus, and comets can be quite accurately determined by production rate of the obstacle to the solar wind flow. While plasma tails of Mars and Venus are investigated by in situ measurements from spacecraft, observations of comet tails from the Earth make it possible to see the entire object under study and to monitor changes in its structure. A certain similarity of cometary and planetary tails can be explained by the nonmagnetic nature of both types of bodies. Thus, it is reasonable to suppose that investigations of plasma tails of comets can supplement the information obtained by in situ methods of the study of the planets. In this paper, plasma tails of comets, presumably analogous to the plasma tails of Mars and Venus, have been identified on modern photographs of comets (more than 1500 photographs viewed). Only quasi-steady laminar tails are considered. They are divided into two types: double structures and outflows. The paper attempts to define the 3D structure of double structures and to determine certain characteristics of outflows.

  3. Finding long-lost Comet Lexell

    Science.gov (United States)

    Wiegert, Paul

    2015-11-01

    Comet D/1770 L1 (Lexell) made the closest observed pass by a comet to the Earth at approximately 0.015 AU on 1 July 1770. A naked-eye object observed by many astronomers of the time, it was subsequently lost: the best contemporary estimates had it removed from its 1770 orbit by Jupiter in 1779 and sent to the outer Solar System.Near-Earth asteroid 2010 JL33 has an orbit similar to that followed by Lexell's comet during its observed apparition. However, this NEA's nominal orbit, which is well-known on the basis of a decade-long arc which includes radar observations, does not approach the Earth at the correct time to be Lexell's comet. That is, unless modest non-gravitational forces are applied, in which case the famous near-miss can be reproduced.Modern measurements of 2010 JL33 together with those Lexell's comet made in the 18th century -which include motion exceeding 40 degrees per day on the sky at closest approach- provide exquisite constraints on the dynamical processes at work, cometary, Yarkovsky or other. I will discuss the implications of and the conditions required for asteroid 2010 JL33 to be, in fact, long-lost comet Lexell.

  4. Mid-infrared spectra of comet nuclei

    CERN Document Server

    Kelley, Michael S P; Gehrz, Robert D; Reach, William T; Harker, David E

    2016-01-01

    Jovian Trojan D-type asteroids have mid-infrared emissivity features strikingly similar to comet comae, suggesting that they have the same compositions and that the surfaces of the Trojans are highly porous. However, a direct comparison between a comet and asteroid surface has not been possible due to the paucity of spectra of comet nuclei at mid-infrared wavelengths. We present 5-35 {\\mu}m thermal emission spectra of comets 10P/Tempel 2, and 49P/Arend-Rigaux observed with the Infrared Spectrograph on the Spitzer Space Telescope. Our analysis suggests the spectra are dominated by the comet nucleus. We fit each spectrum with the near-Earth asteroid thermal model (NEATM) and find sizes in agreement with previous values. However, the NEATM beaming parameters of the nuclei, 0.74 to 0.83, are systematically lower than the Jupiter-family comet population mean of 1.03+/-0.11, derived from 16- and 22-{\\mu}m photometry. When the spectra are normalized by the NEATM model, a weak 10-{\\mu}m silicate plateau is evident, w...

  5. Non-extensive statistical analysis of meteor showers and lunar flashes

    Science.gov (United States)

    Betzler, A. S.; Borges, E. P.

    2015-02-01

    The distribution of meteor magnitudes is usually supposed to be described by power laws. However, this relationship is not able to model the whole data set, and the parameters are considered to be dependent on the magnitude intervals. We adopt a statistical distribution derived from Tsallis non-extensive statistical mechanics which is able to model the whole magnitude range. We combined meteor data from various sources, ranging from telescopic meteors to lunar impactors. Our analysis shows that the probability distribution of magnitudes of International Meteor Organization (IMO) and Meteor Observation and Recovery Project data are similar. The distribution of IMO visual magnitudes indicates that 2.4 ± 0.5 per cent of the meteors of a shower may be telescopic (m > 6). We note that the distribution of duration of lunar flashes follows a power law, and a comparison with the distribution of meteor showers suggests the occurrence of observational bias. The IMO sporadic meteor distribution also seems to be influenced by observational factors.

  6. Plasma distributions in meteor head echoes and implications for radar cross section interpretation

    Science.gov (United States)

    Marshall, Robert A.; Brown, Peter; Close, Sigrid

    2017-09-01

    The derivation of meteoroid masses from radar measurements requires conversion of the measured radar cross section (RCS) to meteoroid mass. Typically, this conversion passes first through an estimate of the meteor plasma density derived from the RCS. However, the conversion from RCS to meteor plasma density requires assumptions on the radial electron density distribution. We use simultaneous triple-frequency measurements of the RCS for 63 large meteor head echoes to derive estimates of the meteor plasma size and density using five different possible radial electron density distributions. By fitting these distributions to the observed meteor RCS values and estimating the goodness-of-fit, we determine that the best fit to the data is a 1 /r2 plasma distribution, i.e. the electron density decays as 1 /r2 from the center of the meteor plasma. Next, we use the derived plasma distributions to estimate the electron line density q for each meteor using each of the five distributions. We show that depending on the choice of distribution, the line density can vary by a factor of three or more. We thus argue that a best estimate for the radial plasma distribution in a meteor head echo is necessary in order to have any confidence in derived meteoroid masses.

  7. Martian Atmospheric Methane Plumes from Meteor Shower Infall: A Hypothesis

    Science.gov (United States)

    Fries, M.; Christou, A.; Archer, D.; Conrad, P.; Cooke, W.; Eigenbrode, J.; ten Kate, I. L.; Matney, M.; Niles, P.; Sykes, M.

    2016-01-01

    Methane plumes in the martian atmosphere have been detected using Earth-based spectroscopy, the Planetary Fourier Spectrometer on the ESA Mars Express mission, and the NASA Mars Science Laboratory. The methane's origin remains a mystery, with proposed sources including volcanism, exogenous sources like impacts and interplanetary dust, aqueous alteration of olivine in the presence of carbonaceous material, release from ancient deposits of methane clathrates, and/or biological activity. To date, none of these phenomena have been found to reliably correlate with the detection of methane plumes. An additional source exists, however: meteor showers could generate martian methane via UV pyrolysis of carbon-rich infall material. We find a correlation between the dates of Mars/cometary orbit encounters and detections of methane on Mars. We hypothesize that cometary debris falls onto Mars during these interactions, depositing freshly disaggregated meteor shower material in a regional concentration. The material generates methane via UV photolysis, resulting in a localized "plume" of short-lived methane.

  8. Charge Balance in the Mesosphere with Meteoric Dust Particles

    Science.gov (United States)

    Robertson, S. H.; Asmus, H.; Dickson, S.; Friedrich, M.; Megner, L. S.

    2013-12-01

    An aerosol particle charging model developed initially for noctilucent cloud particles has been extended in several steps in order to better explain data for charged meteoric smoke particles (MSPs) returned by the nighttime and daytime CHAMPS rockets launched from the Andøya rocket Range, Norway, in October 2011. Addition of photodetachment to the model shows that this process reduces the number density of positively charged MSPs as well as the number density of negatively charged MSPs as a consequence of the photodetached electrons neutralizing the positively charged MSPs. In addition, the model shows that the ionization rate can be deduced from the electron number density and the electron-ion recombination rate only at the highest altitudes as a consequence of recombination of electrons on the MSPs at lower altitudes. The differences between the daytime and nighttime data place constraints on the photodetachment rate. A further extension of the model to include the formation of negative ions and their destruction by atomic oxygen helps explain the ledge seen in the number density of the lightest negatively charged particles. MSP particle densities from the CARMA/CHEM2D model are in better agreement with rocket data for assumed values of the meteor input flux that are at the low end of the generally accepted range.

  9. Development of artificial meteor for observation of upper atmosphere

    Science.gov (United States)

    Watanabe, Masaki; Sahara, Hironori; Abe, Shinsuke; Watanabe, Takeo; Nojiri, Yuta; Okajima, Lena

    2016-04-01

    This study proposes a method for the observation of the upper atmosphere using an artificial meteor injected by a mass driver installed on a microsatellite. The mass driver injects a pill at a velocity of 200 m/s and deorbits it into the atmosphere. The emission of the pill can then be observed from the ground at the necessary time and location. This approach could contribute to a better understanding of the global environment as well as different aspects of astronomy and planetary science. To realize the proposed method, the required size and emission of the pill have to be determined. Therefore, we conducted flow-field simulations, spectroscopic estimations, and an experiment on an artificial meteor in the arc heater wind tunnel at the Institute of Space and Astronautical Science in the Japan Aerospace Exploration Agency (ISAS/JAXA). From the results, we confirmed that the light emission could be observed as a shooting star by the naked eye and thus verified the feasibility of the method.

  10. The Comet With a Broken Heart

    Science.gov (United States)

    2006-04-01

    On the night of April 23 to 24, ESO's Very Large Telescope observed fragment B of the comet Schwassmann-Wachmann 3 that had split a few days earlier. To their great surprise, the ESO astronomers discovered that the piece just ejected by fragment B was splitting again! Five other mini-comets are also visible on the image. The comet seems thus doomed to disintegrate but the question remains in how much time. Comet 73P/Schwassmann-Wachmann 3 (SW 3) is a body with a very tormented past. This comet revolves around the Sun in about 5.4 years, in a very elongated orbit that brings it from inwards of the Earth's orbit to the neighbourhood of giant planet Jupiter. In 1995, when it was coming 'close' to the Earth, it underwent a dramatic and completely unexpected, thousand-fold brightening. Observations in 1996, with ESO's New Technology Telescope and 3.6-m telescope, at La Silla, showed that this was due to the fact that the comet had split into three distinct pieces. Later, in December 1996, two more fragments were discovered. At the last comeback, in 2001, of these five fragments only three were still seen, the fragments C (the largest one), B and E. No new fragmentations happened during this approach, apparently. ESO PR Photo 15a/06 ESO PR Photo 15a/06 Fragment B of Comet SW-3 Things were different this time, when the comet moved again towards its closest approach to the Sun - and to the Earth. Early in March, seven fragments were observed, the brightest (fragment C) being of magnitude 12, i.e. 250 fainter than what the unaided can see, while fragment B was 10 times fainter still. In the course of March, 6 new fragments were seen. Early in April, fragment B went into outburst, brightening by a factor 10 and on 7 April, six new fragments were discovered, confirming the high degree of fragmentation of the comet. On 12 April, fragment B was as bright as the main fragment C, with a magnitude around 9 (16 times fainter than what a keen observer can see with unaided eyes

  11. The Working Group on Meteor Showers Nomenclature: a History, Current Status and a Call for Contributions

    Science.gov (United States)

    Jopek, T. J.; Jenniskens, P. M.

    2011-01-01

    During the IAU General Assembly in Rio de Janeiro in 2009, the members of Commission 22 established the Working Group on Meteor Shower Nomenclature, from what was formerly the Task Group on Meteor Shower Nomenclature. The Task Group had completed its mission to propose a first list of established meteor showers that could receive officially names. At the business meeting of Commission 22 the list of 64 established showers was approved and consequently officially accepted by the IAU. A two-step process is adopted for showers to receive an official name from the IAU: i) before publication, all new showers discussed in the literature are first added to the Working List of Meteor Showers, thereby receiving a unique name, IAU number and three-letter code; ii) all showers which come up to the verification criterion are selected for inclusion in the List of Established Meteor Showers, before being officially named at the next IAU General Assembly.

  12. Meteor studies in the framework of the JEM-EUSO program

    Science.gov (United States)

    Abdellaoui, G.; Abe, S.; Acheli, A.; Adams, J. H.; Ahmad, S.; Ahriche, A.; Albert, J.-N.; Allard, D.; Alonso, G.; Anchordoqui, L.; Andreev, V.; Anzalone, A.; Aouimeur, W.; Arai, Y.; Arsene, N.; Asano, K.; Attallah, R.; Attoui, H.; Ave Pernas, M.; Bacholle, S.; Bakiri, M.; Baragatti, P.; Barrillon, P.; Bartocci, S.; Batsch, T.; Bayer, J.; Bechini, R.; Belenguer, T.; Bellotti, R.; Belov, A.; Belov, K.; Benadda, B.; Benmessai, K.; Berlind, A. A.; Bertaina, M.; Biermann, P. L.; Biktemerova, S.; Bisconti, F.; Blanc, N.; Błȩcki, J.; Blin-Bondil, S.; Bobik, P.; Bogomilov, M.; Bonamente, M.; Boudaoud, R.; Bozzo, E.; Briggs, M. S.; Bruno, A.; Caballero, K. S.; Cafagna, F.; Campana, D.; Capdevielle, J.-N.; Capel, F.; Caramete, A.; Caramete, L.; Carlson, P.; Caruso, R.; Casolino, M.; Cassardo, C.; Castellina, A.; Castellini, G.; Catalano, C.; Catalano, O.; Cellino, A.; Chikawa, M.; Chiritoi, G.; Christl, M. J.; Connaughton, V.; Conti, L.; Cordero, G.; Crawford, H. J.; Cremonini, R.; Csorna, S.; Dagoret-Campagne, S.; De Donato, C.; de la Taille, C.; De Santis, C.; del Peral, L.; Di Martino, M.; Djemil, T.; Djenas, S. A.; Dulucq, F.; Dupieux, M.; Dutan, I.; Ebersoldt, A.; Ebisuzaki, T.; Engel, R.; Eser, J.; Fang, K.; Fenu, F.; Fernández-González, S.; Fernández-Soriano, J.; Ferrarese, S.; Finco, D.; Flamini, M.; Fornaro, C.; Fouka, M.; Franceschi, A.; Franchini, S.; Fuglesang, C.; Fujimoto, J.; Fukushima, M.; Galeotti, P.; García-Ortega, E.; Garipov, G.; Gascón, E.; Geary, J.; Gelmini, G.; Genci, J.; Giraudo, G.; Gonchar, M.; González Alvarado, C.; Gorodetzky, P.; Guarino, F.; Guehaz, R.; Guzmán, A.; Hachisu, Y.; Haiduc, M.; Harlov, B.; Haungs, A.; Hernández Carretero, J.; Hidber, W.; Higashide, K.; Ikeda, D.; Ikeda, H.; Inoue, N.; Inoue, S.; Isgrò, F.; Itow, Y.; Jammer, T.; Joven, E.; Judd, E. G.; Jung, A.; Jochum, J.; Kajino, F.; Kajino, T.; Kalli, S.; Kaneko, I.; Kang, D.; Kanouni, F.; Karadzhov, Y.; Karczmarczyk, J.; Karus, M.; Katahira, K.; Kawai, K.; Kawasaki, Y.; Kedadra, A.; Khales, H.; Khrenov, B. A.; Kim, Jeong-Sook; Kim, Soon-Wook; Kim, Sug-Whan; Kleifges, M.; Klimov, P. A.; Kolev, D.; Kreykenbohm, I.; Kudela, K.; Kurihara, Y.; Kusenko, A.; Kuznetsov, E.; Lacombe, M.; Lachaud, C.; Lahmar, H.; Lakhdari, F.; Larsson, O.; Lee, J.; Licandro, J.; Lim, H.; López Campano, L.; Maccarone, M. C.; Mackovjak, S.; Mahdi, M.; Maravilla, D.; Marcelli, L.; Marcos, J. L.; Marini, A.; Martens, K.; Martín, Y.; Martinez, O.; Masciantonio, G.; Mase, K.; Matev, R.; Matthews, J. N.; Mebarki, N.; Medina-Tanco, G.; Mehrad, L.; Mendoza, M. A.; Merino, A.; Mernik, T.; Meseguer, J.; Messaoud, S.; Micu, O.; Mimouni, J.; Miyamoto, H.; Miyazaki, Y.; Mizumoto, Y.; Modestino, G.; Monaco, A.; Monnier-Ragaigne, D.; Morales de los Ríos, J. A.; Moretto, C.; Morozenko, V. S.; Mot, B.; Murakami, T.; Nadji, B.; Nagano, M.; Nagata, M.; Nagataki, S.; Nakamura, T.; Napolitano, T.; Nardelli, A.; Naumov, D.; Nava, R.; Neronov, A.; Nomoto, K.; Nonaka, T.; Ogawa, T.; Ogio, S.; Ohmori, H.; Olinto, A. V.; Orleański, P.; Osteria, G.; Painter, W.; Panasyuk, M. I.; Panico, B.; Parizot, E.; Park, I. H.; Park, H. W.; Pastircak, B.; Patzak, T.; Paul, T.; Pennypacker, C.; Perdichizzi, M.; Pérez-Grande, I.; Perfetto, F.; Peter, T.; Picozza, P.; Pierog, T.; Pindado, S.; Piotrowski, L. W.; Piraino, S.; Placidi, L.; Plebaniak, Z.; Pliego, S.; Pollini, A.; Popescu, E. M.; Prat, P.; Prévôt, G.; Prieto, H.; Putis, M.; Rabanal, J.; Radu, A. A.; Rahmani, M.; Reardon, P.; Reyes, M.; Rezazadeh, M.; Ricci, M.; Rodríguez Frías, M. D.; Ronga, F.; Roth, M.; Rothkaehl, H.; Roudil, G.; Rusinov, I.; Rybczyński, M.; Sabau, M. D.; Sáez Cano, G.; Sagawa, H.; Sahnoune, Z.; Saito, A.; Sakaki, N.; Sakata, M.; Salazar, H.; Sanchez, J. C.; Sánchez, J. L.; Santangelo, A.; Santiago Crúz, L.; Sanz-Andrés, A.; Sanz Palomino, M.; Saprykin, O.; Sarazin, F.; Sato, H.; Sato, M.; Schanz, T.; Schieler, H.; Scotti, V.; Segreto, A.; Selmane, S.; Semikoz, D.; Serra, M.; Sharakin, S.; Shibata, T.; Shimizu, H. M.; Shinozaki, K.; Shirahama, T.; Siemieniec-Oziȩbło, G.; Sledd, J.; Słomińska, K.; Sobey, A.; Stan, I.; Sugiyama, T.; Supanitsky, D.; Suzuki, M.; Szabelska, B.; Szabelski, J.; Tahi, H.; Tajima, F.; Tajima, N.; Tajima, T.; Takahashi, Y.; Takami, H.; Takeda, M.; Takizawa, Y.; Talai, M. C.; Tenzer, C.; Tibolla, O.; Tkachev, L.; Tokuno, H.; Tomida, T.; Tone, N.; Toscano, S.; Traïche, M.; Tsenov, R.; Tsunesada, Y.; Tsuno, K.; Tymieniecka, T.; Uchihori, Y.; Unger, M.; Vaduvescu, O.; Valdés-Galicia, J. F.; Vallania, P.; Vankova, G.; Vigorito, C.; Villaseñor, L.; Vlcek, B.; von Ballmoos, P.; Vrabel, M.; Wada, S.; Watanabe, J.; Watanabe, S.; Watts, J., Jr.; Weber, M.; Weigand Muñoz, R.; Weindl, A.; Weiler, T. J.; Wibig, T.; Wiencke, L.; Wille, M.; Wilms, J.; Włodarczyk, Z.; Yamamoto, T.; Yamamoto, Y.; Yang, J.; Yano, H.; Yashin, I. V.; Yonetoku, D.; Yoshida, S.; Young, R.; Zgura, I. S.; Zotov, M. Yu.; Zuccaro Marchi, A.

    2017-09-01

    We summarize the state of the art of a program of UV observations from space of meteor phenomena, a secondary objective of the JEM-EUSO international collaboration. Our preliminary analysis indicates that JEM-EUSO, taking advantage of its large FOV and good sensitivity, should be able to detect meteors down to absolute magnitude close to 7. This means that JEM-EUSO should be able to record a statistically significant flux of meteors, including both sporadic ones, and events produced by different meteor streams. Being unaffected by adverse weather conditions, JEM-EUSO can also be a very important facility for the detection of bright meteors and fireballs, as these events can be detected even in conditions of very high sky background. In the case of bright events, moreover, exhibiting some persistence of the meteor train, preliminary simulations show that it should be possible to exploit the motion of the ISS itself and derive at least a rough 3D reconstruction of the meteor trajectory. Moreover, the observing strategy developed to detect meteors may also be applied to the detection of nuclearites, exotic particles whose existence has been suggested by some theoretical investigations. Nuclearites are expected to move at higher velocities than meteoroids, and to exhibit a wider range of possible trajectories, including particles moving upward after crossing the Earth. Some pilot studies, including the approved Mini-EUSO mission, a precursor of JEM-EUSO, are currently operational or in preparation. We are doing simulations to assess the performance of Mini-EUSO for meteor studies, while a few meteor events have been already detected using the ground-based facility EUSO-TA.

  13. Diurnal and annual variations of meteor rates at the arctic circle

    Directory of Open Access Journals (Sweden)

    W. Singer

    2004-01-01

    Full Text Available Meteors are an important source for (a the metal atoms of the upper atmosphere metal layers and (b for condensation nuclei, the existence of which are a prerequisite for the formation of noctilucent cloud particles in the polar mesopause region. For a better understanding of these phenomena, it would be helpful to know accurately the annual and diurnal variations of meteor rates. So far, these rates have been little studied at polar latitudes. Therefore we have used the 33 MHz meteor radar of the ALOMAR observatory at 69° N to measure the meteor rates at this location for two full annual cycles. This site, being within 3° of the Arctic circle, offers in addition an interesting capability: The axis of its antenna field points (almost towards the North ecliptic pole once each day of the year. In this particular viewing direction, the radar monitors the meteoroid influx from (almost the entire ecliptic Northern hemisphere. We report on the observed diurnal variations (averaged over one month of meteor rates and their significant alterations throughout the year. The ratio of maximum over minimum meteor rates throughout one diurnal cycle is in January and February about 5, from April through December 2.3±0.3. If compared with similar measurements at mid-latitudes, our expectation, that the amplitude of the diurnal variation is to decrease towards the North pole, is not really borne out. Observations with the antenna axis pointing towards the North ecliptic pole showed that the rate of deposition of meteoric dust is substantially larger during the Arctic NLC season than the annual mean deposition rate. The daylight meteor showers of the Arietids, Zeta Perseids, and Beta Taurids supposedly contribute considerably to the June maximum of meteor rates. We note, though, that with the radar antenna pointing as described above, all three meteor radiants are close to the local horizon but all three radiants were detected.

  14. Acellular comet assay: a tool for assessing variables influencing the alkaline comet assay.

    Science.gov (United States)

    Kennedy, Erin K; McNamee, James P; Prud'homme Lalonde, Louise; Jones, Trevor; Wilkinson, Diana

    2012-01-01

    In this study, an acellular modification to the alkaline comet assay to further evaluate key variables within the assay that may influence the outcome of genotoxicity studies is described. This acellular comet assay can detect differences of 0.2 Gy of (60)Co gamma-ray radiation between 0 and 1 Gy and differences of 1 Gy between 0 and 8 Gy; thus, this assay is applicable for a wide range of DNA damage levels. It is also shown that DNA damage from different radiation energies was not significantly different from (60)Co gamma-ray. This assay displayed a statistical increase in DNA damage due to uncontrolled exposure to natural light; however, the slope of the dose-response curve for light-exposed samples was similar to that for samples protected from light. A comparison of the alkaline comet assay with the acellular comet assay allowed for the intrinsic repair capacity of the alkaline comet assay to be quantified.

  15. "The 2009 Apparition of Methuselah Comet 107P/Wilson-Harrington: A Case of Comet Rejuvenation?"

    CERN Document Server

    Ferrín, I; Hamanowa, Hiroko; Hernández, J; Sira, E; Sánchez, A; Zhao, H; Miles, R

    2012-01-01

    (1) We find that comet 107P/WH was active in 1949, 1979, 1992, 2005, and 2009. (2) Its age can be measured. We find T-AGE=4700 comet years, WB-AGE=7800 cy. (3) This is a methuselah comet very near to its dormancy phase, being temporarily rejuvenated due to a diminution of its perihelion distance. (4) We measured the diameter as Deffe=3.67\\pm0.06 km, and the rotational period, Prot=6.093\\pm0.002 h. (5) We define the region of the graveyard of comets, and three comets belong to the graveyard: 107P/Wilson-Harrington, 133P/Elst-Pizarro and D/1891W1 Blanpain.

  16. Tails of a Recent Comet

    CERN Document Server

    Zysman, Milton

    2010-01-01

    Drain away the earth's oceans and a global pattern of great ridges appears. Adjacent to these continental and undersea mountain ranges are layers of silt and clay, so thick that they fill the gaps between ridges, creating extensive plateaus. Ranging across this planet's higher latitudes are thousands of tiny replicas of these ridge systems. These esker and drumlin swarms run up hills and across streams in roughly parallel discontinuous strands for hundreds of kilometers. Preserved by encapsulation in the ice and snow of our last ice age, eskers, drumlins and their related structures will be the focus of this paper. We contend that Greater and lesser ridge systems alike, including the water and sediments that fill them are cometary debris. Each ridge may be traced to a single stream, or 'jet' of disintegrating materials emanating from shifting areas on a comet's nucleus. A band of these jets, captured into planetary orbit, will land its debris in a unique manner. All debris will be laid down in a sheet perpend...

  17. Evidence for geologic processes on comets

    Science.gov (United States)

    Sunshine, Jessica M.; Thomas, Nicolas; El-Maarry, Mohamed Ramy; Farnham, Tony L.

    2016-11-01

    Spacecraft missions have resolved the nuclei of six periodic comets and revealed a set of geologically intriguing and active small bodies. The shapes of these cometary nuclei are dominantly bilobate reflecting their formation from smaller cometesimals. Cometary surfaces include a diverse set of morphologies formed from a variety of mechanisms. Sublimation of ices, driven by the variable insolation over the time since each nucleus was perturbed into the inner Solar System, is a major process on comets and is likely responsible for quasi-circular depressions and ubiquitous layering. Sublimation from near-vertical walls is also seen to lead to undercutting and mass wasting. Fracturing has only been resolved on one comet but likely exists on all comets. There is also evidence for mass redistribution, where material lifted off the nucleus by subliming gases is deposited onto other surfaces. It is surprising that such sedimentary processes are significant in the microgravity environment of comets. There are many enigmatic features on cometary surfaces including tall spires, kilometer-scale flows, and various forms of depressions and pits. Furthermore, even after accounting for the differences in resolution and coverage, significant diversity in landforms among cometary surfaces clearly exists. Yet why certain landforms occur on some comets and not on others remains poorly understood. The exploration and understanding of geologic processes on comets is only beginning. These fascinating bodies will continue to provide a unique laboratory for examining common geologic processes under the uncommon conditions of very high porosity, very low strength, small particle sizes, and near-zero gravity.

  18. Radar observations of meteor trails, and their interpretation using Fresnel holography: a new tool in meteor science

    Directory of Open Access Journals (Sweden)

    W. G. Elford

    2004-01-01

    Full Text Available A Fresnel transform technique has been developed at Adelaide to analyse radar meteor echoes detected in the transverse mode. The genesis for this technique was the study of the structure of the scattering ionization immediately behind the head of the trail, in order to deduce the degree of fragmentation of the ablating meteoroid. The technique has been remarkably successful in not only giving insight into the fragmentation of meteoroids, but also revealing other significant features of the trails including diffusion, lateral motion of the trail during formation due to wind drift, and phase of the scattered signal in the vicinity of the head of the trail. A serendipitous outcome of the analysis is the measurement of the speed and deceleration of the meteoroid producing the trail to a precision far exceeding that available from any other method applied to transverse scatter data. Examples of the outcomes of the technique applied to meteor echoes obtained with a 54MHz narrow beam radar are presented.

  19. Diurnal and annual variations of meteor rates at the Arctic circle

    Directory of Open Access Journals (Sweden)

    W. Singer

    2004-01-01

    Full Text Available Meteors are an important source for (a the metal atoms of the upper atmosphere metal layers and (b for condensation nuclei, the existence of which are a prerequisite for the formation of noctilucent cloud particles in the polar mesopause region. For a better understanding of these phenomena, it would be helpful to know accurately the annual and diurnal variations of meteor rates. So far, these rates have been little studied at polar latitudes. Therefore we have used the 33 MHz meteor radar of the ALOMAR observatory at 69° N to measure the meteor rates at this location for two full annual cycles. This site, being within 3° of the Arctic circle, offers in addition an interesting capability: The axis of its antenna field points (almost towards the North ecliptic pole once each day of the year. In this particular viewing direction, the radar monitors the meteoroid influx from (almost the entire ecliptic Northern hemisphere.

    We report on the observed diurnal variations (averaged over one month of meteor rates and their significant alterations throughout the year. The ratio of maximum over minimum meteor rates throughout one diurnal cycle is in January and February about 5, from April through December 2.3±0.3. If compared with similar measurements at mid-latitudes, our expectation, that the amplitude of the diurnal variation is to decrease towards the North pole, is not really borne out.

    Observations with the antenna axis pointing towards the North ecliptic pole showed that the rate of deposition of meteoric dust is substantially larger during the Arctic NLC season than the annual mean deposition rate. The daylight meteor showers of the Arietids, Zeta Perseids, and Beta Taurids supposedly contribute considerably to the June maximum of meteor rates. We note, though, that with the radar antenna pointing as described above, all three meteor radiants are close to the local horizon. This radiant location should cause most of these

  20. Mid-infrared spectra of comet nuclei

    Science.gov (United States)

    Kelley, Michael S. P.; Woodward, Charles E.; Gehrz, Robert D.; Reach, William T.; Harker, David E.

    2017-03-01

    Comet nuclei and D-type asteroids have several similarities at optical and near-IR wavelengths, including near-featureless red reflectance spectra, and low albedos. Mineral identifications based on these characteristics are fraught with degeneracies, although some general trends can be identified. In contrast, spectral emissivity features in the mid-infrared provide important compositional information that might not otherwise be achievable. Jovian Trojan D-type asteroids have emissivity features strikingly similar to comet comae, suggesting that they have the same compositions and that the surfaces of the Trojans are highly porous. However, a direct comparison between a comet and asteroid surface has not been possible due to the paucity of spectra of comet nuclei at mid-infrared wavelengths. We present 5-35 μm thermal emission spectra of comets 10P/Tempel 2, and 49P/Arend-Rigaux observed with the Infrared Spectrograph on the Spitzer Space Telescope. Our analysis reveals no evidence for a coma or tail at the time of observation, suggesting the spectra are dominated by the comet nucleus. We fit each spectrum with the near-Earth asteroid thermal model (NEATM) and find sizes in agreement with previous values. However, the NEATM beaming parameters of the nuclei, 0.74-0.83, are systematically lower than the Jupiter-family comet population mean of 1.03 ± 0.11, derived from 16- and 22-μm photometry. We suggest this may be either an artifact of the spectral reduction, or the consequence of an emissivity low near 16 μm. When the spectra are normalized by the NEATM model, a weak 10-μm silicate plateau is evident, with a shape similar to those seen in mid-infrared spectra of D-type asteroids. A silicate plateau is also evident in previously published Spitzer spectra of the nucleus of comet 9P/Tempel 1. We compare, in detail, these comet nucleus emission features to those seen in spectra of the Jovian Trojan D-types (624) Hektor, (911) Agamemnon, and (1172) Aneas, as well

  1. Color Systematics of Comets and Related Bodies

    Science.gov (United States)

    Jewitt, David

    2015-12-01

    Most comets are volatile-rich bodies that have recently entered the inner solar system following long-term storage in the Kuiper belt and the Oort cloud reservoirs. These reservoirs feed several distinct, short-lived "small body" populations. Here, we present new measurements of the optical colors of cometary and comet-related bodies including long-period (Oort cloud) comets, Damocloids (probable inactive nuclei of long-period comets) and Centaurs (recent escapees from the Kuiper belt and precursors to the Jupiter family comets). We combine the new measurements with published data on short-period comets, Jovian Trojans and Kuiper belt objects to examine the color systematics of the comet-related populations. We find that the mean optical colors of the dust in short-period and long-period comets are identical within the uncertainties of measurement, as are the colors of the dust and of the underlying nuclei. These populations show no evidence for scattering by optically small particles or for compositional gradients, even at the largest distances from the Sun, and no evidence for ultrared matter. Consistent with earlier work, ultrared surfaces are common in the Kuiper belt and on the Centaurs, but not in other small body populations, suggesting that this material is hidden or destroyed upon entry to the inner solar system. The onset of activity in the Centaurs and the disappearance of the ultrared matter in this population begin at about the same perihelion distance (˜10 AU), suggesting that the two are related. Blanketing of primordial surface materials by the fallback of sub-orbital ejecta, for which we calculate a very short timescale, is the likely mechanism. The same process should operate on any mass-losing body, explaining the absence of ultrared surface material in the entire comet population. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the

  2. Abundant Solar Nebula Solids in Comets

    Science.gov (United States)

    Messenger, S.; Keller, L. P.; Nakamura-Messenger, K.; Nguyen, A. N.; Clemett, S.

    2016-01-01

    Comets have been proposed to consist of unprocessed interstellar materials together with a variable amount of thermally annealed interstellar grains. Recent studies of cometary solids in the laboratory have shown that comets instead consist of a wide range of materials from across the protoplanetary disk, in addition to a minor complement of interstellar materials. These advances were made possible by the return of direct samples of comet 81P/Wild 2 coma dust by the NASA Stardust mission and recent advances in microscale analytical techniques. Isotopic studies of 'cometary' chondritic porous interplanetary dust particles (CP-IDPs) and comet 81P/Wild 2 Stardust samples show that preserved interstellar materials are more abundant in comets than in any class of meteorite. Identified interstellar materials include sub-micron-sized presolar silicates, oxides, and SiC dust grains and some fraction of the organic material that binds the samples together. Presolar grain abundances reach 1 weight percentage in the most stardust-rich CP-IDPs, 50 times greater than in meteorites. Yet, order of magnitude variations in presolar grain abundances among CP-IDPs suggest cometary solids experienced significant variations in the degree of processing in the solar nebula. Comets contain a surprisingly high abundance of nebular solids formed or altered at high temperatures. Comet 81P/Wild 2 samples include 10-40 micron-sized, refractory Ca- Al-rich inclusion (CAI)-, chondrule-, and ameboid olivine aggregate (AOA)-like materials. The O isotopic compositions of these refractory materials are remarkably similar to their meteoritic counterparts, ranging from 5 percent enrichments in (sup 16) O to near-terrestrial values. Comet 81P/Wild 2 and CP-IDPs also contain abundant Mg-Fe crystalline and amorphous silicates whose O isotopic compositions are also consistent with Solar System origins. Unlike meteorites, that are dominated by locally-produced materials, comets appear to be composed of

  3. Satellite Meteorology Education & Training Resources from COMET

    Science.gov (United States)

    Abshire, W. E.; Dills, P. N.; Weingroff, M.; Lee, T. F.

    2012-12-01

    The COMET® Program (www.comet.ucar.edu) receives funding from NOAA NESDIS as well as EUMETSAT and the Meteorological Service of Canada to support education and training in satellite meteorology. These partnerships enable COMET to create educational materials of global interest on geostationary and polar-orbiting remote sensing platforms. These materials focus on the capabilities and applications of current and next-generation satellites and their relevance to operational forecasters and other user communities. By partnering with experts from the Naval Research Laboratory, NOAA-NESDIS and its Cooperative Institutes, Meteorological Service of Canada, EUMETSAT, and other user communities, COMET stimulates greater use of satellite data observations and products. This presentation provides an overview of COMET's recent satellite education efforts in the area of polar orbiting satellites. COMET has a new module on Suomi NPP, which describes the satellite system and discusses the improvements that it is bringing to forecasting, numerical weather prediction, and environmental monitoring. COMET has also published an updated version of its module on the VIIRS instrument. "Imaging with VIIRS: A Convergence of Technologies and Experience, 2nd Edition" covers the instrument's enhanced capabilities by examining the systems that contributed to its development. Special attention is paid to the Day/Night Visible channel as VIIRS is the first instrument on a civilian satellite to image atmospheric and terrestrial features with and without moonlight. An upcoming module will exclusively focus on nighttime imaging with the VIIRS Day/Night Band (DNB). "Applications of the VIIRS Day-Night Band" will introduce the capabilities of DNB imagery to a wide audience ranging from forecasters and emergency managers to wildfire fighters and oceanographers. DNB products will be compared to traditional satellite products made from infrared data, including the "fog" product. Users will learn how DNB

  4. Comet assay on mice testicular cells

    Directory of Open Access Journals (Sweden)

    Anoop Kumar Sharma

    2015-05-01

    Full Text Available Heritable mutations may result in a variety of adverse outcomes including genetic disease in the offspring. In recent years the focus on germ cell mutagenicity has increased and the “Globally Harmonized System of Classification and Labelling of Chemicals (GHS” has published classification criteria for germ cell mutagens (Speit et al., 2009. The in vivo Comet assay is considered a useful tool for investigating germ cell genotoxicity. In the present study DNA strand breaks in testicular cells of mice were investigated. Different classes of chemicals were tested in order to evaluate the sensitivity of the comet assay in testicular cells. The chemicals included environmentally relevant substances such as Bisphenol A, PFOS and Tetrabrombisphenol A. Statistical power calculations will be presented to aid in the design of future Comet assay studies on testicular cells. Power curves were provided with different fold changes in % tail DNA, different number of cells scored and different number of gels (Hansen et al., 2014. An example is shown in Figure 1. A high throughput version of the Comet assay was used. Samples were scored with a fully automatic comet assay scoring system that provided faster scoring of randomly selected cells.

  5. Study of some comets through imaging polarimetry

    Science.gov (United States)

    Roy Choudhury, S.; Hadamcik, E.; Sen, A. K.

    2015-12-01

    Comets C/2007 N3 (Lulin), C/2011 L4 (PANSTARRS) and 290P/Jager were observed at phase angles <40○; between 2009 and 2014; with the 0.8 m Telescope at Haute-Provence Observatory (OHP) in France. The observations were polarimetric and mainly carried out in the red and near infra-red wavelength domains to reduce gaseous contaminations. The overall shape of the coma of comet Lulin is about circular without evident jet structure. The coma of comet C/2011 L4 is enlarged in the antisolar direction. Jets in a fan-like structure have been noticed between position angles 135°-245° in the treated intensity images. A correlated higher polarization region is noted on the corresponding polarization map. The shape of the coma of 290P/Jager is slightly elongated in the antisolar direction. Deeper negative polarization is found in the inner coma. The whole coma polarization values of these three comets correspond to the synthetic phase curve for comets at similar phase angles and wavelength.

  6. Galactic tide and orbital evolution of comets

    CERN Document Server

    Komar, L; Pastor, P

    2009-01-01

    Equation of motion for a comet in the Oort cloud is numerically solved. Orbital evolution of the comet under the action of the gravity of the Sun and the Galaxy is presented for various initial conditions. Oscillations of the Sun with respect to the galactic equatorial plane are taken into account. Real values of physical quantities concerning the gravitational action of the galactic neighbourhood of the Sun are important. The results are compared with currently used more simple models of the galactic tide. It turns out that physically improved models yield results which significantly differ from the results obtained on the basis of the conventional models. E.g., the number of returns of the comets into the inner part of the Solar System are about two times greater than it is in the conventional models. It seems that a comet from the Oort cloud can be a source of the dinosaurs extinction at about 65 Myr ago. A close encounter of a star or an interstellar cloud disturbed a comet of the Oort cloud in the way th...

  7. The micrometeoric input in the upper atmosphere. A comparison between model predictions and HPLA and meteor radars observations and AIM-CDE dust detections

    Science.gov (United States)

    Janches, Diego; Sparks, Jonathan; Johnson, Kyle; Poppe, Andrew; James, David; Fentzke, Jonathan; Palo, Scott; Horanyi, Mihaly

    It is now widely accepted that microgram extraterrestrial particles from the sporadic background are the major contributors of metals in the Mesosphere/Lower Thermosphere (MLT). It is also well established that this material gives rise to the upper atmospheric metallic and ion layers observed by radars and lidars. In addition, micrometeoroids are believed to be an important source for condensation nuclei (CN), the existence of which is a prerequisite for the formation of NLC and PMSE particles in the polar mesopause region. In order to understand how this flux gives rise to these atmospheric phenomena, accurate knowledge of the global meteoric input function (MIF) is critical. This function accounts for the annual and diurnal variations of meteor rates, global distribution, directionality, and velocity and mass distributions. Estimates of most of these parameters are still under investigation. In this talk, we present results of a detailed model of the diurnal, seasonal and geographical variability of the micrometeoric activity in the upper atmosphere. The principal goal of this effort is to construct a new and more precise sporadic MIF needed for the subsequent modeling of the atmospheric chemistry of meteoric material and the origin and formation of metal layers in the MLT. The model uses Monte Carlo simulation techniques and includes an accepted mass flux provided by six main known meteor sources (i.e. orbital families of dust) and a detailed modeling of the meteoroid atmospheric entry physics. We compare the model predictions with meteor head-echo observations using the 430 MHz Arecibo (AO) radar in Puerto Rico and the 450 MHz Advance Modular ISR in Poker Flat (PFISR), AK. The results indicate, that although the Earth's Apex centered source, thought to be composed mostly of dust from long period comets, is required to be only about ˜33% of dust in the Solar System at 1 AU, it accounts for 60 to 70% of the actual dust that ablates in the atmosphere. These

  8. Physical characteristics of faint meteors by light curve and high-resolution observations, and the implications for parent bodies

    Science.gov (United States)

    Subasinghe, Dilini; Campbell-Brown, Margaret D.; Stokan, Edward

    2016-04-01

    Optical observations of faint meteors (10-7 single body objects) show mostly symmetric light curves, surprisingly, and this indicates that light-curve shape is not an indication of fragility or fragmentation behaviour. Approximately 90 per cent of meteors observed with high-resolution video cameras show some form of fragmentation. Our results also show, unexpectedly, that meteors which show negligible fragmentation are more often on high-inclination orbits (i > 60°) than low-inclination ones. We also find that dynamically asteroidal meteors fragment as often as dynamically cometary meteors, which may suggest mixing in the early Solar system, or contamination between the dynamic groups.

  9. Meteor Crater: Energy of formation - Implications of centrifuge scaling

    Science.gov (United States)

    Schmidt, R. M.

    1980-01-01

    Recent work on explosive cratering has demonstrated the utility of performing subscale experiments on a geotechnic centrifuge to develop scaling rules for very large energy events. The present investigation is concerned with an extension of this technique to impact cratering. Experiments have been performed using a projectile gun mounted directly on the centrifuge rotor to launch projectiles into a suitable soil container undergoing centripetal accelerations in excess of 500 G. The pump tube of a two-stage light-gas gun was used to attain impact velocities of approximately 2 km/sec. The results of the experiments indicate that the energy of formation of any large impact crater depends upon the impact velocity. This dependence, shown for the case of Meteor Crater, is consistent with analogous results for the specific energy dependence of explosives and is expected to persist to impact velocities in excess of 25 km/sec.

  10. Odin-OSIRIS detection of the Chelyabinsk meteor

    Directory of Open Access Journals (Sweden)

    L. A. Rieger

    2013-09-01

    Full Text Available On 15 February 2013 an 11 000 ton meteor entered Earth's atmosphere south east of Chelyabinsk creating a large fireball at 23 km altitude. The resulting stratospheric aerosol loading was detected by the Ozone Mapping and Profiler Suite (OMPS in a high altitude polar belt. This work confirms the presence and lifetime of the stratospheric debris using the Optical Spectrograph and InfraRed Imaging System (OSIRIS onboard the Odin satellite. Although OSIRIS coverage begins in mid-March, the measurements show a belt of enhanced scattering near 35 km altitude between 50° N and 70° N. Initially, enhancements show increased scattering of up to 15% over the background conditions, decaying in intensity and dropping in altitude until they are indistinguishable from background conditions by mid-May.

  11. Meteor burst communications. I - MBC advances assist C3 objectives

    Science.gov (United States)

    Richmond, R. L.

    1982-08-01

    Recent advances in Meteor Burst Communications (MBC) systems are assessed from the viewpoint of the trans- and post-attack phases of nuclear warfare. The burst mode nature of the MBC channel dictates the consideration of system parameters unique to digital burst mode communications. New methods have been developed in the areas of burst synchronization and on-line encryption, in an effort to increase MBC performance. MBC offers a simple, reliable and cost-effective means of communication at a time when conventional systems have become inoperative, as well as a medium for such delayed communications tasks as full duplex, half duplex, and simplex conveyance of administrative data, electronic mail, and automatic facsimile transmission. Distances may range from a few hundred to 1200 miles, and may be further extended by recourse to relaying.

  12. Simultaneous optical and radar observations of meteor head-echoes utilizing SAAMER

    Science.gov (United States)

    Michell, R. G.; Janches, D.; Samara, M.; Hormaechea, J. L.; Brunini, C.; Bibbo, I.

    2015-12-01

    We present simultaneous optical and radar observations of meteors observed with the Southern Argentine Agile MEteor Radar (SAAMER). Although such observations were performed in the past using High Power and Large Aperture radars, the focus here is on meteors that produced head echoes that can be detected by a significantly less sensitive but more accessible radar system. An observational campaign was conducted in August of 2011, where an optical imager was operated near the radar site in Rio Grande, Tierra del Fuego, Argentina. Six head echo events out of 150 total detections were identified where simultaneous optical meteors could also be clearly seen within the main radar beam. The location of the meteors derived from the radar interferometry agreed very well with the optical location, verifying the accuracy of the radar interferometry technique. The meteor speeds and origin directions calculated from the radar data were accurate-compared with the optics-for the 2 meteors that had radar signal-to-noise ratios above 2.5. The optical meteors that produced the head echoes had horizontal velocities in the range of 29-91 km/s. These comparisons with optical observations improve the accuracy of the radar detection and analysis techniques, such that, when applied over longer periods of time, will improve the statistics of southern hemisphere meteor observations. Mass estimates were derived using both the optical and radar data and the resulting masses agreed well with each other. All were within an order of magnitude and in most cases, the agreement was within a factor of two.

  13. Search for Cyclopropenylidene in Comet Lulin

    Science.gov (United States)

    Kuan, Yi-Jehng; Chuang, Yo-Ling; Charnley, Steven

    The Oort-Cloud comet C/2007 N3 (Lulin) was observed in the 1.3-mm band with the Sub-millimeter Telescope of Arizona Radio Observatory between 2009 February and March during the apparition. Many of the molecules observed in cometary comae could be pristine remnants of the interstellar material that collapsed to form the protosolar nebula. The coma species observed may either be distinct interstellar molecules sublimated from the nuclear ices, or frag-ments of larger organic macromolecules which decomposed farther out in the coma. With a water production rate of 1E+29 mol s-1 near its perihelion, the bright Comet Lulin was only 0.4 AU from Earth at perigee; we therefore searched for c-C3H2, a simple ring molecule. Cy-clopropenylidene is ubiquitous in interstellar space but unknown in comets. Here, we report the first detection of cyclopropenylidene in the cometary coma of Lulin.

  14. A unidimensional model of comet ionosphere structure

    Science.gov (United States)

    Eviatar, Aharon; Goldstein, Bruce E.

    1988-01-01

    The one-dimensional continuity and momentum equations for the plasma formed in the expanding coma of a comet near the sun are studied. An analytic expression for the magnetic field configuration in the presence of outflow, photoionization, dissociative recombination, plasma fluid pressure, and friction between the ions and neutrals is obtained. It is suggested that for a Halley-type comet there will be a region sunward of the nucleus from which the magnetic field is excluded, consistent with Giotto observations. Calculations have been performed for Halley and Giacobini-Zinner type comets, and in the field-free regions it is shown that the dominant terms in the momentum equation balancing the magnetic pressure gradient are the ion neutral friction and the net mass loading momentum gain.

  15. Optical polarimetry of Comet West 1976 VI

    Energy Technology Data Exchange (ETDEWEB)

    Michalsky, J.J.

    1981-09-01

    Four narrowband filters covering the 440-850 nm wavelengths were used to measure the polarization of the continuum of Comet West 1976 VI. Postperihelion observations indicated wavelength-independent linear polarization in all of the three measurements made, in agreement with other polarization measurements of the comet from the visible to the near-infrared but in contrast with the general tendency in comets toward polarization increase with wavelength. No circular polarization was detected, and it is suggested by (1) the magnitude of polarization as a function of scattering angle, (2) wavelength independence, and (3) infrared and optical photometric properties, that dirty silicates with radii approaching 5 microns may be responsible for the phenomena observed.

  16. To Catch A Comet...Learning From Halley's.

    Science.gov (United States)

    National Aeronautics and Space Administration, Washington, DC.

    Comet chronicles and stories extend back over thousands of years. A common theme has been that comets are a major cause of catastrophe and tragedy here on earth. In addition, both Aristotle and Ptolemy believed that comets were phenomena within the earth's atmosphere, and it wasn't until the 16th century, when Danish astronomer Tycho Brache…

  17. A (revised) confidence index for the forecasting of the meteor showers

    Science.gov (United States)

    Vaubaillon, Jeremie

    2016-10-01

    The prediction of meteor shower is known to provide several quality results depending on how it is performed. As a consequence it is hard to have an idea of how much one can trust a given prediction. In this paper I will present a revised confidence index, aiming to provide users with information regarding the way the prediction was performed. An effort to quantify the influence of close encounters with the parent body of a meteor shower is part of this confidence index. In fine, a single code will be provided for each prediction of meteor showers at any planet with a focus on Earth, Mars and Venus.

  18. POSITION OBSERVATIONS OF THE COMET HYAKUTAKE

    Institute of Scientific and Technical Information of China (English)

    Wu Guangjie; Ji Kaifan

    2000-01-01

    On March 16 of 1996, we used a new developed 1024×1024 CCD camera attached to the 1 meter telescope at Yunnan Observatory, to take photometric observations for the Comet Hyakutake. The positions have been measured accurately. Our result clearly states that even a new ephemeris of this comet just given by EMPC on February 29 of 1996 still has obvious systematical deviation with our observations.From images observed, we can clearly see that the cometary coma is very large and basically symmetric with a peach shape. It means that there is material flowing along the cometary tail which opposited the solar direction.

  19. Comets: mechanisms of x-ray activity

    Science.gov (United States)

    Ibadov, Subhon

    2016-07-01

    Basic mechanisms of X-ray activity of comets are considered, including D-D mechanism corresponding to generation of X-rays due to production of hot short-living plasma clumps at high-velocity collisions between cometary and interplanetary dust particles as well as M-M one corresponding to production of X-rays due to recombination of multicharge ions of solar wind plasma via charge exchange process at their collisions with molecules/atoms of the cometary atmospheres. Peculiarities of the variation of the comet X-ray spectrum and X-ray luminosity with variation of its heliocentric distance are revealed.

  20. Meteoric 10Be as a tool to investigate human induced soil fluxes: a conceptual model

    Science.gov (United States)

    Campforts, Benjamin; Govers, Gerard; Vanacker, Veerle; De Vente, Joris; Boix-Fayos, Carolina; Minella, Jean; Baken, Stijn; Smolders, Erik

    2014-05-01

    The use of meteoric 10Be as a tool to understand long term landscape behavior is becoming increasingly popular. Due its high residence time, meteoric 10Be allows in principle to investigate in situ erosion rates over time scales exceeding the period studied with classical approaches such as 137Cs. The use of meteoric 10Be strongly contributes to the traditional interpretation of sedimentary archives which cannot be unequivocally coupled to sediment production and could provide biased information over longer time scales (Sadler, 1981). So far, meteoric 10Be has successfully been used in geochemical fingerprinting of sediments, to date soil profiles, to assess soil residence times and to quantify downslope soil fluxes using accumulated 10Be inventories along a hill slope. However, less attention is given to the potential use of the tracer to directly asses human induced changes in soil fluxes through deforestation, cultivation and reforestation. A good understanding of the processes governing the distribution of meteoric 10Be both within the soil profile and at landscape scale is essential before meteoric 10Be can be successfully applied to assess human impact. We developed a spatially explicit 2D-model (Be2D) in order to gain insight in meteoric 10Be movement along a hillslope that is subject to human disturbance. Be2D integrates both horizontal soil fluxes and vertical meteoric 10Be movement throughout the soil prolife. Horizontal soil fluxes are predicted using (i) well studied geomorphical laws for natural erosion and soil formation as well as (ii) human accelerated water and tillage erosion. Vertical movement of meteoric 10Be throughout the soil profile is implemented by inserting depth dependent retardation calculated using experimentally determined partition coefficients (Kd). The model was applied to different environments such as (i) the Belgian loess belt, characterized by aeolian deposits enriched in inherited meteoric 10Be, (ii) highly degraded and stony

  1. Orbits of Comets C/1845 L1 (Great June Comet) and C/1846 D1 (de Vico)

    Science.gov (United States)

    Branham, R. L., Jr.

    2009-04-01

    Orbits are calculated for Comet C/1845 L1 (the Great June Comet) and C/1846 D1 (de Vico), the former based on 157 observations in right ascension and 152 in declination and the latter on 10 and 9, respectively. Both orbits are hyperbolic and statistically distinguishable from parabolas. Statistical tests indicate that the residuals are random and thus the orbits satisfactory. The Great June Comet is in no way associated with the comet Tycho Brahe observed in 1596.

  2. Comets and the origin and evolution of life

    CERN Document Server

    McKay, Christopher P

    2006-01-01

    Nine years after the publication of Comets and the Origin and Evolution of Life, one of the pioneering books in Astrobiology, this second edition revisits the role comets may have played in the origins and evolution of life. Recent analyses of Antarctic micrometeorites and ancient rocks in Australia and South Africa, the continuing progress in discovering complex organic macromolecules in comets, protostars and interstellar clouds, new insights into organic synthesis in comets, and numerical simulations of comet impacts on the Earth and other members of the solar system yield a spectacular wea

  3. New meteor showers identified in the CAMS and SonotaCo meteoroid orbit surveys

    CERN Document Server

    Rudawska, Regina

    2014-01-01

    A cluster analysis was applied to the combined meteoroid orbit database derived from low-light level video observations by the SonotaCo consortium in Japan (64,650 meteors observed between 2007 and 2009) and by the Cameras for All-sky Meteor Surveillance (CAMS) project in California, during its first year of operation (40,744 meteors from Oct. 21, 2010 to Dec. 31, 2011). The objective was to identify known and potentially new meteoroid streams and identify their parent bodies. The database was examined by a single-linking algorithm using the Southworth and Hawkins D-criterion to identify similar orbits, with a low criterion threshold of D < 0.05. A minimum member threshold of 6 produced a total of 88 meteoroid streams. 43 are established streams and 45 are newly identified streams. The newly identified streams were included as numbers 448-502 in the IAU Meteor Shower Working List. Potential parent bodies are proposed.

  4. Interferometric radar observation of fast moving meteor trails in strong electric field

    Science.gov (United States)

    Lee, Y.; Kirkwood, S.; Kwak, Y. S.

    2014-12-01

    Usually, at mid-latitudes, field-aligned irregularities cause non-specular trails while in the polar region long-lasting irregularities are possibly sustained by charged meteor dust. Unusual, non-specular, fast-moving meteor trail echoes are observed in the summer polar mesosphere at Kiruna, Sweden. The unusual meteor trails propagate downward and upward at speeds of a few kilometers per second along a slanted path between 87-93 km altitudes, merging in the middle and lasting for several seconds. Here we propose that an electrical discharge is responsible for these trails. The corresponding horizontal electric field for the observed speeds is estimated up to tens of volts per meter at 90 km. Both the long-lasting merging of two fast-moving plasma trails likely suggest a new type of meteor-trail leader discharge occurring in the summer polar upper mesosphere.

  5. Neutral density variation from specular meteor echo observations spanning one solar cycle

    Science.gov (United States)

    Stober, G.; Matthias, V.; Brown, P.; Chau, J. L.

    2014-10-01

    Specular meteor radars have provided essential information about the mesospheric/lower thermosphere (MLT) dynamics. The Canadian Meteor Orbit Radar has been conducting continuous meteor echo observations in a fixed, stable configuration since 2002. Here we present estimates of the neutral air density variations derived from observations of the meteor peak flux altitude. Using a simple model assuming a linear trend and a sinusoidal solar cycle we derived a trend of a decreasing neutral density of 5.8 ± 1.1% per decade at approximately 91 km altitude and an amplitude across the most recent solar cycle, the solar cycle of 2.4 ± 0.7% for solar cycle 23/24. The long-term trend of decreasing neutral air density in the MLT is in good agreement with the model results from Akmaev et al. (2006).

  6. Debiasing the NEOWISE Cryogenic Mission Comet Populations

    Science.gov (United States)

    Bauer, James M.; Grav, Tommy; Fernández, Yanga R.; Mainzer, A. K.; Kramer, Emily A.; Masiero, Joseph R.; Spahr, Timothy; Nugent, C. R.; Stevenson, Rachel A.; Meech, Karen J.; Cutri, Roc M.; Lisse, Carey M.; Walker, Russell; Dailey, John W.; Rosser, Joshua; Krings, Phillip; Ruecker, Kinjal; Wright, Edward L.; the NEOWISE Team

    2017-08-01

    We use NEOWISE data from the four-band and three-band cryogenic phases of the Wide-field Infrared Survey Explorer mission to constrain size distributions of the comet populations and debias measurements of the short- and long-period comet (LPC) populations. We find that the fit to the debiased LPC population yields a cumulative size-frequency distribution (SFD) power-law slope (β) of -1.0 ± 0.1, while the debiased Jupiter-family comet (JFC) SFD has a steeper slope with β = -2.3 ± 0.2. The JFCs in our debiased sample yielded a mean nucleus size of 1.3 km in diameter, while the LPCs’ mean size is roughly twice as large, 2.1 km, yielding mean size ratios ( / ) that differ by a factor of 1.6. Over the course of the 8 months of the survey, our results indicate that the number of LPCs passing within 1.5 au are a factor of several higher than previous estimates, while JFCs are within the previous range of estimates of a few thousand down to sizes near 1.3 km in diameter. Finally, we also observe evidence for structure in the orbital distribution of LPCs, with an overdensity of comets clustered near 110° inclination and perihelion near 2.9 au that is not attributable to observational bias.

  7. Summer fireworks on comet 67P

    CERN Document Server

    Vincent, J -B; Lin, Z -Y; El-Maarry, M R; Pajola, M; Sierks, H; Barbieri, C; Lamy, P L; Rodrigo, R; Koschny, D; Rickman, H; Keller, H U; Agarwal, J; Barucci, M A; Bertaux, J -L; Bertini, I; Besse, S; Bodewits, D; Cremonese, G; Da Deppo, V; Davidsson, B; Debei, S; De Cecco, M; Deller, J; Fornasier, S; Fulle, M; Gicquel, A; Groussin, O; Gutierrez, P J; Gutierrez-Marquez, P; Guettler, C; Hoefner, S; Hofmann, M; Hviid, S F; Ip, W -H; Jorda, L; Knollenberg, J; Kovacs, G; Kramm, J -R; Kuehrt, E; Kueppers, M; Lara, L M; Lazzarin, M; Moreno, J J Lopez; Marzari, F; Massironi, M; Mottola, S; Naletto, G; Oklay, N; Preusker, F; Scholten, F; Shi, X; Thomas, N; Toth, I; Tubiana, C

    2016-01-01

    During its two years mission around comet 67P/Churyumov-Gerasimenko, ESA's Rosetta spacecraft had the unique opportunity to follow closely a comet in the most active part of its orbit. Many studies have presented the typical features associated to the activity of the nucleus, such as localized dust and gas jets. Here we report on series of more energetic transient events observed during the three months surrounding the comet's perihelion passage in August 2015. We detected and characterized 34 outbursts with the Rosetta cameras, one every 2.4 nucleus rotation. We identified 3 main dust plume morphologies associated to these events: a narrow jet, a broad fan, and more complex plumes featuring both previous types together. These plumes are comparable in scale and temporal variation to what has been observed on other comets. We present a map of the outbursts source locations, and discuss the associated topography. We find that the spatial distribution sources on the nucleus correlates well with morphological reg...

  8. An infrared search for HDO in comets

    Science.gov (United States)

    Gibb, E. L.; Mumma, M. J.; Disanti, M. A.; dello Russo, N.; Magee-Sauer, K.

    2002-11-01

    We searched for HDO emission in our infrared database of six Oort Cloud comets (C/2002 C1 (Ikeya-Zhang), C/2001 A2 (LINEAR), C/2000 WM1 (LINEAR), C/1999 H1 (Lee), C/1999 S4 (LINEAR), and C/1999 T1 (McNaught-Hartley)). Spectral lines of the ν1 fundamental vibrational band of HDO were sampled using high resolution infrared spectra acquired with both CSHELL at NASA's IRTF and NIRSPEC at the W.M. Keck Observatory. Of these comets, the recent apparition of the bright Comet Ikeya-Zhang, with its high gas production rate and good geocentric Doppler shift, provided an exceptional opportunity to search for minor constituents such as HDO. We report tentative detections of HDO in three Oort Cloud comets with upper limits determined for the remaining three. These data, combined with future observations, will be used to test models of nebular chemistry and delivery of water and organics to the early Earth.

  9. Comet assay on mice testicular cells

    DEFF Research Database (Denmark)

    Sharma, Anoop Kumar

    2015-01-01

    for germ cell mutagens (Speit et al., 2009). The in vivo Comet assay is considered a useful tool for investigating germ cell genotoxicity. In the present study DNA strand breaks in testicular cells of mice were investigated. Different classes of chemicals were tested in order to evaluate the sensitivity...

  10. Does Comet WILD-2 contain Gems?

    Science.gov (United States)

    Chi, M.; Ishii, H.; Dai, Z. R.; Toppani, A.; Joswiak, D. J.; Leroux, H.; Zolensky, M.; Keller, L. P.; Browning, N. D.

    2007-01-01

    It is expected that Comet Wild-2 dust should resemble anhydrous carbon-rich, chondritic porous (CP) interplanetary dust particles (IDPs) collected in the stratosphere because some CP IDPs are suspected to be from comets. The rarity of carbonaceous grains and presolar silicates, as well as the presence of high-temperature inner solar nebula minerals in the Wild-2 sample (e.g. osbornite and melilite), appear incompatible with most CP IDPs. However, it is premature to draw firm conclusions about the mineralogy of comet Wild-2 because only approx. 1% of the sample has been examined. The most abundant silicates in CP IDPs are GEMS (glass with embedded metal and sulfides). Nonsolar O isotopic compositions confirm that at least some GEMS in IDPs are presolar amorphous silicates. The presence or absence of GEMS in the Wild-2 sample is important because it addresses, (a) the relationship between CP IDPs and comets, and (b) the hypothesis that other GEMS in IDPs formed in the solar nebula. Here we show that most of the GEMSlike materials so far identified in Stardust aerogel were likely impact generated during collection. At the nanometer scale, they are compositionally and crystallographically distinct from GEMS in IDPs.

  11. NASA returns rocks from a comet.

    Science.gov (United States)

    Burnett, Don S

    2006-12-15

    Cometary particles returned by the Stardust Discovery Mission are primarily silicate materials of solar system origin. Some of the grains were formed at high temperatures close to the Sun, but then transported far out to the Kuiper belt region of the solar system before being incorporated in the comet.

  12. Spectral analysis of the Chandra comet survey

    NARCIS (Netherlands)

    Bodewits, D.; Christian, D. J.; Torney, M.; Dryer, M.; Lisse, C. M.; Dennerl, K.; Zurbuchen, T. H.; Wolk, S. J.; Tielens, A. G. G. M.; Hoekstra, R.

    2007-01-01

    Aims. We present results of the analysis of cometary X-ray spectra with an extended version of our charge exchange emission model (Bodewits et al. 2006). We have applied this model to the sample of 8 comets thus far observed with the Chandra X-ray observatory and acis spectrometer in the 300 - 1000

  13. Assessing soil fluxes using meteoric 10Be: development and application of the Be2D model

    Science.gov (United States)

    Campforts, Benjamin; Govers, Gerard; Vanacker, Veerle; Baken, Stijn; Smolders, Erik; Vanderborght, Jan

    2015-04-01

    Meteoric 10Be is a promising and increasingly popular tool to better understand soil fluxes at different timescales. Unlike other, more classical, methods such as the study of sedimentary archives it enables a direct coupling between eroding and deposition sites. However, meteoric 10Be can be mobilized within the soil. Therefore, spatial variations in meteoric 10Be inventories cannot directly be translated into spatial variations in erosion and sedimentation rates: a correct interpretation of measured 10Be inventories requires that both lateral and vertical movement of meteoric 10Be are accounted for. Here, we present a spatially explicit 2D model that allows to simulate the behaviour of meteoric 10Be in the soil system over timescales of up to 1 million year and use the model to investigate the impact of accelerated erosion on meteoric 10Be inventories. The model consists of two parts. A first component deals with advective and diffusive mobility within the soil profile, whereas a second component describes lateral soil (and meteoric 10Be) fluxes over the hillslope. Soil depth is calculated dynamically, accounting for soil production through weathering and lateral soil fluxes. Different types of erosion such as creep, water and tillage erosion are supported. Model runs show that natural soil fluxes can be well reconstructed based on meteoric 10Be inventories, and this for a wide range of geomorphological and pedological conditions. However, extracting signals of human impact and distinguishing them from natural soil fluxes is only feasible when the soil has a rather high retention capacity so that meteoric 10Be is retained in the top soil layer. Application of the Be2D model to an existing data set in the Appalachian Mountains [West et al.,2013] using realistic parameter values for the soil retention capacity as well as for vertical advection resulted in a good agreement between simulated and observed 10Be inventories. This confirms the robustness of the model. We

  14. On the influence of neutral turbulence on ambipolar diffusivities deduced from meteor trail expansion

    Directory of Open Access Journals (Sweden)

    C. M. Hall

    Full Text Available By measuring fading times of radar echoes from underdense meteor trails, it is possible to deduce the ambipolar diffusivities of the ions responsible for these radar echoes. It could be anticipated that these diffusivities increase monotonically with height akin to neutral viscosity. In practice, this is not always the case. Here, we investigate the capability of neutral turbulence to affect the meteor trail diffusion rate.

    Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; turbulence

  15. Data Reduction and Control Software for Meteor Observing Stations Based on CCD Video Systems

    Science.gov (United States)

    Madiedo, J. M.; Trigo-Rodriguez, J. M.; Lyytinen, E.

    2011-01-01

    The SPanish Meteor Network (SPMN) is performing a continuous monitoring of meteor activity over Spain and neighbouring countries. The huge amount of data obtained by the 25 video observing stations that this network is currently operating made it necessary to develop new software packages to accomplish some tasks, such as data reduction and remote operation of autonomous systems based on high-sensitivity CCD video devices. The main characteristics of this software are described here.

  16. Identifying Meteor Streams Containing 10-m Bolides in Near-Earth Space and Determining their Temporal Evolution

    Science.gov (United States)

    Lai, H.; Russell, C. T.; Wei, H.; Delzanno, G.; Connors, M. G.

    2013-12-01

    The collision rate of small bodies orbiting the Sun increases with decreasing size. While small bodies in the 10-m class are difficult to detect from Earth, they are relatively easily detected by interplanetary spacecraft with magnetometers. A 10m body need be struck by a body only 20 cm across (traveling at 20 km/s) to be completely disrupted. The solar wind will sweep up the charged nano-scale dust as it flows through the debris forming a magnetic cloud. Because of the large size of the magnetic cloud only a small drop in the solar wind speed is needed to provide the momentum flux required to accelerate the cloud radially from the Sun. The cloud is carried outward and can be detected by any one of several interplanetary spacecraft. This procedure was first utilized on debris co-orbiting with the comet 2201 Oljato as monitored beginning in 1978 by the Pioneer Venus Orbiter and followed up by Venus Express that is still in operation. The meteoroid trail dissipated in just 30 years. We have used ACE, Wind and STEREO to identify a meteor stream co-orbiting with asteroid 138175 whose descending node is aligned with the Sun and the Earth on about April 17 each year. We have followed this trail from 1998 to the present and find that material extends to over 30° in front of the asteroid. It has been a steady producer of collisions over the last 15 years. The period of very close approach of this material to Earth may be over for a while but the material should be accessible by robotic or crewed missions as the orbit of 139175 has only a modest eccentricity and inclination to the ecliptic plane. Matching orbits with it should be similar in difficulty to a Venus flyby mission.

  17. The mass disruption of Jupiter Family comets

    Science.gov (United States)

    Belton, Michael J. S.

    2015-01-01

    I show that the size-distribution of small scattered-disk trans-neptunian objects when derived from the observed size-distribution of Jupiter Family comets (JFCs) and other observational constraints implies that a large percentage (94-97%) of newly arrived active comets within a range of 0.2-15.4 km effective radius must physically disrupt, i.e., macroscopically disintegrate, within their median dynamical lifetime. Additional observational constraints include the numbers of dormant and active nuclei in the near-Earth object (NEO) population and the slope of their size distributions. I show that the cumulative power-law slope (-2.86 to -3.15) of the scattered-disk TNO hot population between 0.2 and 15.4 km effective radius is only weakly dependent on the size-dependence of the otherwise unknown disruption mechanism. Evidently, as JFC nuclei from the scattered disk evolve into the inner Solar System only a fraction achieve dormancy while the vast majority of small nuclei (e.g., primarily those with effective radius Morbidelli, A., Dones, L., Jedicke, R., Wiegert, P.A., Bottke Jr., W.F. [2002]. Science 296, 2212-2215) suggesting that all types of comet nuclei may have similar structural characteristics even though they may have different source regions and thermal histories. The typical disruption rate for a 1 km radius active nucleus is ∼5 × 10-5 disruptions/year and the dormancy rate is typically 3 times less. We also estimate that average fragmentation rates range from 0.01 to 0.04 events/year/comet, somewhat above the lower limit of 0.01 events/year/comet observed by Chen and Jewitt (Chen, J., Jewitt, D.C. [1994]. Icarus 108, 265-271).

  18. Secular orbital evolution of Jupiter family comets

    Science.gov (United States)

    Rickman, H.; Gabryszewski, R.; Wajer, P.; Wiśniowski, T.; Wójcikowski, K.; Szutowicz, S.; Valsecchi, G. B.; Morbidelli, A.

    2017-02-01

    Context. The issue of the long term dynamics of Jupiter family comets (JFCs) involves uncertain assumptions about the physical evolution and lifetimes of these comets. Contrary to what is often assumed, real effects of secular dynamics cannot be excluded and therefore merit investigation. Aims: We use a random sample of late heavy bombardment cometary projectiles to study the long-term dynamics of JFCs by a Monte Carlo approach. In a steady-state picture of the Jupiter family, we investigate the orbital distribution of JFCs, including rarely visited domains like retrograde orbits or orbits within the outer parts of the asteroid main belt. Methods: We integrate 100 000 objects over a maximum of 100 000 orbital revolutions including the Sun, a comet, and four giant planets. Considering the steady-state number of JFCs to be proportional to the total time spent in the respective orbital domain, we derive the capture rate based on observed JFCs with small perihelia and large nuclei. We consider a purely dynamical model and one where the nuclei are eroded by ice sublimation. Results: The JFC inclination distribution is incompatible with our erosional model. This may imply that a new type of comet evolution model is necessary. Considering that comets may live for a long time, we show that JFCs can evolve into retrograde orbits as well as asteroidal orbits in the outer main belt or Cybele regions. The steady-state capture rate into the Jupiter family is consistent with 1 × 109 scattered disk objects with diameters D > 2 km. Conclusions: Our excited scattered disk makes it difficult to explain the JFC inclination distribution, unless the physical evolution of JFCs is more intricate than assumed in standard, erosional models. Independent of this, the population size of the Jupiter family is consistent with a relatively low-mass scattered disk.

  19. Cosmic meteor dust: potentially the dominant source of bio-available iron in the Southern Ocean

    Science.gov (United States)

    Dyrud, L. P.; Marsh, D. R.; Del Castillo, C. E.; Fentzke, J.; Lopez-Rosado, R.; Behrenfeld, M.

    2012-12-01

    Johnson, 2001 [Johnson, Kenneth. S. (2001), Iron supply and demand in the upper ocean: Is extraterrestrial dust a significant source of bioavailable iron?, Global Biogeochem. Cycles, 15(1), 61-63, doi:10.1029/2000GB001295], first suggested that meteoric particulate flux could be a significant source of bio-available iron, particularly in regions with little or no eolean sources, such as the Southern Ocean. While these calculations raised intriguing questions, there were many large unknowns in the input calculations between meteor flux and bio-available ocean molecular densities. There has been significant research in the intervening decade on related topics, such as the magnitude (~200 ktons per year) and composition of the meteoric flux, its atmospheric evaporation, transport, mesospheric formation of potentially soluble meteoric smoke, and extraterrestrial iron isotope identification. Paramount of these findings are recent NCAR WACCM atmosphere model results demonstrating that the majority of meteoric constituents are transported towards the winter poles and the polar vortex. This may lead to a focusing of meteoritic iron deposition towards the Southern Ocean. We present a proposed research plan involving Southern Ocean sample collection and analysis and atmospheric and biological modeling to determine both the current relevance of meteoric iron, and examine the past and future consequences of cosmic dust under a changing climate.

  20. A first report on meteor-generated seismic signals as detected by the SANSN

    Directory of Open Access Journals (Sweden)

    Frederick Roelofse

    2013-05-01

    Full Text Available A bright meteor with an apparent magnitude of -18 was seen over large parts of southern Africa at ~23:00 South African Standard Time on 21 November 2009. Here we discuss the eye-witness accounts related to the meteor as well as the seismic signals generated by the meteor's passage through the atmosphere as detected by the Mussina seismograph station forming part of the South African National Seismograph Network. Two signals were identified on the seismogram; the first arrival is interpreted as a precursor coupled seismic wave and the second, which arrived ~138 s after the first, as a directly coupled airwave. The meteor is thought to have entered the atmosphere close to Mussina shortly before 22:55.06 local time, from where it proceeded in a westerly to northwesterly direction with an elevation angle not exceeding 43°. Our results presented here dispel the beliefs of many observers who thought that the meteor must have made landfall very close to their localities. In addition, this contribution documents the first instance of meteor-related seismic signals recorded by the South African National Seismograph Network.

  1. Comet Tempel 1 Went Back to Sleep

    Science.gov (United States)

    2005-07-01

    Astronomers Having Used ESO Telescopes Start Analysing Unique Dataset on the Comet Following the Deep Impact Mission Ten days after part of the Deep Impact spacecraft plunged onto Comet Tempel 1 with the aim to create a crater and expose pristine material from beneath the surface, astronomers are back in the ESO Offices in Santiago, after more than a week of observing at the ESO La Silla Paranal Observatory. In this unprecedented observing campaign - among the most ambitious ever conducted by a single observatory - the astronomers have collected a large amount of invaluable data on this comet. The astronomers have now started the lengthy process of data reduction and analysis. Being all together in a single place, and in close contacts with the space mission' scientific team, they will try to assemble a clear picture of the comet and of the impact. The ESO observations were part of a worldwide campaign to observe this unique experiment. During the campaign, ESO was connected by phone, email, and videoconference with colleagues in all major observatories worldwide, and data were freely exchanged between the different groups. This unique collaborative spirit provides astronomers with data taken almost around the clock during several days and this, with the largest variety of instruments, making the Deep Impact observing campaign one of the most successful of its kind, and thereby, ensuring the greatest scientific outcome. From the current analysis, it appears most likely that the impactor did not create a large new zone of activity and may have failed to liberate a large quantity of pristine material from beneath the surface. ESO PR Photo 22/05 ESO PR Photo 22/05 Evolution of Comet Tempel 1 (FORS2/VLT) [Preview - JPEG: 400 x 701 pix - 128k] [Normal - JPEG: 800 x 1401 pix - 357k] ESO PR Photo 22/05 Animated Gif Caption: ESO PR Photo 22/05 shows the evolution of Comet Tempel 1 as observed with the FORS2 instrument on Antu (VLT). The images obtained at the VLT show that

  2. Planetary perturbations for Oort cloud comets: II. Implications for the origin of observable comets

    Science.gov (United States)

    Fouchard, M.; Rickman, H.; Froeschlé, Ch.; Valsecchi, G. B.

    2014-03-01

    We present Monte Carlo simulations of the dynamical history of the Oort cloud, where in addition to the main external perturbers (Galactic tides and stellar encounters) we include, as done in a companion paper (Fouchard, M., Rickman, H., Froeschlé, Ch., Valsecchi, G.B. [2013b]. Icarus, in press), the planetary perturbations experienced each time the comets penetrate to within 50 AU of the Sun. Each simulation involves an initial sample of four million comets and extends over a maximum of 5 Gyr. For better understanding of the outcomes, we supplement the full dynamical model by others, where one or more of the effects are left out. We concentrate on the production of observable comets, reaching for the first time a perihelion within 5 AU of the Sun. We distinguish between four categories, depending on whether the comet jumps across, or creeps through, the Jupiter-Saturn barrier (perihelion distances between 5 and 15 AU), and whether the orbit leading to the observable perihelion is preceded by a major planetary perturbation or not. For reasons explained in the paper, we call the strongly perturbed comets "Kaib-Quinn comets". We thus derive a synthetic picture of the Oort spike, from which we draw two main conclusions regarding the full dynamical model. One is that 2/3 of the observable comets are injected with the aid of a planetary perturbation at the previous perihelion passage, and about half of the observable comets are of the Kaib-Quinn type. The other is that the creepers dominate over the jumpers. Due to this fact, the spike peaks at only 31 000 AU, and the majority of new comets have semi-major axes less than this value. The creepers show a clear preference for retrograde orbits as a consequence of the need to avoid untimely, planetary ejection before becoming observable. Thus, the new comets should have a 60/40 preference for retrograde against prograde orbits in apparent conflict with observations. However, both these and other results depend on our model

  3. Maverick Comet Splits during Dramatic Outburst

    Science.gov (United States)

    1996-01-01

    New ESO Observations of P/Schwassmann-Wachmann 3 A few months ago, Periodic Comet Schwassmann-Wachmann 3 underwent a dramatic and completely unexpected, thousand-fold brightening. At that time, the cause for this interesting event was unknown. However, observations with the two largest ESO telescopes have now shown that the ``dirty snowball'' nucleus of this comet has recently split into at least four individual pieces [1]. There is little doubt that the outburst and the splitting event(s) are closely related and that the greatly increased dust and gas production is due to ``fresh'' material of the icy cometary nucleus becoming exposed to the surrounding space for the first time. A Comet with a Troubled History Comet Schwassmann-Wachmann 3 was discovered on May 2, 1930, on a photographic plate obtained at the Hamburg Observatory (Germany) by two astronomers at this institution, Arnold Schwassmann and Arthur Arno Wachmann. The subsequent observations showed that the comet moved in an elliptical orbit with a revolution period of somewhat more than 5 years. Great efforts were expended to observe the comet during the next returns, but it was not recovered until nearly 50 years and eight revolutions later, when its faint image was found of a plate obtained in August 1979 with a telescope at the Perth Observatory in Western Australia. It was missed in 1984, but was sighted again in 1989 and most recently in 1994. Thus this comet has only been observed during four out of thirteen approaches since 1930. While this may be partly due to a less advantageous location in the sky at some returns, it is also a strong indication that the comet behaves unpredictably and must have a quite variable brightness. For the sake of convenience this comet is often referred to as ``SW-3'' by professional astronomers. Recent orbital calculations have shown that it was inserted into the present, short-period orbit by the strong gravitational pull of Jupiter during several, relatively close

  4. Novel Experimental Simulations of the Atmospheric Injection of Meteoric Metals

    Science.gov (United States)

    Gómez Martín, J. C.; Bones, D. L.; Carrillo-Sánchez, J. D.; James, A. D.; Trigo-Rodríguez, J. M.; Fegley, B., Jr.; Plane, J. M. C.

    2017-02-01

    A newly developed laboratory, Meteoric Ablation Simulator (MASI), is used to test model predictions of the atmospheric ablation of interplanetary dust particles (IDPs) with experimental Na, Fe, and Ca vaporization profiles. MASI is the first laboratory setup capable of performing time-resolved atmospheric ablation simulations, by means of precision resistive heating and atomic laser-induced fluorescence detection. Experiments using meteoritic IDP analogues show that at least three mineral phases (Na-rich plagioclase, metal sulfide, and Mg-rich silicate) are required to explain the observed appearance temperatures of the vaporized elements. Low melting temperatures of Na-rich plagioclase and metal sulfide, compared to silicate grains, preclude equilibration of all the elemental constituents in a single melt. The phase-change process of distinct mineral components determines the way in which Na and Fe evaporate. Ca evaporation is dependent on particle size and on the initial composition of the molten silicate. Measured vaporized fractions of Na, Fe, and Ca as a function of particle size and speed confirm differential ablation (i.e., the most volatile elements such as Na ablate first, followed by the main constituents Fe, Mg, and Si, and finally the most refractory elements such as Ca). The Chemical Ablation Model (CABMOD) provides a reasonable approximation to this effect based on chemical fractionation of a molten silicate in thermodynamic equilibrium, even though the compositional and geometric description of IDPs is simplistic. Improvements in the model are required in order to better reproduce the specific shape of the elemental ablation profiles.

  5. A First-Principle Kinetic Theory of Meteor Plasma Formation

    Science.gov (United States)

    Dimant, Yakov; Oppenheim, Meers

    2015-11-01

    Every second millions of tiny meteoroids hit the Earth from space, vast majority too small to observe visually. However, radars detect the plasma they generate and use the collected data to characterize the incoming meteoroids and the atmosphere in which they disintegrate. This diagnostics requires a detailed quantitative understanding of formation of the meteor plasma. Fast-descending meteoroids become detectable to radars after they heat due to collisions with atmospheric molecules sufficiently and start ablating. The ablated material then collides into atmospheric molecules and forms plasma around the meteoroid. Reflection of radar pulses from this plasma produces a localized signal called a head echo. Using first principles, we have developed a consistent collisional kinetic theory of the near-meteoroid plasma. This theory shows that the meteoroid plasma develops over a length-scale close to the ion mean free path with a non-Maxwellian velocity distribution. The spatial distribution of the plasma density shows significant deviations from a Gaussian law usually employed in head-echo modeling. This analytical model will serve as a basis for more accurate quantitative interpretation of the head echo radar measurements. Work supported by NSF Grant 1244842.

  6. [Abdominal spasms, meteorism, diarrhea: fructose intolerance, lactose intolerance or IBS?].

    Science.gov (United States)

    Litschauer-Poursadrollah, Margaritha; El-Sayad, Sabine; Wantke, Felix; Fellinger, Christina; Jarisch, Reinhart

    2012-12-01

    Meteorism, abdominal spasms, diarrhea, casually obstipation, flatulence and nausea are symptoms of fructose malabsorption (FIT) and/or lactose intolerance (LIT), but are also symptoms of irritable bowel syndrome (IBS). Therefore these diseases should be considered primarily in patients with digestive complaints. For diagnosis an H(2)-breath test is used.In 1,935 patients (526 m, 1,409 f) a fructose intolerance test and in 1,739 patients (518 m,1,221 f) a lactose intolerance test was done.FIT is found more frequently than LIT (57 versus 52 % in adults (p intolerance (HIT). Headache (ca. 10 %), fatigue (ca. 5 %) and dizziness (ca. 3 %) may occur after the test, irrespective whether the test was positive or negative.In more than 2/3 of patients a diet reduced in fructose or lactose may lead to improvement or remission of these metabolic disorders. IBS, which is often correlated with FIT (183/221 patients = 83 %), can be improved by relevant but also not relevant diets indicating that irritable bowel disease seems to be caused primarily by psychological disorders.

  7. Be2D: A model to understand the distribution of meteoric 10Be in soilscapes

    Science.gov (United States)

    Campforts, Benjamin; Vanacker, Veerle; Vanderborght, Jan; Govers, Gerard

    2016-04-01

    Cosmogenic nuclides have revolutionised our understanding of earth surface process rates. They have become one of the standard tools to quantify soil production by weathering, soil redistribution and erosion. Especially Beryllium-10 has gained much attention due to its long half-live and propensity to be relatively conservative in the landscape. The latter makes 10Be an excellent tool to assess denudation rates over the last 1000 to 100 × 103 years, bridging the anthropogenic and geological time scale. Nevertheless, the mobility of meteoric 10Be in soil systems makes translation of meteoric 10Be inventories into erosion and deposition rates difficult. Here we present a coupled soil hillslope model, Be2D, that is applied to synthetic and real topography to address the following three research questions. (i) What is the influence of vertical meteoric Be10 mobility, caused by chemical mobility, clay translocation and bioturbation, on its lateral redistribution over the soilscape, (ii) How does vertical mobility influence erosion rates and soil residence times inferred from meteoric 10Be inventories and (iii) To what extent can a tracer with a half-life of 1.36 Myr be used to distinguish between natural and human-disturbed soil redistribution rates? The model architecture of Be2D is designed to answer these research questions. Be2D is a dynamic model including physical processes such as soil formation, physical weathering, clay migration, bioturbation, creep, overland flow and tillage erosion. Pathways of meteoric 10Be mobility are simulated using a two step approach which is updated each timestep. First, advective and diffusive mobility of meteoric 10Be is simulated within the soil profile and second, lateral redistribution because of lateral soil fluxes is calculated. The performance and functionality of the model is demonstrated through a number of synthetic and real model runs using existing datasets of meteoric 10Be from case-studies in southeastern US. Brute

  8. Analysis of the technical biases of meteor video cameras used in the CILBO system

    Science.gov (United States)

    Albin, Thomas; Koschny, Detlef; Molau, Sirko; Srama, Ralf; Poppe, Björn

    2017-02-01

    In this paper, we analyse the technical biases of two intensified video cameras, ICC7 and ICC9, of the double-station meteor camera system CILBO (Canary Island Long-Baseline Observatory). This is done to thoroughly understand the effects of the camera systems on the scientific data analysis. We expect a number of errors or biases that come from the system: instrumental errors, algorithmic errors and statistical errors. We analyse different observational properties, in particular the detected meteor magnitudes, apparent velocities, estimated goodness-of-fit of the astrometric measurements with respect to a great circle and the distortion of the camera. We find that, due to a loss of sensitivity towards the edges, the cameras detect only about 55 % of the meteors it could detect if it had a constant sensitivity. This detection efficiency is a function of the apparent meteor velocity. We analyse the optical distortion of the system and the goodness-of-fit of individual meteor position measurements relative to a fitted great circle. The astrometric error is dominated by uncertainties in the measurement of the meteor attributed to blooming, distortion of the meteor image and the development of a wake for some meteors. The distortion of the video images can be neglected. We compare the results of the two identical camera systems and find systematic differences. For example, the peak magnitude distribution for ICC9 is shifted by about 0.2-0.4 mag towards fainter magnitudes. This can be explained by the different pointing directions of the cameras. Since both cameras monitor the same volume in the atmosphere roughly between the two islands of Tenerife and La Palma, one camera (ICC7) points towards the west, the other one (ICC9) to the east. In particular, in the morning hours the apex source is close to the field-of-view of ICC9. Thus, these meteors appear slower, increasing the dwell time on a pixel. This is favourable for the detection of a meteor of a given magnitude.

  9. Meteor Trails in the Lower Thermosphere: What Do Large Radars Really Detect?

    Science.gov (United States)

    Oppenheim, M. M.; Dimant, Y. S.

    2014-12-01

    Tens of millions of detectable meteors ablate in the Earth's upper atmosphere each second, creating turbulent plasma trails that persist for up to minutes as they dissipate into the background ionosphere. These trails produce easily detected radar signals with a wealth of information. This talk will present a detailed analysis of two aspects of meteor physics: (1) the early evolution of meteors as they first ionize and create radar reflections called head echoes, and (2) the later evolution as meteor plasmas develop turbulence and create radar signals called non-specular or range spread meteor trail echoes. Head echoes form when sublimated material from a meteoroid initially collides with atmospheric molecules and ionize. Kinetic theory shows that this plasma develops over a length-scale close to the ion mean-free-path but with a highly non-Maxwellian velocity distribution. We have developed an analytical model that improves the quantitative interpretation of head echo radar measurements and ionization efficiency (called the Beta parameter). This will help us calculate meteoroid and atmosphere parameters from radar head-echo observations. Non-specular meteor trail echoes develop when meteor plasmas become turbulent allowing the reflection of radar signals. We will analyze this system using 3D simulations of a dense column of meteor plasma embedded in a background ionosphere/thermosphere. While the meteor diffuses across the Earth's geomagnetic field B0, large electric fields develop because of the interplay between highly mobile but magnetized electrons and the heavier but collisionally demagnetized ions. These fields point mostly perpendicular to B0 and change slowly in the direction of B0. These simulations show that the electric field causes a substantial restructuring of the ionospheric plasma outside the trail but connected to it via B0. They also demonstrate the diffusive expansion of the trail and the development of waves both within and outside the trail

  10. An Orbital Meteoroid Stream Survey Using the Southern Argentina Agile Meteor Radar (SAAMER) Based on a Wavelet Approach

    Science.gov (United States)

    Pokorny, P.; Janches, D.; Brown, P. G.; Hormaechea, J. L.

    2017-01-01

    Over a million individually measured meteoroid orbits were collected with the Southern Argentina Agile MEteor Radar (SAAMER) between 2012-2015. This provides a robust statistical database to perform an initial orbital survey of meteor showers in the Southern Hemisphere via the application of a 3D wavelet transform. The method results in a composite year from all 4 years of data, enabling us to obtain an undisturbed year of meteor activity with more than one thousand meteors per day. Our automated meteor shower search methodology identified 58 showers. Of these showers, 24 were associated with previously reported showers from the IAU catalogue while 34 showers are new and not listed in the catalogue. Our searching method combined with our large data sample provides unprecedented accuracy in measuring meteor shower activity and description of shower characteristics in the Southern Hemisphere. Using simple modeling and clustering methods we also propose potential parent bodies for the newly discovered showers.

  11. An orbital meteoroid stream survey using the Southern Argentina Agile MEteor Radar (SAAMER) based on a wavelet approach

    Science.gov (United States)

    Pokorný, P.; Janches, D.; Brown, P. G.; Hormaechea, J. L.

    2017-07-01

    Over a million individually measured meteoroid orbits were collected with the Southern Argentina Agile MEteor Radar (SAAMER) between 2012-2015. This provides a robust statistical database to perform an initial orbital survey of meteor showers in the Southern Hemisphere via the application of a 3D wavelet transform. The method results in a composite year from all 4 years of data, enabling us to obtain an undisturbed year of meteor activity with more than one thousand meteors per day. Our automated meteor shower search methodology identified 58 showers. Of these showers, 24 were associated with previously reported showers from the IAU catalogue while 34 showers are new and not listed in the catalogue. Our searching method combined with our large data sample provides unprecedented accuracy in measuring meteor shower activity and description of shower characteristics in the Southern Hemisphere. Using simple modeling and clustering methods we also propose potential parent bodies for the newly discovered showers.

  12. A Monte-Carlo based extension of the Meteor Orbit and Trajectory Software (MOTS) for computations of orbital elements

    Science.gov (United States)

    Albin, T.; Koschny, D.; Soja, R.; Srama, R.; Poppe, B.

    2016-01-01

    The Canary Islands Long-Baseline Observatory (CILBO) is a double station meteor camera system (Koschny et al., 2013; Koschny et al., 2014) that consists of 5 cameras. The two cameras considered in this report are ICC7 and ICC9, and are installed on Tenerife and La Palma. They point to the same atmospheric volume between both islands allowing stereoscopic observation of meteors. Since its installation in 2011 and the start of operation in 2012 CILBO has detected over 15000 simultaneously observed meteors. Koschny and Diaz (2002) developed the Meteor Orbit and Trajectory Software (MOTS) to compute the trajectory of such meteors. The software uses the astrometric data from the detection software MetRec (Molau, 1998) and determines the trajectory in geodetic coordinates. This work presents a Monte-Carlo based extension of the MOTS code to compute the orbital elements of simultaneously detected meteors by CILBO.

  13. Comet classification with new methods for gas and dust spectroscopy

    Science.gov (United States)

    Langland-Shula, Laura E.; Smith, Graeme H.

    2011-05-01

    We present the results of a program of comet long-slit spectroscopy with the Kast Dual Spectrograph on the 3-m Shane Telescope at Lick Observatory. A total of 26 comets, from a variety of dynamical families, were observed on 39 different nights from 1996 to 2007. A new statistical method extracted the twilight sky from comet frames, because traditional sky subtraction techniques were inadequate. Because previously published Haser model parent and daughter scale lengths did not fit the data well, unbiased ranges of scale lengths were searched for the best-fitting pairs. Coma gas production rates for OH, CN, C 2, C 3, NH, NH 2, and OH confirmed the widely reported carbon-chain depletion for a sub-class of comets, most notably high-perihelion Jupiter-family comets observed at rh > 1.5 AU, with different behaviors for C 2 and C 3. Our long-slit spectroscopy data was also adapted for the A( θ) fρ dust production parameter. The assumption that A( θ) fρ is constant throughout the nucleus was not upheld. High dust-to-gas ratios for comets with large perihelia were not a selection effect, and suggest that the dust was released earlier in the formation of the coma than the gas. The dust-to-gas ratio did not exhibit any evolutionary traces between different comet dynamical families. The comet survey illuminates the diversity among comets, including the unusually carbon poor Comet 96P/Machholz.

  14. Reducing the Asteroid and Comet Impact Hazard

    Science.gov (United States)

    Crawford, David

    1998-10-01

    Of the 140 impact craters known on the surface of Earth, the most famous was created about 65 million years ago when a 10 km asteroid or comet came down in shallow water near the present day town of Chicxulub, Mexico. With a kinetic energy equivalent to 100 trillion tons of TNT, the impact event lofted enough debris onto globe-straddling trajectories to flash heat much of the surface of the Earth and then darken the skies for several years. Numerous investigations have demonstrated that such an event, which happens, on average, every 100 million years, caused extreme stress on Earth's climate and most likely led to the extinction of many species. Computational simulations demonstrate that more numerous asteroids or comets as small as 1 km in diameter, impacting, on average, every 300,000 years may be globally catastrophic. Indeed, the odds of an individual dying from a relatively frequent 1 km impacting object (about 1 in 10,000) are substantially greater than from the impact of an infrequent dinosaur killer (1 in 1,000,000). What can we do to reduce the hazard from impacting comets and asteroids? First, we should find what's out there with our name on it. Only about 10 percent of the potential Earth-crossing asteroids have been found. Even at the greatly increased detection rate of recent years, it will be several decades before we've found 90 percent of the Earth-crossers. Second, we should learn everything we can about the physical, compositional and mechanical properties of asteroids and comets. A recent computational study demonstrated that weakly bound asteroids (little more than rubble piles) are easier to break than deflect(E. Asphaug, S. J. Ostro, R. S. Hudson, D. J. Scheeres and W. Benz (1998), Nature, Vol. 393, pp. 437-440.). Is this an advantage or disadvantage? Third, we should study potential means of mitigating the hazard by deflecting the object while still in space or evacuating affected regions (such as coastlines) of the Earth. Because the

  15. Eclipses, transits, and comets of the nineteenth century how America's perception of the skies changed

    CERN Document Server

    Cottam, Stella

    2015-01-01

    Grabbing the attention of poets, politicians and the general public alike, a series of spectacular astronomical events in the late 1800s galvanized Americans to take a greater interest in astronomy than ever before. At a time when the sciences were not yet as well established in the United States as they were in Europe, this public interest and support provided the growing scientific community in the United States with the platform they needed to advance the field of astronomy in the United States.   Earlier in the 19th century comets, meteors and the discovery of the planet Neptune were all sources of inspiration to the general public. The specific events to be considered here are the total solar eclipses of 1868, 1869 and 1878 and the transits of Venus of 1874 and 1882. The available media responded to public interest as well as generating more interest. These events laid the groundwork that led to today's thriving network of American amateur astronomers, and provide a fascinating look at earlier conc...

  16. Simulating the mobility of meteoric 10Be in the landscape through a coupled soil-hillslope model (Be2D)

    Science.gov (United States)

    Campforts, Benjamin; Vanacker, Veerle; Vanderborght, Jan; Baken, Stijn; Smolders, Erik; Govers, Gerard

    2016-04-01

    Meteoric 10Be allows for the quantification of vertical and lateral soil fluxes over long time scales (103-105 yr). However, the mobility of meteoric 10Be in the soil system makes a translation of meteoric 10Be inventories into erosion and deposition rates complex. Here, we present a spatially explicit 2D model simulating the behaviour of meteoric 10Be on a hillslope. The model consists of two parts. The first component deals with advective and diffusive mobility of meteoric 10Be within the soil profile, and the second component describes lateral soil and meteoric 10Be fluxes over the hillslope. Soil depth is calculated dynamically, accounting for soil production through weathering as well as downslope fluxes of soil due to creep, water and tillage erosion. Synthetic model simulations show that meteoric 10Be inventories can be related to erosion and deposition across a wide range of geomorphological and pedological settings. Our results also show that meteoric 10Be can be used as a tracer to detect human impact on soil fluxes for soils with a high affinity for meteoric 10Be. However, the quantification of vertical mobility is essential for a correct interpretation of the observed variations in meteoric 10Be profiles and inventories. Application of the Be2D model to natural conditions using data sets from the Southern Piedmont (Bacon et al., 2012) and Appalachian Mountains (Jungers et al., 2009; West et al., 2013) allows to reliably constrain parameter values. Good agreement between simulated and observed meteoric 10Be concentrations and inventories is obtained with realistic parameter values. Furthermore, our results provide detailed insights into the processes redistributing meteoric 10Be at the soil-hillslope scale.

  17. Meteor Ablation as Origin for the D-region Ledge in Electrical Conductivity

    Science.gov (United States)

    Williams, E. R.; Wu, Y. J.; Friedrich, M.; Hsu, R. R.

    2015-12-01

    The ledge in electron density and electrical conductivity in the 80-90 km altitude range has been a consistent feature in rocket and electromagnetic observations of the D-region for half a century. Most conspicuous at nighttime and at low latitudes, the abrupt increase in electron density with altitude near 85 km often shows a scale height of less than 1 km. This observed behavior is a marked departure from the Wait-Spies exponential profile that is often used to model the D-region. Calculations show that the conduction current and displacement current are matched at the height of the observed ledge over a wide range of VLF frequencies, pinning this altitude as the sharp boundary for the global VLF waveguide. Meteor ablation involves the abrupt transformation in altitude of faint sub-millimeter-sized meteoroids to nanometer-sized dust, when the meteor boiling temperature near 2100K is attained. The ablation dust can reach concentrations comparable to electron density near the ledge height and in the polluted continental boundary layer. The electron affinity of this silicate mineral dust together with the suppression of negative molecular ions (e.g., O2- ) by monatomic O (Plane et al., 2014), serves to reduce the free electron concentration to form the ledge in conductivity. Calculations with the classical model for meteor ablation require a mean incoming meteor speed of 15 km/s. with rapid decline at higher speeds, to produce a ledge height at 85 km altitude. The key role for meteor ablation in this ionosphere context has likely not received due recognition because neither the meteoric dust nor the meteors that create it are readily detectable by remote sensing, and in situ observations of the mesosphere are scarce.

  18. Seismic detections of the 15 February 2013 Chelyabinsk meteor from the dense ChinArray

    Science.gov (United States)

    Li, Lu; Wang, Baoshan; Peng, Zhigang; Wang, Weitao

    2016-08-01

    ChinArray is a dense portable broadband seismic network to cover the entire continental China, and the Phase I is deployed along the north-south seismic belt in southwest China. In this study, we analyze seismic data recorded on the ChinArray following the February 15, 2013 Chelyabinsk (Russia) meteor. This was the largest known object entering the Earth's atmosphere since the 1908 Tunguska meteor. The seismic energy radiated from this event was recorded by seismic stations worldwide including the dense ChinArray that are more than 4000 km away. The weak signal from the meteor event was contaminated by a magnitude 5.8 Tonga earthquake occurred ~20 min earlier. To test the feasibility of detecting the weak seismic signals from the meteor event, we compute vespagram and perform F-K analysis to the surface-wave data. We identify a seismic phase with back azimuth (BAZ) of 329.7° and slowness of 34.73 s/deg, corresponding to the surface wave from the Russian meteor event (BAZ ~325.97°). The surface magnitude ( M S) of the meteor event is 3.94 ± 0.18. We also perform similar analysis on the data from the broadband array F-net in Japan, and find the BAZ of the surface waves to be 316.61°. With the different BAZs of ChinArray and F-net, we locate the Russian meteor event at 58.80°N, 58.72°E. The relatively large mislocation (~438 km as compared with 55.15°N, 61.41°E by others) may be a result of the bending propagation path of surface waves, which deviates from the great circle path. Our results suggest that the dense ChinArray and its subarrays could be used to detect weak signals at teleseismic distances.

  19. The end states of long-period comets and the origin of Halley-type comets

    Science.gov (United States)

    Fernández, Julio A.; Gallardo, Tabaré; Young, Juan D.

    2016-09-01

    We analyse a sample of 73 old long-period comets (LPCs) (orbital periods 200 lifetimes. We can fit the computed energy distribution of comets with q lifetimes of about 200-300 revolutions (for a comet with a standard q = 1 au). We find that neither a purely dynamical evolution, nor a physico-dynamical one can reproduce the long tail of larger binding energies (x ≳ 0.04 au-1) that correspond to most Halley-type comets (HTCs) and Jupiter-family comets. We conclude that most HTCs are not the end states of the evolution of LPCs, but come from a different source, a flattened one that we identify with the Centaurs that are scattered to the inner planetary region from the trans-Neptunian belt. These results also show that the boundary between LPCs and HTCs should be located at an energy x ˜ 0.04 au-1 (P ˜ 125 yr), rather than the conventional classical boundary at P = 200 yr.

  20. The end states of long-period comets and the origin of Halley-type comets

    CERN Document Server

    Fernández, Julio A; Young, Juan D

    2016-01-01

    We analyze a sample of 73 old long-period comets (LPCs) (orbital periods $200 < P < 1000$ yr) with perihelion distances $q < 2.5$ au, discovered in the period 1850-2014. We cloned the observed comets and also added fictitious LPCs with perihelia in the Jupiter's zone. We consider both a purely dynamical evolution and a physico-dynamical one with different physical lifetimes. We can fit the computed energy distribution of comets with $q < 1.3$ au to the observed one only within the energy range $0.01 < x < 0.04$ au$^{-1}$ (or periods $125 < P < 1000$ yr), where the "energy" is taken as the inverse of the semimajor axis $a$, namely $x \\equiv 1/a$. The best results are obtained for physical lifetimes of about 200-300 revolutions (for a comet with a standard $q = 1$ au). We find that neither a purely dynamical evolution, nor a physico-dynamical one can reproduce the long tail of larger binding energies ($x \\gsim 0.04$ au$^{-1}$) that correspond to most Halley-type comets (HTCs) and Jupiter...

  1. Comet assay on tetraploid yeast cells

    DEFF Research Database (Denmark)

    Rank, Jette; Syberg, Kristian; Jensen, Klara

    2009-01-01

    Tetraploid yeast cells (Saccharomyces cerevisiae) were used in the comet assay with the intention of developing a new, fast and easy assay for detecting environmental genotoxic agents without using higher organisms. Two DNA-damaging chemicals, H2O2 and acrylamide, together with wastewater from...... three municipal treatment plants were tested for their effect on the yeast-cell DNA. The main problem with using yeast in the comet assay is the necessity to degrade the cell wall. This was achieved by using Zymolase 100 T twice during the procedure, since Zymolase 20 T did not open the cell wall....... Analytical problems that arose due to the small amount of DNA in the yeast nuclei in haploid and diploid cells, which contain 13 Mbp and 26 Mbp DNA per cell, respectively, were solved by using tetraploid yeast cells (52 Mbp) instead. DNA damage was shown after exposure to H2O2 and acrylamide. The lowest dose...

  2. Probing heavy neutrinos in the COMET experiment

    CERN Document Server

    Asaka, Takehiko

    2015-01-01

    We argue that the COMET experiment --- a dedicated experiment for the $\\mu$-$e$ conversion search --- can be a powerful facility to search for heavy neutrinos in the mass range $1\\,{\\rm MeV} \\lesssim M \\lesssim 100\\,{\\rm MeV}$. The stopped muons captured by the target nuclei or decaying in orbit are efficiently produce heavy neutrinos via the active-sterile mixing. The produced heavy neutrinos then decay to electron-positron pair (plus an active neutrino), which events are clearly seen by the cylindrical drift chamber surrounding the target. The expected sensitivity is comparable to the PS191 bound when the COMET experiment achieves $\\sim 10^{17}$ stopping muons in the target.

  3. The Origin of Life in Comets

    Science.gov (United States)

    Napier, W. M.; Wickramasinghe, J. T.; Wickramasinghe, N. C.

    Mechanisms of interstellar panspermia have recently been identified whereby life, wherever it has originated, will disperse throughout the habitable zone of the Galaxy within a few billion years. This re-opens the question of where life originated. The interiors of comets, during their aqueous phase, seem to provide environments no less favourable for the origin of life than that of the early Earth. Their combined mass throughout the Galaxy overwhelms that of suitable terrestrial environments by about 20 powers of ten, while the lifetimes of friendly prebiotic environments within them exceeds that of localised terrestrial regions by another four or five powers of ten. We propose that the totality of comets around G-dwarf Sun-like stars offers an incomparably more probable setting for the origin of life than any that was available on the early Earth.

  4. Identification of irradiated pepper with comet assay

    Energy Technology Data Exchange (ETDEWEB)

    Prieto Miranda, Enrique Fco.; Moreno Alvarez, Damaris L.; Carro Palacio, Sandra [Centro de Aplicaciones Tecnologicas y Desarrollo Nuclear. (CEADEN), Ciudad de La Habana (Cuba)]. E-mail: efprieto@ceaden.edu.cu; damaris@ceaden.edu.cu; Iglesia Enriquez, Isora [Instituto de Investigacion para la Industria Alimenticia (IIIA), Ciudad de La Habana (Cuba)

    2007-07-01

    The treatment of foods with ionizing radiations is a technological process utilized in order to increase the hygienic quality and the storage time of the foods. Several methods of detection of irradiated foods have been recommended. The comet assay of DNA is one fast and economical technique for the qualitative identification of irradiated foods. The objective of the present paper was to identify with the comet assay technique the modifications of the DNA molecule of irradiated pepper storage at environment and refrigeration temperatures and different post-irradiation times for different absorbed dose values, (0.1, 0.3 and 0.5 kGy). It was demonstrated that for the high absorbed dose values was observed a greater break into fragments of the DNA molecule, which shows the application of this technique for the identification of irradiated foods. (author)

  5. New developments in comet-FISH.

    Science.gov (United States)

    Spivak, Graciela

    2015-01-01

    The comet assay combined with fluorescence in-situ hybridisation (FISH) is a powerful technique for comparative analyses of damage induction and repair in genomes and in specific DNA sequences within single cells. Recent advances in the methodology of comet-FISH will be considered here, with particular attention to the design and generation of fluorescent probes. In general, all the approaches must fulfil a few basic requirements: the probes should be no longer than ~300 nucleotides in length (single or double stranded) to be able to penetrate the gel in which the target genomic DNA is embedded, they should be sequence-specific, and their signal should be detectable and distinct from the background fluorescence and the dye used to stain the DNA.

  6. Mitigation of Hazardous Comets and Asteroids

    Science.gov (United States)

    Belton, Michael J. S.; Morgan, Thomas H.; Samarasinha, Nalin H.; Yeomans, Donald K.

    2011-03-01

    Preface; 1. Recent progress in interpreting the nature of the near-Earth object population W. Bottke, A. Morbidelli and R. Jedicke; 2. Earth impactors: orbital characteristics and warning times S. R. Chesley and T. B. Spahr; 3. The role of radar in predicting and preventing asteroid and comet collisions with Earth S. J. Ostro and J. D. Giorgini; 4. Interior structures for asteroids and cometary nuclei E. Asphaug; 5. What we know and don't know about surfaces of potentially hazardous small bodies C. R. Chapman; 6. About deflecting asteroids and comets K. A. Holsapple; 7. Scientific requirements for understanding the near-Earth asteroid population A. W. Harris; 8. Physical properties of comets and asteroids inferred from fireball observations M. D. Martino and A. Cellino; 9. Mitigation technologies and their requirements C. Gritzner and R. Kahle; 10. Peering inside near-Earth objects with radio tomography W. Kofman and A. Safaeinili; 11. Seismological imvestigation of asteroid and comet interiors J. D. Walker and W. F. Huebner; 12. Lander and penetrator science for near-Earth object mitigation studies A. J. Ball, P. Lognonne, K. Seiferlin, M. Patzold and T. Spohn; 13. Optimal interpretation and deflection of Earth-approaching asteroids using low-thrust electric propulsion B. A. Conway; 14. Close proximity operations at small bodies: orbiting, hovering, and hopping D. J. Scheeres; 15. Mission operations in low gravity regolith and dust D. Sears, M. Franzen, S. Moore, S. Nichols, M. Kareev and P. Benoit; 16. Impacts and the public: communicating the nature of the impact hazard D. Morrison, C. R. Chapman, D. Steel and R. P. Binzel; 17. Towards a program to remove the threat of hazardous NEOs M. J. S. Belton.

  7. Realistic Detectability of Close Interstellar Comets

    Science.gov (United States)

    Cook, Nathaniel V.; Ragozzine, Darin; Granvik, Mikael; Stephens, Denise C.

    2016-07-01

    During the planet formation process, billions of comets are created and ejected into interstellar space. The detection and characterization of such interstellar comets (ICs) (also known as extra-solar planetesimals or extra-solar comets) would give us in situ information about the efficiency and properties of planet formation throughout the galaxy. However, no ICs have ever been detected, despite the fact that their hyperbolic orbits would make them readily identifiable as unrelated to the solar system. Moro-Martín et al. have made a detailed and reasonable estimate of the properties of the IC population. We extend their estimates of detectability with a numerical model that allows us to consider “close” ICs, e.g., those that come within the orbit of Jupiter. We include several constraints on a “detectable” object that allow for realistic estimates of the frequency of detections expected from the Large Synoptic Survey Telescope (LSST) and other surveys. The influence of several of the assumed model parameters on the frequency of detections is explored in detail. Based on the expectation from Moro-Martín et al., we expect that LSST will detect 0.001-10 ICs during its nominal 10 year lifetime, with most of the uncertainty from the unknown number density of small (nuclei of ˜0.1-1 km) ICs. Both asteroid and comet cases are considered, where the latter includes various empirical prescriptions of brightening. Using simulated LSST-like astrometric data, we study the problem of orbit determination for these bodies, finding that LSST could identify their orbits as hyperbolic and determine an ephemeris sufficiently accurate for follow-up in about 4-7 days. We give the hyperbolic orbital parameters of the most detectable ICs. Taking the results into consideration, we give recommendations to future searches for ICs.

  8. The TRAPPIST comet survey in 2014

    Science.gov (United States)

    Jehin, Emmanuel; Opitom, Cyrielle; Manfroid, Jean; Hutsemékers, Damien; Gillon, Michael

    2014-11-01

    TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope) is a 60-cm robotic telescope that has been installed in June 2010 at the ESO La Silla Observatory [1]. Operated from Liège (Belgium) it is devoted to the detection and characterisation of exoplanets and to the study of comets and other small bodies in the Solar System. A set of narrowband cometary filters designed by the NASA for the Hale-Bopp Observing Campaign [2] is permanently mounted on the telescope along with classic Johnson-Cousins filters. We describe here the hardware and the goals of the project. For relatively bright comets (V < 12) we measure several times a week the gaseous production rates (using a Haser model) and the spatial distribution of several species among which OH, NH, CN, C2 and C3 as well as ions like CO+. The dust production rates (Afrho) and color of the dust aredetermined through four dust continuum bands from the UV to the red (UC, BC, GC, RC filters). We will present the dust and gas production rates of the brightest comets observed in 2014: C/2012 K1 (PANSTARRS), C/2014 E2 (Jacques), C/2013 A1 (Siding Springs) and C/2013 V5 (Oukaimeden). Each of these comets have been observed at least once a week for several weeks to several months. Light curves with respect to the heliocentric distance will be presented and discussed. [1] Jehin et al., The Messenger, 145, 2-6, 2011.[2] Farnham et al., Icarus, 147, 180-204, 2000.

  9. Are comets connected to the origin of life

    Science.gov (United States)

    Delsemme, A. H.

    1981-01-01

    Possible connections between comets and the origin of life on earth are discussed. The orbital evolution of comets and their origin are considered within a framework for the origin of the solar system, with particular attention given to the origin of the biosphere, and the origin of the Oort cloud. Evidence suggesting that cometary nuclei are undifferentiated throughout is considered, and a model of the average composition of a mean new comet is obtained from observational data which is similar to that of an interstellar frost. The chemistry of the model composition giving rise to the species observed in cometary spectra is considered, as well as the relations of cometary to cosmic abundances of oxygen, carbon and sulfur. The characteristics of possible sites for prebiotic chemistry, including interstellar clouds, the protosolar nebula, comets in the Oort cloud, periodic comets and the primitive earth, are examined, and a possible role of comets in bringing the interstellar prebiotic chemistry to earth is suggested.

  10. Navigation of the EPOXI Spacecraft to Comet Hartley 2

    Science.gov (United States)

    Bhaskaran, Shyam; Abrahamson, Matt; Chesley, Steven; Chung, Min-Kun; Halsell, Allen; Haw, Robert; Helfrich, Cliff; Jefferson, David; Kennedy, Brian; McElrath, Tim; Owen, William; Rush, Brian; Smith, Jonathon; Wang, Tseng-Chan; Yen, Chen-Wan

    2011-01-01

    On November 4, 2010, the EPOXI spacecraft flew by the comet Hartley 2, marking the fourth time that a NASA spacecraft successfully captured high resolution images of a cometary nucleus. EPOXI is the extended mission of the Deep Impact mission, which delivered an impactor on comet Tempel-1 on July 4, 2005. EPOXI officially started in September 2007 and eventually took over 3 years of flight time and had 3 Earth gravity assists to achieve the proper encounter conditions. In the process, the mission was redesigned to accommodate a new comet as the target and changes in the trajectory to achieve better imaging conditions at encounter. Challenges in navigation of the spacecraft included precision targeting of several Earth flybys and the comet encounter, uncertainties in determining the ephemeris of the comet relative to the spacecraft, and the high accuracy trajectory knowledge needed to image the comet during the encounter. This paper presents an overview of the navigation process used for the mission.

  11. Comet nucleus and asteroid sample return missions

    Science.gov (United States)

    1992-01-01

    Three Advanced Design Projects have been completed this academic year at Penn State. At the beginning of the fall semester the students were organized into eight groups and given their choice of either a comet nucleus or an asteroid sample return mission. Once a mission had been chosen, the students developed conceptual designs. These were evaluated at the end of the fall semester and combined into three separate mission plans, including a comet nucleus same return (CNSR), a single asteroid sample return (SASR), and a multiple asteroid sample return (MASR). To facilitate the work required for each mission, the class was reorganized in the spring semester by combining groups to form three mission teams. An integration team consisting of two members from each group was formed for each mission so that communication and information exchange would be easier among the groups. The types of projects designed by the students evolved from numerous discussions with Penn State faculty and mission planners at the Johnson Space Center Human/Robotic Spacecraft Office. Robotic sample return missions are widely considered valuable precursors to manned missions in that they can provide details about a site's environment and scientific value. For example, a sample return from an asteroid might reveal valuable resources that, once mined, could be utilized for propulsion. These missions are also more adaptable when considering the risk to humans visiting unknown and potentially dangerous locations, such as a comet nucleus.

  12. Comets: Role and importance to exobiology

    Science.gov (United States)

    Delsemme, Armand H.

    1992-01-01

    The transfer of organic compounds from interstellar space to the outskirts of a protoplanetary disk, their accretion into cometary objects, and the transport of the latter into the inner solar system by orbital diffusion throw a new light on the central problem of exobiology. It suggests the existence of a cosmic mechanism, working everywhere, that can supply prebiotic compounds to ubiquitous rocky planets, in search of the proper environment to start life in many places in the Universe. Under the heading of chemistry of the cometary nucleus, the following topics are covered: radial homogeneity of the nucleus; the dust-to-ice ratio; nature of the dust grains; origin of the dust in comets; nature of the volatile fraction; the CO distribution in comet Halley; dust contribution to the volatile fraction; elemental balance sheet of comet Halley; quantitative molecular analysis of the volatile fraction; and isotopic ratios. Under the heading of exogenous origin of carbon on terrestrial planets the following topics are covered: evidence for a high-temperature phase; from planetesimals to planets; a veneer of volatile and organic material; and cometary contribution.

  13. Carbon-rich particles in Comet Halley

    Science.gov (United States)

    Clark, Benton C.

    1990-01-01

    The majority of particles detected in the coma of Comet Halley contain carbon atoms; many of these grains appear to consist preponderately or only of light elements. These light-element particles may be composed of organic compounds. Of the possible combinations of the elements hydrogen, carbon, nitrogen, and oxygen, numerous examples are found of particles containing the combinations (H,C,O,N), (H,C,N), (H,C,O), and (H,C). These results may bear on the recent detection of polyoxymethylene fragments, the observation of cyanojets (CN patterns consistent with release from solid particles), the possible presence of cyanopolyacetylenes or HCN polymer and the make-up of the CHON particles. If cometary matter could reach the surface of the earth without complete disruption, these diverse organic and mixed particles could create unique microenvironments, possibly with significant or even pivotal prebiotic chemical activity. Here a speculative insight into possible relationships between carbon in comets and carbon in life is given, as well as a brief overview of on-going analysis of data from the highly successful Particle Impact Analyzer (PIA) experiment flown on the Giotto spacecraft for the flyby of Comet Halley (development and implementation of PIA was under the direction of J. Kissel of the Max Planck Institute for Kernphysik, Heidelberg). PIA is a time-of-flight analyzer which obtains mass spectra of ions from individual particles impacting on a Pt-Ag foil target within the instrument.

  14. Unexpected Delivery of Meteoric 10Be to Critical Zone Soils, Front Range, Colorado

    Science.gov (United States)

    Ouimet, W. B.; Dethier, D. P.; Bierman, P. R.; Wyshnytsky, C.; Rood, D. H.

    2011-12-01

    Using meteoric 10Be in geomorphic studies requires knowing its long-term delivery rate to the earth surface. Delivery rates vary by latitude due to the influence of geomagnetic field intensity and solar activity and locally due to differences in precipitation and rates of dustfall accumulation, which are responsible for depositing primary and recycled meteoric 10Be to geomorphic surfaces, respectively. Because influences on delivery rate vary in space and time, recent studies emphasize the use of inventory sites where the total concentration of meteoric 10Be is measured on stable landforms of known age to determine site-specific, long-term delivery rates. To date, measured long-term delivery rates typically have fallen within the range of expected rates for the site's latitude and modern annual rate of precipitation, including minor contributions of dust to the total inventory of meteoric 10Be. Here, we present the results of a meteoric 10Be inventory measured on a Pinedale (~15 ka) moraine within the Boulder Creek Critical Zone Observatory, Front Range, Colorado. We report a long-term delivery rate of meteoric 10Be for this site of 4.2 to 4.6 × 106 atoms/cm2/yr, significantly higher than the expected delivery rate (1 to 1.3 × 106 atoms/cm2/yr) for it's latitude (40 degrees) and annual precipitation rate (85-95 cm/yr). A detailed analysis of soils in the Front Range (of various age) indicate that long-term dust accumulation rates are less than ~0.1 grams/cm2/kyr and therefore do not significantly influence the total amount of meteoric 10Be delivered to geomorphic surfaces. When applied to measured concentrations of meteoric 10Be in soils within the Gordon Gulch CZO catchment, our high, inventory-based delivery rate suggests that hillslopes are 10 to 40 ka younger (all post-LGM) than suggested by published precipitation based delivery rates. Furthermore, this result, combined with a long-term delivery rate calibrated nearby on the High Plains (1200 m lower in

  15. Meteoric 10Be in Lake Cores as a Measure of Climatic and Erosional Change

    Science.gov (United States)

    Jensen, R. E.; Dixon, J. L.

    2015-12-01

    Utilization of meteoric 10Be as a paleoenvironmental proxy has the potential to offer new insights into paleoprecipitation records and paleoclimate models, as well as to long-term variations in erosion with climate. The delivery of meteoric 10Be to the surface varies with precipitation and its strong adsorption to sediment has already proven useful in studies of erosion. Thus, it is likely meteoric 10Be concentrations in lake sediments vary under both changing climate and changing sediment influx. Assessment of the relative importance of these changes requires the comparison of 10Be concentrations in well-dated lake cores with independent paleoenvironmental proxies, including oxygen isotope, pollen, and charcoal records, as well as variation in geochemical composition of the sediments. Blacktail Pond details 15,000 years of climatic change in the Yellowstone region. We develop a new model framework for predicting meteoric 10Be concentrations with depth in the core, based on sedimentation rates of both lake-derived and terrigenous sediments and changes in the flux of meteoric 10Be with precipitation. Titanium concentrations and previously determined 10Be concentrations in wind-derived loess provide proxies for changing delivery of 10Be to the lake by terrigenous sources. We use existing paleoenvironmental data obtained from this core and the surrounding region to develop models for changing rainfall across the region and predict meteoric 10Be delivery to the lake by precipitation. Based on a suite of ~10 models, sedimentation rate is the primary control of meteoric 10Be in the Blacktail Pond core unless terrestrial input is very high, as it was post-glacial in the early Holocene when the lake experienced a high influx of loess and terrigenous sediments. We used these models to inform sample selection for 10Be analysis along the Blacktail pond core. Core sediments are processed for meteoric 10Be analysis using sequential digestions and standard extraction procedures

  16. The solar wind interaction with comets: A post encounter view

    Science.gov (United States)

    Mendis, D. A.

    1987-01-01

    The recent spacecraft encounters with comets Giacobini-Zinner and Halley have led to an enormous increase in our knowledge of comets, including their dust, neutral gas, plasma, and magnetic field environments. The latter has in turn led to better understanding of the nature of the solar wind interaction with the well developed atmosphere of a comet. The post-encounter understanding of this interaction is reviewed, underscoring the differences with pre-encounter reasoning. The problems outstanding in this area are emphasized.

  17. Mitigation of transient meteor events in sodium layer by TMT NFIRAOS

    Science.gov (United States)

    Herriot, Glen; Irvin, Craig

    2012-07-01

    NFIRAOS Small meteors usually bum up near the bottom of the sodium layer. Meteor trails can lead to temporary dra­ matic changes in the altitude of the sodium layer. This altitude change is very rapid, typically over 1 second, and after some unpredictable period of 10-20 seconds, can transition back to the nominal mean altitude also in about 1 second. The altitude change is very drastic and can jump by up to 1 km which, on the face of it, would cause 4 micrometers defocus errors on LGS WFS measurements for a 30-m telescope, unless properly tracked. Measurements by the UBC Lidar detected 20 meteor trails I hour, and of these, 1-2 are significant events. We report on a full end-to-end Simulink simulation for TMT NFIRAOS including: meteor events measured by the UBC Lidar; on-instrument NGS focus sensor running at 90 Hz (median sky coverage frame rate); optimal temporal blending with LGS WFS focus measurements; LGS WFS centroiding matched filter update and Truth WFS update very 3s; full trombone servo model including non-linear focus range vs stage position. We optimized our control architecture and traded off motor power dissipation versus residual wavefront error and Shack-Hartmann spot displacement and found range tracking errors induce 12 nm WFE in normal conditions and brief (Is) jumps of 30-80 nm WFE at the beginning and ending of meteor transients.

  18. Calibrating a long-term meteoric 10Be accumulation rate in soil

    Science.gov (United States)

    Reusser, Lucas; Graly, Joseph; Bierman, Paul; Rood, Dylan

    2010-10-01

    Using 13 samples collected from a 4.1 meter profile in a well-dated and stable New Zealand fluvial terrace, we present the first long-term accumulation rate for meteoric 10Be in soil (1.68 to 1.72 × 106 at/(cm2·yr)) integrated over the past ˜18 ka. Site-specific accumulation data, such as these, are prerequisite to the application of meteoric 10Be in surface process studies. Our data begin the process of calibrating long-term meteoric 10Be delivery rates across latitude and precipitation gradients. Our integrated rate is lower than contemporary meteoric 10Be fluxes measured in New Zealand rainfall, suggesting that long-term average precipitation, dust flux, or both, at this site were less than modern values. With accurately calibrated long-term delivery rates, such as this, meteoric 10Be will be a powerful tool for studying rates of landscape change in environments where other cosmogenic nuclides, such as in situ 10Be, cannot be used.

  19. METEOR: An Enterprise Health Informatics Environment to Support Evidence-Based Medicine.

    Science.gov (United States)

    Puppala, Mamta; He, Tiancheng; Chen, Shenyi; Ogunti, Richard; Yu, Xiaohui; Li, Fuhai; Jackson, Robert; Wong, Stephen T C

    2015-12-01

    The aim of this paper is to propose the design and implementation of next-generation enterprise analytics platform developed at the Houston Methodist Hospital (HMH) system to meet the market and regulatory needs of the healthcare industry. For this goal, we developed an integrated clinical informatics environment, i.e., Methodist environment for translational enhancement and outcomes research (METEOR). The framework of METEOR consists of two components: the enterprise data warehouse (EDW) and a software intelligence and analytics (SIA) layer for enabling a wide range of clinical decision support systems that can be used directly by outcomes researchers and clinical investigators to facilitate data access for the purposes of hypothesis testing, cohort identification, data mining, risk prediction, and clinical research training. Data and usability analysis were performed on METEOR components as a preliminary evaluation, which successfully demonstrated that METEOR addresses significant niches in the clinical informatics area, and provides a powerful means for data integration and efficient access in supporting clinical and translational research. METEOR EDW and informatics applications improved outcomes, enabled coordinated care, and support health analytics and clinical research at HMH. The twin pressures of cost containment in the healthcare market and new federal regulations and policies have led to the prioritization of the meaningful use of electronic health records in the United States. EDW and SIA layers on top of EDW are becoming an essential strategic tool to healthcare institutions and integrated delivery networks in order to support evidence-based medicine at the enterprise level.

  20. Neutral Air Density Variations Derived from Specular Meteor Echo Observation Spanning One Solar Cycle

    Science.gov (United States)

    Stober, G.; Matthias, V.; Chau, J. L.; Brown, P.

    2014-12-01

    Specular meteor radars (SMR) are a wide spread and established method to investigate mesospheric/ lower thermospheric (MLT) dynamics. Since 2002 the Canadian Meteor Orbit Radar (CMOR) conducts observations of meteor echoes in a fixed, stable configuration. Here we present measurements of the meteor peak flux altitude (MPFA) spanning one solar cycle at an altitude of 91 km. The MPFA is converted into neutral air density variations using a single body meteor ablation model and a NRLMSIS background atmosphere. We were able to separate the long term trend from the solar cycle effect assuming a linear trend and a sinusoidal solar cycle effect. The neutral air density shows a solar cycle signature of 2.4 +/-0.7% for solar cycle 23/24. The long term trend indicates a decreasing neutral air density of 5.8+/-1.1% per decade, which is in reasonable agreement to the model results of Akmaev et al., 2006. They predicted a decrease of neutral air density for the MLT in the order of 5-6% per decade due to greenhouse gas cooling.

  1. Meteor head echo characteristics observed with MAARSY in the polar region

    Science.gov (United States)

    Schult, Carsten; Stober, Gunter; Chau, Jorge L.

    2016-04-01

    The Middle Atmosphere Alomar Radar System (MAARSY, 53.5 MHz), on the North Norwegian island Andoya (69.30° N, 16.04° E) , is the only high power large aperture (HPLA) radar system with interferometric capabilities providing daily meteor head echo observations since November 2013. Meanwhile, the data set of meteor head echoes contains over one million events with a perfect daily and seasonal coverage of the four northern hemisphere sporadic sources. Although, the North Apex meteor source dominates the observation by far (more than 40%), the statistic is large enough for a comparison of the observational meteor parameters for all sporadic sources. Furthermore, due to the large spread of the antenna gain of the HPLA radar system in combination with the interferometric solutions, the observation area can be divided into high and low sensitive regions with different collecting sizes. This separation is equivalent with a measurement of various radar systems with different beam characteristics, observing at the same time and geographical location. This helps answering question on the impact of the radar specifications on the meteor head echo measurements.

  2. Is the Comet Assay a Sensitive Procedure for Detecting Genotoxicity?

    Directory of Open Access Journals (Sweden)

    Satomi Kawaguchi

    2010-01-01

    Full Text Available Although the Comet assay, a procedure for quantitating DNA damage in mammalian cells, is considered sensitive, it has never been ascertained that its sensitivity is higher than the sensitivity of other genotoxicity assays in mammalian cells. To determine whether the power of the Comet assay to detect a low level of genotoxic potential is superior to those of other genotoxicity assays in mammalian cells, we compared the results of Comet assay with those of micronucleus test (MN test. WTK1 human lymphoblastoid cells were exposed to methyl nitrosourea (MNU, ethyl nitrosourea (ENU, methyl methanesulfonate (MMS, ethyl methanesulfonate (EMS, bleomycin (BLM, or UVC. In Comet assay, cells were exposed to each mutagen with (Comet assay/araC and without (Comet assay DNA repair inhibitors (araC and hydroxyurea. Furthermore, acellular Comet assay (acellular assay was performed to determine how single-strand breaks (SSBs as the initial damage contributes to DNA migration and/or to micronucleus formation. The lowest genotoxic dose (LGD, which is defined as the lowest dose at which each mutagen causes a positive response on each genotoxicity assay, was used to compare the power of the Comet assay to detect a low level of genotoxic potential and that of MN test; that is, a low LGD indicates a high power. Results are summarized as follows: (1 for all mutagens studied, LGDs were MN test ≦ Comet assay; (2 except for BLM, LGDs were Comet assay/araC ≦ MN test; (3 except for UVC and MNU, LGDs were acellular assay ≦ Comet assay/araC ≦ MN test ≦ Comet assay. The following is suggested by the present findings: (1 LGD in the Comet assay is higher than that in MN test, which suggests that the power of the MN test to detect a low level of genotoxic potential is superior to that of the Comet assay; (2 for the studied mutagens, all assays were able to detect all mutagens correctly, which suggests that the sensitivity of the Comet assay and that of the MN test were

  3. Active Asteroids: Main-Belt Comets and Disrupted Asteroids

    CERN Document Server

    Hsieh, Henry H

    2015-01-01

    The study of active asteroids has attracted a great deal of interest in recent years since the recognition of main-belt comets (which orbit in the main asteroid belt, but exhibit comet-like activity due to the sublimation of volatile ices) as a new class of comets in 2006, and the discovery of the first disrupted asteroids (which, unlike MBCs, exhibit comet-like activity due to a physical disruption such as an impact or rotational destabilization, not sublimation) in 2010. In this paper, I will briefly discuss key areas of interest in the study of active asteroids.

  4. The brightness variations of Comet Halley at large heliocentric distances

    Science.gov (United States)

    Flammer, K. R.; Jackson, B.; Houpis, H. L. F.; Mendis, D. A.

    1986-01-01

    The reasons for the intrinsic brightness variations of up to 500 percent on time scales as short as a few hours detected by Sekanina (1984) in Comet Halley between October 1982 and February 1984 are discussed. It is shown that solar wind-modulated electrostatic dust blowoff from the night side of the comet is consistent with the observed brightness variations. The variations coincide with the encounter of high-speed streams with the comet. The stream's propagation time to the comet and the sun's rotation during this transit were used to locate the stream origin on the coronal surface, and the results are shown.

  5. Comet 81P/wild 2 under a microscope

    Science.gov (United States)

    Brownlee, D.; Tsou, P.; Aleon, J.; O'D, Alexander; Araki, T.; Bajt, S.; Baratta, G.A.; Bastien, R.; Bland, P.; Bleuet, P.; Borg, J.; Bradley, J.P.; Brearley, A.; Brenker, F.; Brennan, S.; Bridges, J.C.; Browning, N.D.; Brucato, J.R.; Bullock, E.; Burchell, M.J.; Busemann, H.; Butterworth, A.; Chaussidon, M.; Cheuvront, A.; Chi, M.; Cintala, M.J.; Clark, B. C.; Clemett, S.J.; Cody, G.; Colangeli, L.; Cooper, G.; Cordier, P.; Daghlian, C.; Dai, Z.; D'Hendecourt, L.; Djouadi, Z.; Dominguez, G.; Duxbury, T.; Dworkin, J.P.; Ebel, D.S.; Economou, T.E.; Fakra, S.; Fairey, S.A.J.; Fallon, S.; Ferrini, G.; Ferroir, T.; Fleckenstein, H.; Floss, C.; Flynn, G.; Franchi, I.A.; Fries, M.; Gainsforth, Z.; Gallien, J.-P.; Genge, M.; Gilles, M.K.; Gillet, P.; Gilmour, J.; Glavin, D.P.; Gounelle, M.; Grady, M.M.; Graham, G.A.; Grant, P.G.; Green, S.F.; Grossemy, F.; Grossman, L.; Grossman, J.N.; Guan, Y.; Hagiya, K.; Harvey, R.; Heck, P.; Herzog, G.F.; Hoppe, P.; Horz, F.; Huth, J.; Hutcheon, I.D.; Ignatyev, K.; Ishii, H.; Ito, M.; Jacob, D.; Jacobsen, C.; Jacobsen, S.; Jones, S.; Joswiak, D.; Jurewicz, A.; Kearsley, A.T.; Keller, L.P.; Khodja, H.; Kilcoyne, A.L.D.; Kissel, J.; Krot, A.; Langenhorst, F.; Lanzirotti, A.; Le, L.; Leshin, L.A.; Leitner, J.; Lemelle, L.; Leroux, H.; Liu, M.-C.; Luening, K.; Lyon, I.; MacPherson, G.; Marcus, M.A.; Marhas, K.; Marty, B.; Matrajt, G.; McKeegan, K.; Meibom, A.; Mennella, V.; Messenger, K.; Messenger, S.; Mikouchi, T.; Mostefaoui, S.; Nakamura, T.; Nakano, T.; Newville, M.; Nittler, L.R.; Ohnishi, I.; Ohsumi, K.; Okudaira, K.; Papanastassiou, D.A.; Palma, R.; Palumbo, M.E.; Pepin, R.O.; Perkins, D.; Perronnet, M.; Pianetta, P.; Rao, W.; Rietmeijer, F.J.M.; Robert, F.; Rost, D.; Rotundi, A.; Ryan, R.; Sandford, S.A.; Schwandt, C.S.; See, T.H.; Schlutter, D.; Sheffield-Parker, J.; Simionovici, A.; Simon, S.; Sitnitsky, I.; Snead, C.J.; Spencer, M.K.; Stadermann, F.J.; Steele, A.; Stephan, T.

    2006-01-01

    The Stardust spacecraft collected thousands of particles from comet 81P/Wild 2 and returned them to Earth for laboratory study. The preliminary examination of these samples shows that the nonvolatile portion of the comet is an unequilibrated assortment of materials that have both presolar and solar system origin. The comet contains an abundance of silicate grains that are much larger than predictions of interstellar grain models, and many of these are high-temperature minerals that appear to have formed in the inner regions of the solar nebula. Their presence in a comet proves that the formation of the solar system included mixing on the grandest scales.

  6. The EISCAT meteor-head method – a review and recent observations

    Directory of Open Access Journals (Sweden)

    A. Pellinen-Wannberg

    2004-01-01

    Full Text Available Since the very first meteor observations at EISCAT in December 1990, the experimental method has improved significantly. This is due to a better understanding of the phenomenon and a recent major upgrade of the EISCAT signal processing and data storage capabilities. Now the simultaneous spatial-time resolution is under 100 m-ms class. To illuminate the meteor target for as long as possible and simultaneously get as good altitude resolution as possible, various coding techniques have been used, such as alternating Barker codes, Barker codes and random codes with extremely low side lobe effects. This paper presents some background and the current view of the meteor head echo process at EISCAT as well as the observations which support this view, such as altitude distributions, dual-frequency target sizes and vector velocities. It also presents some preliminary results from recent very high resolution tristatic observations.

  7. Spectra of Full 3-D PIC Simulations of Finite Meteor Trails

    Science.gov (United States)

    Tarnecki, L. K.; Oppenheim, M. M.

    2016-12-01

    Radars detect plasma trails created by the billions of small meteors that impact the Earth's atmosphere daily, returning data used to infer characteristics of the meteoroid population and upper atmosphere. Researchers use models to investigate the dynamic evolution of the trails. Previously, all models assumed a trail of infinite length, due to the constraints of simulation techniques. We present the first simulations of 3D meteor trails of finite length. This change more accurately captures the physics of the trails. We characterize the turbulence that develops as the trail evolves and study the effects of varying the external electric field, altitude, and initial density. The simulations show that turbulence develops in all cases, and that trails travel with the neutral wind rather than electric field. Our results will allow us to draw more detailed and accurate information from non-specular radar observations of meteors.

  8. Observations of the Quadrantid meteor shower from 2008 to 2012: Orbits and emission spectra

    Science.gov (United States)

    Madiedo, José M.; Espartero, Francisco; Trigo-Rodríguez, Josep M.; Castro-Tirado, Alberto J.; Pujols, Pep; Pastor, Sensi; de los Reyes, José A.; Rodríguez, Diego

    2016-09-01

    The activity of the Quadrantids in January during several years (2008, 2010, 2011 and 2012) has been investigated in the framework of the SPanish Meteor Network (SPMN). For this purpose, an array of high-sensitivity CCD video devices and CCD all-sky cameras have been used to obtain multi-station observations of these meteors. These allowed to obtain precise radiant and orbital information about this meteoroid stream. This paper presents a large set of orbital data (namely, 85 orbits) of Quadrantid meteoroids. Most meteors produced by these particles were recorded during the activity peak of this shower. Besides, we discuss four Quadrantid emission spectra. The tensile strength of Quadrantid meteoroids has been also obtained.

  9. Observations of the Quadrantid meteor shower from 2008 to 2012: orbits and emission spectra

    CERN Document Server

    Madiedo, José M; Trigo-Rodríguez, Josep M; Castro-Tirado, Alberto J; Pujols, Pep; Pastor, Sensi; Reyes, José A de los; Rodríguez, Diego

    2016-01-01

    The activity of the Quadrantids in January during several years (2008, 2010, 2011 and 2012) has been investigated in the framework of the SPanish Meteor Network (SPMN). For this purpose, an array of high-sensitivity CCD video devices and CCD all-sky cameras have been used to obtain multi-station observations of these meteors. These allowed us to obtain precise radiant and orbital information about this meteoroid stream. This paper presents a large set of orbital data (namely, 85 orbits) of Quadrantid meteoroids. Most meteors produced by these particles were recorded during the activity peak of this shower. Besides, we discuss four Quadrantid emission spectra. The tensile strength of Quadrantid meteoroids has been also obtained.

  10. Meteoric smoke and H2SO4 aerosols in the upper stratosphere and mesosphere

    Science.gov (United States)

    Hervig, Mark E.; Bardeen, Charles G.; Siskind, David E.; Mills, Michael J.; Stockwell, Robert

    2017-01-01

    Meteoric smoke has traditionally been understood as a passive tracer which follows the global mesospheric circulation. Smoke extinction measured by the Solar Occultation For Ice Experiment, however, shows that while this is true in the middle to upper mesosphere (pressure hPa), it is not true near the stratopause. Here the expected winter increase begins 3 months earlier than in models. We suggest that the autumn extinction increase is due to H2SO4 condensing above the nominal stratospheric aerosol layer ( 5 hPa). This is possible due to lowering of the H2SO4 saturation vapor pressure when the acid is neutralized through combination with meteoric metals. The appearance of neutralized H2SO4 aerosol in autumn is associated with the seasonal decrease in temperature. The combination of meteoric smoke and neutralized H2SO4 aerosols explains the observations and supports previous suggestions that H2SO4 could condense above the nominal stratospheric sulfate layer.

  11. FORCAST Observations of a Bright ToO Comet

    Science.gov (United States)

    Wooden, Diane

    2014-10-01

    We propose to measure the dust and organics of an unknown bright comet or comet outburst with this CY3 Target-of-Opportunity (ToO) proposal. A 5-27 micron spectrum coupled with 11, 19, and 31 micron dual-band photometry of a ToO bright comet with FORCAST will address our two primary goals: 1) characterize the coma dust mineralogy; and 2) identify organics in the critical 5-8 micron region. The crystalline fraction of comet dust has become a benchmark for models of heating and radial transport in our protoplanetary disk. In addition, by measuring the wavelengths, relative intensities, and feature asymmetries of crystalline peaks at 11.2, 19, and 23.5, 27.5, and 33 micron, the shapes of forsterite crystals can be constrained and their condensation temperatures inferred by comparison with theoretical and experimental data. Observations of cometary organics probe the unknown precursor materials that were transformed by heat into 'macromolecular carbon' found ubiquitously in carbonaceous chondrite samples from primitive asteroids. Thermal models fitted to FORCAST observations of a bright ToO comet determine the dust properties and the comet's dust properties links to the physical and chemical conditions in the solar nebula, and help to fulfill the SOFIA Science Case for Evolution of Our Solar System. We define a CY3 ToO bright comet as an unpredictable cometary outburst event or a comet discovered after the CY3 submission deadline that produces a comet with an integrated brightness of Veye within 2 months of discovery. FORCAST 5--31.5 micron observations of a bright comet will enable the study of dust mineral compositions and organic materials, will enable the search for controversial species including PAHs, phyllosilicates and carbonates, and will add to 17 comets with model-constrained silicate crystalline fractions.

  12. Extrasolar comets: The origin of dust in exozodiacal disks?

    Science.gov (United States)

    Marboeuf, U.; Bonsor, A.; Augereau, J.-C.

    2016-11-01

    Comets have been invoked in numerous studies as a potentially important source of dust and gas around stars, but none has studied the thermo-physical evolution, out-gassing rate, and dust ejection of these objects in such stellar systems. In this paper we investigate the thermo-physical evolution of comets in exo-planetary systems in order to provide valuable theoretical data required to interpret observations of gas and dust. We use a quasi-3D model of cometary nucleus to study the thermo-physical evolution of comets evolving around a single star from 0.1 to 50 AU, whose homogeneous luminosity varies from 0.1 to 70L⊙. This paper provides thermal evolution, physical alteration, mass ejection, lifetimes, and the rate of dust and water gas mass productions for comets as a function of the distance to the star and stellar luminosity. Results show significant physical changes to comets at high stellar luminosities. The mass loss per revolution and the lifetime of comets depend on their initial size, orbital parameters and follow a power law with stellar luminosity. The models are presented in such a manner that they can be readily applied to any planetary system. By considering the examples of the Solar System, Vega and HD 69830, we show that dust grains released from sublimating comets have the potential to create the observed (exo)zodiacal emission. We show that observations can be reproduced by 1 to 2 massive comets or by a large number of comets whose orbits approach close to the star. Our conclusions depend on the stellar luminosity and the uncertain lifetime of the dust grains. We find, as in previous studies, that exozodiacal dust disks can only survive if replenished by a population of typically sized comets renewed from a large and cold reservoir of cometary bodies beyond the water ice line. These comets could reach the inner regions of the planetary system following scattering by a (giant) planet.

  13. Siderophile element fractionation in meteor crater impact glasses and metallic spherules

    Science.gov (United States)

    Mittlefehldt, David W.; See, T. H.; Scott, E. R. D.

    1993-01-01

    Meteor Crater, Arizona provides an opportunity to study, in detail, elemental fractionation processes occurring during impacts through the study of target rocks, meteorite projectile and several types of impact products. We have performed EMPA and INAA on target rocks, two types of impact glass and metallic spherules from Meteor Crater. Using literature data for the well studied Canyon Diablo iron we can show that different siderophite element fractionations affected the impact glasses than affected the metallic spherules. The impact glasses primarily lost Au, while the metallic spherules lost Fe relative to other siderophile elements.

  14. Outbursting Comet P/2010 V1 (Ikeya-Murakami): A Miniature Comet Holmes

    CERN Document Server

    Ishiguro, Masateru; Hanayama, Hidekazu; Usui, Fumihiko; Sekiguchi, Tomohiko; Yanagisawa, Kenshi; Kuroda, Daisuke; Yoshida, Michitoshi; Ohta, Kouji; Kawai, Nobuyuki; Miyaji, Takeshi; Fukushima, Hideo; Watanabe, Jun-ichi

    2014-01-01

    Short-period comet P/2010 V1 (Ikeya-Murakami, hereafter V1) was discovered visually by two amateur astronomers. The appearance of the comet was peculiar, consisting of an envelope, a spherical coma near the nucleus and a tail extending in the anti-solar direction. We investigated the brightness and the morphological development of the comet by taking optical images with ground-based telescopes. Our observations show that V1 experienced a large-scale explosion between UT 2010 October 31 and November 3. The color of the comet was consistent with the Sun (g'-RC=0.61+-0.20, RC-IC=0.20+-0.20, and B-RC=0.93+-0.25), suggesting that dust particles were responsible for the brightening. We used a dynamical model to understand the peculiar morphology, and found that the envelope consisted of small grains (0.3-1 micron) expanding at a maximum speed of 500+-40 m/s, while the tail and coma were composed of a wider range of dust particle sizes (0.4-570 micron) and expansion speeds 7-390 m/s. The total mass of ejecta is ~5x1...

  15. Carbonaceous Components in the Comet Halley Dust

    Science.gov (United States)

    Fomenkova, M. N.; Chang, S.; Mukhin, L. M.

    1994-01-01

    Cometary grains containing large amounts of carbon and/or organic matter (CHON) were discovered by in situ measurements of comet Halley dust composition during VEGA and GIOTTO flyby missions. In this paper, we report the classification of these cometary, grains by means of cluster analysis, discuss the resulting compositional groups, and compare them with substances observed or hypothesized in meteorites, interplanetary dust particles, and the interstellar medium. Grains dominated by carbon and/or organic matter (CHON grains) represent approx. 22% of the total population of measured cometary dust particles. They, usually contain a minor abundance of rock-forming elements as well. Grains having organic material are relatively more abundant in the vicinity of the nucleus than in the outer regions of the coma, which suggests decomposition of the organics in the coma environment. The majority of comet Halley organic particles are multicomponent mixtures of carbon phases and organic compounds. Possibly, the cometary CHON grains may be related to kerogen material of an interstellar origin in carbonaceous meteorites. Pure carbon grains, hydrocarbons and polymers of cyanopolyynes, and multi-carbon monoxides are present in cometary dust as compositionally simple and distinctive components among a variety of others. There is no clear evidence of significant presence of pure formaldehyde or HCN polymers in Halley dust particles. The diversity of types of cometary organic compounds is consistent with the inter-stellar dust model of comets and probably reflects differences in composition of precursor dust. Preservation of this heterogeneity among submicron particles suggest the gentle formation of cometary, nucleus by aggregation of interstellar dust in the protosolar nebula without complete mixing or chemical homogenization at the submicron level.

  16. Ensemble Properties of Comets in the Sloan Digital Sky Survey

    Energy Technology Data Exchange (ETDEWEB)

    Solontoi, Michael; /Adler Planetarium, Chicago; Ivezic, Zeljko; /Washington U., Seattle, Astron. Dept.; Juric, Mario; /Harvard Coll. Observ.; Becker, Andrew C.; /Washington U., Seattle, Astron. Dept.; Jones, Lynne; /Washington U., Seattle, Astron. Dept.; West, Andrew A.; /Boston U.; Kent, Steve; /Fermilab; Lupton, Robert H.; /Princeton U. Observ.; Claire, Mark; /Washington U., Seattle, Astron. Dept.; Knapp, Gillian R.; /Princeton U. Observ.; Quinn, Tom; /Washington U., Seattle, Astron. Dept. /Princeton U. Observ.

    2012-02-01

    We present the ensemble properties of 31 comets (27 resolved and 4 unresolved) observed by the Sloan Digital Sky Survey (SDSS). This sample of comets represents about 1 comet per 10 million SDSS photometric objects. Five-band (u, g, r, i, z) photometry is used to determine the comets colors, sizes, surface brightness profiles, and rates of dust production in terms of the Afp formalism. We find that the cumulative luminosity function for the Jupiter Family Comets in our sample is well fit by a power law of the form N(comets. The resolved comets show an extremely narrow distribution of colors (0.57 {+-} 0.05 in g - r for example), which are statistically indistinguishable from that of the Jupiter Trojans. Further, there is no evidence of correlation between color and physical, dynamical, or observational parameters for the observed comets.

  17. Will Comet ISON (C/2012 S1) Survive Perihelion?

    Science.gov (United States)

    Knight, Matthew M.; Walsh, Kevin J.

    2013-10-01

    On 2013 November 28 Comet ISON (C/2012 S1) will pass by the Sun with a perihelion distance of 2.7 solar radii. Understanding the possible outcomes for the comet's response to such a close passage by the Sun is important for planning observational campaigns and for inferring ISON's physical properties. We present new numerical simulations and interpret them in context with the historical track record of comet disruptions and of sungrazing comet behavior. Historical data suggest that sizes below ~200 m are susceptible to destruction by sublimation driven mass loss, while we find that for ISON's perihelion distance, densities lower than 0.1 g cm-3 are required to tidally disrupt a retrograde or non-spinning body. Such low densities are substantially below the range of the best-determined comet nucleus densities, though dynamically new comets such as ISON have few measurements of physical properties. Disruption may occur for prograde rotation at densities up to 0.7 g cm-3, with the chances of disruption increasing for lower density, faster prograde rotation, and increasing elongation of the nucleus. Given current constraints on ISON's nucleus properties and the typically determined values for these properties among all comets, we find tidal disruption to be unlikely unless other factors (e.g., spin-up via torquing) affect ISON substantially. Whether or not disruption occurs, the largest remnant must be big enough to survive subsequent mass loss due to sublimation in order for ISON to remain a viable comet well after perihelion.

  18. Water production models for Comet Bradfield (1979 l)

    Science.gov (United States)

    Weaver, H. A.; Feldman, P. D.; Festou, M. C.

    1981-01-01

    The IUE observations of Comet Bradfield (1979 l) made 10 January 1980 to 3 March 1980 permit a detailed study of water production for this comet. Brightness measurements are presented for all three water dissociation products, H, O, and OH, and comparisons are made with model predictions. The heliocentric variation of the water production rate was derived.

  19. Direct Detection of Extra-Solar Comets is Possible

    OpenAIRE

    Jura, M.

    2005-01-01

    The dust tails of comets similar to Hale-Bopp can scatter as much optical light as does the Earth. Space-based observatories such as the Terrestrial Planet Finder or Darwin that will detect extra-solar terrestrial planets also will be able to detect extra-solar comets.

  20. The Formation Age of Comets: Predicted Physical and Chemical Trends

    Science.gov (United States)

    Nuth, J. A., III; Hill, H. G. M.

    2000-01-01

    The chemical composition of a comet has always been considered to be a function of where it formed in the nebula. We suggest that the most important factor in determining a comet's chemistry might actually be when it formed. Specific predictions are presented.

  1. Dormant Comets in the Near-Earth Asteroid Population

    NARCIS (Netherlands)

    Mommert, Michael; Harris, Alan W.; Mueller, Michael; Hora, Joseph L.; Trilling, David E.; Knight, Matthew; Bottke, William F.; Thomas, Cristina; Delbo', Marco; Emery, Josh P.; Fazio, Giovanni; Smith, Howard A.

    2015-01-01

    The population of near-Earth objects comprises active comets and asteroids, covering a wide range of dynamical parameters and physical properties. Dormant (or extinct) comets, masquerading as asteroids, have long been suspected of supplementing the near-Earth asteroid (NEA) population. We present a

  2. Mission to a comet that could save earth

    CERN Multimedia

    Utton, T

    2003-01-01

    Scientists are going to attempt to land a probe on the comet Wirtanen. The GBP640million unmanned craft will travel four billion miles before catching up with the comet Wirtanen and launching a robotic lander called Rosetta, on to its surface (1/2 page).

  3. The Comet Assay: Tails of the (Unexpected. Use of the comet assay in pharmaceutical development.

    Directory of Open Access Journals (Sweden)

    Bas-jan Van Der Leede

    2015-08-01

    Full Text Available In genotoxicity testing of pharmaceuticals the rodent alkaline comet assay is being increasingly used as a second in vivo assay in addition to the in vivo micronucleus assay to mitigate in vitro positive results as recommended by regulatory guidance. In this presentation we want to give insight into the circumstances in vivo comet assay is deployed in a Genetic Toxicology Department of a pharmaceutical company. As the in vivo comet assay is a salvage assay, it means that some events have occurred in an in vitro assay and that the compound (or metabolite responsible for this signal is potentially deselected for further development. More than often the decision to perform an in vivo comet assay is at a very early stage in development and the first time that the compound will be tested in vivo at high/toxic dose levels. As almost no toxicokinetic data and tissue distribution data are available a careful design with maximizes the chances for successful mitigation is necessary. Decisions on acute or repeated dosing need to be made and arrangements for combining the in vivo comet assay with the in vivo micronucleus assay are to be considered. Often synthesis methods need to be scaled up fast to provide the required amount of compound and information on suitable formulations needs to be in place. As exposure data is crucial for interpretation of results, analytical methods need to be brought in place rapidly. An experienced multi skilled and communicative team needs to be available to deploy successfully this kind of assays at an early stage of development. We will present a few scenarios on study conduct and demonstrate how this assay can make a difference for the further development of a new drug.

  4. Interstellar nomads: The problem of detecting comets

    Science.gov (United States)

    Jones, Eric M.; Newman, William I.; Campbell, Donald B.

    1993-01-01

    This paper shows that, using only a modest extrapolation of current phased-array radar and massively parallel processor computer technologies, radar transmitter in the outer solar system or in interstellar space could be used to detect comets passing within 1 or 2 AU of the transmitter. It discusses how this potential development could be instrumental to the colonisation of the outer solar system and beyond. This development is germane to contemporary investigations of the population of the Oort cloud as well as to the Search for Extraterrestrial Intelligence (SETI) question.

  5. The spectroscopy of comets: Introductory remarks

    Science.gov (United States)

    Delsemme, A. H.

    1981-10-01

    Emphasis in cometary spectroscopy is on production rates, becuase they open the door to more fundamental clues about the origin and the history of the solar system, through the understanding of comet chemistry. In order to establish production rates quantitatively, suggestion are provided, in particular: to study the lifetimes of all hypothetical parents, against all processes of decay, namely photodissociations, photoionizations and ion-molecule reactions; and to study the velocity of all molecular fragments resulting from all the decay processes, through the balance sheet of the energy distribution before and after each decay process.

  6. ESA Unveils Its New Comet Chaser.

    Science.gov (United States)

    1999-07-01

    The objective is to study one of these primordial objects at close quarters by placing a lander on its surface and chasing, with an orbiter, the comet for millions of kilometres through space. Comets - among the oldest (4.6 billion years!) and last altered objects in the solar system - are regarded as the building blocks from which the planets formed. Thus the Rosetta's discoveries will allow the scientists to learn more about birth and evolution of the planets and about the origin of life on the Earth. The final design of the Rosetta orbiter will be revealed for the first time at the Royal Society in London on 1 July when a 1:4 scale model will be unveiled by ESA's Director of Science, Prof.. Roger Bonnet. (The full size version of the spacecraft is 32 metres across, so large that it would stretch the entire width of a football pitch. Almost 90 of this is accounted for by the giant solar panels which are needed to provide electrical power in the dark depths of the Solar System). "Rosetta is a mission of major scientific importance," said Prof. Bonnet. "It will build on the discoveries made by Giotto and confirm ESA's leading role in the exploration of the Solar System and the Universe as a whole." The timing of this event has been chosen to coincide with the London meeting of the Rosetta Science Working Team and the second Earth flyby of the now non-operational Giotto spacecraft. In addition, the opening of the British Museum's 'Cracking Codes' Exhibition, for which the Rosetta Stone is the centrepiece, is set to take place on 10 July. The Rosetta mission. Rosetta is the third Cornerstone in ESA's 'Horizon 2000' long-term scientific programme. It will be launched by Ariane 5 rocket from Kourou spaceport in French Guiana in January 2003. In order to gain sufficient speed to reach the distant comet, Rosetta will require gravity assists from the Earth (twice) and Mars. After swinging around Mars in May 2005, Rosetta will return to Earth's vicinity in October 2005 and

  7. On shock waves and the role of hyperthermal chemistry in the early diffusion of overdense meteor trains

    Science.gov (United States)

    Silber, Elizabeth A.; Hocking, Wayne K.; Niculescu, Mihai L.; Gritsevich, Maria; Silber, Reynold E.

    2017-08-01

    Studies of meteor trails have until now been limited to relatively simple models, with the trail often being treated as a conducting cylinder, and the head (if considered at all) treated as a ball of ionized gas. In this article, we bring the experience gleaned from other fields to the domain of meteor studies, and adapt this prior knowledge to give a much clearer view of the microscale physics and chemistry involved in meteor-trail formation, with particular emphasis on the first 100 or so milliseconds of the trail formation. We discuss and examine the combined physicochemical effects of meteor-generated and ablationally amplified cylindrical shock waves that appear in the ambient atmosphere immediately surrounding the meteor train, as well as the associated hyperthermal chemistry on the boundaries of the high temperature post-adiabatically expanding meteor train. We demonstrate that the cylindrical shock waves produced by overdense meteors are sufficiently strong to dissociate molecules in the ambient atmosphere when it is heated to temperatures in the vicinity of 6000 K, which substantially alters the considerations of the chemical processes in and around the meteor train. We demonstrate that some ambient O2, along with O2 that comes from the shock dissociation of O3, survives the passage of the cylindrical shock wave, and these constituents react thermally with meteor metal ions, thereby subsequently removing electrons from the overdense meteor train boundary through fast, temperature-independent, dissociative recombination governed by the second Damköhler number. Possible implications for trail diffusion and lifetimes are discussed.

  8. Onset of sublimation in comet P/Halley (1982i)

    Science.gov (United States)

    Wyckoff, S.; Wagner, R. M.; Wehinger, P. A.; Schleicher, D. G.; Festou, M. C.

    1985-01-01

    The first direct evidence for the onset of sublimation of a comet nucleus is reported. Emission due to CN observed in spectra of the comet P/Halley provides evidence for the development of the gas coma. Broad-band photometric observations of the comet indicate that the dust coma developed near a preperihelion heliocentric distance r of about 6 AU. Rates of gas production and brightening for the comet have been derived at r of 4-6 AU. The mean preperihelion nuclear magnitude derived for the comet was used to calculate an effective radius of the nucleus, which for plausible values of the geometric albedo lies in the range 1-4 km.

  9. Modelling the surface deposition of meteoric smoke particles

    Science.gov (United States)

    Brooke, James S. A.; Feng, Wuhu; Mann, Graham W.; Dhomse, Sandip S.; Bardeen, Charles G.; Plane, John M. C.

    2016-04-01

    The flux of meteoric smoke particles (MSPs) in Greenland and Antarctica has been measured using Ir and Pt observations in ice cores, by Gabrielli et al. [1,2]. They obtained MSP deposition fluxes of 1.5 ± 0.45 × 10-4 g m-2 yr-1 (209 ± 63 t d-1) in Greenland and 3.9 ± 1.4 × 10-5 g m-2 yr-1 (55 ± 19 t d-1) in Antarctica, where the values in parentheses are total atmospheric inputs, assuming a uniform global deposition rate. These results show reasonable agreement with those of Lanci et al. [3], who used ice core magnetisation measurements, resulting in MSP fluxes of 1.7 ± 0.23 × 10-4 g m-2 yr-1 (236 ± 50 t d-1) (Greenland) and 2.0 ± 0.52 × 10-5 g m-2 yr-1 (29 ± 5.0 t d-1) (Antarctica). Atmospheric modelling studies have been performed to assess the transport and deposition of MSPs, using WACCM (Whole Atmosphere Community Climate Model), and the CARMA (Community Aerosol and Radiation Model) aerosol microphysics package. An MSP input function totalling 44 t d-1 was added between about 80 and 105 km. Several model runs have been performed in which the aerosol scavenging by precipitation was varied. Wet deposition is expected (and calculated here) to be the main deposition process; however, rain and snow aerosol scavenging coefficients have uncertainties spanning up to two and three orders of magnitude, respectively [4]. The model experiments that we have carried out include simple adjustments of the scavenging coefficients, full inclusion of a parametrisation reported by Wang et al. [4], and a scheme based on aerosol removal where relative humidity > 100 %. The MSP fluxes obtained vary between 1.4 × 10-5 and 2.6 × 10-5 g m-2 yr-1 for Greenland, and 5.1 × 10-6 and 1.7 × 10-5 g m-2 yr-1 for Antarctica. These values are about an order of magnitude lower than the Greenland observations, but show reasonable agreement for Antarctica. The UM (Unified Model), UKCA (United Kingdom Chemistry and Aerosols Model), and GLOMAP (GLObal Model of Aerosol Processes) have

  10. Meteor bodies entering the Martian atmosphere: possible impact consequences

    Science.gov (United States)

    Kuznetsova, Daria; Gritsevich, Maria

    The investigation of meteorite production on Mars has attracted considerable attention during the recent years. The possible meteorite showers are identified e.g. [1], and the estimates of meteorite fluxes on Mars are found e.g. [2,3]. In this study, we develop the theory describing a meteoroid entry into an atmosphere of a planet and apply our results to the Martian atmosphere. We introduce two key dimensionless parameters, which are based on physical parameterization and have unique values for every single meteoroid case. This allows us to derive the condition for the meteorite fall identification in a simple analytical form, which can be directly implemented for analysis and classification of the possible impact consequences. To describe the motion we use the classical equations of the model of meteor body deceleration [4,5]. The analytical dimensionless solution for the mass-velocity dependence and the height-velocity dependence can be expressed using two main parameters: (i) the ballistic coefficient alpha, which shows the ratio between the mass of the atmospheric column along the trajectory and the body's pre-entry mass, and (ii) the mass loss parameter beta, which is proportional to the ratio between the initial kinetic energy of the body and energy which is required to insure total mass loss of the body due to ablation and fragmentation [6-8]. To determine the possible consequences of impact for any given meteoroid, we use the meteorite-fall condition: the terminal mass of the meteoroid should exceed or be equal to a certain chosen value. This condition can be written using the parameters alpha and beta, so the impact consequences are described by the position of the case-under-investigation point relatively to the boundary curve in the (alpha,beta) space. Following a number of studies [9-11] we analyze the hypothesis that describes the possible evolution of Martian atmospheric density until present. Based on the properties of the meteorites recently found

  11. THE PHOTODISSOCIATION OF FORMALDEHYDE IN COMETS

    Energy Technology Data Exchange (ETDEWEB)

    Feldman, Paul D., E-mail: pfeldman@jhu.edu [Department of Physics and Astronomy, The Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218 (United States)

    2015-10-20

    Observations of comets in the 905–1180 Å spectral band made with the Far Ultraviolet Spectroscopic Explorer in 2001 and 2004 show unusual features in the fluorescent emissions of CO and H{sub 2}. These include emission from a non-thermal high-J rotational population of CO and solar Lyα induced fluorescence from excited vibrational levels of H{sub 2}, both of which are attributed to the photodissociation of formaldehyde. In this paper we model the large number of observed H{sub 2} lines and demonstrate the dependence of the pumping on the heliocentric velocity of the comet and the solar line profiles. We also derive the rotational and vibrational populations of H{sub 2} and show that they are consistent with the results of laboratory studies of the photodissociation of H{sub 2}CO. In addition to the principal series of H i and O i, the residual spectrum is found to consist mainly of the Rydberg series of C i multiplets from which we derive the mean carbon column abundance in the coma. Fluorescent emissions from N i and N{sub 2} are also searched for.

  12. Carbon production in comet West 1975n

    Energy Technology Data Exchange (ETDEWEB)

    Feldman, P.D.; Brune, W.H.

    1976-10-01

    Ultraviolet spectra of comet West at moderate resolution in the wavelength range 1200--3200 A were obtained with scanning spectrophotometers aboard an Aerobee 200 rocket launched 1976 March 5.49. The principal emission features observed are lines of C, O, and C/sup +/ and bands of OH, CO, CO/sup +/, and CO/sub 2//sup +/. Estimates of the production rates of OH (and thus H/sub 2/O), C, CO, and O are 9.6, 3.1, 4.2, and 11 (all in units of 10/sup 29/ s/sup -1/), respectively. These rates are consistent with photodissociation of H/sub 2/O and CO from a source in which the CO is one-third as abundant as water. The C I (/sup 1/D--/sup 1/P/sup 0/) line at 1931 A indicates that a large fraction of the carbon is produced in the metastable /sup 1/D state. While CO/sub 2/ cannot be definitively excluded, the spectroscopic evidence favors CO as the major carbon constituent of the comet. (AIP)

  13. Design Architecture and Initial Results from an FPGA Based Digital Receiver for Multistatic Meteor Measurements

    Science.gov (United States)

    Palo, Scott; Vaudrin, Cody

    Defined by a minimal RF front-end followed by an analog-to-digital converter (ADC) and con-trolled by a reconfigurable logic device (FPGA), the digital receiver will replace conventional heterodyning analog receivers currently in use by the COBRA meteor radar. A basic hardware overview touches on the major digital receiver components, theory of operation and data han-dling strategies. We address concerns within the community regarding the implementation of digital receivers in small-scale scientific radars, and outline the numerous benefits with a focus on reconfigurability. From a remote sensing viewpoint, having complete visibility into a band of the EM spectrum allows an experiment designer to focus on parameter estimation rather than hardware limitations. Finally, we show some basic multistatic receiver configurations enabled through GPS time synchronization. Currently, the digital receiver is configured to facilitate range and radial velocity determination of meteors in the MLT region for use with the COBRA meteor radar. Initial measurements from data acquired at Platteville, Colorado and Tierra Del Fuego in Argentina will be presented. We show an improvement in detection rates compared to conventional analog systems. Scientific justification for a digital receiver is clearly made by the presentation of RTI plots created using data acquired from the receiver. These plots reveal an interesting phenomenon concerning vacillating power structures in a select number of meteor trails.

  14. New additional material of meteor showers during 9th -19th centuries in the Islamic history

    CERN Document Server

    Basurah, Hassan M

    2012-01-01

    This article presents twelve records of meteor showers in Arabic chronicles covering period from the 9th to the 19th century. The observations were in Egypt, Morocco, Syria and Yemen. These new addition historical records are considered to be important events which indicate a serious current interest in astronomy.

  15. MU head echo observations of the 2010 Geminids: radiant, orbit, and meteor flux observing biases

    Directory of Open Access Journals (Sweden)

    J. Kero

    2013-03-01

    Full Text Available We report Geminid meteor head echo observations with the high-power large-aperture (HPLA Shigaraki middle and upper atmosphere (MU radar in Japan (34.85° N, 136.10° E. The MU radar observation campaign was conducted from 13 December 2010, 08:00 UTC to 15 December, 20:00 UTC and resulted in 48 h of radar data. A total of ~ 270 Geminids were observed among ~ 8800 meteor head echoes with precisely determined orbits. The Geminid head echo activity is consistent with an earlier peak than the visual Geminid activity determined by the International Meteor Organization (IMO. The observed flux of Geminids is a factor of ~ 3 lower than the previously reported flux of the 2009 Orionids measured with an identical MU~radar setup. We use the observed flux ratio to discuss the relation between the head echo mass–velocity selection effect, the mass distribution indices of meteor showers and the mass threshold of the MU radar.

  16. Fragmentation of specular overdense meteor trail echoes observed with Gadanki MST radar

    Science.gov (United States)

    Chenna Reddy, K.; Yellaiah, G.

    2016-02-01

    The pulse-integrated signal to noise ratio as a function of time known as radar meteor light curve (analogous to optical light curve), is an indicative of ablation processes during meteoroid flight in the atmosphere. In this study, we present and discuss few examples of light curves of long duration specular overdense meteor echoes detected with 53 MHz Gadanki (13.5°N, 79.2°E) MST radar. These echoes are of several seconds duration, where pulsation in amplitude is about ten cycles within few seconds. This means the fluctuations in amplitude are much slower than typical Fresnel oscillations of underdense as well as the head echo fluctuations. These light curves reveal several features unreported previously in the radar meteor returns that are consistent with meteoroid fragmentation. Some of them provide the strong observational evidence of a sub-millimeter-sized meteoroid, breaking apart into two distinct fragments. The pulsations in light curves are interpreted as being due to interference from two distinct scattering centers. Some other meteor events such as meteoroids undergoing quasi-continuous disintegration are also discussed.

  17. In situ 10Be-26Al exposure ages at Meteor Crater, Arizona

    Science.gov (United States)

    Nishiizumi, K.; Kohl, C.P.; Shoemaker, E.M.; Arnold, J.R.; Klein, J.; Fink, D.; Middleton, R.

    1991-01-01

    A new method of dating the surface exposure of rocks from in situ production of 10Be and 26Al has been applied to determine the age of Meteor Crater, Arizona. A lower bound on the crater age of 49,200 ?? 1,700 years has been obtained by this method. ?? 1991.

  18. In situ Be-10-Al-26 exposure ages at Meteor Crater, Arizona

    Science.gov (United States)

    Nishiizumi, K.; Kohl, C. P.; Arnold, J. R.; Shoemaker, E. M.; Klein, J.; Fink, D.; Middleton, R.

    1991-01-01

    A new method of dating the surface exposure of rocks from in situ production of Be-10 and Al-26 has been applied to determine the age of Meteor Crater, Arizona. A lower bound on the crater age of 49,200 + or - 1,700 years has been obtained by this method.

  19. An analysis of the physical, chemical, optical, and historical impacts of the 1908 Tunguska meteor fall

    Science.gov (United States)

    Turco, R. P.; Toon, O. B.; Park, C.; Whitten, R. C.; Pollack, J. B.; Noerdlinger, P.

    1982-01-01

    An analysis is presented of the physical characteristics and photochemical aftereffects of the 1908 Tunguska explosive cometary meteor, whose physical manifestations are consistent with a five million ton object's entry into the earth's atmosphere at 40 km/sec. Aerodynamic calculations indicate that the shock waves emanating from the falling meteor could have generated up to 30 million tons of nitric oxide in the stratosphere and mesosphere. A fully interactive one-dimensional chemical-kinetics model of atmospheric trace constituents is used to estimate the photochemical consequences of such a large NO injection. The 35-45% hemispherical ozone depletion predicted by the model is in keeping with the 30 + or - 15% ozone variation reported for the first year after the Tunguska fall. Attention is also given to the optical anomalies which followed the event for indications of NO(x)-O(x) chemiluminescent emissions, NO2 solar absorption, and meteoric dust turbidity, along with possible climate changes due to the nearly one million tons of pulverized dust deposited in the mesosphere and stratosphere by the meteor.

  20. Meteor reporting made easy- The Fireballs in the Sky smartphone app

    Science.gov (United States)

    Sansom, E.; Ridgewell, J.; Bland, P.; Paxman, J.

    2016-01-01

    Using smartphone technology, the award-winning 'Fireballs in the Sky' app provides a new approach to public meteor reporting. Using the internal GPS and sensors of a smartphone, a user can record the start and end position of a meteor sighting with a background star field as reference. Animations are used to visualize the duration and characteristics of the meteor. The intuitive application can be used in situ, providing a more accurate eye witness account than after-the-fact reports (although reports may also be made through a website interface). Since its launch in 2013, the app has received over 2000 submissions, including 73 events which were reported by multiple users. The app database is linked to the Desert Fireball Network in Australia (DFN), meaning app reports can be confirmed by DFN observatories. Supporting features include an integrated meteor shower tool that provides updates on active showers, their visibility based on moon phase, as well as a tool to point the user toward the radiant. The locations of reports are also now shown on a live map on the Fireballs in the Sky webpage.

  1. Effects of probiotics on the faecal production of hydrogen and methane in patients with meteorism

    DEFF Research Database (Denmark)

    Schrøder, Julie Bernstorf; Jespersen, Lene; Westermann, Peter

    Meteorism is a dominating problem in the western world, especially in women. The condition is very difficult to quantify, and effective and documented therapies are not avaiable. We wanted to develop a method for measuring anaerobic production of hydrogen and methane in faeces, and to correlate t...

  2. Theories of comets to the age of Laplace

    Science.gov (United States)

    Heidarzadeh, Tofigh

    Although the development of ideas about cometary motion has been investigated in several projects, a comprehensive and detailed survey of physical theories of comets has not been conducted. The available works either illustrate relatively short periods in the history of physical cometology or portray a landscape view without adequate details. The present study is an attempt to depict the details of the major physical theories of comets from Aristotle to the age of Laplace. The basic question from which this project originated was simple: how did natural philosophers and astronomers define the nature and place of a new category of celestial objects--the comets--after Brahe's estimation of cometary distances? However, a study starting merely from Brahe without covering classical and medieval thought about comets would be incomplete. Thus, based on the fundamental physical characteristics attributed to comets, the history of cometology may be divided into three periods: from Aristotle to Brahe, in which comets were assumed to be meteorological phenomena; from Brahe to Newton, when comets were admitted as celestial bodies but with unknown trajectories; and from Newton to Laplace, in which they were treated as members of the solar system having more or less the same properties of the planets. By estimating the mass of comets in the 1800s, Laplace diverted cometology into a different direction wherein they were considered among the smallest bodies in the solar system and deprived of the most important properties that had been used to explain their physical constitution during the previous two millennia. Ideas about the astrological aspects of comets are not considered in this study. Also, topics concerning the motion of comets are explained to the extent that is helpful in illustrating their physical properties. The main objective is to demonstrate the foundations of physical theories of comets, and the interaction between observational and mathematical astronomy, and

  3. Comet Hunters: A Citizen Science Project to Search for Comets in the Main Asteroid Belt

    Science.gov (United States)

    Hsieh, Henry H.; Schwamb, Megan Elizabeth; Zhang, Zhi-Wei; Chen, Ying-Tung; Wang, Shiang-Yu; Lintott, Chris

    2016-10-01

    Fully automated detection of comets in wide-field surveys remains a challenge, as even highly successful comet-finding surveys like Pan-STARRS rely on a combination of both automated flagging algorithms and vetting by human eyes. To take advantage of the long-noted superiority of the human eye over computer algorithms in certain types of pattern recognition, particularly when dealing with a range of target morphologies of interest, we have created a citizen science website with the aim of allowing the general public to aid in the search for active asteroids, which are objects that occupy dynamically asteroidal orbits yet exhibit comet-like dust emission due to sublimation, impact disruption, rotational destabilization, or other effects. Located at comethunters.org, the Comet Hunters website was built using the Zooniverse Project Builder (https://www.zooniverse.org/lab), and displays images of known asteroids obtained either from archival data obtained between 1999 and 2014 by the Suprime-Cam wide-field imager mounted on the 8-m Subaru telescope on Mauna Kea in Hawaii, or more contemporary data obtained by the Hyper Suprime-Cam (HSC) wide-field imager also on the Subaru Telescope as part of the ongoing HSC Subaru Strategic Program (SSP) survey. By using observations from such a large-aperture telescope, most of which have never been searched for solar system objects, much less cometary ones, we expect that volunteers should be able to make genuinely scientifically significant discoveries, and also provide valuable insights into the potential and challenges of searching for comets in the LSST era. To date, over 13,000 registered volunteers have contributed 350,000 classifications. We will discuss the design and construction of the Comet Hunters website, and also discuss early results from the project.This work uses data generated via the Zooniverse.org platform, development of which was supported by a Global Impact Award from Google, and by the Alfred P. Sloan

  4. Observations of meteor-head echoes using the Jicamarca 50MHz radar in interferometer mode

    Directory of Open Access Journals (Sweden)

    J. L. Chau

    2004-01-01

    Full Text Available We present results of recent observations of meteor-head echoes obtained with the high-power large-aperture Jicamarca 50MHz radar (11.95°S, 76.87°W in an interferometric mode. The large power-aperture of the system allows us to record more than 3000 meteors per hour in the small volume subtended by the 1° antenna beam, albeit when the cluttering equatorial electrojet (EEJ echoes are not present or are very weak. The interferometry arrangement allows the determination of the radiant (trajectory and speed of each meteor. It is found that the radiant distribution of all detected meteors is concentrated in relative small angles centered around the Earth's Apex as it transits over the Jicamarca sky, i.e. around the corresponding Earth heading for the particular observational day and time, for all seasons observed so far. The dispersion around the Apex is ~18° in a direction transverse to the Ecliptic plane and only 8.5° in heliocentric longitude in the Ecliptic plane both in the Earth inertial frame of reference. No appreciable interannual variability has been observed. Moreover, no population related to the optical (larger meteors Leonid showers of 1998-2002 is found, in agreement with other large power-aperture radar observations. A novel cross-correlation detection technique (adaptive match-filtering is used in combination with a 13 baud Barker phase-code. The technique allows us to get good range resolution (0.75km without any sensitivity deterioration for the same average power, compared to the non-coded long pulse scheme used at other radars. The matching Doppler shift provides an estimation of the velocity within a pulse with the same accuracy as if a non-coded pulse of the same length had been used. The velocity distribution of the meteors is relatively narrow and centered around 60kms-1. Therefore most of the meteors have an almost circular retrograde orbit around the Sun. Less than 8% of the velocities correspond to interstellar orbits

  5. Tracing hillslope sediment production and transport with in situ and meteoric 10Be

    Science.gov (United States)

    Jungers, Matthew C.; Bierman, Paul R.; Matmon, Ari; Nichols, Kyle; Larsen, Jennifer; Finkel, Robert

    2009-12-01

    We use in situ-produced and meteoric 10Be, analyzed in soils from 28 pits on four hillcrest-parallel transects along a 14° hillslope in the Great Smoky Mountains, North Carolina, as tracers of soil production and transport. We rely upon amalgamation both to investigate and smooth spatial variability in 10Be concentrations. Lidar indicates that the hillslope is topographically complex and that soil is moved downslope diffusively until it encounters the ephemeral channel network and is rapidly exported. In situ-produced 10Be, measured in depth profiles, indicates that over millennial timescales, soils are mixed above the soil-saprolite boundary. In contrast, meteoric 10Be concentrations increase with depth and are correlated to concurrent increases of dithionite-extractable Al and pH, observations explained by similar Al and Be mobility in the soil. The concentrations of both meteoric and in situ-produced 10Be increase downslope proportional to the maximum soil particle path length. The data suggest virtual downslope soil velocities of 1.1-1.7 cm yr-1 in a well-mixed active transport layer ˜60 cm thick. The thickness of this transport layer is constant downslope and depends on the rooting depth and consequent root wad thickness of downed trees on the slope, both of which reflect depth to the soil/saprolite boundary. Both meteoric and in situ-produced 10Be suggest that soil production is balanced by surface denudation at rates between 10 and 13 m Myr-1. Soil residence times on the slope range from 21 to 33 kyr based on the meteoric 10Be inventories. Major element geochemical analysis suggests little if any elemental loss during soil transport downslope.

  6. Meteoroid orbits from video meteors. The case of the Geminid stream

    Science.gov (United States)

    Hajduková, Mária, Jr.; Koten, Pavel; Kornoš, Leonard; Tóth, Juraj

    2017-09-01

    We use the Slovak and Czech video meteor observations, as well as video meteoroid orbits collected in the CAMS, SonotaCo, EDMOND and DMS catalogues, for an analysis of the distribution of meteoroid orbits within the stream of the Geminids and of the dispersion of their radiants. We concentrate on the influence of the measurement errors on the precision of the orbits obtained from the video networks that are based on various meteor-detection software packages and various meteor orbital element softwares. The Geminids radiant dispersion obtained from the large video catalogues reaches the dispersion of the radio observed Geminids, whereby the diffused marginal regions are affected mostly by meteoroids with extreme values (small or large) of the semi-major axes. Meteoroids of shorter semi-major axes concentrate at the eastern side of the radiant area and those of longer semi-major axes at the western part. The observed orbital dispersions in the Geminid stream described by the median absolute deviation range from 0.029 to 0.042 AU-1 for the video catalogues. The distribution of the semi-major axes of video meteors in all the databases, except for the Ondřejov (Czech) data, seem to be systematically biased in comparison with the photographic and radio meteors. The determined velocities of the video data are underestimated, probably as a consequence of the methods used for the positional and velocity measurements. The largest shift is observed in the EDMOND and SonotaCo catalogues. Except for the measurement errors which influence the analyses and their interpretations, we also point out the problem of the uncertainties of the numerical integration procedures that influence the simulations' results. Several experimental integrations of the Geminids parent asteroid, which we performed from the present to the past and then back to the year 2015, showed that a complete reproduction, including also the mean anomaly, is only possible for a time span of about 2700 years.

  7. Meteor head echo polarization at 930 MHz studied with the EISCAT UHF HPLA radar

    Directory of Open Access Journals (Sweden)

    G. Wannberg

    2011-06-01

    Full Text Available The polarization characteristics of 930-MHz meteor head echoes have been studied for the first time, using data obtained in a series of radar measurements carried out with the tristatic EISCAT UHF high power, large aperture (HPLA radar system in October 2009. An analysis of 44 tri-static head echo events shows that the polarization of the echo signal recorded by the Kiruna receiver often fluctuates strongly on time scales of tens of microseconds, illustrating that the scattering process is essentially stochastic. On longer timescales (> milliseconds, more than 90 % of the recorded events show an average polarization signature that is independent of meteor direction of arrival and echo strength and equal to that of an incoherent-scatter return from underdense plasma filling the tristatic observation volume. This shows that the head echo plasma targets scatter isotropically, which in turn implies that they are much smaller than the 33-cm wavelength and close to spherically symmetric, in very good agreement with results from a previous EISCAT UHF study of the head echo RCS/meteor angle-of-incidence relationship.

    Significant polarization is present in only three events with unique target trajectories. These all show a larger effective target cross section transverse to the trajectory than parallel to it. We propose that the observed polarization may be a signature of a transverse charge separation plasma resonance in the region immediately behind the meteor head, similar to the resonance effects previously discussed in connection with meteor trail echoes by Herlofson, Billam and Browne, Jones and Jones and others.

  8. Autonomous Onboard Science Data Analysis for Comet Missions

    Science.gov (United States)

    Thompson, David R.; Tran, Daniel Q.; McLaren, David; Chien, Steve A.; Bergman, Larry; Castano, Rebecca; Doyle, Richard; Estlin, Tara; Lenda, Matthew

    2012-01-01

    Coming years will bring several comet rendezvous missions. The Rosetta spacecraft arrives at Comet 67P/Churyumov-Gerasimenko in 2014. Subsequent rendezvous might include a mission such as the proposed Comet Hopper with multiple surface landings, as well as Comet Nucleus Sample Return (CNSR) and Coma Rendezvous and Sample Return (CRSR). These encounters will begin to shed light on a population that, despite several previous flybys, remains mysterious and poorly understood. Scientists still have little direct knowledge of interactions between the nucleus and coma, their variation across different comets or their evolution over time. Activity may change on short timescales so it is challenging to characterize with scripted data acquisition. Here we investigate automatic onboard image analysis that could act faster than round-trip light time to capture unexpected outbursts and plume activity. We describe one edge-based method for detect comet nuclei and plumes, and test the approach on an existing catalog of comet images. Finally, we quantify benefits to specific measurement objectives by simulating a basic plume monitoring campaign.

  9. Comet plasma densities deduced from refraction of occulted radio sources

    Energy Technology Data Exchange (ETDEWEB)

    Wright, C.S. (Commonwealth Department of Science, Ionospheric Prediction Service, Narrabri, New South Wales, Australia); Nelson, G.J. (Commonwealth Scientific and Industrial Research Organization, Div. of Radiophysics, Narrabri, New South Wales, Australia)

    1979-04-01

    Observations of the occultation of radio sources by comet plasma tails are used to derive the electron density and density gradients in the tails. Occultations of source Culgoora-1 0300+16 by Comet Kohoutek and of Culgoora-1 2313-14 by Comet West were measured by radioheliograph at 80 MHz. After corrections for ionospheric refraction, a 2 arcmin anomaly was observed in the declination of 0300+16, attributed to refraction by the tail of Comet Kohoutek, while none was observed for Comet West. The maximum electron density in the tail of Comet Kohoutek is calculated to be 2 x 10 to the 4th/cu cm, while that of Comet West is 5 x 10 to the 4th/cu cm, with density gradients of about 0.05 per cu cm per km. The direction of refraction observed suggests that the tail of Kohoutek is either highly asymmetric about its axis or has the form of a hollow, cylindrical plasma sheath. The high electron densities observed in Kohoutek may indicate the presence of undetected ion species or a low ionization loss rate.

  10. Dynamic Sublimation Pressure and the Catastrophic Breakup of Comet ISON

    CERN Document Server

    Steckloff, Jordan K; Bowling, Timothy; Melosh, H Jay; Minton, David; Lisse, Carey M; Battams, Karl

    2015-01-01

    Previously proposed mechanisms have difficulty explaining the disruption of Comet C/2012 S1 (ISON) as it approached the Sun. We describe a novel cometary disruption mechanism whereby comet nuclei fragment and disperse through dynamic sublimation pressure, which induces differential stresses within the interior of the nucleus. When these differential stresses exceed its material strength, the nucleus breaks into fragments. We model the sublimation process thermodynamically and propose that it is responsible for the disruption of Comet ISON. We estimate the bulk unconfined crushing strength of Comet ISON's nucleus and the resulting fragments to be 0.5 Pa and 1-9 Pa respectively, assuming typical Jupiter Family Comet (JFC) albedos. However, if Comet ISON has an albedo similar to Pluto, this strength estimate drops to 0.2 Pa for the intact nucleus and 0.6-4 Pa for its fragments. Regardless of assumed albedo, these are similar to previous strength estimates of JFCs. This suggests that, if Comet ISON is representat...

  11. Sodium D-line emission in Comet West (1975n) and the sodium source in Comets

    Energy Technology Data Exchange (ETDEWEB)

    Oppenheimer, M.

    1980-09-15

    A spectrum of the sodium D-line emission from Comet West (1975n) taken at heliocentric distance 1.4 AU is analyzed by comparing the D-line brightness to that in the underlying continuum. Using the observations of this comet by Ney and Merrill, we find that the dust grains which dominate the visible and infrared continua are too cool to to provide the observed sodium atoms through evaporation of sodium metal or a sodium compound from grain surfaces. Though sodium metal may evaporate from a small-grain component, we suggest that molecules embedded in the volatile nuclear matrix are a more plausible source of sodium. The relationship between this source and the interstellar sodium abundance is discussed.

  12. Dust emission from comets at large heliocentric distances. I - The case of comet Bowell /1980b/

    Science.gov (United States)

    Houpis, H. L. F.; Mendis, D. A.

    1981-01-01

    Alternative processes of dust emission from comets at large heliocentric distances are considered, in order to explain the dust coma observed in comet Bowell (1980b) at a heliocentric distance as large as 7.17 AU. It is shown that the electrostatic blow-off of dust from a charged, H2O-dominated nucleus having a layer of loose, fine dust may be the formation process of the dust coma, with the coma size expected from the process being comparable to the observed value and the dust grain size being equal to or less than 0.4 microns in size. The upper limit for the total mass in the coma is 3.9 x 10 to the 8th g, and the spatial extension less than 10,000 km. The observed activity may alternatively be due to dust entrainment by the sublimating gas from a CO2-dominated nucleus.

  13. Recommendations for safety testing with the in vivo comet assay.

    Science.gov (United States)

    Vasquez, Marie Z

    2012-08-30

    While the in vivo comet assay increases its role in regulatory safety testing, deliberations about the interpretation of comet data continue. Concerns can arise regarding comet assay publications with limited data from non-blind testing of positive control compounds and using protocols (e.g. dose concentrations, sample times, and tissues) known to give an expected effect. There may be a tendency towards bias when the validation or interpretation of comet assay data is based on results generated by widely accepted but non-validated assays. The greatest advantages of the comet assay are its sensitivity and its ability to detect genotoxicity in tissues and at sample times that could not previously be evaluated. Guidelines for its use and interpretation in safety testing should take these factors into account. Guidelines should be derived from objective review of data generated by blind testing of unknown compounds dosed at non-toxic concentrations and evaluated in a true safety-testing environment, where the experimental design and conclusions must be defensible. However, positive in vivo comet findings with such compounds are rarely submitted to regulatory agencies and this data is typically unavailable for publication due to its proprietary nature. To enhance the development of guidelines for safety testing with the comet assay, and with the permission of several sponsors, this paper presents and discusses relevant data from multiple GLP comet studies conducted blind, with unknown pharmaceuticals and consumer products. Based on these data and the lessons we have learned through the course of conducting these studies, I suggest significant adjustments to the current conventions, and I provide recommendations for interpreting in vivo comet assay results in situations where risk must be evaluated in the absence of carcinogenicity or clinical data.

  14. Where are the mini Kreutz-family comets?

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Quan-Zhi; Wiegert, Paul A. [Department of Physics and Astronomy, The University of Western Ontario, London, Ontario N6A 3K7 (Canada); Hui, Man-To [Department of Earth, Planetary and Space Sciences, University of California at Los Angeles, 595 Charles Young Drive East, Los Angeles, CA 90095-1567 (United States); Kracht, Rainer, E-mail: qye22@uwo.ca [Ostlandring 53, D-25335 Elmshorn, Schleswig-Holstein (Germany)

    2014-12-01

    The Kreutz family of sungrazing comets contains over 2000 known members, many of which are believed to be under ∼100 m sizes (mini comets) and have only been studied at small heliocentric distances (r {sub H}) with space-based SOHO/STEREO spacecraft. To understand the brightening process of mini Kreutz comets, we conducted a survey using CFHT/MegaCam at moderate r {sub H} guided by SOHO/STEREO observations. We identify two comets that should be in our search area but are not detected, indicating that the comets have either followed a steeper brightening rate within the previously reported rapid brightening stage (the brightening burst), or the brightening burst starts earlier than expected. We present a composite analysis of the pre-perihelion light curves of five Kreutz comets that cover to ∼1 AU. We observe significant diversity in the light curves that can be used to grossly classify them into two types: C/Ikeya-Seki and C/SWAN follow the canonical r{sub H}{sup −4} while the others follow r{sub H}{sup −7}. In particular, C/SWAN seems to have undergone an outburst (Δm > 5 mag) or a rapid brightening (n ≳ 11) between r {sub H} = 1.06 AU and 0.52 AU, and shows hints of structural/compositional differences compared to other bright Kreutz comets. We also find evidence that the Kreutz comets as a population lose their mass less efficiently than the dynamically new comet, C/ISON, and are relatively devoid of species that drive C/ISON's activity at large r {sub H}. Concurrent observations of C/STEREO in different wavelengths also suggest that a blueward species such as CN may be the main driver for brightening bursts, instead of sodium as previously thought.

  15. Gas Arcs in Comet Hyakutake: Revisited

    Science.gov (United States)

    Combi, M. R.; Harris, W. M.; Kabin, K.

    2000-10-01

    The recent break-up of the nucleus of Comet LINEAR S4 demonstrates that fragmentation is an important cometary process and that it is not a rare phenomenon. Comet Hyakutake (1996 B2) underwent an outburst of gas production on March 21, 1996. Subsequent to the outburst, fragments, or condensations as they have been called, were observed moving tailward from the position of the nucleus. Arc-shaped structures were seen in images of gas species (OH, CN and C2) providing clear evidence of production of gas from cometary nucleus debris also tailward of the nucleus. We have already (Harris et al. 1997, Science 277, 676) described observations taken with the WIYN telescope consisting of a 6-hour time sequence of images on March 26, 1996 of CN and dust continuum and a single OH image showing that the arc, and by inference it's source, was generally moving tailward with the visible condensations. The entire OH arc was reproduced using a kinetic Direct Simulation Monte Carlo (DSMC) calculation for water and all its photodissociation products. DSMC is suited to this physical environment that is in transition from fluid conditions in the inner coma to free-expansion in the outer coma. Our model asuming a string of fragments within the apex of the arc (i.e., the intersection of the arc and the tailward sun-comet line) reproduced the arc. Here we present a more extensive parameter study of the arc using DSMC and a solution of the standard perfect-fluid Euler equations. We find that a secondary source just behind the apex of the arc can reproduce the OH arc, but the location of the source must be much closer to the apex than indicated by solutions of the Navier-Stokes equations (NSE) (Rodionov et al. 1998, Icarus 136, 232). We find that we must use unrealistically large collision cross sections to reproduce the NSE results, and that the NSE results are not substantially different from a simpler Euler equation approach. This work has been supported by NASA Planetary Atmospheres

  16. Outbursting Comet P/2010 V1 (Ikeya-Murakami): A Miniature Comet Holmes

    Science.gov (United States)

    Ishiguro, Masateru; Jewitt, David; Hanayama, Hidekazu; Usui, Fumihiko; Sekiguchi, Tomohiko; Yanagisawa, Kenshi; Kuroda, Daisuke; Yoshida, Michitoshi; Ohta, Kouji; Kawai, Nobuyuki; Miyaji, Takeshi; Fukushima, Hideo; Watanabe, Jun-ichi

    2014-05-01

    The short-period comet P/2010 V1 (Ikeya-Murakami, hereafter "V1") was discovered visually by two amateur astronomers. The appearance of the comet was peculiar, consisting of an envelope, a spherical coma near the nucleus and a tail extending in the anti-solar direction. We investigated the brightness and the morphological development of the comet by taking optical images with ground-based telescopes. Our observations show that V1 experienced a large-scale explosion between UT 2010 October 31 and November 3. The color of the comet was consistent with the Sun (g' - R C = 0.61 ± 0.20, R C - I C = 0.20 ± 0.20, and B - R C = 0.93 ± 0.25), suggesting that dust particles were responsible for the brightening. We used a dynamical model to understand the peculiar morphology, and found that the envelope consisted of small grains (0.3-1 μm) expanding at a maximum speed of 500 ± 40 m s-1, while the tail and coma were composed of a wider range of dust particle sizes (0.4-570 μm) and expansion speeds 7-390 m s-1. The total mass of ejecta is ~5 × 108 kg and kinetic energy ~5 × 1012 J. These values are much smaller than in the historic outburst of 17P/Holmes in 2007, but the energy per unit mass (1 × 104 J kg-1) is comparable. The energy per unit mass is about 10% of the energy released during the crystallization of amorphous water ice suggesting that crystallization of buried amorphous ice can supply the mass and energy of the outburst ejecta.

  17. Outbursting comet P/2010 V1 (Ikeya-Murakami): A miniature comet Holmes

    Energy Technology Data Exchange (ETDEWEB)

    Ishiguro, Masateru [Department of Physics and Astronomy, Seoul National University, Gwanak, Seoul 151-742 (Korea, Republic of); Jewitt, David [Department of Earth, Planetary and Space Sciences, University of California at Los Angeles, 595 Charles Young Drive East, Los Angeles, CA 90095-1567 (United States); Hanayama, Hidekazu; Miyaji, Takeshi; Fukushima, Hideo; Watanabe, Jun-ichi [Ishigakijima Astronomical Observatory, National Astronomical Observatory of Japan, Ishigaki, Okinawa 907-0024 (Japan); Usui, Fumihiko [Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Sekiguchi, Tomohiko [Department of Teacher Training, Hokkaido University of Education, 9 Hokumon, Asahikawa 070-8621 (Japan); Yanagisawa, Kenshi; Kuroda, Daisuke [Okayama Astrophysical Observatory, National Astronomical Observatory of Japan, Asaguchi, Okayama 719-0232 (Japan); Yoshida, Michitoshi [Hiroshima Astrophysical Science Center, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Ohta, Kouji [Department of Astronomy, Kyoto University, Kyoto 606-8502 (Japan); Kawai, Nobuyuki [Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551 (Japan)

    2014-05-20

    The short-period comet P/2010 V1 (Ikeya-Murakami, hereafter {sup V}1{sup )} was discovered visually by two amateur astronomers. The appearance of the comet was peculiar, consisting of an envelope, a spherical coma near the nucleus and a tail extending in the anti-solar direction. We investigated the brightness and the morphological development of the comet by taking optical images with ground-based telescopes. Our observations show that V1 experienced a large-scale explosion between UT 2010 October 31 and November 3. The color of the comet was consistent with the Sun (g' – R {sub C} = 0.61 ± 0.20, R {sub C} – I {sub C} = 0.20 ± 0.20, and B – R {sub C} = 0.93 ± 0.25), suggesting that dust particles were responsible for the brightening. We used a dynamical model to understand the peculiar morphology, and found that the envelope consisted of small grains (0.3-1 μm) expanding at a maximum speed of 500 ± 40 m s{sup –1}, while the tail and coma were composed of a wider range of dust particle sizes (0.4-570 μm) and expansion speeds 7-390 m s{sup –1}. The total mass of ejecta is ∼5 × 10{sup 8} kg and kinetic energy ∼5 × 10{sup 12} J. These values are much smaller than in the historic outburst of 17P/Holmes in 2007, but the energy per unit mass (1 × 10{sup 4} J kg{sup –1}) is comparable. The energy per unit mass is about 10% of the energy released during the crystallization of amorphous water ice suggesting that crystallization of buried amorphous ice can supply the mass and energy of the outburst ejecta.

  18. Comet C/2011 L4 (PanStarrs): Small nucleus, fast rotator and dust rich comet observed after perihelion

    CERN Document Server

    Scarmato, Toni

    2016-01-01

    Orbital elements of C2011 L4 (PanStarrs) Oort cloud comet, computed by MPC (Minor Planet Center, Minor Planet Electronic Circular 2012-T08), show that the closest approach to the Sun occurred on 2013 March 10th, at about 0.3 A.U., then about 4,51x10^7 km. Discovered by Richard Wainscoat (Institute for Astronomy, University of Hawaii) on four CCD images taken with the 1.8-m "Pan-STARRS 1" telescope at Haleakala taken on 2011 June 6th. My first observation of the comet was on 2013 March 10th whit the comet visible in the twilight. I did the following visual estimation; Mar. 10.73,-1.0*,5'(T. Scarmato, Calabria, Italy, 7x50 binoculars; altitude 7 deg, tail 1 deg in pa 140 deg), reported to the ICQ (International Comet Quarterly). Easy comet in 7x50 binoculars I started to see C/2011 L4 at 18:35 L.T. when the comet was at about 7{\\deg} above the horizon. I saw a tail long about 1,5{\\deg} in pa 140{\\deg} with a coma well condensed and large about 5'. I followed the comet until to the set at 18:55 L.T., still clear...

  19. Imaging polarimetry of Comet C/2013 V1 (Boattini) and Comet 290P/Jager before and after perihelion

    CERN Document Server

    Roy, P Deb; Das, H S; Medhi, B J

    2015-01-01

    We report the results obtained from the optical polarimetric study of the light scattered by Comet C/2013 V1 (Boattini) and Comet 290P/Jager at lower phase angles. The polarimetric observations of two comets have been performed with the 1.04-metre Sampurnanand telescope of ARIES near Nainital in India on 4th \\& 5th of December, 2013 and on 24th April, 2014 using R photometric band ($\\lambda$ = 630 nm, $\\Delta$$\\lambda$ =120nm). We covered observations in both the pre and post perihelion passage of Comet C/2013 V1 (Boattini) and Comet 290P/Jager at two phase angles $\\sim$ 13$^\\circ$ and 27$^\\circ$. The degree of polarization changes from ($-1.4$$\\pm 0.3$)\\% to (+2.8$\\pm 0.5$)\\% for Comet C/2013 V1 (Boattini) and ($-1.6$$\\pm 0.5$)\\% to (+2.5$\\pm 0.5$)\\% for Comet 290P/Jager at phase angles $\\sim$ 13$^\\circ$ and 27$^\\circ$ respectively. The change in the physical properties of cometary dust is being well studied from the polarization maps obtained for both the period of observations. It is found that the ape...

  20. A new proxy of comet impacts?

    Science.gov (United States)

    Kasatkina, E.; Shumilov, O.; Lukina, N.

    Environmental consequences of impacts by comets and asteroids depend on their sizes. The impact of 10 km sized asteroid killed off the dinosaurs 65 million years ago. A comet impact in AD 536 (>500 m diameter) caused a global climatic downturn. An impact of Tunguska-sized (50 m diameter) object (TO) could devastate a 2000 km -2 forest area, roughly the size of Moscow or New York. Among some misteries of the Tunguska event an important role plays the cause of the accelerated tree growth after 1908 in the catastrophe area. The main explanation is that an accelerated growth of old trees is a result of decrease of the level of competition due to falling of trees. We analyzed tree rings in larch samples collected in the Taymir region of Northern Siberia (72N; 105E) at a distance of about 1500 km to the North from the Tunguska catastrophe epicenter (61N; 102E). It was found that tree ring growth is 150% higher in 1908. We also analyzed all available Siberian tree-ring series (more than 100). It was found that there is a considerable increase of tree ring growth in 1908 over a huge area of Siberia (60N-75N; 60E-110E). It is obvious that the above mentioned interpretation could hardly explain the effect observed. Most likely the tree growth was stimulated by the TO matter spreaded over a large territory of Eurasia and introduced into the soil. It is generally believed that meteorites and comets delivered large amounts of organic to the early Earth. Another hypothesis is connected to NO produced during the Tunguska event. The cometary (probably fragment of the comet Enke) tail started to influence the Earth atmosphere several days before the fall of the meteorite causing optical anomalies observed mainly to the West from the place of TO explosion (Western Siberia, European Russia, Northern Europe). It is interesting that we've discovered nearly the similar, but smaller (about 50%) increase of tree ring growth connected to the Chulym bolide impact in 1984. The Chulym bolide