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Sample records for sunspot penumbra detected

  1. Detection of sea-serpent field lines in sunspot penumbrae

    CERN Document Server

    Dalda, A Sainz

    2007-01-01

    We investigate the spatial distribution of magnetic polarities in the penumbra of a spot observed very close to disk center. High-spatial resolution, high-cadence magnetograms taken with the Narrowband Filter Imager aboard Hinode are used in this study. They provide continuous and stable measurements in the photospheric Fe I 630.25 line for long periods of time. We discover small-scale, elongated, bipolar magnetic structures that appear in the mid penumbra and move radially outward across the penumbra. They occur in between the more vertical fields of the penumbra, and can be associated with the horizontal fields that harbor the Evershed flow. Many of them cross the outer penumbral boundary, becoming moving magnetic features in the sunspot moat. We determine the properties of these structures, including their sizes, proper motions, footpoint separation, and lifetimes. The bipolar patches can be interpreted as being produced by sea-serpent field lines that originate in the mid-penumbra and eventually leave the...

  2. Anomalous flows in a sunspot penumbra

    CERN Document Server

    Louis, Rohan E; Mathew, Shibu K; Venkatakrishnan, P

    2014-01-01

    High-resolution spectropolarimetric observations of active region NOAA 11271 were obtained with the spectro-polarimeter on board Hinode to analyze the properties of an anomalous flow in the photosphere in a sunspot penumbra. We detect a blue-shifted feature that appeared on the limb-side penumbra of a sunspot and that was present intermittently during the next two hours. It exhibited a maximum blue-shift of 1.6 km/s, an area of 5.2 arcsec^2, and an uninterrupted lifetime of 1 hr. The blue-shifted feature, when present, lies parallel to red-shifts. Both blue and red shifts flank a highly inclined/horizontal magnetic structure that is radially oriented in the penumbra. The low-cadence SP maps reveal changes in size, radial position in the penumbra and line-of-sight velocity of the blue-shifted feature, from one scan to the other. There was an increase of nearly 500 G in the field strength and a marginal reduction in the field inclination of about 10 deg with the onset of the blue-shifts. In the chromosphere, in...

  3. Models and observations of sunspot penumbrae

    Institute of Scientific and Technical Information of China (English)

    BORRERO; Juan; Manuel

    2009-01-01

    The mysteries of sunspot penumbrae have been under an intense scrutiny for the past 10 years. During this time, some models have been proposed and refuted, while the surviving ones had to be modified, adapted and evolved to explain the ever-increasing array of observational constraints. In this contribution I will review two of the present models, emphasizing their contributions to this field, but also pinpointing some of their inadequacies to explain a number of recent observations at very high spatial resolution (0.32 ). To help explaining these new observations I propose some modifications to each of those models. These modifications bring those two seemingly opposite models closer together into a general picture that agrees well with recent 3D magneto-hydrodynamic simulations.

  4. Models and Observations of Sunspot Penumbrae

    CERN Document Server

    Borrero, J M

    2008-01-01

    The mysteries of sunspot penumbrae have been under an intense scrutiny for the past 10 years. During this time, some models have been proposed and refuted, while the surviving ones had to be modified, adapted and evolved to explain the ever-increasing array of observational constraints. In this contribution I will review two of the present models, emphasizing their contributions to this field, but also pinpointing some of their inadequacies to explain a number of recent observations at very high spatial resolution. To help explaining these new observations I propose some modifications to each of them. These modifications bring those two seemingly opposite models closer together into a general picture that agrees well with recent 3D magneto-hydrodynamic simulations.

  5. A Curious History of Sunspot Penumbrae

    CERN Document Server

    Hathaway, D H

    2013-01-01

    Daily records of sunspot group areas compiled by the Royal Observatory, Greenwich, from May of 1874 through 1976 indicate a curious history for the penumbral areas of the smaller sunspot groups. On average, the ratio of penumbral area to umbral area in a sunspot group increases from 5 to 6 as the total sunspot group area increases from 100 to 2000 microHem (a microHem is a millionth the area of a solar hemisphere). This relationship does not vary substantially with sunspot group latitude or with the phase of the sunspot cycle. However, for the sunspot groups with total areas <100 microHem, this ratio changes dramatically and systematically through this historical record. The ratio for these smallest sunspots is near 5.5 from 1874 to 1900. After a rapid rise to more than 7 in 1905 it drops smoothly to less than 3 by 1930 and then rises smoothly back to more than 7 in 1961. It then returns to near 5.5 from 1965 to 1976. The smooth variation from 1905 to 1961 shows no indication of any step-like changes that ...

  6. Peculiarity of the oscillation stratification in sunspot penumbrae

    CERN Document Server

    Kolobov, D Y; Kobanov, N I

    2016-01-01

    Spatial distributions of the dominant oscillation frequency obtained for four sunspots show a feature shared by all the analysed levels of the solar atmosphere in these sunspots. This feature located in the inner penumbrae indicates that this region has favourable conditions for 2.5-4 mHz oscillation propagation. This agrees with the fact that the spectral composition of the oscillations at three atmospheric heights (FeI 6173{\\AA}, 1700{\\AA}, and He II 304{\\AA}) in this region are similar. There have been previous evidence of particular similarities along height of photospheric magnetic field strength, line-of-sight velocity, and temperature profile in the inner penumbra, where the internal boundary of the Evershed flow is located. The finding of the same dominant oscillation frequency at a range of altitudes from the chromosphere up to the transition region extends the height range, suggesting similarities in physical conditions.

  7. Inclination of magnetic fields and flows in sunspot penumbrae

    Science.gov (United States)

    Langhans, K.; Scharmer, G. B.; Kiselman, D.; Löfdahl, M. G.; Berger, T. E.

    2005-06-01

    An observational study of the inclination of magnetic fields and flows in sunspot penumbrae at a spatial resolution of 0.2 arcsec is presented. The analysis is based on longitudinal magnetograms and Dopplergrams obtained with the Swedish 1-m Solar Telescope on La Palma using the Lockheed Solar Optical Universal Polarimeter birefringent filter. Data from two sunspots observed at several heliocentric angles between 12 ° and 39 ° were analyzed. We find that the magnetic field at the level of the formation of the Fe i-line wing (630.25 nm) is in the form of coherent structures that extend radially over nearly the entire penumbra giving the impression of vertical sheet-like structures. The inclination of the field varies up to 45 ° over azimuthal distances close to the resolution limit of the magnetograms. Dark penumbral cores, and their extensions into the outer penumbra, are prominent features associated with the more horizontal component of the magnetic field. The inclination of this dark penumbral component - designated B - increases outwards from approximately 40 ° in the inner penumbra such that the field lines are nearly horizontal or even return to the solar surface already in the middle penumbra. The bright component of filaments - designated A - is associated with the more vertical component of the magnetic field and has an inclination with respect to the normal of about 35 ° in the inner penumbra, increasing to about 60 ° towards the outer boundary. The magnetogram signal is lower in the dark component B regions than in the bright component A regions of the penumbral filaments. The measured rapid azimuthal variation of the magnetogram signal is interpreted as being caused by combined fluctuations of inclination and magnetic field strength. The Dopplergrams show that the velocity field associated with penumbral component B is roughly aligned with the magnetic field while component A flows are more horizontal than the magnetic field. The observations give

  8. The formation of sunspot penumbra. I. Magnetic field properties

    CERN Document Server

    Rezaei, Reza; Schlichenmaier, Rolf

    2011-01-01

    We study the formation of a sunspot penumbra in the active region NOAA11024. We simultaneously observed the Stokes parameters of the photospheric iron lines at 1089.6 nm with the TIP and 617.3 nm with the GFPI spectropolarimeters along with broad-band images using G-band and CaIIK filters at the German VTT. The formation of the penumbra is intimately related to the inclined magnetic field. Within 4.5 h observing time, the magnetic flux of the penumbra increases from 9.7E+20 to 18.2E+20 Mx, while the magnetic flux of the umbra remains constant at about 3.8E+20 Mx. Magnetic flux in the immediate surroundings is incorporated into the spot, and new flux is supplied via small flux patches (SFPs), which on average have a flux of 2-3E+18 Mx. The spot's flux increase rate of 4.2E+16 Mx/s corresponds to the merging of one SFP per minute. We also find that during the formation of the spot penumbra: a) the maximum magnetic field strength of the umbra does not change, b) the magnetic neutral line keeps the same position ...

  9. Convective motions and net circular polarization in sunspot penumbrae

    CERN Document Server

    Borrero, J M

    2009-01-01

    We have employed a penumbral model, that includes the Evershed flow and convective motions inside penumbral filaments, to reproduce the azimuthal variation of the net circular polarization (NCP) in sunspot penumbrae at different heliocentric angles for two different spectral lines. The theoretical net circular polarization fits the observations as satisfactorily as penumbral models based on flux-tubes. The reason for this is that the effect of convective motions on the NCP is very small compared to the effect of the Evershed flow. In addition, the NCP generated by convective upflows cancels out the NCP generated by the downflows. We have also found that, in order to fit the observed NCP, the strength of the magnetic field inside penumbral filaments must be very close to 1000 G. In particular, field-free or weak-field filaments fail to reproduce both the correct sign of the net circular polarization, as well as its dependence on the azimuthal and heliocentric angles.

  10. The Fine-Structure of the Net-Circular Polarization in a Sunspot Penumbra

    CERN Document Server

    Tritschler, A; Schlichenmaier, R; Hagenaar, H J

    2007-01-01

    We present novel evidence for a fine structure observed in the net-circular polarization (NCP) of a sunspot penumbra based on spectropolarimetric measurements utilizing the Zeeman sensitive FeI 630.2 nm line. For the first time we detect a filamentary organized fine structure of the NCP on spatial scales that are similar to the inhomogeneities found in the penumbral flow field. We also observe an additional property of the visible NCP, a zero-crossing of the NCP in the outer parts of the center-side penumbra, which has not been recognized before. In order to interprete the observations we solve the radiative transfer equations for polarized light in a model penumbra with embedded magnetic flux tubes. We demonstrate that the observed zero-crossing of the NCP can be explained by an increased magnetic field strength inside magnetic flux tubes in the outer penumbra combined with a decreased magnetic field strength in the background field. Our results strongly support the concept of the uncombed penumbra.

  11. High-resolution proper motions in a sunspot penumbra

    CERN Document Server

    Márquez, I; Bonet, J A

    2006-01-01

    Local correlation tracking techniques are used to measure proper motions in a series of high angular resolution (~0.1 arcsec) penumbra images. If these motions trace true plasma motions, then we have detected converging flows that arrange the plasma in long narrow filaments co-spatial with dark penumbral filaments. Assuming that these flows are stationary, the vertical stratification of the atmosphere and the conservation of mass suggest downflows in the filaments of the order of 200 m/s. The association between downflows and dark features may be a sign of convection, as it happens with the non-magnetic granulation. Insufficient spatial resolution may explain why the estimated vertical velocities are not fast enough to supply the radiative losses of penumbrae.

  12. Analytical Model of an Asymmetric Sunspot with a Steady Plasma Flow in its Penumbra

    Science.gov (United States)

    Solov'ev, A. A.; Kirichek, E. A.

    2016-08-01

    A new exact analytical solution to the stationary problem of ideal magnetohydrodynamics is derived for an unipolar asymmetric sunspot immersed in a realistic solar atmosphere. The radial and vertical profiles of pressure, plasma density, and temperature in the visible layers of the sunspot are calculated. The reduction in plasma density in the magnetic funnel of the sunspot, corresponding to the Wilson depression, is also obtained. The magnetic structure of the sunspot is given analytically in a realistic way: a part of the magnetic flux of the sunspot approaches the surrounding photosphere at the outer edge of the penumbra. The magnetic field of the sunspot is not assumed to be axially symmetric. For the first time, the angular dependence of the physical variables in this model allows us to simulate not only a deviation from the circular shape of the sunspot, but also a fine filamentary structure of the sunspot penumbra. The Alfvén Mach number (the ratio of the plasma speed to the Alfvén speed) is zero at the center of the sunspot and rises slowly toward the periphery of the sunspot; this corresponds to the structure of the Evershed flow in the penumbra. The Evershed flow in our model is mainly concentrated in dark penumbral filaments, as is observed.

  13. Twist, Writhe & Helicity in the inner penumbra of a sunspot

    CERN Document Server

    Cobo, Basilio Ruiz

    2011-01-01

    The aim of this work is the determination of the twist, writhe, and self magnetic helicity of penumbral filaments located in an inner Sunspot penumbra. To this extent, we inverted data taken with the spectropolarimeter (SP) aboard {\\it Hinode} with the SIR (Stokes Inversion based on Response function) code. For the construction of a 3D geometrical model we applied a genetic algorithm minimizing the divergence of $\\vec{B}$ and the net magnetohydrodynamic force, consequently a force-free solution would be reached if possible. We estimated two proxies to the magnetic helicity frequently used in literature: the force-free parameter $\\alpha_z$ and the current helicity term $h_{c_{z}}$. We show that both proxies are only qualitative indicators of the local twist as the magnetic field in the area under study significantly departures from a force-free configuration. The local twist shows significant values only at the borders of bright penumbral filaments with opposite signs on each side. These locations are precisel...

  14. Magnetic fields of opposite polarity in sunspot penumbrae

    Science.gov (United States)

    Franz, M.; Collados, M.; Bethge, C.; Schlichenmaier, R.; Borrero, J. M.; Schmidt, W.; Lagg, A.; Solanki, S. K.; Berkefeld, T.; Kiess, C.; Rezaei, R.; Schmidt, D.; Sigwarth, M.; Soltau, D.; Volkmer, R.; von der Luhe, O.; Waldmann, T.; Orozco, D.; Pastor Yabar, A.; Denker, C.; Balthasar, H.; Staude, J.; Hofmann, A.; Strassmeier, K.; Feller, A.; Nicklas, H.; Kneer, F.; Sobotka, M.

    2016-11-01

    Context. A significant part of the penumbral magnetic field returns below the surface in the very deep photosphere. For lines in the visible, a large portion of this return field can only be detected indirectly by studying its imprints on strongly asymmetric and three-lobed Stokes V profiles. Infrared lines probe a narrow layer in the very deep photosphere, providing the possibility of directly measuring the orientation of magnetic fields close to the solar surface. Aims: We study the topology of the penumbral magnetic field in the lower photosphere, focusing on regions where it returns below the surface. Methods: We analyzed 71 spectropolarimetric datasets from Hinode and from the GREGOR infrared spectrograph. We inferred the quality and polarimetric accuracy of the infrared data after applying several reduction steps. Techniques of spectral inversion and forward synthesis were used to test the detection algorithm. We compared the morphology and the fractional penumbral area covered by reversed-polarity and three-lobed Stokes V profiles for sunspots at disk center. We determined the amount of reversed-polarity and three-lobed Stokes V profiles in visible and infrared data of sunspots at various heliocentric angles. From the results, we computed center-to-limb variation curves, which were interpreted in the context of existing penumbral models. Results: Observations in visible and near-infrared spectral lines yield a significant difference in the penumbral area covered by magnetic fields of opposite polarity. In the infrared, the number of reversed-polarity Stokes V profiles is smaller by a factor of two than in the visible. For three-lobed Stokes V profiles the numbers differ by up to an order of magnitude.

  15. Flare induced penumbra formation in the sunspot of NOAA 10838

    CERN Document Server

    Padinhatteeri, Sreejith

    2010-01-01

    We have observed formation of penumbrae on a pore in the active region NOAA10838 using Dunn Solar Telescope at NSO,Sunpot,USA. Simultaneous observations using different instruments (DLSP,UBF,Gband and CaK) provide us with vector magnetic field at photosphere, intensity images and Doppler velocity at different heights from photosphere to chromosphere. Results from our analysis of this particular data-set suggests that penumbrae are formed as a result of relaxation of magnetic field due to a flare happening at the same time. Images in \\Halpha\\ show the flare (C 2.9 as per GOES) and vector magnetic fields show a re-orientation and reduction in the global $\\alpha$ value (a measure of twist). We feel such relaxation of loop structures due to reconnections or flare could be one of the way by which field lines fall back to the photosphere to form penumbrae.

  16. Flare induced penumbra formation in the sunspot of NOAA 10838

    OpenAIRE

    Padinhatteeri, Sreejith; K., Sankarasubramanian

    2010-01-01

    We have observed formation of penumbrae on a pore in the active region NOAA10838 using Dunn Solar Telescope at NSO,Sunpot,USA. Simultaneous observations using different instruments (DLSP,UBF,Gband and CaK) provide us with vector magnetic field at photosphere, intensity images and Doppler velocity at different heights from photosphere to chromosphere. Results from our analysis of this particular data-set suggests that penumbrae are formed as a result of relaxation of magnetic field due to a fl...

  17. The multi-component field topology of sunspot penumbrae - A diagnostic tool for spectropolarimetric measurements

    CERN Document Server

    Mueller, D A N; Fritz, G; Beck, C

    2006-01-01

    Context: Sunspot penumbrae harbor highly structured magnetic fields and flows. The moving flux tube model offers an explanation for several observed phenomena, e.g. the Evershed effect and bright penumbral grains. Aims: A wealth of information can be extracted from spectropolarimetric observations. In order to deduce the structure of the magnetic field in sunspot penumbrae, detailed forward modeling is necessary. On the one hand, it gives insight into the sensitivity of various spectral lines to different physical scenarios. On the other hand, it is a very useful tool to guide inversion techniques. In this work, we present a generalized 3D geometrical model that embeds an arbitrarily shaped flux tube in a stratified magnetized atmosphere. Methods: The new semi-analytical geometric model serves as a frontend for a polarized radiative transfer code. The advantage of this model is that it preserves the discontinuities of the physical parameters across the flux tube boundaries. This is important for the detailed ...

  18. On the fine structure of the sunspot penumbrae. II. The nature of the Evershed flow

    CERN Document Server

    Borrero, J M; Solanki, S K; Collados, M

    2005-01-01

    We investigate the fine structure of the sunspot penumbra by means of a model that allows for a flux tube in horizontal pressure balance with the magnetic background atmosphere in which it is embedded. We apply this model to spectropolarimetric observations of two neutral iron lines at 1.56 $\\mu$m and invert several radial cuts in the penumbra of the same sunspot at two different heliocentric angles. In the inner part of the penumbra we find hot flux tubes that are somewhat inclined to the horizontal. They become gradually more horizontal and cooler with increasing radial distance. This is accompanied by an increase in the velocity of the plasma and a decrease of the gas pressure difference between flux tube and the background component. At large radial distances the flow speed exceeds the critical speed and evidence is found for the formation of a shock front. These results are in good agreement with simulations of the penumbral fine structure and provide strong support for the siphon flow as the physical me...

  19. On the temperature and velocity through the photosphere of a sunspot penumbra

    Science.gov (United States)

    del Toro Iniesta, J. C.; Tarbell, T. D.; Ruiz Cobo, B.

    1994-11-01

    We investigate the structure in depth of a sunspot penumbra by means of the inversion code of the radiative transfer equation proposed by Ruiz Cobo & del Toro Iniesta (1992), applied to a set of filtergrams of a sunspot, scanning the Fe I line at 5576.1 A, with a sampling interval of 30 mA, from -120 to 120 mA from line center (data previously analyzed by Title et al. 1993). The temperature structure of this penumbra is obtained for each of the 801 pixels selected (0.32 sec x 0.32 sec). On the average, the temperatures seem to decrease as we move inward, but the differences are of the order of the rms values (approximately equal 100-200 K) at a given distance to sunspot center. The outer parts of the penumbra have also a bigger curvature in the T versus log tau5 relation than the inner parts. We realize, however, that these differences might be influenced by possible stray light effects. Compared to the quiet Sun, penumbral temperatures are cooler at deep layers and hotter at high layers. A mean penumbral model atmosphere is presented. The asymmetries observed in the intensity profile (the line is magnetically insensitive) are deduced to be produced by strong gradients of the line-of-sight velocity that sharply vary spatially along slices of almost constant distance to sunspot center. These variations suggest that such gradients are not only needed to explain the broadband circular polarization observed in sunspots (see Sanchez Almeida & Lites 1992) but are a main characteristic of the fine-scale penumbra. The results are compatible with an Evershed flow present everywhere, but its gradient with depth turns out to vary so that the flow seems to be mainly concentrated in some penumbral fibrils when studied through Dopplergrams. Finally, as by-products of this study, we put constraints to the practical usefulness of the Eddington-Barbier relation, and we explain the values of the Fourier Dopplergrams to be carrying information of layers around the centroid of the

  20. Explanation of the sea-serpent magnetic structure of sunspot penumbrae

    CERN Document Server

    Kitiashvili, I N; Kosovichev, A G; Mansour, N N; Dalda, A Sainz; Wray, A A

    2010-01-01

    Recent spectro-polarimetric observations of a sunspot showed the formation of bipolar magnetic patches in the mid penumbra and their propagation toward the outer penumbral boundary. The observations were interpreted as being caused by sea-serpent magnetic fields near the solar surface (Sainz Dalda & Bellot Rubio 2008). In this Letter, we develop a 3D radiative MHD numerical model to explain the sea-serpent structure and the wave-like behavior of the penumbral magnetic field lines. The simulations reproduce the observed behavior, suggesting that the sea-serpent phenomenon is a consequence of magnetoconvection in a strongly inclined magnetic field. It involves several physical processes: filamentary structurization, high-speed overturning convective motions in strong, almost horizontal magnetic fields with partially frozen field lines, and traveling convective waves. The results demonstrate a correlation of the bipolar magnetic patches with high-speed Evershed downflows in the penumbra. This is the first ti...

  1. On the origin of reverse polarity patches found by Hinode in sunspot penumbrae

    CERN Document Server

    Almeida, J Sanchez

    2009-01-01

    The satellite Hinode has recently revealed penumbral structures with a magnetic polarity opposite to the main sunspot polarity. They may be a direct confirmation of magnetic field lines and mass flows returning to the solar interior throughout the penumbra, a configuration previously inferred from interpretation of observed Stokes profile asymmetries. The paper points out the relationship between the reverse polarity features found by Hinode, and the model Micro-Structured Magnetic Atmospheres (MISMAs) proposed for sunspots. We show how the existing model MISMAs produce strongly redshifted reverse polarity structures as found by Hinode. Ad hoc model MISMAs also explain the asymmetric Stokes profiles observed by Hinode. The same modeling may be consistent with magnetograms of dark cored penumbral filaments if the dark cores are associated with the reverse polarity. Such hypothetical relationship will show up only in the far red wings of the spectral lines.

  2. Magnetic fields of opposite polarity in sunspot penumbrae

    CERN Document Server

    Franz, M; Bethge, C; Schlichenmaier, R; Borrero, J M; Schmidt, W; Lagg, A; Solanki, S K; Berkefeld, T; Kiess, C; Rezaei, R; Schmidt, D; Sigwarth, M; Soltau, D; Volkmer, R; von der Luhe, O; Waldmann, T; Orozco, D; Yabar, A Pastor; Denker, C; Balthasar, H; Staude, J; Hofmann, A; Strassmeier, K; Feller, A; Nicklas, H; Kneer, F; Sobotka, M

    2016-01-01

    Context. A significant part of the penumbral magnetic field returns below the surface in the very deep photosphere. For lines in the visible, a large fraction of this return field can only be detected indirectly by studying its imprints on strongly asymmetric and 3-lobe Stokes V profiles. Infrared lines probe a narrow layer in the very deep photosphere, providing the possibility to directly measure the orientation of magnetic fields close to the solar surface. Aims. We study the topology of the penumbral magnetic field in the lower photosphere, focussing on regions where it returns below the surface. Methods. We analyze 71 spectropolarimetric datasets from Hinode and from the GREGOR infrared spectrograph. We infer the quality and polarimetric accuracy of the infrared data after applying a number of reduction steps. Techniques of spectral inversion and forward synthesis are used to test the detection algorithm. We compare the morphology and the fractional penumbral area covered by reversed polarity and 3-lobe ...

  3. Deep probing of the photospheric sunspot penumbra: no evidence for magnetic field-free gaps

    CERN Document Server

    Borrero, J M; Collados, M; Schlichenmaier, R; Balthasar, H; Franz, M; Rezaei, R; Kiess, C; Suarez, D Orozco; Pastor, A; Berkefeld, T; von der Luehe, O; Schmidt, D; Schmidt, W; Sigwarth, M; Soltau, D; Volkmer, R; Waldmann, T; Denker, C; Hofmann, A; Staude, J; Strassmeier, K G; Feller, A; Lagg, A; Solanki, S K; Sobotka, M; Nicklas, H

    2016-01-01

    Some models for the topology of the magnetic field in sunspot penumbrae predict the existence of field-free or dynamically weak-field regions in the deep Photosphere. To confirm or rule out the existence of weak-field regions in the deepest photospheric layers of the penumbra. The magnetic field at $\\log\\tau_5=0$ is investigated by means of inversions of spectropolarimetric data of two different sunspots located very close to disk center with a spatial resolution of approximately 0.4-0.45 arcsec. The data have been recorded using the GRIS instrument attached to the 1.5-meters GREGOR solar telescope at El Teide observatory. It includes three Fe I lines around 1565 nm, whose sensitivity to the magnetic field peaks at half a pressure-scale-height deeper than the sensitivity of the widely used Fe I spectral line pair at 630 nm. Prior to the inversion, the data is corrected for the effects of scattered light using a deconvolution method with several point spread functions. At $\\log\\tau_5=0$ we find no evidence for...

  4. Deep probing of the photospheric sunspot penumbra: no evidence of field-free gaps

    Science.gov (United States)

    Borrero, J. M.; Asensio Ramos, A.; Collados, M.; Schlichenmaier, R.; Balthasar, H.; Franz, M.; Rezaei, R.; Kiess, C.; Orozco Suárez, D.; Pastor, A.; Berkefeld, T.; von der Lühe, O.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Soltau, D.; Volkmer, R.; Waldmann, T.; Denker, C.; Hofmann, A.; Staude, J.; Strassmeier, K. G.; Feller, A.; Lagg, A.; Solanki, S. K.; Sobotka, M.; Nicklas, H.

    2016-11-01

    Context. Some models for the topology of the magnetic field in sunspot penumbrae predict regions free of magnetic fields or with only dynamically weak fields in the deep photosphere. Aims: We aim to confirm or refute the existence of weak-field regions in the deepest photospheric layers of the penumbra. Methods: We investigated the magnetic field at log τ5 = 0 is by inverting spectropolarimetric data of two different sunspots located very close to disk center with a spatial resolution of approximately 0.4-0.45''. The data have been recorded using the GRIS instrument attached to the 1.5-m solar telescope GREGOR at the El Teide observatory. The data include three Fe i lines around 1565 nm, whose sensitivity to the magnetic field peaks half a pressure scale height deeper than the sensitivity of the widely used Fe i spectral line pair at 630 nm. Before the inversion, the data were corrected for the effects of scattered light using a deconvolution method with several point spread functions. Results: At log τ5 = 0 we find no evidence of regions with dynamically weak (Bdata, and does not depend on the amount of stray light (i.e., wide-angle scattered light) considered.

  5. Automatic Detection of Magnetic delta in Sunspot Groups

    CERN Document Server

    Padinhatteeri, Sreejith; Bloomfield, D Shaun; Gallagher, Peter T

    2015-01-01

    Large and magnetically complex sunspot groups are known to be associated with flares. To date, the Mount Wilson scheme has been used to classify sunspot groups based on their morphological and magnetic properties. The most flare prolific class, the delta sunspot-group, is characterised by opposite polarity umbrae within a common penumbra, separated by less than 2 degrees. In this article, we present a new system, called the Solar Monitor Active Region Tracker - Delta Finder (SMART-DF), that can be used to automatically detect and classify magnetic deltas in near-realtime. Using continuum images and magnetograms from the Helioseismic and Magnetic Imager (HMI) onboard NASA's Solar Dynamics Observatory (SDO), we first estimate distances between opposite polarity umbrae. Opposite polarity pairs having distances of less that 2 degrees are then identified, and if these pairs are found to share a common penumbra, they are identified as a magnetic delta configuration. The algorithm was compared to manual delta detect...

  6. Polarimetry and spectroscopy of a simple sunspot. I - On the magnetic field of a sunspot penumbra

    Science.gov (United States)

    Schmidt, W.; Hofmann, A.; Balthasar, H.; Tarbell, T. D.; Frank, Z. A.

    1992-01-01

    We investigate the magnetic field structure of a medium sized sunspot using high resolution magnetograms and spectrograms and derive a relationship between the brightness of penumbral structures and the inclination of the magnetic field. The field inclination to the spot normal is larger in the dark structures than in the bright ones. We show that the field strength does not vary between dark and bright structures. At the inner penumbral boundary the field strength is 2000 Gauss and about 1000 Gauss at the outer penumbral edge. The line-of sight component of the material flow decreases rapidly within one arcsecond at the photospheric boundary of the spot.

  7. The electrical current density vector in the inner penumbra of a Sunspot

    CERN Document Server

    Puschmann, K G; Pillet, V Martínez

    2010-01-01

    We determine the entire electrical current density vector in a geometrical 3D volume of the inner penumbra of a sunspot from an inversion of spectropolarimetric data obtained with Hinode/SP. Significant currents are seen to wrap around the hotter, more elevated regions with lower and more horizontal magnetic field that harbor strong upflows and radial outflows (the intraspines). The horizontal component of the current density vector is 3-4 times larger than the vertical; nearly all previous studies only obtain the vertical component and thus strongly underestimate the current density. The current density and the magnetic field vectors form an angle of about 20 degrees. The plasma beta at the 0 km level is larger than 1 in the intraspines and is one order of magnitude lower in the background component of the penumbra (spines). At the 200 km level, the plasma beta is below 0.3 nearly everywhere. The plasma beta surface as well as the surface optical depth unity are very corrugated. At the borders of intraspines...

  8. Coupling of the magnetic field and gas flows in sunspot penumbra inferred from the Hinode/SOT observation

    Science.gov (United States)

    Ichimoto, Kiyoshi; Shaltout, Abdelrazek Mohammed

    2012-07-01

    Sunspot penumbrae has been an enigmatic region that consists of fine scale filamentary structures harboring conspicuous gas flows known as the Evershed flow in the base of photosphere and the inverse-Evershed flow in higher layer. Recent high resolution observations including those by Hinode/SOT revealed that the penumbral magnetic field is highly fluctuating in its strength and inclination in space, and the geometry is called as interlocking comb structure. There is a strong coupling of the magnetic field and gas flow, i.e., many observational aspects suggest the origin of the sunspot penumbra as the vigorous thermal-convection of plasma under the inclined strong magnetic field of sunspots. However the relation between the magnetic field and gas flow is still an open issue to be settled. A number of observational and theoretical works suggest that the convective hot gas with a large flow speed is associated with a weak field. In this paper, we present an evidence of contradictory relation, i.e., a positive correlation between the field strength and flow velocity in photosphere. The geometry of the inverse-Evershed flow in conjunction with the interlocking magnetic field structure of penumbra is another issue that is not understood. We present an insight on the relation between the magnetic field structure and the inverse-Evershed flow based on the SOT/SP observations.

  9. Upper Chromospheric Magnetic Field of a Sunspot Penumbra: Observations of Fine Structure

    CERN Document Server

    Joshi, J; Solanki, S K; Feller, A; Collados, M; Suárez, D Orozco; Schlichenmaier, R; Franz, M; Balthasar, H; Denker, C; Berkefeld, T; Hofmann, A; Kiess, C; Nicklas, H; Yabar, A Pastor; Rezaei, R; Schmidt, D; Schmidt, W; Sobotka, M; Soltau, D; Staude, J; Strassmeier, K G; Volkmer, R; von der Lühe, O; Waldmann, T

    2016-01-01

    The fine-structure of magnetic field of a sunspot penumbra in the upper chromosphere is to be explored and compared to that in the photosphere. High spatial resolution spectropolarimetric observations were recorded with the 1.5-meter GREGOR telescope using the GREGOR Infrared Spectrograph (GRIS). The observed spectral domain includes the upper chromospheric He I triplet at 1083.0 nm and the photospheric Si I 1082.7 nm and Ca I 1083.3 nm spectral lines. The upper chromospheric magnetic field is obtained by inverting the He I triplet assuming a Milne-Eddington type model atmosphere. A height dependent inversion was applied to the Si I 1082.7 nm and Ca I 1083.3 nm lines to obtain the photospheric magnetic field. We find that the inclination of the magnetic field shows variations in the azimuthal direction both in the photosphere, but also in the upper chromosphere. The chromospheric variations remarkably well coincide with the variations in the inclination of the photospheric field and resemble the well-known sp...

  10. Coupling of the magnetic field and gas flows inferred from the net circular polarization in a sunspot penumbra

    Science.gov (United States)

    Shaltout, Abdelrazek M. K.; Ichimoto, Kiyoshi

    2015-04-01

    We analyze penumbral fine structure using high-resolution spectropolarimetric data obtained by the Solar Optical Telescope on board the Hinode satellite. The spatial correlation between the net circular polarization (NCP) and Evershed flow is investigated in detail. Here we obtain that negative NCP structures are correlated with the Evershed flow channels in the limb-side penumbra, and that negative NCP or depressions of positive NCP are associated with the Evershed flow channels in the disk center-side of the penumbra for a negative-polarity sunspot in NOAA 10923. The positive NCP dominant in the disk center-side penumbra is essentially attributed to interflow channels instead of Evershed flow channels. The stratification of magnetic field and velocity are investigated by using SIR-JUMP inversion with a one-component atmosphere, and the NCP of spectral lines in the limb-side and disk center-side of the penumbra is successfully reproduced. The inversion results show that an increased Evershed flow is associated with a strong magnetic field located in the deep photosphere. Our result does not match with the simple two-component penumbral models in which the penumbra consists of Evershed flow and interflow channels and the global NCP is attributed only to the Evershed flow channels.

  11. On the velocity field of sunspot penumbrae - I. A global view

    CERN Document Server

    Franz, Morten

    2009-01-01

    We investigated the vertical penumbral plasma flow on small spatial scales using data recorded by the spectropolarimeter of the solar optical telescope onboard Hinode. To this end we computed maps of apparent Doppler velocities by comparing the spectral position of the Fe I 630.15 nm & Fe I 630.25 nm lines with the averaged line profiles of the quiet Sun. To visualize the flow pattern in the low photosphere, we used a bisector of the wing of the absorption lines. Due to the small heliocentric angle (3 0.6 km/s down-flows prevail. Additionally, the maximal up-flow velocity in penumbrae is smaller, while the maximal down-flow velocity is larger with respect to the QS velocities. Furthermore, on a spatial average, the penumbra shows a red-shift, corresponding to a down-flow of more than 0.1 km/s. Up-flows are elongated and appear predominately in the inner penumbra. Strong down-flows with velocities of up to 9 km/s are concentrated at the penumbra-QS boundary. They are magnetized and are rather round in sha...

  12. Automatic Detection of Magnetic δ in Sunspot Groups

    Science.gov (United States)

    Padinhatteeri, Sreejith; Higgins, Paul A.; Bloomfield, D. Shaun; Gallagher, Peter T.

    2016-01-01

    Large and magnetically complex sunspot groups are known to be associated with flares. To date, the Mount Wilson scheme has been used to classify sunspot groups based on their morphological and magnetic properties. The most flare-prolific class, the δ sunspot group, is characterised by opposite-polarity umbrae within a common penumbra, separated by less than 2∘. In this article, we present a new system, called the Solar Monitor Active Region Tracker-Delta Finder (SMART-DF), which can be used to automatically detect and classify magnetic δs in near-realtime. Using continuum images and magnetograms from the Helioseismic and Magnetic Imager (HMI) onboard NASA's Solar Dynamics Observatory (SDO), we first estimate distances between opposite-polarity umbrae. Opposite-polarity pairs with distances of less that 2∘ are then identified, and if these pairs are found to share a common penumbra, they are identified as a magnetic δ configuration. The algorithm was compared to manual δ detections reported by the Space Weather Prediction Center (SWPC), operated by the National Oceanic and Atmospheric Administration (NOAA). SMART-DF detected 21 out of 23 active regions (ARs) that were marked as δ spots by NOAA during 2011 - 2012 (within {±} 60° longitude). SMART-DF in addition detected five ARs that were not announced as δ spots by NOAA. The near-realtime operation of SMART-DF resulted in many δs being identified in advance of NOAA's daily notification. SMART-DF will be integrated into SolarMonitor (www.solarmonitor.org) and the near-realtime information will be available to the public.

  13. Flows in Sunspot Plumes Detected with SOHO

    Science.gov (United States)

    Brynildsen, N.; Maltby, P.; Brekke, P.; Fredvik, T.; Haugan, S. V. H.; Kjeldseth-Moe, O.; Wikstol, O.

    1998-09-01

    In the Letter, ``Flows in Sunspot Plumes Detected with the Solar and Heliospheric Observatory'' by N. Brynildsen, P. Maltby, P. Brekke, T. Fredvik, S. V. H. Haugan, O. Kjeldseth-Moe, and Ø. Wikstøl (ApJ, 502, L85 [1998]), the following correction should be made: In the last line on page L86, which reads ``peak line intensity I>=5 are located (1) above the umbra or, '' an ``Ī'' should be inserted so that the revised line reads ``peak line intensity I>=5Ī are located (1) above the umbra or.''

  14. Coupling of the magnetic field and gas flows inferred from the net circular polarization in a sunspot penumbra

    OpenAIRE

    2015-01-01

    We analyze penumbral fine structure using high-resolution spectropolarimetric data obtained by the Solar Optical Telescope on board the Hinode satellite. The spatial correlation between the net circular polarization (NCP) and Evershed flow is investigated in detail. Here we obtain that negative NCP structures are correlated with the Evershed flow channels in the limb-side penumbra, and that negative NCP or depressions of positive NCP are associated with the Evershed flow channels in the disk ...

  15. Flows in Sunspot Plumes Detected with SOHO

    CERN Document Server

    Brynildsen, N; Brekke, P; Fredvik, T; Haugan, S V H; Kjeldseth-Moe, O; Wikstøl, O

    1998-01-01

    Bright EUV sunspot plumes have been observed in eight out of eleven different sunspot regions with the Coronal Diagnostic Spectrometer -- CDS on SOHO. From wavelength shifts we derive the line-of-sight velocity, relative to the average velocity in the rastered area, 120 arcsec x 120 arcsec. In sunspot plumes we find that the motion is directed away from the observer and increases with increasing line formation temperature, reaches a maximum between 15 and 41 km~s$^{-1}$ close to log T $\\approx$ 5.5, then decreases abruptly. The flow field in the corona is not well correlated with the flow in the transition region and we discuss briefly the implication of this finding.

  16. Detection of Emerging Sunspot Regions in the Solar Interior

    Science.gov (United States)

    Ilonidis, Stathis; Zhao, Junwei; Kosovichev, Alexander

    2011-08-01

    Sunspots are regions where strong magnetic fields emerge from the solar interior and where major eruptive events occur. These energetic events can cause power outages, interrupt telecommunication and navigation services, and pose hazards to astronauts. We detected subsurface signatures of emerging sunspot regions before they appeared on the solar disc. Strong acoustic travel-time anomalies of an order of 12 to 16 seconds were detected as deep as 65,000 kilometers. These anomalies were associated with magnetic structures that emerged with an average speed of 0.3 to 0.6 kilometer per second and caused high peaks in the photospheric magnetic flux rate 1 to 2 days after the detection of the anomalies. Thus, synoptic imaging of subsurface magnetic activity may allow anticipation of large sunspot regions before they become visible, improving space weather forecast.

  17. Technique for Automated Recognition of Sunspots on Full-Disk Solar Images

    Directory of Open Access Journals (Sweden)

    Zharkov S

    2005-01-01

    Full Text Available A new robust technique is presented for automated identification of sunspots on full-disk white-light (WL solar images obtained from SOHO/MDI instrument and Ca II K1 line images from the Meudon Observatory. Edge-detection methods are applied to find sunspot candidates followed by local thresholding using statistical properties of the region around sunspots. Possible initial oversegmentation of images is remedied with a median filter. The features are smoothed by using morphological closing operations and filled by applying watershed, followed by dilation operator to define regions of interest containing sunspots. A number of physical and geometrical parameters of detected sunspot features are extracted and stored in a relational database along with umbra-penumbra information in the form of pixel run-length data within a bounding rectangle. The detection results reveal very good agreement with the manual synoptic maps and a very high correlation with those produced manually by NOAA Observatory, USA.

  18. Fully Automated Sunspot Detection and Classification Using SDO HMI Imagery in MATLAB

    Science.gov (United States)

    2014-03-27

    The features of a sunspot and other local sunspots considered part of a group are assigned a classification, defined by the solar astrophysics ...processing. In the second stage, elementary image processing techniques are used to condition the data. The third stage involves the detection of...active regions and coronal holes on euv images, arXiv preprint arXiv:1208.1483, 2012. Foukal, P. V., Solar astrophysics , Wiley-VCH, 2008. Gonzalez, R

  19. Detection of Fast-Moving Waves Propagating Outward along Sunspots' Radial Direction in the Photosphere

    CERN Document Server

    Zhao, Junwei; Hartlep, Thomas; Kosovichev, Alexander G

    2015-01-01

    Helioseismic and magnetohydrodynamic waves are abundant in and above sunspots. Through cross-correlating oscillation signals in the photosphere observed by the SDO/HMI, we reconstruct how waves propagate away from virtual wave sources located inside a sunspot. In addition to the usual helioseismic wave, a fast-moving wave is detected traveling along the sunspot's radial direction from the umbra to about 15 Mm beyond the sunspot boundary. The wave has a frequency range of 2.5 - 4.0 mHz with a phase velocity of 45.3 km/s, substantially faster than the typical speeds of Alfven and magnetoacoustic waves in the photosphere. The observed phenomenon is consistent with a scenario of that a magnetoacoustic wave is excited at approximately 5 Mm beneath the sunspot, and its wavefront travels to and sweeps across the photosphere with a speed higher than the local magnetoacoustic speed. The fast-moving wave, if truly excited beneath the sunspot's surface, will help open a new window to study the internal structure and dyn...

  20. Development of a Code to Analyze the Solar White-Light Images from the Kodaikanal Observatory: Detection of Sunspots, Computation of Heliographic Coordinates and Area

    Indian Academy of Sciences (India)

    Ragadeepika Pucha; K. M. Hiremath; Shashanka R. Gurumath

    2016-03-01

    Sunspots are the most conspicuous aspects of the Sun. They have a lower temperature, as compared to the surrounding photosphere; hence, sunspots appear as dark regions on a brighter background. Sunspots cyclically appear and disappear with a 11-year periodicity and are associated with a strong magnetic field $(\\sim 10^3$ G) structure. Sunspots consist of a dark umbra, surrounded by a lighter penumbra. Study of umbra–penumbra area ratio can be used to give a rough idea as to how the convective energy of the Sun is transported from the interior, as the sunspot’s thermal structure is related to this convective medium. An algorithm to extract sunspots from the white-light solar images obtained from the Kodaikanal Observatory is proposed. This algorithm computes the radius and center of the solar disk uniquely and removes the limb darkening from the image. It also separates the umbra and computes the position as well as the area of the sunspots. The estimated results are compared with the Debrecen photoheliographic results. It is shown that both area and position measurements are in quite good agreement.

  1. EUV Sunspot Plumes Observed with SOHO

    CERN Document Server

    Maltby, P; Brekke, P; Haugan, S V H; Kjeldseth-Moe, O; Wikstøl, O; Rimmele, T R; Wikstøl, O

    1998-01-01

    Bright EUV sunspot plumes have been observed in five out of nine sunspot regions with the Coronal Diagnostic Spectrometer -- CDS on SOHO. In the other four regions the brightest line emissions may appear inside the sunspot but are mainly concentrated in small regions outside the sunspot areas. These results are in contrast to those obtained during the Solar Maximum Mission, but are compatible with the Skylab mission results. The present observations show that sunspot plumes are formed in the upper part of the transition region, occur both in magnetic unipolar-- and bipolar regions, and may extend from the umbra into the penumbra.

  2. LATERAL DOWNFLOWS IN SUNSPOT PENUMBRAL FILAMENTS AND THEIR TEMPORAL EVOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Esteban Pozuelo, S.; Rubio, L. R. Bellot [Instituto de Astrofísica de Andalucía (CSIC), Apdo. 3004, E-18008 Granada (Spain); Rodríguez, J. de la Cruz, E-mail: sesteban@iaa.es [Institute for Solar Physics, Dept. of Astronomy, Stockholm University, Albanova University Center, SE-10691 Stockholm (Sweden)

    2015-04-20

    We study the temporal evolution of downflows observed at the lateral edges of penumbral filaments in a sunspot located very close to the disk center. Our analysis is based on a sequence of nearly diffraction-limited scans of the Fe i 617.3 nm line taken with the CRisp Imaging Spectro-Polarimeter instrument at the Swedish 1 m Solar Telescope. We compute Dopplergrams from the observed intensity profiles using line bisectors and filter the resulting velocity maps for subsonic oscillations. Lateral downflows appear everywhere in the center-side penumbra as small, weak patches of redshifts next to or along the edges of blueshifted flow channels. These patches have an intermittent life and undergo mergings and fragmentations quite frequently. The lateral downflows move together with the hosting filaments and react to their shape variations, very much resembling the evolution of granular convection in the quiet Sun. There is a good relation between brightness and velocity in the center-side penumbra, with downflows being darker than upflows on average, which is again reminiscent of quiet Sun convection. These results point to the existence of overturning convection in sunspot penumbrae, with elongated cells forming filaments where the flow is upward but very inclined, and weak lateral downward flows. In general, the circular polarization profiles emerging from the lateral downflows do not show sign reversals, although sometimes we detect three-lobed profiles that are suggestive of opposite magnetic polarities in the pixel.

  3. Vertical magnetic field gradient in the photospheric layers of sunspots

    CERN Document Server

    Joshi, Jayant; Hirzberger, Johann; Solanki, Sami K; Tiwari, Sanjiv K

    2016-01-01

    We investigate the vertical gradient of the magnetic field of sunspots in the photospheric layer. Independent observations were obtained with the SOT/SP onboard the Hinode spacecraft and with the TIP-2 mounted at the VTT. We apply state-of-the-art inversion techniques to both data sets to retrieve the magnetic field and the corresponding vertical gradient. In the sunspot penumbrae we detected patches of negative vertical gradients of the magnetic field strength, i.e.,the magnetic field strength decreases with optical depth in the photosphere. The negative gradient patches are located in the inner and partly in the middle penumbrae in both data sets. From the SOT/SP observations, we found that the negative gradient patches are restricted mainly to the deep photospheric layers and are concentrated near the edges of the penumbral filaments. MHD simulations also show negative gradients in the inner penumbrae, also at the locations of filaments. Both in the observations and simulation negative gradients of the mag...

  4. Vertical magnetic field gradient in the photospheric layers of sunspots

    Science.gov (United States)

    Joshi, Jayant; Lagg, Andreas; Hirzberger, Johann; Solanki, Sami K.; Tiwari, Sanjiv K.

    2017-03-01

    Aims: We investigate the vertical gradient of the magnetic field of sunspots in the photospheric layer. Methods: Independent observations were obtained with the Solar Optical Telescope/Spectropolarimeter (SOT/SP) on board the Hinode spacecraft and with the Tenrife Infrared Polarimeter-2 (TIP-2) mounted at the German Vacuum Tower Telescope (VTT). We apply state-of-the-art inversion techniques to both data sets to retrieve the magnetic field and the corresponding vertical gradient along with other atmospheric parameters in the solar photosphere. Results: In the sunspot penumbrae we detected patches of negative vertical gradients of the magnetic field strength, i.e., the magnetic field strength decreases with optical depth in the photosphere. The negative gradient patches are located in the inner and partly in the middle penumbrae in both data sets. From the SOT/SP observations we found that the negative gradient patches are restricted mainly to the deep photospheric layers and are concentrated near the edges of the penumbral filaments. Magnetohydrodynamic (MHD) simulations also show negative gradients in the inner penumbrae, also at the locations of filaments. In the observations and the simulation negative gradients of the magnetic field vs. optical depth dominate at some radial distances in the penumbra. The negative gradient with respect to optical depth in the inner penumbrae persists even after averaging in the azimuthal direction in the observations and, to a lesser extent, in the MHD simulations. If the gradients in the MHD simulations are determined with respect to geometrical height, then the azimuthal averages are always positive within the sunspot (above log τ = 0), corresponding to magnetic field increasing with depth, as generally expected. Conclusions: We interpret the observed localized presence of negative vertical gradient of the magnetic field strength in the observations as a consequence of stronger field from spines expanding with height and

  5. Solar transition region above sunspots

    CERN Document Server

    Tian, H; Teriaca, L; Landi, E; Marsch, E

    2009-01-01

    We study the TR properties above sunspots and the surrounding plage regions, by analyzing several sunspot spectra obtained by SUMER in March 1999 and November 2006. We compare the SUMER spectra observed in the umbra, penumbra, plage, and sunspot plume regions. The Lyman line profiles averaged in each region are presented. For the sunspot observed in 2006, the electron densities, DEM, and filling factors of the TR plasma in the four regions are also investigated. The self-reversals of the Lyman line profiles are almost absent in umbral regions at different locations (heliocentric angle up to $49^\\circ$) on the solar disk. In the sunspot plume, the Lyman lines are also not reversed, whilst the lower Lyman line profiles observed in the plage region are obviously reversed. The TR densities of the umbra and plume are similar and one order of magnitude lower than those of the plage and penumbra. The DEM curve of the sunspot plume exhibits a peak centered around $\\log(T/\\rm{K})\\sim5.45$, which exceeds the DEM of oth...

  6. Magnetic topology of a naked sunspot: Is it really naked?

    CERN Document Server

    Dalda, A Sainz; Tarbell, T D; 10.1088/2041-8205/746/1/L13

    2012-01-01

    The high spatial, temporal and spectral resolution achieved by Hinode instruments give much better understanding of the behavior of some elusive solar features, such as pores and naked sunspots. Their fast evolution and, in some cases, their small sizes have made their study difficult. The moving magnetic features, despite being more dynamic structures, have been studied during the last 40 years. They have been always associated with sunspots, especially with the penumbra. However, a recent observation of a naked sunspot (one with no penumbra) has shown MMF activity. The authors of this reported observation expressed their reservations about the explanation given to the bipolar MMF activity as an extension of the penumbral filaments into the moat. How can this type of MMFs exist when a penumbra does not? In this paper, we study the full magnetic and (horizontal) velocity topology of the same naked sunspot, showing how the existence of a magnetic field topology similar to that observed in sunspots can explain ...

  7. Automated Sunspot Detection and Classification Using SOHO/MDI Imagery

    Science.gov (United States)

    2015-03-01

    18 3.3.1 Center and Radius Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 3.3.2 Flat-Field and Window...20 5. Comparison of results for Canny edge detection method (red) and binary thresholding method (green) determining the solar radius ...devices are therefore sensitive to stray radiation, such as cosmic rays, which can produce signals not associated with the object of interest

  8. Acoustic absorption by sunspots

    Science.gov (United States)

    Braun, D. C.; Labonte, B. J.; Duvall, T. L., Jr.

    1987-01-01

    The paper presents the initial results of a series of observations designed to probe the nature of sunspots by detecting their influence on high-degree p-mode oscillations in the surrounding photosphere. The analysis decomposes the observed oscillations into radially propagating waves described by Hankel functions in a cylindrical coordinate system centered on the sunspot. From measurements of the differences in power between waves traveling outward and inward, it is demonstrated that sunspots appear to absorb as much as 50 percent of the incoming acoustic waves. It is found that for all three sunspots observed, the amount of absorption increases linearly with horizontal wavenumber. The effect is present in p-mode oscillations with wavelengths both significantly larger and smaller than the diameter of the sunspot umbrae. Actual absorption of acoustic energy of the magnitude observed may produce measurable decreases in the power and lifetimes of high-degree p-mode oscillations during periods of high solar activity.

  9. Ischaemic penumbra: highlights.

    Science.gov (United States)

    Pestalozza, Isabella F; Di Legge, Silvia; Calabresi, Marco; Lenzi, Gian Luigi

    2002-01-01

    The ischaemic penumbra was described for the first time in the late 1970s as a ring of hypoperfused zone surrounding the region of complete infarction. The penumbral zone is a functionally silent tissue which is able to regain its function if promptly reperfused. This implies that the ischaemic penumbra is not a static but a "dynamic" and "time-dependent" concept. In this paper we describe the role of neuroimmaging tecniques such as single photon emission tomography (SPET), positron emission tomography (PET), and diffusion-weighted and perfusion-weighted magnetic resonance imaging (DWI and PWI) in the study of ischaemic penumbra. These functional imaging techniques have the advantage of giving "in vivo" quantitative estimate of cerebral blood flow (CBF) as well as information on how the ischaemic tissue metabolic changes develop. It follows that, as therapeutic options for treating acute stroke evolve, neuroimaging strategies are assuming an increasingly important role in the initial evaluation and management of the acute ischaemic patient. In this regard, a wide range of therapeutic approaches have been investigated for either ameliorating the perfusion, or interfering with the pathobiochemical cascade leading to ischaemic neuronal damage, or improving endogenous neuroprotection pathways. The "time windows" required for these treatments to be effective varies being rather short for reperfusion and longer for neuroprotection. Salvaging more penumbra would enhance recovery and thereby allow the most appropriate candidate for therapeutic trials to be selected.

  10. Wave phenomena in sunspots

    Science.gov (United States)

    Löhner-Böttcher, Johannes

    2016-03-01

    magnetic field lines. Signatures of umbral flashes and running penumbral waves are found already in the middle to upper photosphere. The signal and velocity increases toward the chromosphere. The shock wave behavior of the umbral flashes is confirmed by the evolving saw-tooth pattern in velocity and the strong downward motion of the plasma right after the passage of the shock front. The power spectra and peak periods of sunspot waves vary significantly with atmospheric altitude and position within the sunspot. In the vertical field of the umbra, the mixture of wave periods in the lower photosphere transforms into a domination of the 2.5min range in the upper photosphere and chromosphere. In the differentially inclined penumbra, the dominating wave periods increase with radial distance. The acoustic cut-off frequency which blocks the propagation of long-period waves is considered to increase with the field inclination and the ambient sound speed. The reconstruction of the sunspot's magnetic field inclination based on the peak period distribution yields consistent results with the inferred photospheric and extrapolated coronal magnetic field.

  11. Local Helioseismology of Sunspots: Current Status and Perspectives (Invited Review)

    CERN Document Server

    Kosovichev, A G

    2010-01-01

    Mechanisms of formation and stability of sunspots are among the longest-standing and intriguing puzzles of solar physics and astrophysics. Sunspots are controlled by subsurface dynamics hidden from direct observations. Recently, substantial progress in our understanding of physics of the turbulent magnetized plasma has been made by numerical simulations and local helioseismology. Both, the simulations and helioseismic measurements, are extremely challenging, but it becomes clear that the key to understanding the enigma of sunspots is a synergy between models and observations. Recent observations and radiative MHD numerical simulations have provided a convincing explanation to the Evershed flows in sunspot penumbra. Also, they lead to the understanding of sunspots as self-organized magnetic structures in the turbulent plasma of the upper convection zone, which are maintained by a large-scale dynamics. Local helioseismic diagnostics of sunspots still have many uncertainties, some of which are discussed in this ...

  12. On sunspots

    CERN Document Server

    Galilei, Galileo; Reeves, Eileen; Helden, Albert van

    2010-01-01

    Galileo's telescopic discoveries, and especially his observation of sunspots, caused great debate in an age when the heavens were thought to be perfect and unchanging. Christoph Scheiner, a Jesuit mathematician, argued that sunspots were planets or moons crossing in front of the Sun. Galileo, on the other hand, countered that the spots were on or near the surface of the Sun itself, and he supported his position with a series of meticulous observations and mathematical demonstrations that eventually convinced even his rival.  On Sunspots collects the correspondenc

  13. Disintegration of Magnetic Flux in Decaying Sunspots as Observed with the Hinode SOT

    CERN Document Server

    Kubo, M; Ichimoto, K; Shimizu, T; Suematsu, Y; Katsukawa, Y; Tarbell, T D; Shine, R A; Title, A M; Nagata, S; Tsuneta, S

    2008-01-01

    Continuous observations of sunspot penumbrae with the Solar Optical Telescope aboard \\textit{Hinode} clearly show that the outer boundary of the penumbra fluctuates around its averaged position. The penumbral outer boundary moves inward when granules appear in the outer penumbra. We discover that such granules appear one after another while moving magnetic features (MMFs) are separating from the penumbral ``spines'' (penumbral features that have stronger and more vertical fields than those of their surroundings). These granules that appear in the outer penumbra often merge with bright features inside the penumbra that move with the spines as they elongate toward the moat region. This suggests that convective motions around the penumbral outer boundary are related to the disintegration of magnetic flux in the sunspot. We also find that dark penumbral filaments frequently elongate into the moat region in the vicinity of MMFs that detach from penumbral spines. Such elongating dark penumbral filaments correspond ...

  14. PRECURSOR OF SUNSPOT PENUMBRAL FORMATION DISCOVERED WITH HINODE SOLAR OPTICAL TELESCOPE OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Toshifumi [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210 (Japan); Ichimoto, Kiyoshi [Kwasan and Hida Observatories, Kyoto University, Kamitakara-cho, Takayama, Gifu 506-1314 (Japan); Suematsu, Yoshinori, E-mail: shimizu.toshifumi@isas.jaxa.jp [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan)

    2012-03-10

    We present observations of a precursory signature that would be helpful for understanding the formation process of sunspot penumbrae. The Hinode Solar Optical Telescope successfully captured the entire evolution of a sunspot from the pore to a large well-developed sunspot with penumbra in an emerging flux region appearing in NOAA Active Region 11039. We found an annular zone (width 3''-5'') surrounding the umbra (pore) in Ca II H images before the penumbra formed around the umbra. The penumbra developed as if to fill the annular zone. The annular zone shows weak magnetogram signals, meaning less magnetic flux or highly inclined fields there. Pre-existing ambient magnetic field islands were distributed at the outer edge of the annular zone and did not come into the zone. There are no strong systematic flow patterns in the zone, but we occasionally observed small magnetic flux patches streaming out. The observations indicate that the annular zone is different from the sunspot moat flow region and that it represents the structure in the chromosphere. We conclude that the annular zone reflects the formation of a magnetic canopy overlying the region surrounding the umbra at the chromospheric level, long before the formation of the penumbra at the photospheric level. The magnetic field structure in the chromosphere needs to be considered in the formation process of the penumbrae.

  15. Oscillations in a sunspot with light bridges

    CERN Document Server

    Yuan, Ding; Huang, Zhenghua; Li, Bo; Su, Jiangtao; Yan, Yihua; Tan, Baolin

    2014-01-01

    Solar Optical Telescope onboard Hinode observed a sunspot (AR 11836) with two light bridges (LBs) on 31 Aug 2013. We analysed a 2-hour \\ion{Ca}{2} H emission intensity data set and detected strong 5-min oscillation power on both LBs and in the inner penumbra. The time-distance plot reveals that 5-min oscillation phase does not vary significantly along the thin bridge, indicating that the oscillations are likely to originate from the underneath. The slit taken along the central axis of the wide light bridge exhibits a standing wave feature. However, at the centre of the wide bridge, the 5-min oscillation power is found to be stronger than at its sides. Moreover, the time-distance plot across the wide bridge exhibits a herringbone pattern that indicates a counter-stream of two running waves originated at the bridge sides. Thus, the 5-min oscillations on the wide bridge also resemble the properties of running penumbral waves. The 5-min oscillations are suppressed in the umbra, while the 3-min oscillations occupy...

  16. RAPID PENUMBRA AND LORENTZ FORCE CHANGES IN AN X1.0 SOLAR FLARE

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Zhe; Jiang, Yunchun; Yang, Jiayang; Yang, Bo; Bi, Yi, E-mail: xuzhe6249@ynao.ac.cn [Yunnan Observatories, Chinese Academy of Sciences, P.O. Box 110, Kunming 650011 (China)

    2016-03-20

    We present observations of the violent changes in photospheric magnetic structures associated with an X1.1 flare, which occurred in a compact δ-configuration region in the following part of AR 11890 on 2013 November 8. In both central and peripheral penumbra regions of the small δ sunspot, these changes took place abruptly and permanently in the reverse direction during the flare: the inner/outer penumbra darkened/disappeared, where the magnetic fields became more horizontal/vertical. Particularly, the Lorentz force (LF) changes in the central/peripheral region had a downward/upward and inward direction, meaning that the local pressure from the upper atmosphere was enhanced/released. It indicates that the LF changes might be responsible for the penumbra changes. These observations can be well explained as the photospheric response to the coronal field reconstruction within the framework of the magnetic implosion theory and the back reaction model of flares.

  17. Formation and decay of rudimentary penumbra around a pore

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Hiroko [Unit of Synergetic Studies for Space, Kyoto University, Yamashina-ku, Kyoto 607-8417 (Japan); Kitai, Reizaburo [Kwasan and Hida Observatories, Kyoto University, Yamashina-ku, Kyoto 607-8417 (Japan); Otsuji, Kenichi, E-mail: watanabe@kwasan.kyoto-u.ac.jp [Solar Observatory, National Astronomical Observatory, Mitaka, Tokyo 181-8588 (Japan)

    2014-12-01

    We analyze the evolution of a pore in the active region NOAA 10940 using the data obtained by the Hinode satellite on 2007 February 3. The pore we analyzed showed the formation of a rudimentary penumbra structure, succeeded by an abrupt disappearance after about 5 hr. The pore had an approximate radius of 3.5 Mm and a total magnetic flux of 3.0 × 10{sup 19} Mx, which is a little smaller than the necessary magnetic flux for penumbral formation supposed by Rucklidge et al. (1-1.5 × 10{sup 20} Mx). Our observation describes a rare phenomenon which was in the unstable phase between a pore and a sunspot. The area of the dark umbra gradually decreased when the rudimentary penumbral filaments formed the penumbral structure, meaning that the penumbra develops at the expense of the umbral magnetic flux. This statement was confirmed by a rough estimation of the magnetic flux variation observed by the Hinode Fe I magnetogram. Five hours after the formation phase, the decay phase began. In this decaying phase, multiple opposite polarity patches are found to appear in the exterior of the pore (a different location from the penumbra formation site). We interpret these opposite polarities as signatures of the horizontal magnetic field, which preferably appears in the course of the unstable reconfiguration of the magnetic field structure. During the course of the disappearance of the penumbra, the horizontal penumbral field seems to become vertical because of the dark umbral area that recovered by about 10%.

  18. The Growth of a Primitive Penumbra

    Science.gov (United States)

    Sreejith, P.; Tritschler, A.; Sankarasubramanian, K.

    We report on the penumbral formation in active region NOAA 10837. The penumbra observed on continuum intensity images grew from a quiet-Sun area to a primitive penumbra and then to a fully developed penumbra over about 5 h. The growth indicates nonlinear development with time.

  19. Properties of a Decaying Sunspot

    CERN Document Server

    Balthasar, H; Gömöry, P; Muglach, K; Puschmann, K G; Shimizu, T; Verma, M

    2013-01-01

    A small decaying sunspot was observed with the Vacuum Tower Telescope (VTT) on Tenerife and the Japanese Hinode satellite. We obtained full Stokes scans in several wavelengths covering different heights in the solar atmosphere. Imaging time series from Hinode and the Solar Dynamics Observatory (SDO) complete our data sets. The spot is surrounded by a moat flow, which persists also on that side of the spot where the penumbra already had disappeared. Close to the spot, we find a chromospheric location with downflows of more than 10 km/s without photospheric counterpart. The height dependence of the vertical component of the magnetic field strength is determined in two different ways that yielded different results in previous investigations. Such a difference still exists in our present data, but it is not as pronounced as in the past.

  20. Sunspot Modeling: From Simplified Models to Radiative MHD Simulations

    Directory of Open Access Journals (Sweden)

    Rolf Schlichenmaier

    2011-09-01

    Full Text Available We review our current understanding of sunspots from the scales of their fine structure to their large scale (global structure including the processes of their formation and decay. Recently, sunspot models have undergone a dramatic change. In the past, several aspects of sunspot structure have been addressed by static MHD models with parametrized energy transport. Models of sunspot fine structure have been relying heavily on strong assumptions about flow and field geometry (e.g., flux-tubes, "gaps", convective rolls, which were motivated in part by the observed filamentary structure of penumbrae or the necessity of explaining the substantial energy transport required to maintain the penumbral brightness. However, none of these models could self-consistently explain all aspects of penumbral structure (energy transport, filamentation, Evershed flow. In recent years, 3D radiative MHD simulations have been advanced dramatically to the point at which models of complete sunspots with sufficient resolution to capture sunspot fine structure are feasible. Here overturning convection is the central element responsible for energy transport, filamentation leading to fine-structure and the driving of strong outflows. On the larger scale these models are also in the progress of addressing the subsurface structure of sunspots as well as sunspot formation. With this shift in modeling capabilities and the recent advances in high resolution observations, the future research will be guided by comparing observation and theory.

  1. On the Formation of Penumbrae as Observed with the German VTT SOHO/MDI, and SDO/HMI

    Science.gov (United States)

    Schlichenmaier, R.; Rezaei, R.; González, N. B.

    2012-05-01

    Solar magnetic fields are generated in the solar interior and pop up at the solar surface to form active regions. As the magnetic field appears on the surface, it forms various structures like small magnetic elements, pores, and sunspots. The nature of these formation processes is largely unknown. In this contribution we elaborate on the formation of sunspots and particularly on the formation of penumbrae. We report on observations that we obtained at the German Vacuum Tower Telescope (VTT) on July 4, 2009 on the formation of the spot in AR 11024. This data set is complemented with data from the Michelson Doppler Imager (MDI) aboard SOHO, which offers an entire time coverage. Moreover, the evolution of AR 11024 is compared with a particular event of penumbra formation in AR 11124 around November 13, 2010, using intensity images from the Helioseismic and Magnetic Imager (HMI) onboard SDO. We conclude that two processes contribute to the increase of the magnetic flux of a sunspot: (1) merging pores, and (2) emerging bipoles of which the spot polarity migrates towards and merges with the spot. As the penumbra forms, the area, magnetic flux, and maximum field strength in the umbra stay constant or increase slightly, i.e., the formation of the penumbra is associated with flux emergence and flux increase of the proto-spot. If two pores merge or if a pore merges with a proto-spot a light bridge is created. This initial light bridge dissolves in the further evolution.

  2. DETECTION OF SUPERSONIC DOWNFLOWS AND ASSOCIATED HEATING EVENTS IN THE TRANSITION REGION ABOVE SUNSPOTS

    Energy Technology Data Exchange (ETDEWEB)

    Kleint, L.; Martínez-Sykora, J. [Bay Area Environmental Research Institute, 625 2nd Street, Ste. 209, Petaluma, CA (United States); Antolin, P. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Tian, H.; Testa, P.; Reeves, K. K.; McKillop, S.; Saar, S.; Golub, L. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Judge, P. [High Altitude Observatory/NCAR, P.O. Box 3000, Boulder, CO 80307 (United States); De Pontieu, B.; Wuelser, J. P.; Boerner, P.; Hurlburt, N.; Lemen, J.; Tarbell, T. D.; Title, A. [Lockheed Martin Solar and Astrophysics Laboratory, 3251 Hanover St., Org. ADBS, Bldg. 252, Palo Alto, CA 94304 (United States); Carlsson, M.; Hansteen, V. [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, NO-0315 Oslo (Norway); Jaeggli, S., E-mail: lucia.kleint@fhnw.ch [Department of Physics, Montana State University, Bozeman, P.O. Box 173840, Bozeman, MT 59717 (United States); and others

    2014-07-10

    Interface Region Imaging Spectrograph data allow us to study the solar transition region (TR) with an unprecedented spatial resolution of 0.''33. On 2013 August 30, we observed bursts of high Doppler shifts suggesting strong supersonic downflows of up to 200 km s{sup –1} and weaker, slightly slower upflows in the spectral lines Mg II h and k, C II 1336, Si IV 1394 Å, and 1403 Å, that are correlated with brightenings in the slitjaw images (SJIs). The bursty behavior lasts throughout the 2 hr observation, with average burst durations of about 20 s. The locations of these short-lived events appear to be the umbral and penumbral footpoints of EUV loops. Fast apparent downflows are observed along these loops in the SJIs and in the Atmospheric Imaging Assembly, suggesting that the loops are thermally unstable. We interpret the observations as cool material falling from coronal heights, and especially coronal rain produced along the thermally unstable loops, which leads to an increase of intensity at the loop footpoints, probably indicating an increase of density and temperature in the TR. The rain speeds are on the higher end of previously reported speeds for this phenomenon, and possibly higher than the free-fall velocity along the loops. On other observing days, similar bright dots are sometimes aligned into ribbons, resembling small flare ribbons. These observations provide a first insight into small-scale heating events in sunspots in the TR.

  3. Depth-dependent global properties of a sunspot observed by Hinode using the Solar Optical Telescope/Spectropolarimeter

    Science.gov (United States)

    Tiwari, Sanjiv K.; van Noort, Michiel; Solanki, Sami K.; Lagg, Andreas

    2015-11-01

    Context. For the past two decades, the three-dimensional structure of sunspots has been studied extensively. A recent improvement in the Stokes inversion technique prompts us to revisit the depth-dependent properties of sunspots. Aims: In the present work, we aim to investigate the global depth-dependent thermal, velocity, and magnetic properties of a sunspot, as well as the interconnection between various local properties. Methods: We analysed high-quality Stokes profiles of the disk-centred, regular, leading sunspot of NOAA AR 10933, acquired by the Solar Optical Telescope/Spectropolarimeter (SOT/SP) on board the Hinode spacecraft. To obtain depth-dependent stratification of the physical parameters, we used the recently developed, spatially coupled version of the SPINOR inversion code. Results: First, we study the azimuthally averaged physical parameters of the sunspot. We find that the vertical temperature gradient in the lower- to mid-photosphere is at its weakest in the umbra, while it is considerably stronger in the penumbra, and stronger still in the spot's surroundings. The azimuthally averaged field becomes more horizontal with radial distance from the centre of the spot, but more vertical with height. At continuum optical depth unity, the line-of-sight velocity shows an average upflow of ~300 ms-1 in the inner penumbra and an average downflow of ~1300 ms-1 in the outer penumbra. The downflow continues outside the visible penumbral boundary. The sunspot shows, at most, a moderate negative twist of qualitative similarity to that of a standard penumbral filament and its surrounding spines. Conclusions: The large-scale variation in the physical parameters of a sunspot at various optical depths is presented. Our results suggest that the spines in the penumbra are basically the outward extension of the umbra. The spines and the penumbral filaments, together, are the basic elements that form a sunspot penumbra.

  4. Detection of polarization from the E^4\\Pi-A^4\\Pi system of FeH in sunspot spectra

    CERN Document Server

    Ramos, A A; Collados, M

    2004-01-01

    Here we report the first detection of polarization signals induced by the Zeeman effect in spectral lines of the E^4\\Pi-A^4\\Pi system of FeH located around 1.6 $\\mu$m. Motivated by the tentative detection of this band in the intensity spectrum of late-type dwarfs, we have investigated the full Stokes sunspot spectrum finding circular and linear polarization signatures that we associate with the FeH lines of the E^4\\Pi-A^4\\Pi band system. We investigate the Zeeman effect in these molecular transitions pointing out that in Hund's case (a) coupling the effective Land\\'e factors are never negative. For this reason, the fact that our spectropolarimetric observations indicate that the Land\\'e factors of pairs of FeH lines have opposite signs, prompt us to conclude that the E^4\\Pi-A^4\\Pi system must be in intermediate angular momentum coupling between Hund's cases (a) and (b). We emphasize that theoretical and/or laboratory investigations of this molecular system are urgently needed for exploiting its promising diag...

  5. Generation of a Solar Cycle of Sunspot Metadata Using the AIA Event Detection Framework - A Test of the System

    Science.gov (United States)

    Slater, G. L.; Zharkov, S.

    2008-12-01

    The soon-to-be-launched Solar Dynamics Observatory (SDO) will generate roughly 2 TB of image data per day, far more than previous solar missions. Because of the difficulty of widely distributing this enormous volume of data and in order to maximize discovery and scientific return, a sophisticated automated metadata extraction system is being developed at Stanford University and Lockheed Martin Solar and Astrophysics Laboratory in Palo Alto, CA. A key component in this system is the Event Detection System, which will supervise the execution of a set of feature and event extraction algorithms running in parallel, in real time, on all images recorded by the four telescopes of the key imaging instrument, the Atmospheric Imaging Assembly (AIA). The system will run on a beowulf cluster of 160 processors. As a test of the new system, we will run feature extraction software developed under the European Grid of Solar Observatories (EGSO) program to extract sunspot metadata from the 12 year SOHO MDI mission archive of full disk continuum and magnetogram images and also from the TRACE high resolution image archive. Although the main goal will be to test the performance of the production line framework, the resulting database will have applications for both research and space weather prediction. We examine some of these applications and compare the databases generated with others currently available.

  6. Penumbra

    DEFF Research Database (Denmark)

    Bengtsen, Søren Smedegaard; Wisker, Gina; Robinson, Gill

    2016-01-01

    the ‘darkside’, verging on plagiarism, substitution of effort, bad practice. We identify those in support as resembling a ‘penumbra’ a light around the main activity, and adopted an analogy of dramatic production roles to explore work of the various cast and production team supporting PhD students’ work....

  7. Penumbra

    DEFF Research Database (Denmark)

    Bengtsen, Søren Smedegaard; Wisker, Gina; Robinson, Gill

    2016-01-01

    the ‘darkside’, verging on plagiarism, substitution of effort, bad practice. We identify those in support as resembling a ‘penumbra’ a light around the main activity, and adopted an analogy of dramatic production roles to explore work of the various cast and production team supporting PhD students’ work....... consider formal and informal learning communities supporting students in their research journeys, and roles played by families, friends and others, sometimes offering encouragement and sometimes an added stress. However, little has yet been explored, exposed and shared concerning the often unofficial...

  8. Sunspots are in many ways similar to terrestrial vortices

    CERN Document Server

    Vatistas, Georgios H

    2011-01-01

    In this letter we identify similarities amongst sunspots and terrestrial vortices. The dark appearance of the central part of any sunspot is currently justified by an anticipated cooling effect experienced by the ionized gas. However, it cannot single-handedly reconcile the halo that surrounds the penumbra, the subsequent second dim ring that could be possibly followed by a second halo. In antithesis, light refraction due to density variations in a compressible whirl can give reason for all of these manifestations. Certain data of Wilson's depression fit better the geometric depth profile of a two-celled vortex. The last provides a hurricane equivalent manifestation for the normal and reverse Evershed effect. There is compelling evidence that alike to atmospheric vortices sunspots do also spawn meso-cyclones.

  9. On the Formation of Penumbrae as Observed with the German VTT, SOHO/MDI, and SDO/HMI

    CERN Document Server

    Schlichenmaier, Rolf; Gonzalez, Nazaret Bello

    2011-01-01

    Solar magnetic fields are generated in the solar interior and pop up at the solar surface to form active regions. As the magnetic field appears on the surface, it forms various structures like small magnetic elements, pores, and sunspots. The nature of these formation processes is largely unknown. In this contribution we elaborate on the formation of sunspots and particularly on the formation of penumbrae. We report on observations that we obtained at the German VTT on July 4, 2009 on the formation of the spot in AR 11024. This data set is accomplished with data from SOHO/MDI which offers an entire time coverage. Moreover, the evolution of AR 11024 is compared with a particular event of penumbra formation in AR 11124 around November 13, 2010, using intensity images from SDO/HMI. We conclude that two processes contribute to the increase of the magnetic flux of a sunspot: (1) merging pores, and (2) emerging bipoles of which the spot polarity migrates towards and merges with the spot. As the penumbra forms the a...

  10. Global Twist of Sunspot Magnetic Fields Obtained from High Resolution Vector Magnetograms

    CERN Document Server

    Tiwari, Sanjiv Kumar; Sankarasubramanian, K

    2009-01-01

    The presence of fine structures in the sunspot vector magnetic fields has been confirmed from Hinode as well as other earlier observations. We studied 43 sunspots based on the data sets taken from ASP/DLSP, Hinode (SOT/SP) and SVM (USO). In this \\emph{Letter}, (i) We introduce the concept of signed shear angle (SSA) for sunspots and establish its importance for non force-free fields. (ii) We find that the sign of global $\\alpha$ (force-free parameter) is well correlated with the global SSA and the photospheric chirality of sunspots. (iii) Local $\\alpha$ patches of opposite signs are present in the umbra of each sunspot. The amplitude of the spatial variation of local $\\alpha$ in the umbra is typically of the order of the global $\\alpha$ of the sunspot. (iv) We find that the local $\\alpha$ is distributed as alternately positive and negative filaments in the penumbra. The amplitude of azimuthal variation of the local $\\alpha$ in the penumbra is approximately an order of magnitude larger than that in the umbra. ...

  11. Research progress in traumatic brain penumbra

    Institute of Scientific and Technical Information of China (English)

    Wang Kai; Liu Baiyun; Ma Jun

    2014-01-01

    Objective Following traumatic brain injury (TBI),brain tissue that surrounding the regional primary lesion is known as traumatic penumbra; this region may undergo secondary injury and is considered to have the potential to recover.This review aimed to reveal the existence and significance of traumatic penumbra by analyzing all relevant studies concerning basic pathologic changes and brain imaging after TBI.Data sources We collected all relevant studies about TBI and traumatic penumbra in Medline (1995 to June 2013) and ISI (1997 to March 2013),evaluated their quality and relevance,then extracted and synthesized the information.Study selection We included all relevant studies concerning TBI and traumatic penumbra (there was no limitation of research design and article language) and excluded the duplicated articles.Results The crucial pathological changes after TBI include cerebral blood flow change,cerebral edema,blood-brain barrier damage,cell apoptosis and necrosis.Besides,traditional imaging method cannot characterize the consequences of CBF reduction at an early stage and provides limited insights into the underlying pathophysiology.While advanced imaging technique,such as diffusion tensor imaging (DTI) and positron emission tomography (PET),may provide better characterization of such pathophysiology.Conclusions The future of traumatic brain lesions depends to a large extent on the evolution of the penumbra.Therefore,understanding the formation and pathophysiologic process of the traumatic penumbra and its imaging research progress is of great significant for early clinical determination and timely brain rescue.

  12. On the Relationship Between Sunspot Structure and Magnetic Field Changes Associated with Solar Flares

    Science.gov (United States)

    Song, Y. L.; Zhang, M.

    2016-08-01

    Many previous studies have shown that magnetic fields and sunspot structures present rapid and irreversible changes associated with solar flares. In this paper, we first use five X-class flares observed by Solar Dynamics Observatory/Helioseismic and Magnetic Imager to show that not only do magnetic fields and sunspot structures show rapid, irreversible changes, but also that these changes are closely related both spatially and temporally. The magnitudes of the correlation coefficients between the temporal variations of the horizontal magnetic field and sunspot intensity are all larger than 0.90, with a maximum value of 0.99 and an average value of 0.96. Then, using four active regions during quiescent periods, three observed and one simulated, we show that in sunspot penumbra regions there also exists a close correlation between sunspot intensity and horizontal magnetic field strength in addition to the well-known correlation between sunspot intensity and the normal magnetic field strength. By connecting these two observational phenomena, we show that the sunspot structure change and magnetic field change are two facets of the same phenomena of solar flares; one change might be induced by the change of the other due to a linear correlation between sunspot intensity and magnetic field strength out of a local force balance.

  13. Numerical simulations of the subsurface structure of sunspots

    Science.gov (United States)

    Rempel, M.; Cheung, M.; Birch, A. C.; Braun, D. C.

    2011-12-01

    Knowledge of the subsurface magnetic field and flow structure of sunspots is essential for understanding the processes involved in their formation, dynamic evolution and decay. Information on the subsurface structure can be obtained by either direct numerical modeling or helioseismic inversions. Numerical simulations have reached only in recent years the point at which entire sunspots or even active regions can be modeled including all relevant physical processes such as 3D radiative transfer and a realistic equation of state. We present in this talk results from a series of different models: from simulations of individual sunspots (with and without penumbrae) in differently sized computational domains to simulations of the active region formation process (flux emergence). It is found in all models that the subsurface magnetic field fragments on an intermediate scale (larger than the scale of sunspot fine structure such as umbral dots); most of these fragmentations become visible as light bridges or flux separation events in the photosphere. The subsurface field strength is found to be in the 5-10 kG range. The simulated sunspots are surrounded by large scale flows, the most dominant and robust flow component is a deep reaching outflow with an amplitude reaching about 50% of the convective RMS velocity at the respective depth. The simulated sunspots show helioseismic signatures (frequency dependent travel time shifts) similar to those in observed sunspots. On the other hand it is clear from the simulations that these signatures originate in the upper most 2-3 Mm of the convection zone, since only there substantial perturbations of the wave speed are present. The contributions from deeper layers are insignificant, in particular a direct comparison between an 8 Mm and 16 Mm deep simulation leads to indiscernible helioseismic differences. The National Center for Atmospheric Research is sponsored by the National Science Foundation. This work is in part supported

  14. The formation of a penumbra as observed with the German VTT and SoHO/MDI

    CERN Document Server

    Schlichenmaier, Rolf; Rezaei, Reza

    2010-01-01

    The generation of magnetic flux in the solar interior and its transport to the outer solar atmosphere will be in the focus of solar physics research for the next decades. One key-ingredient is the process of magnetic flux emergence into the solar photosphere, and the reorganization to form the magnetic phenomena of active regions like sunspots and pores. On July 4, 2009, we observed a region of emerging magnetic flux, in which a proto-spot without penumbra forms a penumbra within some 4.5 hours. This process is documented by multi-wavelength observations at the German VTT: (a) imaging, (b) data with high resolution and temporal cadence acquired in Fe I 617.3 nm with the 2D imaging spectropolarimter GFPI, and (c) scans with the slit based spectropolarimeter TIP in Fe I 1089.6 nm. MDI contiuum maps and magnetograms are used to follow the formation of the proto-spot, and the subsequent evolution of the entire active region. During the formation of the penumbra, the area and the magnetic flux of the spot increase...

  15. Automatic Recognition of Sunspots in HSOS Full-Disk Solar Images

    Science.gov (United States)

    Zhao, Cui; Lin, GangHua; Deng, YuanYong; Yang, Xiao

    2016-05-01

    A procedure is introduced to recognise sunspots automatically in solar full-disk photosphere images obtained from Huairou Solar Observing Station, National Astronomical Observatories of China. The images are first pre-processed through Gaussian algorithm. Sunspots are then recognised by the morphological Bot-hat operation and Otsu threshold. Wrong selection of sunspots is eliminated by a criterion of sunspot properties. Besides, in order to calculate the sunspots areas and the solar centre, the solar limb is extracted by a procedure using morphological closing and erosion operations and setting an adaptive threshold. Results of sunspot recognition reveal that the number of the sunspots detected by our procedure has a quite good agreement with the manual method. The sunspot recognition rate is 95% and error rate is 1.2%. The sunspot areas calculated by our method have high correlation (95%) with the area data from the United States Air Force/National Oceanic and Atmospheric Administration (USAF/NOAA).

  16. Automatic Recognition of Sunspots in HSOS Full-Disk Solar Images

    CERN Document Server

    Zhao, Cui; Deng, YuanYong; Yang, Xiao

    2016-01-01

    A procedure is introduced to recognise sunspots automatically in solar full-disk photosphere images obtained from Huairou Solar Observing Station, National Astronomical Observatories of China. The images are first pre-processed through Gaussian algorithm. Sunspots are then recognised by the morphological Bot-hat operation and Otsu threshold. Wrong selection of sunspots is eliminated by a criterion of sunspot properties. Besides, in order to calculate the sunspots areas and the solar centre, the solar limb is extracted by a procedure using morphological closing and erosion operations and setting an adaptive threshold. Results of sunspot recognition reveal that the number of the sunspots detected by our procedure has a quite good agreement with the manual method. The sunspot recognition rate is 95% and error rate is 1.2%. The sunspot areas calculated by our method have high correlation (95%) with the area data from USAF/NOAA.

  17. Hi-C Observations of Sunspot Penumbral Bright Dots

    OpenAIRE

    Alpert, Shane E.; Tiwari, Sanjiv K.; Moore, Ronald L.; Winebarger, Amy R.; Savage, Sabrina L.

    2016-01-01

    We report observations of bright dots (BDs) in a sunspot penumbra using High Resolution Coronal Imager (Hi-C) data in 193 \\AA\\ and examine their sizes, lifetimes, speeds, and intensities. The sizes of the BDs are on the order of 1\\arcsec\\ and are therefore hard to identify in the Atmospheric Imaging Assembly (AIA) 193 \\AA\\ images, which have 1.2\\arcsec\\ spatial resolution, but become readily apparent with Hi-C's five times better spatial resolution. We supplement Hi-C data with data from AIA'...

  18. Radiative transfer effects on Doppler measurements as sources of surface effects in sunspot seismology

    CERN Document Server

    Rajaguru, S P; Wachter, R; Scherrer, P H

    2006-01-01

    We show that the use of Doppler shifts of Zeeman sensitive spectral lines to observe wavesn in sunspots is subject to measurement specific phase shifts arising from, (i) altered height range of spectral line formation and the propagating character of p mode waves in penumbrae, and (ii) Zeeman broadening and splitting. We also show that these phase shifts depend on wave frequencies, strengths and line of sight inclination of magnetic field, and the polarization state used for Doppler measurements. We discuss how these phase shifts could contribute to local helioseismic measurements of 'surface effects' in sunspot seismology.

  19. Short dynamic fibrils in sunspot chromospheres

    CERN Document Server

    van der Voort, Luc Rouppe

    2013-01-01

    Sunspot chromospheres display vigorous oscillatory signature when observed in chromospheric diagnostics like the strong Ca II lines and H-alpha. New high-resolution sunspot observations from the Swedish 1-m Solar Telescope show the ubiquitous presence of small-scale periodic jet-like features that move up and down. This phenomenon has not been described before. Their typical width is about 0.3 arcsec and they display clear parabolic trajectories in space-time diagrams. The maximum extension of the top of the jets is lowest in the umbra, a few 100 km, and progressively longer further away from the umbra in the penumbra, with the longest more than 1000 km. These jets resemble dynamic fibrils found in plage regions but at smaller extensions. LTE inversion of spectro-polarimetric Ca II 8542 observations enabled for a comparison of the magnetic field inclination and the properties of these short jets. We find that the most extended of these jets also have longer periods and tend to be located in regions with more ...

  20. On the relationship between sunspot structure and magnetic field changes associated with solar flares

    CERN Document Server

    Song, Yongliang

    2016-01-01

    Many previous studies have shown that magnetic fields as well as sunspot structures present rapid and irreversible changes associated with solar flares. In this paper we first use five X-class flares observed by SDO/HMI to show that not only the magnetic fields and sunspot structures do show rapid, irreversible changes but also these changes are closely related, both spatially and temporally. The magnitudes of the correlation coefficients between the temporal variations of horizontal magnetic field and sunspot intensity are all larger than 0.90, with a maximum value of 0.99 and an average value of 0.96. Then using four active regions in quiescent times, three observed and one simulated, we show that in sunspot penumbra regions there also exists a close correlation between sunspot intensity and horizontal magnetic field strength, in addition to the well-known one between sunspot intensity and normal magnetic field strength. Connecting these two observational phenomena, we show that the sunspot structure change...

  1. A Fully Automated Penumbra Segmentation Tool

    DEFF Research Database (Denmark)

    Nagenthiraja, Kartheeban; Ribe, Lars Riisgaard; Hougaard, Kristina Dupont

    2012-01-01

    salavageable tissue, quickly and accurately. We present a fully Automated Penumbra Segmentation (APS) algorithm using PWI and DWI images. We compare automatically generated PWI-DWI mismatch mask to mask outlined manually by experts, in 168 patients. Method: The algorithm initially identifies PWI lesions...

  2. Subsurface magnetic field and flow structure of simulated sunspots

    CERN Document Server

    Rempel, Matthias

    2011-01-01

    We present a series of numerical sunspot models addressing the subsurface field and flow structure in up to 16 Mm deep domains covering up to 2 days of temporal evolution. Changes in the photospheric appearance of the sunspots are driven by subsurface flows in several Mm depth. Most of magnetic field is pushed into a downflow vertex of the subsurface convection pattern, while some fraction of the flux separates from the main trunk of the spot. Flux separation in deeper layers is accompanied in the photosphere with light bridge formation in the early stages and formation of pores separating from the spot at later stages. Over a time scale of less than a day we see the development of a large scale flow pattern surrounding the sunspots, which is dominated by a radial outflow reaching about 50% of the convective rms velocity in amplitude. Several components of the large scale flow are found to be independent from the presence of a penumbra and the associated Evershed flow. While the simulated sunspots lead to blo...

  3. MHD waves in sunspots

    CERN Document Server

    Sych, Robert

    2015-01-01

    The review addresses the spatial frequency morphology of sources of sunspot oscillations and waves, including their localization, size, oscillation periods, height localization with the mechanism of cut-off frequency that forms the observed emission variability. Dynamic of sunspot wave processes, provides the information about the structure of wave fronts and their time variations, investigates the oscillation frequency transformation depending on the wave energy is shown. The initializing solar flares caused by trigger agents like magnetoacoustic waves, accelerated particle beams, and shocks are discussed. Special attention is paid to the relation between the flare reconnection periodic initialization and the dynamics of sunspot slow magnetoacoustic waves. A short review of theoretical models of sunspot oscillations is provided.

  4. Altered resting-state FMRI signals in acute stroke patients with ischemic penumbra.

    Directory of Open Access Journals (Sweden)

    Yuan-Hsiung Tsai

    Full Text Available Identifying the ischemic penumbra in acute stroke subjects is important for the clinical decision making process. The aim of this study was to use resting-state functional magnetic resonance singal (fMRI to investigate the change in the amplitude of low-frequency fluctuations (ALFF of these subjects in three different subsections of acute stroke regions: the infarct core tissue, the penumbra tissue, and the normal brain tissue. Another aim of this study was to test the feasilbility of consistently detecting the penumbra region of the brain through ALFF analysis.Sixteen subjects with first-ever acute ischemic stroke were scanned within 27 hours of the onset of stroke using magnetic resonance imaging. The core of infarct regions and penumbra regions were determined by diffusion and perfusion-weighted imaging respectively. The ALFF were measured from resting-state blood oxygen level dependent (BOLD fMRI scans. The averaged relative ALFF value of each regions were correlated with the time after the onset of stroke.Relative ALFF values were significantly different in the infarct core tissue, penumbra tissue and normal brain tissue. The locations of lesions in the ALFF maps did not match perfectly with diffusion and perfusion-weighted imagings; however, these maps provide a contrast that can be used to differentiate between penumbra brain tissue and normal brain tissue. Significant correlations between time after stroke onset and the relative ALFF values were present in the penumbra tissue but not in the infarct core and normal brain tissue.Preliminary results from this study suggest that the ALFF reflects the underlying neurovascular activity and has a great potential to estimate the brain tissue viability after ischemia. Results also show that the ALFF may contribute to acute stroke imaging for thrombolytic or neuroprotective therapies.

  5. Revisiting the Sunspot Number

    CERN Document Server

    Clette, Frédéric; Vaquero, José M; Cliver, Edward W

    2014-01-01

    Our knowledge of the long-term evolution of solar activity and of its primary modulation, the 11-year cycle, largely depends on a single direct observational record: the visual sunspot counts that retrace the last 4 centuries, since the invention of the astronomical telescope. Currently, this activity index is available in two main forms: the International Sunspot Number initiated by R. Wolf in 1849 and the Group Number constructed more recently by Hoyt and Schatten (1998a,b). Unfortunately, those two series do not match by various aspects, inducing confusions and contradictions when used in crucial contemporary studies of the solar dynamo or of the solar forcing on the Earth climate. Recently, new efforts have been undertaken to diagnose and correct flaws and biases affecting both sunspot series, in the framework of a series of dedicated Sunspot Number Workshops. Here, we present a global overview of our current understanding of the sunspot number calibration. While the early part of the sunspot record befor...

  6. Sunspot Sizes and the Solar Cycle: Analysis Using Kodaikanal White-light Digitized Data

    Science.gov (United States)

    Mandal, Sudip; Banerjee, Dipankar

    2016-10-01

    Sizes of the sunspots vary widely during the progression of a solar cycle. Long-term variation studies of different sunspot sizes are key to better understand the underlying process of sunspot formation and their connection to the solar dynamo. The Kodaikanal white-light digitized archive provides daily sunspot observations for a period of 90 years (1921-2011). Using different size criteria on the detected individual sunspots, we have generated yearly averaged sunspot area time series for the full Sun as well as for the individual hemispheres. In this Letter, we have used the sunspot area values instead of sunspot numbers used in earlier studies. Analysis of these different time series show that different properties of the sunspot cycles depend on the sunspot sizes. The “odd-even rule” double peaks during the cycle maxima and the long-term periodicities in the area data are found to be present for specific sunspot sizes and are absent or not so prominent in other size ranges. Apart from that, we also find a range of periodicities in the asymmetry index that have a dependency on the sunspot sizes. These statistical differences in the different size ranges may indicate that a complex dynamo action is responsible for the generation and dynamics of sunspots with different sizes.

  7. Time-Distance Helioseismology of Two Realistic Sunspot Simulations

    CERN Document Server

    DeGrave, K; Rempel, M

    2014-01-01

    Linear time-distance helioseismic inversions are carried out using several filtering schemes to determine vector flow velocities within two $\\sim100^2\\,{\\rm Mm^2}\\times 20\\,{\\rm Mm}$ realistic magnetohydrodynamic sunspot simulations of 25~hr. One simulation domain contains a model of a full sunspot (i.e. one with both an umbra and penumbra), while the other contains a pore (i.e. a spot without a penumbra). The goal is to test current helioseismic methods using these state-of-the-art simulations of magnetic structures. We find that horizontal flow correlations between inversion and simulation flow maps are reasonably high ($\\sim0.5$--0.8) in the upper 3~Mm at distances exceeding 25--30~Mm from spot center, but are substantially lower at smaller distances and larger depths. Inversions of forward-modeled travel times consistently outperform those of our measured travel times in terms of horizontal flow correlations, suggesting that our inability to recover flow structure near these active regions is largely due ...

  8. Rescuing the ischemic penumbra: Our experience

    Directory of Open Access Journals (Sweden)

    Milosavljević Tamara

    2013-12-01

    Full Text Available Objectives: Over one million strokes per year are occurring in Europe. Brain stroke is one of the most important death and disability causes in Europe and USA. The main role of perfusion is to determine the border of insult core and ischemic penumbra. Penumbra can be saved with thrombolytic therapy but core have irreversible injuries and represent death of brain cells. Aim: to determine the role of CT brain perfusion in cases of acute brain stroke and following thrombolytic therapy. Methods: We examined 64 patients with acute brain stroke who received thrombolytic therapy after that. All patients were examining on 16 MDCT with 50 ml of iodine contrast agent following the standard procedure for CT perfusion. Patients were 34 male and 30 female with middle age of 64 years. MRI was made after thrombolytic therapy and compare with perfusion results before therapy. Results: Using an artery and a vein as reference three parameters were measured - blood flow (CBF, blood volume (CBV and mean transit time (MTT, for each patient. Hemorrhagic was find in 9 (14.01% patients after thrombolytic therapy. 4 (6.25% other patients develop new stroke of same but mostly other side of brain. 8 (12.50% more patients finished lethally. From other 42 patients with thrombolytic therapy we can positively say that in 31 (48.44% patients penumbra was rescued. For other 11 (17.19% stroke was same size like firstly involved core and penumbra but not bigger. Conclusion: CT perfusion plays major role by showing a curable parts of tissue in brain strokes.

  9. Ca II H sunspot tomography from the photosphere to the chromosphere

    Science.gov (United States)

    Henriques, V. M. J.; Kiselman, D.

    2013-09-01

    Aims: We aim at gaining insight into the thermal properties of different small-scale structures related to sunspots. Methods: We use filtergrams in the Ca ii H filter at the Swedish 1-m Solar Telescope to study the relationship between fine structure at different heights in a sunspot. Results: The methods for destretching and aligning the different image data work well. The magnetic spine structure in the outer parts of the sunspot penumbra is found to be associated with higher intensities in the Ca ii H wing passbands but with less steep vertical temperature gradients. Dark lanes in a light bridge behave very similarly to dark cores in penumbral filaments. Fibril structures are seen in the line-core images over the umbra and penumbra. Conclusions: The observations add support to the idea that penumbral filaments, light bridges, and umbral dots are caused by similar processes of overturning convection. Observations in the Ca ii H & K wings are a promising observable, complementing others, for testing simulation results for sunspots at high spatial resolution.

  10. Using the knowledge of penumbra with a trick simulation

    CERN Document Server

    Bülbül, Mustafa Şahin

    2016-01-01

    The study is about a basic shadow experiment, which was enriched with a simulation to understand the reasoning of participants when we use a trick. Two light sources create an umbra and penumbra behind the objects. With this experiment, we asked what would happen when the penumbras interact. Most of the participants predicted the correct solution, that there should be an umbra. Some of the participants choose wrong alternative, and explained in terms of the structure of penumbra.

  11. Evolution of sunspot properties during solar cycle 23

    CERN Document Server

    Watson, Fraser T; Marshall, Stephen; 10.1051/0004-6361/201116655

    2011-01-01

    The long term study of the Sun is necessary if we are to determine the evolution of sunspot properties and thereby inform modeling of the solar dynamo, particularly on scales of a solar cycle. We aim to determine a number of sunspot properties over cycle 23 using the uniform database provided by the SOHO Michelson Doppler Imager data. We focus in particular on their distribution on the solar disk, maximum magnetic field and umbral/penumbral areas. We investigate whether the secular decrease in sunspot maximum magnetic field reported in Kitt Peak data is present also in MDI data. We have used the Sunspot Tracking And Recognition Algorithm (STARA) to detect all sunspots present in the SOHO Michelson Doppler Imager continuum data giving us 30 084 separate detections. We record information on the sunspot locations, area and magnetic field properties and corresponding information for the umbral areas detected within the sunspots, and track them through their evolution. We find the total visible umbral area is 20-4...

  12. Sunspot Sizes and The Solar Cycle: Analysis Using Kodaikanal White-light Digitized Data

    CERN Document Server

    Mandal, Sudip

    2016-01-01

    Sizes of the sunspots vary in a wide range during the progression of a solar cycle. Long-term variation study of different sunspot sizes are key to better understand the underlying process of sunspot formation and their connection to the solar dynamo. Kodaikanal white-light digitized archive provides daily sunspot observations for a period of 90 years (1921-2011). Using different size criteria on the detected individual sunspots, we have generated yearly averaged sunspot area time series for the full Sun as well as for the individual hemispheres. In this paper, we have used the sunspot area values instead of sunspot numbers used in earlier studies. Analysis of these different time series show that different properties of the sunspot cycles depend on the sunspot sizes. The `odd-even rule', double peaks during the cycle maxima and the long-term periodicities in the area data are found to be present for specific sunspot sizes and are absent or not so prominent in other size ranges. Apart from that, we also find ...

  13. Transition-Region/Coronal Signatures and Magnetic Setting of Sunspot Penumbral Jets: {\\it Hinode} (SOT/FG), Hi-C and {\\it SDO}/AIA Observations

    CERN Document Server

    Tiwari, Sanjiv K; Winebarger, Amy R; Alpert, Shane E

    2015-01-01

    Penumbral microjets (PJs) are transient narrow bright features in the chromosphere of sunspot penumbrae, first characterized by Katsukawa et al (2007) using the \\CaII\\ H-line filter on {\\it Hinode}'s Solar Optical Telescope (SOT). It was proposed that the PJs form as a result of reconnection between two magnetic components of penumbra (spines and interspines), and that they could contribute to the transition region (TR) and coronal heating above sunspot penumbrae. We propose a modified picture of formation of PJs based on recent results on internal structure of sunspot penumbral filaments. Using data of a sunspot from {\\it Hinode}/SOT, High Resolution Coronal Imager, and different passbands of the Atmospheric Imaging Assembly (AIA) onboard the {\\it Solar Dynamics Observatory}, we examine whether PJs have signatures in the TR and corona. We find hardly any discernible signature of normal PJs in any AIA passbands, except a few of them showing up in the 1600 \\AA\\ images. However, we discovered exceptionally stro...

  14. Depth-dependent global properties of a sunspot observed by Hinode (SOT/SP)

    CERN Document Server

    Tiwari, Sanjiv K; Solanki, Sami K; Lagg, Andreas

    2015-01-01

    The 3D structure of sunspots has been extensively studied for the last two decades. A recent advancement of the Stokes inversion technique prompts us to revisit the problem. We investigate the global depth-dependent thermal, velocity and magnetic properties of a sunspot, as well as the interconnection between various local properties. High quality Stokes profiles of a disk centered, regular sunspot acquired by the SOT/SP (Hinode) are analyzed. To obtain the depth-dependent stratification of the physical parameters, we use the spatially coupled version of the SPINOR code. The vertical temperature gradient in the lower to mid-photosphere is smallest in the umbra, it is considerably larger in the penumbra and still somewhat larger in the spot's surroundings. The azimuthally averaged field becomes more horizontal with radial distance from the center of the spot, but more vertical with height. At tau=1, the LOS velocity shows an average upflow of 300 ms-1 in the inner penumbra and an average downflow of 1300 ms-1 ...

  15. A Peculiar Velocity Pattern in and near the Leading Sunspot of NOAA 10781: Wave Refraction by Large-Scale Magnetic Fields?

    CERN Document Server

    Beck, C

    2010-01-01

    I report observations of unusually strong photospheric and chromospheric velocity oscillations in and near the leading sunspot of NOAA 10781 on 03 July 2005. I investigate an impinging wave as a possible origin of the velocity pattern, and the changes of the wave after the passage through the magnetic fields of the sunspot. The wave pattern found consists of a wave with about 3 Mm apparent wavelength that propagates towards the sunspot. This wave seems to trigger oscillations inside the sunspot's umbra, which originate from a location inside the penumbra on the side of the impinging wave. The wavelength decreases and the velocity amplitude increases by an order of magnitude in the chromospheric layers inside the sunspot. On the side of the sunspot opposite to the impinging plane wave, circular wave fronts centered on the umbra are seen propagating away from the sunspot outside its outer white-light boundary. They lead to a peculiar ring structure around the sunspot, which is visible in both velocity and inten...

  16. Coordination failure caused by sunspots

    DEFF Research Database (Denmark)

    Beugnot, Julie; Gürgüç, Zeynep; Øvlisen, Frederik Roose

    2012-01-01

    In a coordination game with Pareto-ranked equilibria, we study whether a sunspot can lead to either coordination on an inferior equilibrium (mis-coordination) or to out-of equilibrium behavior (dis-coordination). While much of the literature searches for mechanisms to attain coordination...... on the efficient equilibrium, we consider sunspots as a potential reason for coordination failure. We conduct an experiment with a three player 2x2x2 game in which coordination on the efficient equilibrium is easy and should normally occur. In the control session, we find almost perfect coordination on the payoff......-dominant equilibrium, but in the sunspot treatment, dis-coordination is frequent. Sunspots lead to significant inefficiency, and we conclude that sunspots can indeed cause coordination failure....

  17. Hi-C Observations of Sunspot Penumbral Bright Dots

    CERN Document Server

    Alpert, Shane E; Moore, Ronald L; Winebarger, Amy R; Savage, Sabrina L

    2016-01-01

    We report observations of bright dots (BDs) in a sunspot penumbra using High Resolution Coronal Imager (Hi-C) data in 193 \\AA\\ and examine their sizes, lifetimes, speeds, and intensities. The sizes of the BDs are on the order of 1\\arcsec\\ and are therefore hard to identify in the Atmospheric Imaging Assembly (AIA) 193 \\AA\\ images, which have 1.2\\arcsec\\ spatial resolution, but become readily apparent with Hi-C's five times better spatial resolution. We supplement Hi-C data with data from AIA's 193 \\AA\\ passband to see the complete lifetime of the BDs that appeared before and/or lasted longer than Hi-C's 3-minute observation period. Most Hi-C BDs show clear lateral movement along penumbral striations, toward or away from the sunspot umbra. Single BDs often interact with other BDs, combining to fade away or brighten. The BDs that do not interact with other BDs tend to have smaller displacements. These BDs are about as numerous but move slower on average than Interface Region Imaging Spectrograph (IRIS) BDs, rec...

  18. Surface-focused Seismic Holography of Sunspots: I. Observations

    CERN Document Server

    Braun, D C

    2008-01-01

    We present a comprehensive set of observations of the interaction of p-mode oscillations with sunspots using surface-focused seismic holography. Maps of travel-time shifts, relative to quiet-Sun travel times, are shown for incoming and outgoing p modes as well as their mean and difference. We compare results using phase-speed filters with results obtained with filters that isolate single p-mode ridges, and further divide the data into multiple temporal frequency bandpasses. The f mode is removed from the data. The variations of the resulting travel-time shifts with magnetic-field strength and with the filter parameters are explored. We find that spatial averages of these shifts within sunspot umbrae, penumbrae, and surrounding plage often show strong frequency variations at fixed phase speed. In addition, we find that positive values of the mean and difference travel-time shifts appear exclusively in waves observed with phase-speed filters that are dominated by power in the low-frequency wing of the p1 ridge....

  19. Precise Characterization of the Penumbra Revealed by MRI: A Modified Photothrombotic Stroke Model Study.

    Directory of Open Access Journals (Sweden)

    Cheng Qian

    Full Text Available To precisely characterize the penumbra by MRI based on a modified photothrombotic stroke mouse model.The proximal middle cerebral artery was occluded by a convenient laser system in conjunction with an intravenous injection of Rose Bengal in mice. And the suture MCAO model was performed in seven mice as a comparison of the reproducibility. One hour after occlusion, the penumbra was defined in six random photothrombotic stroke mice by mismatch between perfusion-weighted imaging and the apparent diffusion coefficient map on a home-made workstation. After imaging, three random mice of them were chosen to perform the reperfusion surgery. And the other three mice were sacrificed to stain for several potential penumbra markers, such as c-fos and heart shock protein 90. In the remaining mice, the evolution of the lesions was detected on the apparent diffusion coefficient map, diffusion-weighted imaging and T2-weighted imaging at 1, 3, 6, 12 and 24 hours. After evaluating the neurological deficit scores, the brains were sectioned and stained by triphenyltetrazolium chloride and Nissl.The mice subjected to photothrombosis showed significant behavioral deficits. One hour after occlusion, the low perfusion areas on the perfusion-weighted imaging interlaced with the hypointense areas on the apparent diffusion coefficient map, demonstrating that the penumbra was located both surrounding and inside the lesions. This phenomenon was subsequently confirmed by the c-fos and heart shock protein 90 staining. The final T2-weighted images of the mice subjected to the reperfusion surgery were also consistent with the penumbra images at one hour. At early stages, the lesions were clearly identified on the apparent diffusion coefficient map; the volumes of the lesions on the diffusion-weighted imaging and T2-weighted imaging did not reach a maximum until 12 hours. The coefficient of variation (CV of the final lesions in the photothrombotic stroke mice was 21.7% (0.08 of

  20. Precise Characterization of the Penumbra Revealed by MRI: A Modified Photothrombotic Stroke Model Study.

    Science.gov (United States)

    Qian, Cheng; Li, Pei-Cheng; Jiao, Yun; Yao, Hong-Hong; Chen, Yu-Chen; Yang, Jian; Ding, Jie; Yang, Xiang-Yu; Teng, Gao-Jun

    2016-01-01

    To precisely characterize the penumbra by MRI based on a modified photothrombotic stroke mouse model. The proximal middle cerebral artery was occluded by a convenient laser system in conjunction with an intravenous injection of Rose Bengal in mice. And the suture MCAO model was performed in seven mice as a comparison of the reproducibility. One hour after occlusion, the penumbra was defined in six random photothrombotic stroke mice by mismatch between perfusion-weighted imaging and the apparent diffusion coefficient map on a home-made workstation. After imaging, three random mice of them were chosen to perform the reperfusion surgery. And the other three mice were sacrificed to stain for several potential penumbra markers, such as c-fos and heart shock protein 90. In the remaining mice, the evolution of the lesions was detected on the apparent diffusion coefficient map, diffusion-weighted imaging and T2-weighted imaging at 1, 3, 6, 12 and 24 hours. After evaluating the neurological deficit scores, the brains were sectioned and stained by triphenyltetrazolium chloride and Nissl. The mice subjected to photothrombosis showed significant behavioral deficits. One hour after occlusion, the low perfusion areas on the perfusion-weighted imaging interlaced with the hypointense areas on the apparent diffusion coefficient map, demonstrating that the penumbra was located both surrounding and inside the lesions. This phenomenon was subsequently confirmed by the c-fos and heart shock protein 90 staining. The final T2-weighted images of the mice subjected to the reperfusion surgery were also consistent with the penumbra images at one hour. At early stages, the lesions were clearly identified on the apparent diffusion coefficient map; the volumes of the lesions on the diffusion-weighted imaging and T2-weighted imaging did not reach a maximum until 12 hours. The coefficient of variation (CV) of the final lesions in the photothrombotic stroke mice was 21.7% (0.08 of 0.37) on T2

  1. Multi-wavelength fibril dynamics and oscillations above sunspot - I. morphological signature

    Science.gov (United States)

    Sungging Mumpuni, Emanuel; Herdiwijaya, Dhani; Djamal, Mitra; Djamaluddin, Thomas

    2015-11-01

    In this work we selected one particular fibril from a high resolution observation of the solar chromosphere with the Dutch Open Telescope, and tried to obtain a broad picture of the intricate mechanism that might be operating in the multiple layers of the solar atmosphere visible in high cadence multi-wavelength observations. We analyzed the changing fibril pattern using multi-wavelength tomography, which consists of both the Hα line center and the blue wing, Doppler signal, Ca II H, and the G-band. We have found that the intermittent ejected material through the fibril from Doppler images has clearly shown an oscillation mode, as seen in the Hα blue wing. The oscillations in the umbrae and penumbrae magnetic field lines that are above the sunspot cause a broadening and the area forms a ring shape from 3 to 15 minute oscillations as a function of height. These made a distinct boundary between the umbrae and penumbrae which suggests a comb structure, and indicates that the oscillations could propagate along the inclined magnetic flux tubes from below. The 3 minute oscillations strongly appeared in the broadly inclined penumbrae magnetic field lines and showed a clear light bridge. The well known 5 minute oscillations were dominant in the umbrae-penumbrae region boundary. The long 7 minute oscillations were transparent in the Hα blue wing, as well as the 10 and 15 minute oscillations. They were concentrated in the inner-penumbrae, as seen in the Hα line center. From these findings we propose that the fibril acts as a fabric for interaction between the layers, as well as related activities around the active region under investigation.

  2. TRANSITION-REGION/CORONAL SIGNATURES AND MAGNETIC SETTING OF SUNSPOT PENUMBRAL JETS: HINODE (SOT/FG), Hi-C, AND SDO/AIA OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Tiwari, Sanjiv K.; Moore, Ronald L.; Winebarger, Amy R. [NASA Marshall Space Flight Center, Mail Code ZP 13, Huntsville, AL 35812 (United States); Alpert, Shane E., E-mail: sanjiv.k.tiwari@nasa.gov [Department of Physics and Astronomy, Rice University, Houston, TX 77005 (United States)

    2016-01-10

    Penumbral microjets (PJs) are transient narrow bright features in the chromosphere of sunspot penumbrae, first characterized by Katsukawa et al. using the Ca ii H-line filter on Hinode's Solar Optical Telescope (SOT). It was proposed that the PJs form as a result of reconnection between two magnetic components of penumbrae (spines and interspines), and that they could contribute to the transition region (TR) and coronal heating above sunspot penumbrae. We propose a modified picture of formation of PJs based on recent results on the internal structure of sunspot penumbral filaments. Using data of a sunspot from Hinode/SOT, High Resolution Coronal Imager, and different passbands of the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory, we examine whether PJs have signatures in the TR and corona. We find hardly any discernible signature of normal PJs in any AIA passbands, except for a few of them showing up in the 1600 Å images. However, we discovered exceptionally stronger jets with similar lifetimes but bigger sizes (up to 600 km wide) occurring repeatedly in a few locations in the penumbra, where evidence of patches of opposite-polarity fields in the tails of some penumbral filaments is seen in Stokes-V images. These tail PJs do display signatures in the TR. Whether they have any coronal-temperature plasma is unclear. We infer that none of the PJs, including the tail PJs, directly heat the corona in active regions significantly, but any penumbral jet might drive some coronal heating indirectly via the generation of Alfvén waves and/or braiding of the coronal field.

  3. Sunspot areas and tilt angles for solar cycles 7-10

    CERN Document Server

    Pavai, V Senthamizh; Dasi-Espuig, M; Krivova, N; Solanki, S

    2015-01-01

    Extending the knowledge about the properties of solar cycles into the past is essential for understanding the solar dynamo. This paper aims at estimating areas of sunspots observed by Schwabe in 1825-1867 and at calculating the tilt angles of sunspot groups. The sunspot sizes in Schwabe's drawings are not to scale and need to be converted into physical sunspot areas. We employed a statistical approach assuming that the area distribution of sunspots was the same in the 19th century as it was in the 20th century. Umbral areas for about 130,000 sunspots observed by Schwabe were obtained, as well as the tilt angles of sunspot groups assuming them to be bipolar. There is, of course, no polarity information in the observations. The annually averaged sunspot areas correlate reasonably with sunspot number. We derived an average tilt angle by attempting to exclude unipolar groups with a minimum separation of the two alleged polarities and an outlier rejection method which follows the evolution of each group and detect...

  4. The concept of the penumbra: can it be translated to stroke management?

    Science.gov (United States)

    Heiss, Wolf-Dieter

    2010-08-01

    The 'penumbra' is a concept coined in animal experiments suggesting that functionally impaired tissue can survive and recover if sufficient reperfusion is re-established within a limited time period, which depends on the level of residual flow. In an ischaemic territory, irreversible damage progresses over time from the centre of the most severe flow reduction to the periphery with less disturbed perfusion. This centrifugal progression of irreversible tissue damage is characterised by a complex cascade of interconnected electrophysiological, molecular, metabolic and perfusion disturbances. Waves of depolarisations, the peri infarct spreading depressions, inducing activation of ion pumps and liberation of excitatory transmitters play an important role in the drastically increased metabolic demand during reduced oxygen supply causing hypoxic tissue changes and lactacidosis, which further damage the tissue. Positron emission tomography allows the quantification of regional cerebral blood flow, the regional metabolic rate for oxygen and the regional oxygen extraction fraction, which can be used to identify regions with a critical reduction in these physiologic variables as indicators of penumbra and irreversible damage within ischaemic territories in animal models and patients with stroke. These positron emission tomography methods require arterial blood sampling and due to the complex logistics involved, are limited for routine application. Therefore, newer tracers were developed for the noninvasive detection of irreversible tissue damage (flumazenil) and of hypoxic tissue changes (fluoromisonidazole). As a widely applicable clinical tool, diffusion/perfusion-weighted magnetic resonance imaging is used; the 'mismatch' between perfusion and diffusion changes serves as a surrogate marker of the penumbra. However, in comparative studies of magnetic resonance imaging and positron emission tomography, diffusion-weighted imaging showed a high false-positive rate of

  5. Are the sunspots really vanishing?

    Directory of Open Access Journals (Sweden)

    Clette Frédéric

    2012-06-01

    Full Text Available Context: The elapsed solar cycle (23 ended with an exceptionally long period of low activity and with unprecedented low levels for various series of solar irradiance and particle flux measurements. This unpredicted evolution of solar activity raised multiple questions about a future decline of the solar cycles and launched a quest for precursor signs of this possible deep solar transition over the last decade. Aim: We present here a review and overall interpretation of most current diagnostics of solar cycle 23, including the recent disagreements that appeared among solar reference indices and standard solar-based geo-indices, the indication of a changed pattern of internal torsional waves (helioseismology or the announced fading and magnetic weakening of sunspots. Methods: Based on a statistical analysis of detailed sunspot properties over the last 24 years, we complete the picture with new evidence of a strong global deficit of the smallest sunspots starting around 2000, in order to answer the question: are all sunspots about to disappear? Results: This global scale-dependent change in sunspot properties is confirmed to be real and not due to uncontrolled biases in some of the indices. It can also explain the recent discrepancies between solar indices by their different sensitivities to small and weak magnetic elements (small spots. The International Sunspot Index Ri, based on unweighted sunspot counts, proved to be particularly sensitive to this particular small-scale solar evolution. Conclusions: Our results and interpretation show the necessity to look backwards in time, more than 80 years ago. Indeed, the Sun seems to be actually returning to a past and hardly explored activity regime ending before the 1955–1995 Grand Maximum, which probably biased our current space-age view of solar activity.

  6. Sunspot Bright Points

    CERN Document Server

    Choudhary, Debi Prasad

    2010-01-01

    We used the flux calibrated images through the Broad Band Filter Imager and Stokes Polarimeter data obtained with the Solar Optical Telescope onboard the Hinode spacecraft to study the properties of bright points in and around the sunspots. The well isolated bright points were selected and classified as umbral dot, peripheral umbral dot, penumbral grains and G-band bright point depending on their location. Most of the bright points are smaller than about 150 km. The larger points are mostly associated with the penumbral features. The bright points are not uniformly distributed over the umbra but preferentially located around the penumbral boundary and in the fast decaying parts of umbra. The color temperature of the bright points, derived using the continuum irradiance, are in the range of 4600 K to 6600 K with cooler ones located in the umbra. The temperature increases as a function of distance from the center to outside. The G-band, CN-band and CaII H flux of the bright points as a function of their blue ba...

  7. The Effect of Sunspot Weighting

    Science.gov (United States)

    Svalgaard, Leif; Cagnotti, Marco; Cortesi, Sergio

    2017-02-01

    Although W. Brunner began to weight sunspot counts (from 1926), using a method whereby larger spots were counted more than once, he compensated for the weighting by not counting enough smaller spots in order to maintain the same reduction factor (0.6) as was used by his predecessor A. Wolfer to reduce the count to R. Wolf's original scale, so that the weighting did not have any effect on the scale of the sunspot number. In 1947, M. Waldmeier formalized the weighting (on a scale from 1 to 5) of the sunspot count made at Zurich and its auxiliary station Locarno. This explicit counting method, when followed, inflates the relative sunspot number over that which corresponds to the scale set by Wolfer (and matched by Brunner). Recounting some 60,000 sunspots on drawings from the reference station Locarno shows that the number of sunspots reported was "over counted" by {≈} 44 % on average, leading to an inflation (measured by an effective weight factor) in excess of 1.2 for high solar activity. In a double-blind parallel counting by the Locarno observer M. Cagnotti, we determined that Svalgaard's count closely matches that of Cagnotti, allowing us to determine from direct observation the daily weight factor for spots since 2003 (and sporadically before). The effective total inflation turns out to have two sources: a major one (15 - 18 %) caused by weighting of spots, and a minor source (4 - 5 %) caused by the introduction of the Zürich classification of sunspot groups which increases the group count by 7 - 8 % and the relative sunspot number by about half that. We find that a simple empirical equation (depending on the activity level) fits the observed factors well, and use that fit to estimate the weighting inflation factor for each month back to the introduction of effective inflation in 1947 and thus to be able to correct for the over-counts and to reduce sunspot counting to the Wolfer method in use from 1894 onwards.

  8. AAVSO Visual Sunspot Observations vs. SDO HMI Sunspot Catalog

    Science.gov (United States)

    Howe, R.

    2014-06-01

    (Abstract only) The most important issue with regard to using the SDO HMI data from the National Solar Observatory (NSO, http://www.nso.edu/staff/fwatson/STARA) is that their current model for creating sunspot counts does not split in groups and consequently does not provide a corresponding group count and Wolf number. As it is a different quantity, it cannot be mixed with the data from our sunspot networks. For the AAVSO with about seventy stations contributing each day, adding HMI sunspot data would anyway hardly change the resulting index. Perhaps, the best use of HMI data is for an external validation, by exploiting the fact that HMI provides a series that is rather close to the sunspot number and is acquired completely independently. So, it is unlikely to suffer from the same problems (jumps, biases) at the same time. This validation only works for rather short durations, as the lifetime of space instruments is limited and aging effects are often affecting the data over the mission. In addition, successive instruments have different properties: for example, the NSO model has not managed yet to reconcile the series from MDI and HMI. There is a ~10-15% jump. The first challenge that should be addressed by AAVSO using HMI data is the splitting in groups and deriving group properties. Then, together with the sunspot counts and areas per group, a lot more analyses and diagnostics can be derived (like the selective disappearance of the smallest sunspots?), that can help interpreting trends in the ratio SSN/other solar indices and many other solar effects.

  9. Formation of the penumbra and start of the Evershed flow

    CERN Document Server

    Murabito, M; Gugliemino, S L; Zuccarello, F; Solanki, S K

    2016-01-01

    We studied the variations of line-of-sight photospheric plasma flows during the formation phase of the penumbra around a pore in Active Region NOAA 11490. We used a high spatial, spectral, and temporal resolution data set acquired by the Interferometric BIdimensional Spectrometer (IBIS) operating at the NSO/Dunn Solar Telescope as well as data taken by the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory satellite (SDO/HMI). Before the penumbra formed we observed a redshift of the spectral line in the inner part of the annular zone surrounding the pore as well as a blueshift of material associated with opposite magnetic polarity further away from the pore. We found that the onset of the classical Evershed flow occurs in a very short time scale -- 1-3 hours -- while the penumbra is forming. During the same time interval we found changes in the magnetic field inclination in the penumbra, with the vertical field actually changing sign near the penumbral edge, while the total magnetic field...

  10. Development of an Automatic Program to Analyze Sunspot Groups on White Light Images using OpenCV

    Science.gov (United States)

    Park, J.; Moon, Y.; Choi, S.

    2011-12-01

    Sunspots usually appear in a group which can be classified by certain morphological criteria. In this study we examine the moments which are statistical parameters computed by summing over every pixels of contours, for quantifying the morphological characteristics of a sunspot group. The moments can be another additional characteristics to the sunspot group classification such as McIntosh classification. We are developing a program for image processing, detection of contours and computation of the moments using white light full disk images from Big Bear Solar Observatory. We apply the program to count the sunspot number from 530 white light images in 2003. The sunspot numbers obtained by the program are compared with those by SIDC. The comparison shows that they have a good correlation (r=84%). We are extending this application to automatic sunspot classification (e.g., McIntosh classification) and flare forecasting.

  11. Use of susceptibility-weighted imaging in assessing ischemic penumbra

    Science.gov (United States)

    Wu, Xiujuan; Luo, Song; Wang, Ying; Chen, Yang; Liu, Jun; Bai, Jing; Feng, Jiachun; Zhang, Hongliang

    2017-01-01

    Abstract Rationale: The ischemic penumbra assessment is essential for the subsequent therapy and prediction of evolution in patients with acute ischemic infraction. Although controversial as a perfect equivalence to penumbra, perfusion-weighted imaging (PWI)-diffusion-weighted imaging (DWI) mismatch may predict the response to thrombolysis. Due to the reliance of PWI on contrast agents, noninvasive alternatives remain an unmet need. Patient concerns: We reported a 65-year-old man complained of paroxysmal hemiplegia of his right limbs and anepia for 2 days, whereas the symptoms lasted for about 12 hours when he admitted to the hospital. Diagnosis: We diagnosed it as acute ischemic stroke caused by the left middle cerebral artery stenosis. Interventions: Susceptibility-weighted imaging (SWI), multimodal magnetic resonance imaging (MRI) work-up which includes conventional MRI sequences (T1WI, T2WI, and FLAIR), DWI, PWI. Outcomes: His DWI-SWI mismatch was comparable to that of DWI-PWI at admission, suggesting that DWI-SWI could predict ischemic penumbra in patient with acute infarction. He refused the digital subtraction angiography examination or stenting, and he was treated with aspirin, atorvastain, and supportive treatment. The patient received a reexamination of the conventional MRI and SWI 11 days later. Expansion of the infarction in the affected MCA territory resulted from the penumbra indicated by the mismatch between DWI-SWI. Lessons: SWI can be used as a noninvasive alternative to evaluate the ischemic penumbra. Besides, SWI can provide perfusion information comparable to PWI and SWI is sufficient to identify occlusive arteries. PMID:28178170

  12. The Effect of Sunspot Weighting

    CERN Document Server

    Svalgaard, Leif; Cortesi, Sergio

    2015-01-01

    Waldmeier in 1947 introduced a weighting (on a scale from 1 to 5) of the sunspot count made at Zurich and its auxiliary station Locarno, whereby larger spots were counted more than once. This counting method inflates the relative sunspot number over that which corresponds to the scale set by Wolfer and Brunner. Svalgaard re-counted some 60,000 sunspots on drawings from the reference station Locarno and determined that the number of sunspots reported were 'over counted' by 44% on average, leading to an inflation (measured by a weight factor) in excess of 1.2 for high solar activity. In a double-blind parallel counting by the Locarno observer Cagnotti, we determined that Svalgaard's count closely matches that of Cagnotti's, allowing us to determine the daily weight factor since 2003 (and sporadically before). We find that a simple empirical equation fits the observed weight factors well, and use that fit to estimate the weight factor for each month back to the introduction of weighting in 1947 and thus to be ab...

  13. Imaging the ischaemic penumbra after acute ischaemic stroke using PET and {sup 18}F-Fluoromisonidazole

    Energy Technology Data Exchange (ETDEWEB)

    Read, S.J.; Hirano, T.; Abbott, D.F.; Sachinidis, J.I.; Tochon-Danguy, H.J.; Chan, J.G.; Egan, F.; Scott, A.M.; Bladin, C.F.; McKay, W.J.; Donna, G.A. [Austin and Repatriation Medical Centre, Melbourne, VIC (Australia). Departments of Neurology, Nuclear Medicine and Centre for Positron Emission Tomogrpahy]|[University of Melbourne, Melbourne, VIC (Australia). Department of Medicine

    1998-06-01

    Full text: Using PET with {sup 15}O-labelled oxygen and water, the ischaemic penumbra is currently defined as peri-infarct areas demonstrating misery perfusion. We have used PET with the hypoxic tissue marker {sup l8}F-fluoromisonidazole ({sup 18}F-FMISO) to detect hypoxic but viable peri-infarct tissue in patients after acute ischaemic stroke. Fifteen patients with acute ischaemic strokes were studied using PET and {sup 18}F-FMISO. Studies were performed within 48 hours of stroke in 7 patients, at 6-11 days after stroke in 2 patients, and serially during both time epochs in 6 patients. We objectively assessed tracer uptake using a statistically-based image thresholding method. The mean activity in the contralateral (normal) hemisphere was calculated, and the whole image thresholded so that pixels with activity > 3 SD above the mean were identified. Positive studies were those with high activity pixels ipsilateral to the infarct. Hypoxic tissue was detected in peri-infarct regions in 9 of the 13 patients studied within 48 hours of stroke. These areas were generally distributed in the peripheries of the final infarct volume. None of the 8 patients studied 6-11 days after stroke exhibited increased {sup I8}F- FMISO activity. The 6 patients studied both early and late all exhibited areas of increased activity on the early but not the late study, consistent with resolution of the penumbra by this time. The distribution of the hypoxic tissue identified with this method supports the hypothesis that these tissues are likely to comprise the ischaemic penumbra.

  14. Physical Properties of a Sunspot Chromosphere with Umbral Flashes

    CERN Document Server

    Rodríguez, J de la Cruz; Socas-Navarro, H; van Noort, M

    2013-01-01

    We present new high-resolution spectro-polarimetric Ca II 8542 observations of umbral flashes in sunspots. At nearly 0.18", and spanning about one hour of continuous observation, this is the most detailed dataset published thus far. Our study involves both LTE and non-LTE inversions (but includes also a weak field analysis as a sanity check) to quantify temperatures, mass flows and the full magnetic field vector geometry. We confirm earlier reports that UFs have very fine structure with hot and cool material intermixed at sub-arcsecond scales. The shock front is roughly 1000 K hotter than the surrounding material. We do not observe significant fluctuations of the field in the umbra. In the penumbra, however, the passage of the running penumbral waves alter the magnetic field strength by some 200 G (peak-to-peak amplitude) but it does not change the field orientation (at least not significantly within our sensitivity of a few degrees). We find a trend of decreasing high-frequency modulation power for more incl...

  15. Oscillations above sunspots from the temperature minimum to the corona

    CERN Document Server

    Kobanov, N I; Kolobov, D Y

    2013-01-01

    Context. An analysis of the oscillations above sunspots was carried out using simultaneous ground-based and Solar Dynamics Observatory (SDO) observations (SiI 10827A, HeI 10830A, FeI 6173A, 1700A, HeII 304A, FeIX 171A). Aims. Investigation of the spatial distribution of oscillation power in the frequency range 1-8 mHz for the different height levels of the solar atmosphere. Measuring the time lags between the oscillations at the different layers. Methods. We used frequency filtration of the intensity and Doppler velocity variations with Morlet wavelet to trace the wave propagation from the photosphere to the chromosphere and the corona. Results. The 15 min oscillations are concentrated near the outer penumbra in the upper photosphere (1700 A), forming a ring, that expands in the transition zone. These oscillations propagate upward and reach the corona level, where their spatial distribution resembles a fan structure. The spatial distribution of the 5 min oscillation power looks like a circle-shape structure m...

  16. SOHO reveals how sunspots take a stranglehold on the Sun

    Science.gov (United States)

    2001-11-01

    Bernhard Fleck, ESA's project scientist for SOHO, comments, "The origin and stability of sunspots has been one of the long-standing mysteries in solar physics. I am delighted to see that with SOHO we are beginning to crack this problem." The gas flows around and beneath a sunspot have been detected by a team of scientists in the USA, using the Michelsen Doppler Imager (MDI) on SOHO. The instrument explores the solar interior by detecting natural sound waves at a million points on the Sun's surface. "After many years of contradictory theories about sunspots, MDI on SOHO is at last telling us what really happens," comments Junwei Zhao of Stanford University, California, lead author of a report published in the Astrophysical Journal. Inflows and downflows similar to those now detected with SOHO were envisaged in 1974 by Friedrich Meyer of Germany's Max-Planck- Institut für Physik und Astrophysik, and his colleagues. A similar expectation figured in a theory of sunspots advanced in 1979 by Eugene Parker of Chicago. "Our observation seems to provide strong evidence for both predictions," Zhao says. Sunspots have fascinated scientists since Galileo's time, 400 years ago, when they shattered a belief that the Sun was divinely free of any blemish. As symptoms of intense magnetic activity, sunspots are often associated with solar flares and mass ejections that affect space weather and the Earth itself. The Sun's activity peaks roughly every 11 years, and the latest maximum in the sunspot count occurred in 2000. Even with huge advances in helioseismology, which deduces layers and flows inside the Sun by analysis of sound waves that travel through it and agitate the surface, seeing behind the scenes in sunspots was never going to be easy. The MDI team refined a method of measuring the travel time of sound waves, invented in 1993 by Thomas Duvall of NASA Goddard, called solar tomography. It is like deducing what obstacles cross-country runners have faced, just by seeing in

  17. Chromospheric seismology above sunspot umbrae

    CERN Document Server

    Snow, B; Regnier, S

    2015-01-01

    The acoustic resonator is an important model for explaining the three-minute oscillations in the chromosphere above sunspot umbrae. The steep temperature gradients at the photosphere and transition region provide the cavity for the acoustic resonator, which allows waves to be both partially transmitted and partially reflected. In this paper, a new method of estimating the size and temperature profile of the chromospheric cavity above a sunspot umbra is developed. The magnetic field above umbrae is modelled numerically in 1.5D with slow magnetoacoustic wave trains travelling along magnetic fieldlines. Resonances are driven by applying the random noise of three different colours---white, pink and brown---as small velocity perturbations to the upper convection zone. Energy escapes the resonating cavity and generates wave trains moving into the corona. Line of sight (LOS) integration is also performed to determine the observable spectra through SDO/AIA. The numerical results show that the gradient of the coronal ...

  18. Search for torsional oscillations in isolated sunspots

    Science.gov (United States)

    Griñón-Marín, A. B.; Socas-Navarro, H.; Centeno, R.

    2017-07-01

    In this work we seek evidence for global torsional oscillations in alpha sunspots. We have used long time series of continuum intensity and magnetic field vector maps from the Helioseismic and Magnetic Imager (HMI) instrument on board the Solar Dynamics Observatory (SDO) spacecraft. The time series analysed here span the total disk passage of 25 isolated sunspots. We found no evidence of global long-term periodic oscillations in the azimuthal angle of the sunspot magnetic field within 1 degree. This study could help us to understand the sunspot dynamics and its internal structure.

  19. An uncombed inversion of multi-wavelength observations reproducing the Net Circular Polarization in a sunspots' penumbra

    CERN Document Server

    Beck, C

    2010-01-01

    I derived a geometrical model of the penumbral magnetic field topology from an uncombed inversion setup that aimed at reproducing the NCP of simultaneous spectra in near-IR (1.56 mu) and VIS (630 nm) spectral lines. I inverted the spectra of five photospheric lines with a model that mimicked vertically interlaced magnetic fields with two components, labeled background field and flow channels. The flow channels were modeled as a perturbation of the background field with a Gaussian shape using the SIRGAUS code. The location and extension of the Gaussian perturbation in the optical depth scale was then converted to a geometrical height scale. I investigated the relative amount of magnetic flux in the flow channels and the background field atmosphere. The uncombed model is able to reproduce the NCP well on the limb side of the spot and worse on the center side; the VIS lines are better reproduced than the near-IR lines. The Evershed flow happens along nearly horizontal field lines close to the solar surface. The ...

  20. Recurrent Spontaneous Spreading Depolarizations Facilitate Acute Dendritic Injury in the Ischemic Penumbra

    OpenAIRE

    Risher, W Christopher; Ard, Deborah; Yuan, Jianghe; Kirov, Sergei A.

    2010-01-01

    Spontaneous spreading depolarizations (SDs) occur in the penumbra surrounding ischemic core. These SDs, often referred to as peri-infarct depolarizations, cause vasoconstriction and recruitment of the penumbra into the ischemic core in the critical first hours after focal ischemic stroke; however, the real-time spatiotemporal dynamics of SD-induced injury to synaptic circuitry in the penumbra remain unknown. A modified cortical photothrombosis model was used to produce a square-shaped lesion ...

  1. Comments on nonparametric predictions of sunspot numbers

    DEFF Research Database (Denmark)

    Jensen, J.L.

    1993-01-01

    Recent results of Cerrito (1990) are criticized, and the level of unexplainable noise in the observed series of sunspot numbers is discussed.......Recent results of Cerrito (1990) are criticized, and the level of unexplainable noise in the observed series of sunspot numbers is discussed....

  2. Sunspots, Starspots, and Elemental Abundances

    Science.gov (United States)

    Doschek, George A.; Warren, Harry P.

    2017-08-01

    The composition of plasma in solar and stellar atmospheres is not fixed, but varies from feature to feature. These variations are organized by the First Ionization Potential (FIP) of the element. Solar measurements often indicate that low FIP elements (10 eV, such as C, N, O, Ar, He) compared to abundances in the photosphere. Stellar observations have also shown similar enrichments. An inverse FIP effect, where the low FIP elements are depleted, has been observed in stellar coronae of stars believed to have large starspots in their photospheres. The abundances are important for determining radiative loss rates in models, tracing the origin of the slow solar wind, and for understanding wave propagation in the chromosphere and corona. Recently, inverse FIP effects have been discovered in the Sun (Doschek, Warren, & Feldman 2015, ApJ, 808, L7) from spectra obtained by the Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft. The inverse FIP regions seem always to be near sunspots and cover only a very small area (characteristic length = a few arcseconds). However, in pursuing the search for inverse FIP regions, we have found that in some sunspot groups the coronal abundance at a temperature of 3-4 MK can be near photospheric over much larger areas of the sun near the sunspots (e.g., 6,000 arcsec2). Also, sometimes the abundances at 3-4 MK are in between coronal and photospheric values. This can occur in small areas of an active region. It is predicted (Laming 2015, Sol. Phys., 12, 2) that the FIP effect should be highly variable in the corona. Several examples of coronal abundance variations are presented. Our work indicates that a comprehensive re-investigation of solar abundances is highly desirable. This work is supported by a NASA Hinode grant.

  3. Multi-wavelength Fibril Dynamics and Oscillations Above Sunspot - I. Morphological Signature

    CERN Document Server

    Mumpuni, Emanuel Sungging; Djamal, Mitra; Djamaluddin, Thomas

    2015-01-01

    In this work we selected one particular fibril from a high resolution solar chromosphere observation from the Dutch Open Telescope, and tried to obtain a broad picture of the intricate mechanism that might be incorporated in the multiple layer of the Solar atmosphere in high cadence multi-wavelength observation. We analyzed the changingvfibril patter using multi-wavelength tomography, which consists of both H$\\alpha$ line center \\& the blue wing, Doppler-signal, Ca II H, and the G-band. We have found that the intermittent ejected material through fibril from Doppler images has clearly shown oscillation mode, as seen in the H$\\alpha$ blue wing. The oscillations in the umbrae and penumbrae magnetic field lines that are above the sunspot cause a broadening and forms the area like a ring shape from 3 to 15-minute oscillations as function of height. These made a distinct boundary of umbrae and penumbrae which suggest the comb structure, and indicate that the oscillations could propagate along the inclined magn...

  4. Helioseismology of a Realistic Magnetoconvective Sunspot Simulation

    Science.gov (United States)

    Braun, D. C.; Birch, A. C.; Rempel, M.; Duvall, T. L., Jr.

    2012-01-01

    We compare helioseismic travel-time shifts measured from a realistic magnetoconvective sunspot simulation using both helioseismic holography and time-distance helioseismology, and measured from real sunspots observed with the Helioseismic and Magnetic Imager instrument on board the Solar Dynamics Observatory and the Michelson Doppler Imager instrument on board the Solar and Heliospheric Observatory. We find remarkable similarities in the travel-time shifts measured between the methodologies applied and between the simulated and real sunspots. Forward modeling of the travel-time shifts using either Born or ray approximation kernels and the sound-speed perturbations present in the simulation indicates major disagreements with the measured travel-time shifts. These findings do not substantially change with the application of a correction for the reduction of wave amplitudes in the simulated and real sunspots. Overall, our findings demonstrate the need for new methods for inferring the subsurface structure of sunspots through helioseismic inversions.

  5. Wavelet analysis of sunspot relative numbers

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The time series of the monthly smoothed sunspot numbers in 1749-2000 is analyzed with the wavelet.The result shows that besides the known time-variation of the period about 11 years, other main periods of the sunspot numbers, such as the periods of about 100 years and so on,vary with time. We suggest that the time-variation of the main periods is the manifestation of the complex variation of sunspot numbers. It is significant to make a thorough study of the character and mechanism of the time-variation of the periods for proving prediction of sunspot numbers, especially for understanding the variation process of sunspot numbers.

  6. Cyclic Evolution of Sunspots: Gleaning New Results from Old Data

    Indian Academy of Sciences (India)

    S. Κ. Solanki; Μ. Fligge; P. Pulkkinen; P. Hoyng

    2000-09-01

    The records of sunspot number, sunspot areas and sunspot locations gathered over the centuries by various observatories are reanalysed with the aim of finding as yet undiscovered connections between the different parameters of the sunspot cycle and the butterfly diagram. Preliminary results of such interrelationships are presented.

  7. Evaluation of the penumbras of a Philips multileaf collimator

    Energy Technology Data Exchange (ETDEWEB)

    Lafay, F.; Malet, C.; Mombard, C.; Ginestet, C. [Centre de Lutte Contre le Cancer Leon-Berard, 69 - Lyon (France); Blondel, E. [Isotec, Saint-Quentin (France); Desfarges, Y.; Dupin, G. [Philips Medical System, Lyon (France)

    1995-12-01

    Since January 1995, a Philips SL20 linear accelerator which is connected to a multileaf collimator has been used. Computer-controlled multileaf collimators open up the opportunity to practice conformal radiotherapy. Its aim is to adjust as well as possible the Planning Target Volume (PTV) to the effective treated volume with an homogeneous dose distribution in the PTV, and to protect healthy tissues and delicate organs. This is possible by means of a multileaf collimator by increasing the number of complex fields with different incidences during a same session. Moreover, the Beam`s Eye View function of the three-dimensional treatment planning system allows to define the shape of complex fields. For rectangular fields, the penumbra is defined by the distance between the 80% and 20% isodoses relative to the beam axis. In addition, the distances between, respectively, the 95% and 50% isodoses, the 90% and 50% isodoses, the 50% and 20% isodoses relative to the beam axis have been analysed. Different penumbras were evaluated. The result of this work will enable to adjust the reference isodose to the PTV either by integrating this result into dosimetry software, or by taking it into account for drawing the PTV.

  8. Formation of a solar Ha filament from orphan penumbrae

    CERN Document Server

    Buehler, D; van Noort, M; Solanki, S K

    2016-01-01

    The formation of an Ha filament in active region (AR) 10953 is described. Observations from the Solar Optical Telescope (SOT) aboard the Hinode satellite starting on 27th April 2007 until 1st May 2007 were analysed. 20 scans of the 6302A Fe I line pair recorded by SOT/SP were inverted using the SPINOR code. The inversions were analysed together with SOT/BFI G-band and Ca II H and SOT/NFI Ha observations. Following the disappearance of an initial Ha filament aligned along the polarity inversion line (PIL) of the AR, a new Ha filament formed in its place some 20 hours later, which remained stable for at least 1.5 days. The creation of the new Ha filament was driven by the ascent of horizontal magnetic fields from the photosphere into the chromosphere at three separate locations along the PIL. The magnetic fields at two of these locations were situated directly underneath the initial Ha filament and formed orphan penumbrae already aligned along the Ha filament channel. The 700 G orphan penumbrae were stable and ...

  9. The "Penumbra Sign" on Magnetic Resonance Images of Brodie's Abscess: A Case Report.

    Science.gov (United States)

    Afshar, Ahmadreza; Mohammadi, Afshin

    2011-12-01

    This report presents the "penumbra sign" of a Brodie's abscess in a 69-year-old male patient. The lesion was located in the proximal metaphysis of the left tibia. Histopathology confirmed the diagnosis of subacute osteomyelitis. The penumbra sign on magnetic resonance (MR) images is a helpful sign for the diagnosis of Brodie's abscess.

  10. Rounded leaf end effect of multileaf collimator on penumbra width and radiation field offset: an analytical and numerical study

    Directory of Open Access Journals (Sweden)

    Zhou Dong

    2015-09-01

    Full Text Available Background. Penumbra characteristics play a significant role in dose delivery accuracy for radiation therapy. For treatment planning, penumbra width and radiation field offset strongly influence target dose conformity and organ at risk sparing.

  11. Persistent Penumbra in a Rabbit Stroke Model: Incidence and Histologic Characteristics

    Directory of Open Access Journals (Sweden)

    Leah J. Hennings

    2011-01-01

    Full Text Available Duration and extent of penumbra determine the window and brain volume in which interventions may save injured tissue after stroke. Understanding the penumbra in animals is necessary in order to design models that translate to effective clinical therapies. New Zealand white rabbits were embolized with aged autologous clot (n=23 or insoluble microspheres (n=21. To examine effects of treatment on penumbra, sphere-stroked animals were treated with 3 μm microbubbles plus ultrasound (n=19. Rabbits were euthanized at 4 or 24 hr. Infarct volume was measured following triphenyltetrazolium chloride (TTC staining of brain sections. Penumbra was visualized using immunostaining of pimonidazole injected fifteen minutes prior to euthanasia. Potentially reversible penumbra was present in 14.3% stroked rabbits at 4 hours and 15.7% at 24 hours after embolic stroke and represented up to 35% of total lost tissue. Intervention at up to 24 hours may benefit a significant patient population.

  12. Sunspot Dynamics Are Reflected in Human Physiology and Pathophysiology

    Science.gov (United States)

    Hrushesky, William J. M.; Sothern, Robert B.; Du-Quiton, Jovelyn; Quiton, Dinah Faith T.; Rietveld, Wop; Boon, Mathilde E.

    2011-03-01

    Periodic episodes of increased sunspot activity (solar electromagnetic storms) occur with 10-11 and 5-6 year periodicities and may be associated with measurable biological events. We investigated whether this sunspot periodicity characterized the incidence of Pap smear-determined cervical epithelial histopathologies and human physiologic functions. From January 1983 through December 2003, monthly averages were obtained for solar flux and sunspot numbers; six infectious, premalignant and malignant changes in the cervical epithelium from 1,182,421 consecutive, serially independent, screening Pap smears (59°9"N, 4°29"E); and six human physiologic functions of a healthy man (oral temperature, pulse, systolic and diastolic blood pressure, respiration, and peak expiratory flow), which were measured ∼5 times daily during ∼34,500 self-measurement sessions (44°56"N, 93°8"W). After determining that sunspot numbers and solar flux, which were not annually rhythmic, occurred with a prominent 10-year and a less-prominent 5.75-year periodicity during this 21-year study span, each biological data set was analyzed with the same curve-fitting procedures. All six annually rhythmic Pap smear-detected infectious, premalignant and malignant cervical epithelial pathologies showed strong 10-year and weaker 5.75-year cycles, as did all six self-measured, annually rhythmic, physiologic functions. The phases (maxima) for the six histopathologic findings and five of six physiologic measurements were very near, or within, the first two quarters following the 10-year solar maxima. These findings add to the growing evidence that solar magnetic storm periodicities are mirrored by cyclic phase-locked rhythms of similar period length or lengths in human physiology and pathophysiology.

  13. Self-affinity and nonextensivity of sunspots

    Energy Technology Data Exchange (ETDEWEB)

    Moret, M.A., E-mail: mamoret@gmail.com [Programa de Modelagem Computacional, SENAI, Cimatec, Av. Orlando Gomes, 1845, Piatã, 41650-010 Salvador, Bahia (Brazil); UNEB, Rua Silveira Martins, 2555, Cabula, 41150-000 Salvador, Bahia (Brazil)

    2014-01-24

    In this paper we study the time series of sunspots by using two different approaches, analyzing its self-affine behavior and studying its distribution. The long-range correlation exponent α has been calculated via Detrended Fluctuation Analysis and the power law vanishes to values greater than 11 years. On the other hand, the distribution of the sunspots obeys a q-exponential decay that suggests a non-extensive behavior. This observed characteristic seems to take an alternative interpretation of the sunspots dynamics. The present findings suggest us to propose a dynamic model of sunspots formation based on a nonlinear Fokker–Planck equation. Therefore its dynamic process follows the generalized thermostatistical formalism.

  14. Sunspot Numbers from ISOON: A Ten-Year Data Analysis

    CERN Document Server

    Balasubramaniam, K S

    2016-01-01

    Sunspot numbers are important tracers of historical solar activity. They are important in the prediction of oncoming solar maximum, in the design of lifetimes of space assets, and in assessing the extent of solar-radiation impact on the space environment. Sunspot numbers were obtained visually from sunspot drawings. The availability of digital images from the US Air Force Improved Solar Optical Observing Network (ISOON) prototype telescope concurrent to observer-dependent sunspot numbers recorded at the National Solar Observatory (NSO) has provided a basis for comparing sunspot numbers determined from the two methods. We compare sunspot numbers from visual and digital methods observed nearly simultaneously. The advantages of digital imagery are illustrated.

  15. Modeling sunspot and starspot decay by turbulent erosion

    CERN Document Server

    Litvinenko, Yuri E

    2015-01-01

    Disintegration of sunspots (and starspots) by fluxtube erosion, originally proposed by Simon and Leighton, is considered. A moving boundary problem is formulated for a nonlinear diffusion equation that describes the sunspot magnetic field profile. Explicit expressions for the sunspot decay rate and lifetime by turbulent erosion are derived analytically and verified numerically. A parabolic decay law for the sunspot area is obtained. For moderate sunspot magnetic field strengths, the predicted decay rate agrees with the results obtained by Petrovay and Moreno-Insertis. The new analytical and numerical solutions significantly improve the quantitative description of sunspot and starspot decay by turbulent erosion.

  16. Sunspot drawings handwritten character recognition method based on deep learning

    Science.gov (United States)

    Zheng, Sheng; Zeng, Xiangyun; Lin, Ganghua; Zhao, Cui; Feng, Yongli; Tao, Jinping; Zhu, Daoyuan; Xiong, Li

    2016-05-01

    High accuracy scanned sunspot drawings handwritten characters recognition is an issue of critical importance to analyze sunspots movement and store them in the database. This paper presents a robust deep learning method for scanned sunspot drawings handwritten characters recognition. The convolution neural network (CNN) is one algorithm of deep learning which is truly successful in training of multi-layer network structure. CNN is used to train recognition model of handwritten character images which are extracted from the original sunspot drawings. We demonstrate the advantages of the proposed method on sunspot drawings provided by Chinese Academy Yunnan Observatory and obtain the daily full-disc sunspot numbers and sunspot areas from the sunspot drawings. The experimental results show that the proposed method achieves a high recognition accurate rate.

  17. Width of Sunspot Generating Zone and Reconstruction of Butterfly Diagram

    CERN Document Server

    Ivanov, V G; 10.1007/s11207-010-9665-6

    2010-01-01

    Based on the extended Greenwich-NOAA/USAF catalogue of sunspot groups it is demonstrated that the parameters describing the latitudinal width of the sunspot generating zone (SGZ) are closely related to the current level of solar activity, and the growth of the activity leads to the expansion of SGZ. The ratio of the sunspot number to the width of SGZ shows saturation at a certain level of the sunspot number, and above this level the increase of the activity takes place mostly due to the expansion of SGZ. It is shown that the mean latitudes of sunspots can be reconstructed from the amplitudes of solar activity. Using the obtained relations and the group sunspot numbers by Hoyt and Schatten (1998), the latitude distribution of sunspot groups ("the Maunder butterfly diagram") for the 18th and the first half of the 19th centuries is reconstructed and compared with historical sunspot observations.

  18. An alternative measure of solar activity from detailed sunspot datasets

    CERN Document Server

    Muraközy, Judit; Ludmány, András

    2016-01-01

    The sunspot number is analyzed by using detailed sunspot data, including aspects of observability, sunspot sizes, and proper identification of sunspot groups as discrete entities of the solar activity. The tests show that besides the subjective factors there are also objective causes of the ambiguities in the series of sunspot numbers. To introduce an alternative activity measure the physical meaning of the sunspot number has to be reconsidered. It contains two components whose numbers are governed by different physical mechanisms, this is one source of the ambiguity. This article suggests an activity index, which is the amount of emerged magnetic flux. The only long-term proxy measure is the detailed sunspot area dataset with proper calibration to the magnetic flux amount. The Debrecen sunspot databases provide an appropriate source for the establishment of the suggested activity index.

  19. On the insignificance of Herschel's sunspot correlation

    Science.gov (United States)

    Love, Jeffrey J.

    2013-01-01

    We examine William Herschel's hypothesis that solar-cycle variation of the Sun's irradiance has a modulating effect on the Earth's climate and that this is, specifically, manifested as an anticorrelation between sunspot number and the market price of wheat. Since Herschel first proposed his hypothesis in 1801, it has been regarded with both interest and skepticism. Recently, reports have been published that either support Herschel's hypothesis or rely on its validity. As a test of Herschel's hypothesis, we seek to reject a null hypothesis of a statistically random correlation between historical sunspot numbers, wheat prices in London and the United States, and wheat farm yields in the United States. We employ binary-correlation, Pearson-correlation, and frequency-domain methods. We test our methods using a historical geomagnetic activity index, well known to be causally correlated with sunspot number. As expected, the measured correlation between sunspot number and geomagnetic activity would be an unlikely realization of random data; the correlation is “statistically significant.” On the other hand, measured correlations between sunspot number and wheat price and wheat yield data would be very likely realizations of random data; these correlations are “insignificant.” Therefore, Herschel's hypothesis must be regarded with skepticism. We compare and contrast our results with those of other researchers. We discuss procedures for evaluating hypotheses that are formulated from historical data.

  20. Short-Term Variations in the Equatorial Rotation Rate of Sunspot Groups

    CERN Document Server

    Javaraiah, J

    2016-01-01

    We have detected several periodicities in the solar equatorial rotation rate of sunspot groups in the Greenwich Photoheliographic Results (GPR) during the period 1931-1976, the Solar Optical Observing Network (SOON) during the period 1977-2014, and the Debrecen Photoheliographic Data (DPD) during the period 1974-2014. Our results suggest a ~250-day period in the equatorial rotation rate determined from both the Mt. Wilson Doppler-velocity data and the sunspot-group data during 1986-2007. However, a wavelet analysis reveals that this periodicity appears mostly around 1991 in the velocity data, while it is present in most of the solar cycles covered by the sunspot-group data, mainly near the minimum epochs of the solar cycles. We also found the signature of a period of ~1.4 years period in the velocity data during 1990-1995, and in the equatorial rotation rate of sunspot groups mostly around the year 1956. The equatorial rotation rate of sunspot groups reveals a strong ~1.6-year periodicity around 1933 and 1955...

  1. A Statistical Study of Rapid Sunspot Structure Change Associated with Flares

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    We reported recently some rapid changes of sunspot structure in white-light (WL) associated with major flares. We extend the study to smaller events and present here results of a statistical study of this phenomenon. In total, we investigate 403 events from 1998 May 9 to 2004 July 17, including 40 X-class, 174 M-class, and 189 C-class flares. By monitoring the structure of the flaring active regions using the WL observations from the Transition Region and Coronal Explorer (TRACE), we find that segments in the outer sunspot structure decayed rapidly right after many flares; and that, on the other hand, the central part of sunspots near the flare-associated magnetic neutral line became darkened. These rapid and permanent changes are evidenced in the time profiles of WL mean intensity and are not likely resulted from the flare emissions. Our study further shows that the outer sunspot structure decay as well as the central structure darkening are more likely to be detected hi larger solar flares. For X-class flares, over 40% events show distinct sunspot structure change. For M- and C-class flares, this percentage drops to 17% and 10%, respectively. The results of this statistical study support our previously proposed reconnection picture, i.e., the flare-related magnetic fields evolve from a highly inclined to a more vertical configuration.

  2. The ischemic penumbra: correlates in imaging and implications for treatment of ischemic stroke. The Johann Jacob Wepfer award 2011.

    Science.gov (United States)

    Heiss, Wolf-Dieter

    2011-01-01

    achieved in animal models and stroke patients. Additionally, further tracers can be used for early detection of irreversible tissue damage, e.g. by the central benzodiazepine receptor ligand flumazenil. However, PET is a research tool and its complex logistics limit clinical routine applications. As a widely applicable clinical tool, perfusion/diffusion-weighted (PW/DW) MRI is used, and the 'mismatch' between the PW and the DW abnormalities serve as an indicator of the penumbra. However, comparative studies of PW/DW-MRI and PET have pointed to an overestimation of the core of irreversible infarction as well as of the penumbra by MRI modalities. Some of these discrepancies can be explained by unselective application of relative perfusion thresholds, which might be improved by more complex analytical procedures. Heterogeneity of the MRI signatures used for the definition of the mismatch are also responsible for disappointing results in the application of PW/DW-MRI for the selection of patients for clinical trials. As long as a validation of the mismatch selection paradigm is lacking, its use as a surrogate marker of outcome is limited. Copyright © 2011 S. Karger AG, Basel.

  3. Sunspot Catalogue of the Valencia Observatory (1920-1928)

    CERN Document Server

    Carrasco, V M S; Aparicio, A J P; Gallego, M C

    2014-01-01

    A sunspot catalogue was maintained by the Astronomical Observatory of Valencia University (Spain) from 1920 to 1928. Here we present a machine-readable version of this catalogue (OV catalog or OVc), including a quality control analysis. Sunspot number (total and hemispheric) and sunspot area series are constructed using this catalogue. The OV catalog's data are compared with other available solar data, demonstrating that the present contribution provides the scientific community with a reliable catalogue of sunspot data.

  4. Shadow Segmentation and Augmentation Using á-overlay Models that Account for Penumbra

    DEFF Research Database (Denmark)

    Nielsen, Michael; Madsen, Claus B.

    2006-01-01

    that an augmented virtual object can cast an exact shadow. The penumbras (half-shadows) must be taken into account so that we can model the soft shadows.We hope to achieve this by modelling the shadow regions (umbra and penumbra alike) with a transparent overlay. This paper reviews the state-of-the-art shadow...... theories and presents two overlay models. These are analyzed analytically in relation to color theory and tangibility....

  5. Magnetic Tension of Sunspot Fine Structures

    CERN Document Server

    Venkatakrishnan, P

    2010-01-01

    The equilibrium structure of sunspots depends critically on its magnetic topology and is dominated by magnetic forces. Tension force is one component of the Lorentz force which balances the gradient of magnetic pressure in force-free configurations. We employ the tension term of the Lorentz force to clarify the structure of sunspot features like penumbral filaments, umbral light bridges and outer penumbral fine structures. We compute vertical component of tension term of Lorentz force over two active regions namely NOAA AR 10933 and NOAA AR 10930 observed on 05 January 2007 and 12 December 2006 respectively. The former is a simple while latter is a complex active region with highly sheared polarity inversion line (PIL). The vector magnetograms used are obtained from Hinode(SOT/SP). We find an inhomogeneous distribution of tension with both positive and negative signs in various features of the sunspots. The existence of positive tension at locations of lower field strength and higher inclination is compatible...

  6. Deciphering solar turbulence from sunspots records

    CERN Document Server

    Plunian, Franck; Stepanov, Rodion

    2009-01-01

    It is generally believed that sunspots are the emergent part of magnetic flux tubes in the solar interior. These tubes are created at the base of the convection zone and rise to the surface due to their magnetic buoyancy. The motion of plasma in the convection zone being highly turbulent, the surface manifestation of sunspots may retain the signature of this turbulence, including its intermittency. From direct observations of sunspots, and indirect observations of the concentration of cosmogenic isotopes $^{14}$C in tree rings or $^{10}$Be in polar ice, power spectral densities in frequency are plotted. Two different frequency scalings emerge, depending on whether the Sun is quiescent or active. %magnetic activity is maximum or minimum. From direct observations we can also calculate scaling exponents. These testify to a strong intermittency, comparable with that observed in the solar wind.

  7. Deciphering solar turbulence from sunspots records

    Science.gov (United States)

    Plunian, F.; Sarson, G. R.; Stepanov, R.

    2009-11-01

    It is generally believed that sunspots are the emergent part of magnetic flux tubes in the solar interior. These tubes are created at the base of the convection zone and rise to the surface due to their magnetic buoyancy. The motion of plasma in the convection zone being highly turbulent, the surface manifestation of sunspots may retain the signature of this turbulence, including its intermittency. From direct observations of sunspots, and indirect observations of the concentration of cosmogenic isotopes 14C in tree rings or 10Be in polar ice, power spectral densities in frequency are plotted. Two different frequency scalings emerge, depending on whether the Sun is quiescent or active. From direct observations we can also calculate scaling exponents. These testify to a strong intermittency, comparable with that observed in the solar wind.

  8. Dynamics of Subarcsecond Bright Dots in the Transition Region above Sunspots and Their Relation to Penumbral Micro-jets

    Science.gov (United States)

    Samanta, Tanmoy; Tian, Hui; Banerjee, Dipankar; Schanche, Nicole

    2017-02-01

    Recent high-resolution observations have revealed that subarcsecond bright dots (BDs) with sub-minute lifetimes appear ubiquitously in the transition region (TR) above sunspot penumbra. The presence of penumbral micro-jets (PMJs) in the chromosphere was previously reported. It was proposed that both the PMJs and BDs are formed due to a magnetic reconnection process and may play an important role in heating of the penumbra. Using simultaneous observations of the chromosphere from the Solar Optical Telescope (SOT) on board Hinode and observations of the TR from the Interface Region Imaging Spectrograph, we study the dynamics of BDs and their relation to PMJs. We find two types of BDs, one that is related to PMJs, and another that does not show any visible dynamics in the SOT Ca ii H images. From a statistical analysis we show that these two types have different properties. The BDs that are related to PMJs always appear at the top of the PMJs, the vast majority of which show inward motion and originate before the generation of the PMJs. These results may indicate that the reconnection occurs at the lower coronal/TR height and initiates PMJs at the chromosphere. This formation mechanism is in contrast with the formation of PMJs by reconnection in the (upper) photosphere between differently inclined fields.

  9. Planetary model of sunspot emergence: A spectral and autocorrelation analysis

    CERN Document Server

    Edmonds, Ian

    2016-01-01

    This paper is concerned with intermediate range periodicity in the sunspot area spectrum. An empirical model of sunspot area emergence based on Mercury planet conjunctions was developed and the spectra of the model variation and the sunspot area variation compared. By including solar cycle amplitude modulation and the effect of solar magnetic field reversal the model was able to predict fine detail in the sunspot area spectrum. As Mercury planet conjunctions occur predictably it was possible to compare the time variation of band limited components of sunspot area with the corresponding component variations in the model. When the model component variation was stable corresponding components of sunspot area lagged the model variation by a few tens of days. When a 180 degree phase change occurred in the model variation the corresponding component of sunspot area followed the change over an interval of a few hundred days, first by decreasing to zero and then emerging in phase with the model variation. Where perio...

  10. Helioseismology of sunspots: how sensitive are travel times to the Wilson depression and to the subsurface magnetic field?

    CERN Document Server

    Schunker, Hannah; Cameron, Robert H; Birch, Aaron C

    2013-01-01

    In order to assess the ability of helioseismology to probe the subsurface structure and magnetic field of sunspots, we need to determine how helioseismic travel times depend on perturbations to sunspot models. Here we numerically simulate the propagation of f, p1, and p2 wave packets through magnetic sunspot models. Among the models we considered, a ~50 km change in the height of the Wilson depression and a change in the subsurface magnetic field geometry can both be detected above the observational noise level. We also find that the travel-time shifts due to changes in a sunspot model must be modeled by computing the effects of changing the reference sunspot model, and not by computing the effects of changing the subsurface structure in the quiet-Sun model. For p1 modes the latter is wrong by a factor of four. In conclusion, numerical modeling of MHD wave propagation is an essential tool for the interpretation of the effects of sunspots on seismic waveforms.

  11. Does sunspot numbers cause global temperatures? A reconsideration using non-parametric causality tests

    Science.gov (United States)

    Hassani, Hossein; Huang, Xu; Gupta, Rangan; Ghodsi, Mansi

    2016-10-01

    In a recent paper, Gupta et al., (2015), analyzed whether sunspot numbers cause global temperatures based on monthly data covering the period 1880:1-2013:9. The authors find that standard time domain Granger causality test fails to reject the null hypothesis that sunspot numbers do not cause global temperatures for both full and sub-samples, namely 1880:1-1936:2, ​1936:3-1986:11 and 1986:12-2013:9 (identified based on tests of structural breaks). However, frequency domain causality test detects predictability for the full-sample at short (2-2.6 months) cycle lengths, but not the sub-samples. But since, full-sample causality cannot be relied upon due to structural breaks, Gupta et al., (2015) conclude that the evidence of causality running from sunspot numbers to global temperatures is weak and inconclusive. Given the importance of the issue of global warming, our current paper aims to revisit this issue of whether sunspot numbers cause global temperatures, using the same data set and sub-samples used by Gupta et al., (2015), based on an nonparametric Singular Spectrum Analysis (SSA)-based causality test. Based on this test, we however, show that sunspot numbers have predictive ability for global temperatures for the three sub-samples, over and above the full-sample. Thus, generally speaking, our non-parametric SSA-based causality test outperformed both time domain and frequency domain causality tests and highlighted that sunspot numbers have always been important in predicting global temperatures.

  12. Nature's third cycle a story of sunspots

    CERN Document Server

    Choudhuri, Arnab Rai

    2015-01-01

    The cycle of day and night and the cycle of seasons are two familiar natural cycles around which many human activities are organized. But is there a third natural cycle of importance for us humans? On 13 March 1989, six million people in Canada went without electricity for many hours: a large explosion on the sun was discovered as the cause of this blackout. Such explosions occur above sunspots, dark features on the surface of the Sun that have been observed through telescopes since the time of Galileo. The number of sunspots has been found to wax and wane over a period of 11 years. Although this cycle was discovered less than two centuries ago, it is becoming increasingly important for us as human society becomes more dependent on technology. For nearly a century after its discovery, the cause of the sunspot cycle remained completely shrouded in mystery. The 1908 discovery of strong magnetic fields in sunspots made it clear that the 11-year cycle is the magnetic cycle of the sun. It is only during the last ...

  13. Short Periodicities in Latitudinal Variation of Sunspots

    Science.gov (United States)

    Kim, Bang-Yeop; Chang, Heon-Young

    2011-06-01

    The latitudinal variation of sunspots appearing during the period from 1874 to 2009 has been studied in terms of centerof- latitude (COL). The butterfly diagram has been used to study the evolution of the magnetic field and the dynamics at the bottom of the solar convection zone. Short-term periodicities have been of particular interest, in that they are somehow related to the structure and dynamics of the solar interior. We thus have focused our investigation on shortterm periodicities. We first calculated COL by averaging the latitude of sunspots with the weight function in area. Then, we analyzed the time series of COL using the wavelet transform technique. We found that a periodicity of ~5 years is the most dominant feature in the time series of COL, with the exception of the ~11 year solar cycle itself. This periodicity can be easily understood by considering small humps between the minima in the area-weighted butterfly diagram. However, we find that periodicities of ~1.3 (0.064), ~1.5 (0.056), or ~1.8 (0.046) years ( 1/ month ), which have been previously suggested as evidence of links between the changing structure of the sunspot zone and the tachocline rotation rate oscillations, are insignificant and inconsistent. We therefore conclude that the only existing short-term periodicity is of ~5 years, and that periodicities of ~1.3, ~1.5, or ~1.8 years are likely to be artifacts due to random noise of small sunspots.

  14. A new hypothesis of sunspot formation

    CERN Document Server

    Zhukov, V I

    2003-01-01

    The process of sunspot formation is considered with the account of heat effects. According to the Le Chatelier principle, a local overheating must precede to the cooling of solar surface in the places of sunspot formation. The sunspot dynamics is a process close to the surface nucleate-free boiling in a thin layer with formation of bubbles (or craters), so we focus on the analogy between these two processes. Solar spots and surface nucleate-free boiling in a thin layer have similarities in formation conditions, results of impact on the surface were they have been formed, periodicity, and their place in the hierarchy of self-organization in complex systems. The difference is in the working medium and method of channelling of extra energy from the overheated surface -for boiling process, the energy is forwarded to generation of vapor, and in sunspots the solar energy is consumed to formation of a strong magnetic field. This analogy explains the problem of a steady brightness (temperature) of a spot that is inde...

  15. Sunspots and Their Simple Harmonic Motion

    Science.gov (United States)

    Ribeiro, C. I.

    2013-01-01

    In this paper an example of a simple harmonic motion, the apparent motion of sunspots due to the Sun's rotation, is described, which can be used to teach this subject to high-school students. Using real images of the Sun, students can calculate the star's rotation period with the simple harmonic motion mathematical expression.

  16. Vortex attraction and the formation of sunspots

    Science.gov (United States)

    Parker, E. N.

    1992-01-01

    A downdraft vortex ring in a stratified atmosphere exhibits universal attraction for nearby vertical magnetic flux bundles. It is speculated that the magnetic fields emerging through the surface of the sun are individually encircled by one or more subsurface vortex rings, providing an important part of the observed clustering of magnetic fibrils to form pores and sunspots.

  17. Sunspot Group Development in High Resolution

    CERN Document Server

    Muraközy, J; Ludmány, A

    2014-01-01

    The Solar and Heliospheric Obseratory/Michelson Doppler Imager--Debrecen Data (SDD) sunspot catalogue provides an opportunity to study the details and development of sunspot groups on a large statistical sample. The SDD data allow, in particular, the differential study of the leading and following parts with a temporal resolution of 1.5 hours. In this study, we analyse the equilibrium distance of sunspot groups as well as the evolution of this distance over the lifetime of the groups and the shifts in longitude associated with these groups. We also study the asymmetry between the compactness of the leading and following parts, as well as the time-profiles for the development of the area of sunspot groups. A logarithmic relationship has been found between the total area and the distance of leading-following parts of active regions (ARs) at the time of their maximum area. In the developing phase the leading part moves forward; this is more noticeable in larger ARs. The leading part has a higher growth rate than...

  18. Magnetic Splitting of Molecular Lines in Sunspot

    Science.gov (United States)

    Berdyugina, S. V.; Frutiger, C.; Solanki, S. K.

    A study of molecular lines in sunspots is of particular interest because of their high temperature and pressure sensitivity. Many of them are also magnetically sensitive, but this was not yet widely investigated. With high-resolution, high signal-to-noise Fourier spectroscopy in four Stokes parameters now available, the use of molecular lines for studying the structure of sunspots brings real gains. One is the extension of spot models, including magnetic field, up to layers, where atomic lines suffer from NLTE effects but molecules can still be treated in the LTE approximation. Equally important is the fact that since molecular lines are extremely temperature sensitive they can be used to probe the thermal and magnetic structure of the coolest parts of sunspots. We present calculations of splitting and the Stokes parameters for a number of molecular lines in the visible and near-infrared regions. Our first selections are the green system of MgH A2Π-X2σ and the TiO triplet α, γ' and γ systems as the most studied band systems in the sunspot spectrum. The calculations involve different regimes of the molecular Zeeman effect, up to the complete Paschen-Back effect for individual lines. We look for molecular lines which can be used along with atomic lines to derive magnetic, thermal and dynamic properties of the umbra.

  19. Solar magnetic field studies using the 12 micron emission lines. I - Quiet sun time series and sunspot slices

    Science.gov (United States)

    Deming, Drake; Boyle, Robert J.; Jennings, Donald E.; Wiedemann, Gunter

    1988-01-01

    The use of the extremely Zeeman-sensitive IR emission line Mg I, at 12.32 microns, to study solar magnetic fields. Time series observations of the line in the quiet sun were obtained in order to determine the response time of the line to the five-minute oscillations. Based upon the velocity amplitude and average period measured in the line, it is concluded that it is formed in the temperature minimum region. The magnetic structure of sunspots is investigated by stepping a small field of view in linear 'slices' through the spots. The region of penumbral line formation does not show the Evershed outflow common in photospheric lines. The line intensity is a factor of two greater in sunspot penumbrae than in the photosphere, and at the limb the penumbral emission begins to depart from optical thinness, the line source function increasing with height. For a spot near disk center, the radial decrease in absolute magnetic field strength is steeper than the generally accepted dependence.

  20. Check the special moves Halftone a central sun sunspot different angles using local correlation tracking

    Directory of Open Access Journals (Sweden)

    Monireh Askarikhah

    2016-03-01

    Full Text Available Sunspots, solar magnetic field effect on a large scale are outstanding. In this research field study of surface movement (special move in a Lightening Solar Shade Halftone sphere central angle of the sun in three different here. The evolution of current research and special horizontal movement in a sunspot on the basis of time-series observations imaging data in the blue spectral range with a wavelength continuum Central line spots active area of 4504 angstroms During the 3 day 10933NOAA dated 7 January (9.0 hours (UT 12:35 until (UT 12: 56, 8 January (8.0 hours (UT 06: 00 to (UT 06 21, Jan 9 (6/0 of the time (UT 05: 00 to (UT 05: 21, 2007 were obtained by using LCT (local correlation tracking has studied. Halftone stains in the three-averaged (averaged over 10 consecutive images and averaged over 20 consecutive images flow rate for each of the three categories Map angles (total 9 speed stream map obtained, as well as a lot of speed graph speed on the map, each of which is for an angle we examined. What is clear in some parts of the maps quickly climb (eruption in plasma and in some places fall (collapse plasma-level Halftone be observed. The maps quickly, the (current intensity Halftone patterns toward the inner penumbra shadow and movement patterns foreign to the outside strongly suggest Halftone That resulted in the dismissal of this shift is the dividing line that location is reached. Due to the frequency graph maps quickly we realized all three angles to this topic Slick passing moves quickly, especially given that the three angles of the half shadow has fallen. As well as speed of movement of the intensity of the Halftone patterns of the dividing line within the shadows of the reductions in external Halftone dividing line toward the photosphere increases.

  1. Comparative analysis of Debrecen sunspot catalogues

    Science.gov (United States)

    Győri, L.; Ludmány, A.; Baranyi, T.

    2017-02-01

    Sunspot area data are important for studying solar activity and its long-term variations. At the Debrecen Heliophysical Observatory, we compiled three sunspot catalogues: the Debrecen Photoheliographic Data (DPD), the SDO/HMI Debrecen Data (HMIDD) and the SOHO/MDI Debrecen Data. For comparison, we also compiled an additional sunspot catalogue, the Greenwich Photoheliographic Data, from the digitized Royal Greenwich Observatory images for 1974-76. By comparing these catalogues when they overlap in time, we can investigate how various factors influence the measured area of sunspots, and, in addition, we can derive area cross-calibration factors for these catalogues. The main findings are as follows. Poorer seeing increases the individual corrected spot areas and decreases the number of small spots. Interestingly, the net result of these two effects for the total corrected spot area is zero. DPD daily total corrected sunspot areas are 5 per cent smaller than the HMIDD ones. Revised DPD daily total corrected umbra areas are 9 per cent smaller than those of HMIDD. The Greenwich photoheliographic areas are only a few per cent smaller than DPD areas. A 0.2° difference between the north directions of the DPD and MDI images is found. This value is nearly the same as was found (0.22°) by us in a previous paper comparing HMI and MDI images. The area measurement practice (spots smaller than 10 mh were not directly measured but an area of 2 mh was assigned to each) of the Solar Observing Optical Network cannot explain the large area deficit of the Solar Observing Optical Network.

  2. Tests of Sunspot Number Sequences: 4. Discontinuities Around 1946 in Various Sunspot Number and Sunspot-Group-Number Reconstructions

    Science.gov (United States)

    Lockwood, M.; Owens, M. J.; Barnard, L.

    2016-11-01

    We use five test data series to search for, and quantify, putative discontinuities around 1946 in five different annual-mean sunspot-number or sunspot-group-number data sequences. The data series tested are the original and new versions of the Wolf/Zürich/International sunspot number composite [R_{{ISNv1}} and R_{{ISNv2}}] (respectively Clette et al. in Adv. Space Res. 40, 919, 2007 and Clette et al. in The Solar Activity Cycle 35, Springer, New York, 2015); the corrected version of R ISNv1 proposed by Lockwood, Owens, and Barnard ( J. Geophys. Res. 119, 5193, 2014a) [R C]; the new "backbone" group-number composite proposed by Svalgaard and Schatten ( Solar Phys. 291, 2016) [R_{{BB}}]; and the new group-number composite derived by Usoskin et al. ( Solar Phys. 291, 2016) [R_{{UEA}}]. The test data series used are the group-number [NG] and total sunspot area [A G] from the Royal Observatory, Greenwich/Royal Greenwich Observatory (RGO) photoheliographic data; the Ca K index from the recent re-analysis of Mount Wilson Observatory (MWO) spectroheliograms in the Calcium ii K ion line; the sunspot-group-number from the MWO sunspot drawings [N_{{MWO}}]; and the dayside ionospheric F2-region critical frequencies measured by the Slough ionosonde [foF2]. These test data all vary in close association with sunspot numbers, in some cases non-linearly. The tests are carried out using both the before-and-after fit-residual comparison method and the correlation method of Lockwood, Owens, and Barnard, applied to annual mean data for intervals iterated to minimise errors and to eliminate uncertainties associated with the precise date of the putative discontinuity. It is not assumed that the correction required is by a constant factor, nor even linear in sunspot number. It is shown that a non-linear correction is required by RC, R_{BB}, and R_{{ISNv1}}, but not by R_{{ISNv2}} or R_{{UEA}}. The five test datasets give very similar results in all cases. By multiplying the probability

  3. Short-Term Variations in the Equatorial Rotation Rate of Sunspot Groups

    Science.gov (United States)

    Javaraiah, J.; Bertello, L.

    2016-12-01

    We have detected several periodicities in the solar equatorial rotation rate of sunspot groups in the catalog Greenwich Photoheliographic Results (GPR) during the period 1931 - 1976, the Solar Optical Observing Network (SOON) during the period 1977 - 2014, and the Debrecen Photoheliographic Data (DPD) during the period 1974 - 2014. We have compared the results from the fast Fourier transform (FFT), the maximum entropy method (MEM), and the Morlet wavelet power-spectra of the equatorial rotation rates determined from SOON and DPD sunspot-group data during the period 1986 - 2007 with those of the Mount Wilson Doppler-velocity data during the same period determined by Javaraiah et al. ( Solar Phys. 257, 61, 2009). We have also compared the power-spectra computed from the DPD and the combined GPR and SOON sunspot-group data during the period 1974 - 2014 to those from the GPR sunspot-group data during the period 1931 - 1973. Our results suggest a ˜ 250-day period in the equatorial rotation rate determined from both the Mt. Wilson Doppler-velocity data and the sunspot-group data during 1986 - 2007. However, a wavelet analysis reveals that this periodicity appears mostly around 1991 in the velocity data, while it is present in most of the solar cycles covered by the sunspot-group data, mainly near the minimum epochs of the solar cycles. We also found the signature of a period of ˜ 1.4 years in the velocity data during 1990 - 1995, and in the equatorial rotation rate of sunspot groups mostly around the year 1956. The equatorial rotation rate of sunspot groups reveals a strong ˜ 1.6-year periodicity around 1933 and 1955, a weaker one around 1976, and a strong ˜ 1.8-year periodicity around 1943. Our analysis also suggests periodicities of ˜ 5 years, ˜ 7 years, and ˜ 17 years, as well as some other short-term periodicities. However, short-term periodicities are mostly present at the time of solar minima. Hence, short-term periodicities cannot be confirmed because of

  4. Penumbra characteristics of square photon beams delimited by a GEMS multi-leaf collimator

    Energy Technology Data Exchange (ETDEWEB)

    Briot, E.; Julia, F. [Centre de Lutte Contre le Cancer Gustave-Roussy, 94 - Villejuif (France)

    1995-12-01

    A multi-leaf collimator (MLC) has been designed to replace directly the standard collimator of a SATURNE IV Series linac. It consists of 2 x 32 tungsten leaves and one set of upper block jaws. Isodose curves and dose profiles were measured for symmetric fields at the depth of the maximum and the reference depths for 6 MV, 10 MV, 18 MV photon beams. The penumbra (80%-20%) corresponding to the face and the side of the leaves have been compared with the standard collimators. Along with the X direction, the field delimitation is performed primarily with the leaves which are continuously variable in position. Along the Y direction, the field is initially approximated by the closure of opposite leaf pairs; then the Y upper jaws produce the exact size of the required field. As the leaves move linearly the penumbra (80%-20%) corresponding to the leaf ends is minimized and held constant at all positions by curvature of their faces. Penumbra obtained with the superposition of leaves and Y jaws depend on their relative position. The penumbra is minimum when the leaf side and the Y jaw edge coincide and the comparison of the measurement values with the conventional collimator shows that the differences are within 1 mm. When the leaves delineating the field are not entirely covered by the Y block upper jaws, the penumbra increases, and the junction of the opposing leaves, a width increase up to 3.5 mm has been measured.

  5. A technique to sharpen the beam penumbra for Gamma Knife radiosurgery

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero, M; Li, X Allen; Ma Lijun [Department of Radiation Oncology, University of Maryland, School of Medicine, Baltimore, MD 21201 (United States)

    2003-06-21

    In stereotactic radiosurgery, a narrow beam penumbra is often desired for producing steep dose fall-off between the target volume and adjacent critical structures. Due to limited source sizes and the scattering effects, the physical penumbra of the Gamma Knife (GK) is often restricted to a width of 1-2 mm. In this work, we developed a technique to further reduce the beam penumbra and improve the dose profile for the Gamma Knife delivery. Under this technique, a conic filter is inserted into an individual plug collimator of a GK helmet to flatten the beam profile. Monte Carlo calculations were carried out to simulate the GK geometry of the individual plug collimator and to optimize the physical shapes of the filters. The calculations were performed for a series of filter shapes with different collimator sizes. Our results show that a proper filter significantly reduces the single GK beam penumbra width (defined as the distance from the 90% to 50% isodose lines) by 30-60%. The beam intensity is reduced by about 20-50% when the filter is used. A treatment plan was developed for a trigeminal neuralgia case by commissioning the filtered beam profile for Leksell Gamma Plan (version 5.31). Compared with the conventional treatment plan, a significant improvement was found on the critical structure sparing and on the target dose uniformity. In conclusion, the proposed technique is feasible and effective in sharpening the beam penumbra for Gamma Knife beam profiles.

  6. Newly found sunspot observations by Peter Becker from Rostock for 1708, 1709, and 1710

    CERN Document Server

    Neuhaeuser, Ralph; Pfitzner, Elvira; Richter, Susanne

    2015-01-01

    We present a few newly found old sunspot observations from the years AD 1708, 1709, and 1710, which were obtained by Peter Becker from Rostock, Germany. For 1709, Becker gave a detailed drawing: he observed a sunspot group made up of two spots on Jan 5, 6, and 7, and just one of the two spots was observed on Jan 8 and 9. We present his drawing and his explanatory text. We can measure the latitude and longitude of these two spots and estimate their sizes for all five days. While the spots and groups in 1708 and the spot on four of the five days in January 1709 were known before from other observers (e.g. Hoyt & Schatten 1998), the location of the spots in early January 1709 were not known before, so that they can now be considered in reconstructed butterfly diagrams. The sunspots detected by Becker on 1709 Jan 5 and 1710 Sep 10 were not known before at all, as the only observer known for those two dates, La Hire, did not detect that spot (group). We estimate new group sunspot numbers for the relevant days,...

  7. Newly found sunspot observations by Peter Becker from Rostock for 1708, 1709, and 1710

    Science.gov (United States)

    Neuhäuser , R.; Arlt, R.; Pfitzner, E.; Richter, S.

    2015-09-01

    We present a few newly found old sunspot observations from the years AD 1708, 1709, and 1710, which were obtained by Peter Becker from Rostock, Germany. For 1709, Becker gave a detailed drawing: he observed a sunspot group made up of two spots on January 5, 6, and 7, and just one of the two spots was observed on January 8 and 9. We present his drawing and his explanatory text. We can measure the latitude and longitude of these two spots and estimate their sizes for all five days. While the spots and groups in 1708 and the spot on four of the five days in January 1709 were known before from other observers (e.g. Hoyt & Schatten 1998), the location of the spots in early January 1709 were not known before, so that they can now be considered in reconstructed butterfly diagrams. The sunspots detected by Becker on 1709 January 5 and 1710 September 10 were not known before at all, as the only observer known for those two dates, La Hire, did not detect that spot (group). We estimate new group sunspot numbers for the relevant days, months, and years. The time around 1708-1710 is important, because it documents the recovery of solar activity towards the end of the Maunder Grand Minimum. We also show two new spot observations from G. Kirch for 1708 September 13 and 14 as described in his letter to Wurzelbaur (dated Berlin AD 1708 December 19).

  8. The EUV Spectrum of Sunspot Plumes Observed by SUMER on SOHO

    Indian Academy of Sciences (India)

    W. Curdt; B. N. Dwivedi; U. Feldman

    2000-09-01

    We present results from sunspot observations obtained by SUMER on SOHO. In sunspot plumes the EUV spectrum differs from the quiet Sun; continua are observed with different slopes and intensities; emission lines from molecular hydrogen and many unidentified species indicate unique plasma conditions above sunspots. Sunspot plumes are sites of systematic downflow. We also discuss the properties of sunspot oscillations.

  9. Comparing Digital Sunspot Number Counts to the New International Sunspot Numbers

    Science.gov (United States)

    Balasubramaniam, K. S.; Henry, Timothy

    2016-05-01

    The International Sunspot Numbers (ISN; Version 2) have been recently (2015) revised at the Sunspot Index and Long Term Solar Observations maintained at Royal Observatory of Belgium (http://www.sidc.be/silso/datafiles). ISN is a reconciled aggregate over several ground-based observatories, mostly using hand-drawn sunspot recordings. We make a detailed 10-year comparisons between the Improved Solar Observing Optical Network’s prototype digital data (2002-2011) and the ISN V1 (Version 1; pre-2015), and ISN V2. Over the ~ 10-year period, ISN V1 underestimates the sunspot number counts by up to 40% while the ISN V2 overestimates by a similar amount. We also compare the hand-drawn data from a single telescope at the National Solar Observatory with the digital data and ISN numbers. These comparisons reveal caveats that need to be taken into account, as sunspot numbers are used to forecast both the solar cycle and the near term climatology of solar cycle impacts on the space environment.

  10. Sunspots during the Maunder Minimum from Machina Coelestis by Hevelius

    CERN Document Server

    Carrasco, V M S; Vaquero, J M

    2015-01-01

    We revisited the sunspot observations published by Johannes Hevelius in his book Machina Coelestis (1679) corresponding to the period 1653-1675 (just in the middle of the Maunder Minimum). We show detailed translations of the original Latin texts describing the sunspot records and provide the general context of these sunspot observations. From this source only, we present an estimate of the annual values of the Group Sunspot Number based only on the records that explicitly inform about the presence or absence of sunspots. Although we obtain very low values of the Group Sunspot Number, in accordance with a grand minimum of solar activity, these values are significantly higher in general than the values provided by Hoyt and Schatten (1998) for the same period.

  11. Sunspot Numbers from ISOON: A Ten-Year Data Analysis

    Science.gov (United States)

    Balasubramaniam, K. S.; Henry, T. W.

    2016-11-01

    Sunspot numbers are important tracers of historical solar activity. They are important in predicting the oncoming solar maximum, in the design of lifetimes of space assets, and in assessing the extent of solar-radiation impact on the space environment. Historically, sunspot numbers have been obtained visually from sunspot drawings. The availability of digital images from the US Air Force Improved Solar Optical Observing Network (ISOON) prototype telescope concurrent to observer-dependent sunspot numbers recorded at the National Solar Observatory (NSO) has provided a basis for comparing sunspot numbers determined from the two methods. We compare sunspot numbers from visual and digital methods observed nearly simultaneously. The advantages of digital imagery are illustrated.

  12. Pre-Flare Dynamics of Sunspot Groups

    CERN Document Server

    Korsos, M B; Ludmany, A

    2014-01-01

    Several papers provide evidences that the most probable sites of flare onset are the regions of high horizontal magnetic field gradients in solar active regions. Besides the localization of flare producing areas the present work intends to reveal the characteristic temporal variations in these regions prior to flares. This study uses sunspot data instead of magnetograms, it follows the behaviour of a suitable defined proxy measure representing the horizontal magnetic field gradient. The source of the data is the SDD (SOHO/MDI-Debrecen Data) sunspot catalogue. The most promising pre-flare signatures are the following properties of the gradient variation: i) steep increase, ii) high maximum, iii) significant fluctuation and iv) a gradual decrease between the maximum and the flare onset which can be related to the "pull mode" of the current layer. These properties may yield a tool for the assessment of flare probability and intensity within the next 8-10 hours.

  13. Pre-flare dynamics of sunspot groups

    Energy Technology Data Exchange (ETDEWEB)

    Korsós, M. B.; Baranyi, T.; Ludmány, A., E-mail: korsos.marianna@csfk.mta.hu, E-mail: baranyi.tunde@csfk.mta.hu, E-mail: ludmany.andras@csfk.mta.hu [Heliophysical Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, 4010 Debrecen, P.O. Box 30 (Hungary)

    2014-07-10

    Several papers provide evidence that the most probable sites of flare onset are the regions of high horizontal magnetic field gradients in solar active regions. Besides the localization of flare-producing areas, this work intends to reveal the characteristic temporal variations in these regions prior to flares. This study uses sunspot data instead of magnetograms and follows the behavior of a suitable defined proxy measure representing the horizontal magnetic field gradient. The source of the data is the SDD (SOHO/MDI-Debrecen Data) sunspot catalog. The most promising pre-flare signatures are the following properties of gradient variation: (1) steep increase, (2) high maximum, (3) significant fluctuation, and (4) a gradual decrease between the maximum and the flare onset that can be related to the 'pull mode' of the current layer. These properties may yield a tool for the assessment of flare probability and intensity within the following 8-10 hr.

  14. Numerical simulations of sunspot rotation driven by magnetic flux emergence

    OpenAIRE

    Sturrock, Zoe

    2017-01-01

    Magnetic flux continually emerges from the Sun, rising through the solar interior, emerging at the photosphere in the form of sunspots and expanding into the atmosphere. Observations of sunspot rotations have been reported for over a century and are often accompanied by solar eruptions and flaring activity. In this thesis, we present 3D numerical simulations of the emergence of twisted flux tubes from the uppermost layers of the solar interior, examining the rotational movements of sunspots i...

  15. Flare differentially rotates sunspot on Sun's surface

    Science.gov (United States)

    Liu, Chang; Xu, Yan; Cao, Wenda; Deng, Na; Lee, Jeongwoo; Hudson, Hugh S.; Gary, Dale E.; Wang, Jiasheng; Jing, Ju; Wang, Haimin

    2016-10-01

    Sunspots are concentrations of magnetic field visible on the solar surface (photosphere). It was considered implausible that solar flares, as resulted from magnetic reconnection in the tenuous corona, would cause a direct perturbation of the dense photosphere involving bulk motion. Here we report the sudden flare-induced rotation of a sunspot using the unprecedented spatiotemporal resolution of the 1.6 m New Solar Telescope, supplemented by magnetic data from the Solar Dynamics Observatory. It is clearly observed that the rotation is non-uniform over the sunspot: as the flare ribbon sweeps across, its different portions accelerate (up to ~50° h-1) at different times corresponding to peaks of flare hard X-ray emission. The rotation may be driven by the surface Lorentz-force change due to the back reaction of coronal magnetic restructuring and is accompanied by a downward Poynting flux. These results have direct consequences for our understanding of energy and momentum transportation in the flare-related phenomena.

  16. Flare differentially rotates sunspot on Sun's surface

    CERN Document Server

    Liu, Chang; Cao, Wenda; Deng, Na; Lee, Jeongwoo; Hudson, Hugh S; Gary, Dale E; Wang, Jiasheng; Jing, Ju; Wang, Haimin

    2016-01-01

    Sunspots are concentrations of magnetic field visible on the solar surface (photosphere). It was considered implausible that solar flares, as resulted from magnetic reconnection in the tenuous corona, would cause a direct perturbation of the dense photosphere involving bulk motion. Here we report the sudden flare-induced rotation of a sunspot using the unprecedented spatiotemporal resolution of the 1.6 m New Solar Telescope, supplemented by magnetic data from the Solar Dynamics Observatory. It is clearly observed that the rotation is non-uniform over the sunspot: as the flare ribbon sweeps across, its different portions accelerate (up to 50 deg per hr) at different times corresponding to peaks of flare hard X-ray emission. The rotation may be driven by the surface Lorentz-force change due to the back reaction of coronal magnetic restructuring and is accompanied by a downward Poynting flux. These results have direct consequences for our understanding of energy and momentum transportation in the flare-related p...

  17. Flare differentially rotates sunspot on Sun's surface.

    Science.gov (United States)

    Liu, Chang; Xu, Yan; Cao, Wenda; Deng, Na; Lee, Jeongwoo; Hudson, Hugh S; Gary, Dale E; Wang, Jiasheng; Jing, Ju; Wang, Haimin

    2016-10-10

    Sunspots are concentrations of magnetic field visible on the solar surface (photosphere). It was considered implausible that solar flares, as resulted from magnetic reconnection in the tenuous corona, would cause a direct perturbation of the dense photosphere involving bulk motion. Here we report the sudden flare-induced rotation of a sunspot using the unprecedented spatiotemporal resolution of the 1.6 m New Solar Telescope, supplemented by magnetic data from the Solar Dynamics Observatory. It is clearly observed that the rotation is non-uniform over the sunspot: as the flare ribbon sweeps across, its different portions accelerate (up to ∼50° h(-1)) at different times corresponding to peaks of flare hard X-ray emission. The rotation may be driven by the surface Lorentz-force change due to the back reaction of coronal magnetic restructuring and is accompanied by a downward Poynting flux. These results have direct consequences for our understanding of energy and momentum transportation in the flare-related phenomena.

  18. The new Sunspot Number: assembling all corrections

    CERN Document Server

    Frédéric,; Lefèvre, Laure

    2015-01-01

    The Sunspot Number, created by R.Wolf in 1849, provides a direct long-term record of solar activity from 1700 to the present. In spite of its central role in multiple studies of the solar dynamo and of the past Sun-Earth relations, it was never submitted to a global critical revision. However, various discrepancies with other solar indices recently motivated a full re-calibration of this series. Based on various diagnostics and corrections established in the framework of several Sunspot Number Workshops and described in Clette et al. 2014, we assembled all corrections in order to produce a new standard version of this reference time series. In this paper, we explain the three main corrections and the criteria used to choose a final optimal version of each correction factor or function, given the available information and published analyses. We then discuss the good agreement obtained with the Group sunspot Number derived from a recent reconstruction. Among the implications emerging from this re-calibrated ser...

  19. The effect of density on the 10MV photon beam penumbra.

    Science.gov (United States)

    Hoban, P W; Keal, P J; Round, W H

    1992-09-01

    An investigation into the density dependence of the penumbra of the Varian Clinac 18/10 10MV photon beam has been carried out. A water/lung phantom was constructed of polystyrene (r = 1.04 g cm-3) and cork (r = 0.23 g cm-3), in which interfaces exist both parallel and perpendicular to the beam axis. The irradiation of the phantom was also simulated using the EGS4 Monte Carlo system with a cartesian voxel geometry. Experimental (TLD) and Monte Carlo dose profiles are in close agreement, and show a large degree of penumbral broadening in the lung region. This broadening is due primarily to lateral electronic disequilibrium occurring at a larger distance from the geometric beam edge in lung than in water. This disequilibrium can also cause the dose in lung to drop below the dose in water at the same depth and off axis distance, even though the radiological depth is less in lung. Monte Carlo simulations were also performed where the dose is separated into primary and scattered components, for homogeneous media of densities 0.25, 0.50, 0.75 and 1.00 g cm-3. The penumbral width of the primary dose profile was found to be almost constant with depth for a point source of photons (after the initial build-up region), where the lateral distances from the 95-50% and 50-5% dose levels on the dose profile (normalised to the dose at the central axis) are equal in all cases. Also, primary penumbra width was found to be almost inversely proportional to density. The primary penumbra for a unit density material can be fitted accurately by an exponential forming function with empirical determined coefficients. The penumbral shape for the lower densities can then be closely fitted by scaling the coefficients in proportion to density. This scaling method has application in treatment planning, where the predicted primary penumbra shape should take account of inhomogeneities, and is particularly important in matching adjacent fields. When the scattered dose component is added to give the

  20. The Solar Rotation in the 1930s from the Sunspot and Flocculi Catalogs of the Ebro Observatory

    Science.gov (United States)

    de Paula, V.; Curto, J. J.; Casas, R.

    2016-10-01

    The tables of sunspot and flocculi heliographic positions included in the catalogs published by the Ebro Observatory in the 1930s have recently been recovered and converted into digital format by using optical character recognition (OCR) technology. We here analyzed these data by computing the angular velocity of several sunspot and flocculi groups. A difference was found in the rotational velocity for sunspots and flocculi groups at high latitudes, and we also detected an asymmetry between the northern and southern hemispheres, which is especially marked for the flocculi groups. The results were then fitted with a differential-rotation law [ω=a+b sin2 B] to compare the data obtained with the results published by other authors. A dependence on the latitude that is consistent with former studies was found. Finally, we studied the possible relationship between the sunspot/flocculi group areas and their corresponding angular velocity. There are strong indications that the rotational velocity of a sunspot/flocculi group is reduced (in relation to the differential rotation law) when its maximum area is larger.

  1. Numerical sunspot models - subsurface structure and helioseismic forward modeling (Invited)

    Science.gov (United States)

    Rempel, M.; Birch, A. C.; Braun, D. C.

    2009-12-01

    The magnetic and thermal subsurface structure of sunspots has been debated for decades. While local helioseismic inversions allow in principle to constrain the subsurface structure of sunspots, a full inversion is still not possible due to the complicated interaction between waves and magnetic field. As an alternative it is possible to address this problem through forward modeling. Over the past few years numerical MHD models of entire sunspots including radiative transfer and a realistic equation of state have become possible. These simulations include p-modes excited by convection and the full interaction of these modes with the magnetic and thermal structure of the sunspot. In this talk I will present recent progress in MHD modeling of sunspots with special emphasis on the thermal and magnetic structure of numerical sunspot models. It turns out that modeled sunspots so far impose rather shallow perturbations to sound and fast mode speeds in the upper most 2 Mm. Nevertheless the seismic signatures are very similar to observed sunspots.

  2. The Sunspot Catalogues of Carrington, Peters, and de la Rue: Quality Control and Machine-readable Versions

    CERN Document Server

    Casas, R

    2013-01-01

    In the 19th century, several astronomers made observations of sunspots, recording their positions and sometimes their areas. These observations were published in the form of extensive tables, but have been unhelpful until now. Three of these observers were Richard C. Carrington, Christian H. F. Peters, and Warren de la Rue (and their respective collaborators). They published, in various articles the data corresponding to 26 641 sunspot positions (Carrington, Peters, and de la Rue registered 4 900, 14 040, and 7 701 sunspot positions, respectively). In this paper we present a translation of more than 400 pages of their printed numerical tables into a machine readable format, including an initial analysis targeted at detecting possible mistakes in the reading or in the original transcription. The observations carried out by these three astronomers have been made available at the Centre de Don\\'ees Astronomiques de Strasbourg (http://cdsarc.u-strasbg.fr/cgi-bin/VizieR?-source=VI/138).

  3. Investigation of the Relationship between Solar Flares and Sunspot Groups

    Science.gov (United States)

    Eren, S.; Kilcik, A.

    2017-01-01

    We studied the relationship between X-Ray flare numbers (C, M, and, X class flares) and sunspot counts in four categories (Simple (A + B), Medium (C), Large (D + E + F), and End (H)). All data sets cover the whole Solar Cycle 23 and the ascending and maximum phases of Cycle 24 (1996-2014). Pearson correlation analysis method was used to investigate the degree of relationship between monthly solar flare numbers and sunspot counts observed in different sunspot categories. We found that the C, M, and X class flares have highest correlation with the large group sunspot counts, while the small category does not any meaningful correlation. Obtained correlation coefficients between large groups and C, M, and X class flare numbers are 0.79, 0.74, and 0.4, respectively. Thus, we conclude that the main sources of X-Ray solar flares are the complex/large sunspot groups.

  4. Learning and memory changes in rats following exogenous human hepatocyte growth factor gene injection into cerebral ischemic penumbra

    Institute of Scientific and Technical Information of China (English)

    Zhijun You; Yong Liu; Jianye Yang; Qingping Jiang

    2011-01-01

    Human hepatocyte growth factor can be used to treat cerebral infarction, administered by lateral ventricular, cerebellomedullary cistern or subarachnoid injections. However, the target gene expression product is scarcely found in the ischemic penumbra, but extensively distributes in other regions, increasing the risks of gene therapy. The present study directly transfected hepatocyte growth factor gene into the ischemic penumbra of rats with transient middle cerebral artery occlusion. Immunohistochemical analysis revealed that infarct volume was significantly decreased, hepatocyte growth factor protein expression level and vessel quantity in the ischemic penumbra were significantly increased, and learning and memory were significantly improved.

  5. On the maximum rate of change in sunspot number growth and the size of the sunspot cycle

    Science.gov (United States)

    Wilson, Robert M.

    1990-01-01

    Statistically significant correlations exist between the size (maximum amplitude) of the sunspot cycle and, especially, the maximum value of the rate of rise during the ascending portion of the sunspot cycle, where the rate of rise is computed either as the difference in the month-to-month smoothed sunspot number values or as the 'average rate of growth' in smoothed sunspot number from sunspot minimum. Based on the observed values of these quantities (equal to 10.6 and 4.63, respectively) as of early 1989, it is inferred that cycle 22's maximum amplitude will be about 175 + or - 30 or 185 + or - 10, respectively, where the error bars represent approximately twice the average error found during cycles 10-21 from the two fits.

  6. Whole-Brain CT Perfusion to Quantify Acute Ischemic Penumbra and Core.

    Science.gov (United States)

    Lin, Longting; Bivard, Andrew; Krishnamurthy, Venkatesh; Levi, Christopher R; Parsons, Mark W

    2016-06-01

    Purpose To validate the use of perfusion computed tomography (CT) with whole-brain coverage to measure the ischemic penumbra and core and to compare its performance to that of limited-coverage perfusion CT. Materials and Methods Institutional ethics committee approval and informed consent were obtained. Patients (n = 296) who underwent 320-detector CT perfusion within 6 hours of the onset of ischemic stroke were studied. First, the ischemic volume at CT perfusion was compared with the penumbra and core reference values at magnetic resonance (MR) imaging to derive CT perfusion penumbra and core thresholds. Second, the thresholds were tested in a different group of patients to predict the final infarction at diffusion-weighted imaging 24 hours after CT perfusion. Third, the change in ischemic volume delineated by the optimal penumbra and core threshold was determined as the brain coverage was gradually reduced from 160 mm to 20 mm. The Wilcoxon signed-rank test, concordance correlation coefficient (CCC), and analysis of variance were used for the first, second, and third steps, respectively. Results CT perfusion at penumbra and core thresholds resulted in the least volumetric difference from MR imaging reference values with delay times greater than 3 seconds and delay-corrected cerebral blood flow of less than 30% (P = .34 and .33, respectively). When the thresholds were applied to the new group of patients, prediction of the final infarction was allowed with delay times greater than 3 seconds in patients with no recanalization of the occluded artery (CCC, 0.96 [95% confidence interval: 0.92, 0.98]) and with delay-corrected cerebral blood flow less than 30% in patients with complete recanalization (CCC, 0.91 [95% confidence interval: 0.83, 0.95]). However, the ischemic volume with a delay time greater than 3 seconds was underestimated when the brain coverage was reduced to 80 mm (P = .04) and the core volume measured as cerebral blood flow less than 30% was

  7. Hurricanes in the Gulf of Mexico and the Caribbean Sea and their relationship with sunspots

    Science.gov (United States)

    Rojo-Garibaldi, Berenice; Salas-de-León, David Alberto; Sánchez, Norma Leticia; Monreal-Gómez, María Adela

    2016-10-01

    We present the results of a time series analysis of hurricanes and sunspots occurring from 1749 to 2010. Exploratory analysis shows that the total number of hurricanes is declining. This decline is related to an increase in sunspot activity. Spectral analysis shows a relationship between hurricane oscillation periods and sunspot activity. Several sunspot cycles were identified from the time series analysis.

  8. Forecasting the Time Series of Sunspot Numbers

    Science.gov (United States)

    Aguirre, L. A.; Letellier, C.; Maquet, J.

    2008-05-01

    Forecasting the solar cycle is of great importance for weather prediction and environmental monitoring, and also constitutes a difficult scientific benchmark in nonlinear dynamical modeling. This paper describes the identification of a model and its use in the forecasting the time series comprised of Wolf’s sunspot numbers. A key feature of this procedure is that the original time series is first transformed into a symmetrical space where the dynamics of the solar dynamo are unfolded in a better way, thus improving the model. The nonlinear model obtained is parsimonious and has both deterministic and stochastic parts. Monte Carlo simulation of the whole model produces very consistent results with the deterministic part of the model but allows for the determination of confidence bands. The obtained model was used to predict cycles 24 and 25, although the forecast of the latter is seen as a crude approximation, given the long prediction horizon required. As for the 24th cycle, two estimates were obtained with peaks of 65±16 and of 87±13 units of sunspot numbers. The simulated results suggest that the 24th cycle will be shorter and less active than the preceding one.

  9. Sunspot waves and flare energy release

    CERN Document Server

    Sych, R; Altyntsev, A; Dudík, J; Kashapova, L

    2014-01-01

    We address a possibility of the flare process initiation and further maintenance of its energy release due to a transformation of sunspot longitudinal waves into transverse magnetic loop oscillations with initiation of reconnection. This leads to heating maintaining after the energy release peak and formation of a flat stage on the X-ray profile. We applied the time-distance plots and pixel wavelet filtration (PWF) methods to obtain spatio-temporal distribution of wave power variations in SDO/AIA data. To find magnetic waveguides, we used magnetic field extrapolation of SDO/HMI magnetograms. The propagation velocity of wave fronts was measured from their spatial locations at specific times. In correlation curves of the 17 GHz (NoRH) radio emission we found a monotonous energy amplification of 3-min waves in the sunspot umbra before the 2012 June 7 flare. This dynamics agrees with an increase in the wave-train length in coronal loops (SDO/AIA, 171 {\\AA}) reaching the maximum 30 minutes prior to the flare onset...

  10. Modelling repeatedly flaring delta-sunspots

    CERN Document Server

    Chatterjee, Piyali; Carlsson, Mats

    2016-01-01

    Active regions (AR) appearing on the surface of the Sun are classified into $\\alpha$, $\\beta$, $\\gamma$, and $\\delta$ by the rules of the Mount Wilson Observatory, California on the basis of their topological complexity. Amongst these, the $\\delta$-sunspots are known to be super-active and produce the most X-ray flares. Here, we present results from a simulation of the Sun by mimicking the upper layers and the corona, but starting at a more primitive stage than any earlier treatment. We find that this initial state consisting of only a thin sub-photospheric magnetic sheet breaks into multiple flux-tubes which evolve into a colliding-merging system of spots of opposite polarity upon surface emergence, similar to those often seen on the Sun. The simulation goes on to produce many exotic $\\delta$-sunspot associated phenomena: repeated flaring in the range of typical solar flare energy release and ejective helical flux ropes with embedded cool-dense plasma filaments resembling solar coronal mass ejections.

  11. Solar coronal magnetic fields derived using seismology techniques applied to omnipresent sunspot waves

    CERN Document Server

    Jess, D B; Ryans, R S I; Christian, D J; Keys, P H; Mathioudakis, M; Mackay, D H; Prasad, S Krishna; Banerjee, D; Grant, S D T; Yau, S; Diamond, C

    2016-01-01

    Sunspots on the surface of the Sun are the observational signatures of intense manifestations of tightly packed magnetic field lines, with near-vertical field strengths exceeding 6,000 G in extreme cases. It is well accepted that both the plasma density and the magnitude of the magnetic field strength decrease rapidly away from the solar surface, making high-cadence coronal measurements through traditional Zeeman and Hanle effects difficult since the observational signatures are fraught with low-amplitude signals that can become swamped with instrumental noise. Magneto-hydrodynamic (MHD) techniques have previously been applied to coronal structures, with single and spatially isolated magnetic field strengths estimated as 9-55 G. A drawback with previous MHD approaches is that they rely on particular wave modes alongside the detectability of harmonic overtones. Here we show, for the first time, how omnipresent magneto-acoustic waves, originating from within the underlying sunspot and propagating radially outwa...

  12. The sunspot cycle and ``auroral'' F layer irregularities

    Science.gov (United States)

    Aarons, J.; Kersley, L.; Rodger, A. S.

    The use of the word ``aurora'' for many different observations at high latitudes has limited the concepts involved; this is particularly true for F region irregularities. Observations setting the position of the auroral oval (Starkov and Fel'dshtein, 1970) were made using primarily the 555.7-nm green line, which is emitted predominantly at E layer heights. These observations have shown that the change in position of the auroral oval for low values of Kp as a function of sunspot cycle is of the order of 1° to 2° between sunspot maximum and sunspot minimum. However, irregularities in the F region show much larger solar cycle variations in the locations of the equatorward boundary, typically 10°. A review of scintillation data indicates that at a given auroral latitude, the scintillation activity increases with sunspot number. In addition, for a constant scintillation intensity, the equatorward boundary moves to lower latitudes as sunspot maximum is approached. We review existing spread F studies and show that for quiet geomagnetic conductions, there is lower occurrence during years of low sunspot numbers than during years of high sunspot numbers. However, the spread F index, related to Δ f/f0F2, is higher during years of low sunspot number than during years of high sunspot number. We demonstrate that this apparent dichotomy can be reconciled by using a new method of normalizing the spread F index by the maximum electron concentration of the F layer. We briefly discuss the possible explanations for the observed solar cycle variations of irregularity occurrence in terms of the absolute values and gradients of electron concentration and the E region conductivity.

  13. Area and Flux Distributions of Active Regions, Sunspot Groups, and Sunspots: A Multi-Database Study

    CERN Document Server

    Muñoz-Jaramillo, Andrés; Windmueller, John C; Amouzou, Ernest C; Longcope, Dana W; Tlatov, Andrey G; Nagovitsyn, Yury A; Pevtsov, Alexei A; Chapman, Gary A; Cookson, Angela M; Yeates, Anthony R; Watson, Fraser T; Balmaceda, Laura A; DeLuca, Edward E; Martens, Petrus C H

    2014-01-01

    In this work we take advantage of eleven different sunspot group, sunspot, and active region databases to characterize the area and flux distributions of photospheric magnetic structures. We find that, when taken separately, different databases are better fitted by different distributions (as has been reported previously in the literature). However, we find that all our databases can be reconciled by the simple application of a proportionality constant, and that, in reality, different databases are sampling different parts of a composite distribution. This composite distribution is made up by linear combination of Weibull and log-normal distributions -- where a pure Weibull (log-normal) characterizes the distribution of structures with fluxes below (above) $10^{21}$Mx ($10^{22}$Mx). Additionally, we demonstrate that the Weibull distribution shows the expected linear behaviour of a power-law distribution (when extended into smaller fluxes), making our results compatible with the results of Parnell et al.\\ (200...

  14. Improvement of the penumbra for small radiosurgical fields using flattening filter free low megavoltage beams

    Energy Technology Data Exchange (ETDEWEB)

    Yarahmadi, Mehran [Kurdistan Univ. of Medical Sciences, Sanandaj (Iran, Islamic Republic of); Allahverdi, Mahmoud; Nedaie, Hassan A.; Asnaashari, Khadijeh; Vaezzadeh, Sayed A. [Tehran Univ. of Medical Sciences, Tehran (Iran, Islamic Republic of); Sauer, Otto A. [Wuerzburg Univ. (Germany). Klinik und Poliklinik fuer Strahlentherapie

    2013-07-01

    Background: In stereotactic radiosurgery, sharp beam edges have clear advantages to spare normal tissues. In general, the dose gradient is a limiting factor in minimizing dose to nearby critical structures for clinical cases. Therefore the penumbral width should be diminished. Methods: A Varian Clinac 2100 linear accelerator equipped with in-house designed radiosurgical collimator was modeled using the EGSnrc/BEAMnrc Monte Carlo code and compared with the measurements. The 0.015 cm{sup 3} PinPoint chamber was used to measure the 6 MV photon beam characteristics and to validate Monte Carlo calculations. Additional to the standard (STD) linac, a flattening filter free (FFF) linac was simulated. Percent depth doses, beam profiles and output factors were calculated for small field sizes with diameter of 5, 10, 20 and 30 mm with DOSXYZnrc. The mean energy and photon fluence at the water surface were calculated with BEAMDP for both FFF linac and STD linacs. Results: The penumbra width (80%-20%) was decreased by 0.5, 0.3, 0.2 and 0.2 mm for field sizes of 5, 10, 20 and 30 mm respectively when removing the FF. The fluence of photons at the surface increased up to 3.6 times and the mean energy decreased by a factor of 0.69 when removing the FF. The penumbra width (80%-20%) decreased by 17% when a 2 MeV monoenergetic electron pencil beam incident on the target is used instead of 6.2 MeV. Conclusions: It was found that the penumbra of small field sizes is decreased by removing the FF. Likewise using low megavoltage photons reduced the beam penumbra maintaining adequate penetration and skin sparing. (orig.)

  15. Value of perfusion computed tomography in acute ischemic stroke: diagnosis of infarct core and penumbra.

    Science.gov (United States)

    Pan, Jiawei; Zhang, Jun; Huang, Weiyuan; Cheng, Xin; Ling, Yifeng; Dong, Qiang; Geng, Daoying

    2013-01-01

    This study aimed to perform an evaluation of 4 perfusion computed tomographic (PCT) parameters (relative cerebral blood flow, cerebral blood volume, mean transit time [MTT], and delay time [DT]) in a series of patients with acute ischemic stroke to find optimal parameters to predict infarct core and penumbra. Twenty-six patients with symptoms suggesting stroke less than 7 hours from onset were enrolled in this study. They all underwent admission and 24-hour PCT and a 24-hour diffusion-weighted imaging. Perfusion computed tomographic maps were assessed for relative reduced cerebral blood flow and cerebral blood volume and increased MTT and DT. Receiver operating characteristic curve analysis was performed to locate the optimal threshold for each parameter, using diffusion-weighted imaging as the gold standard. The PCT parameter that most accurately describes the penumbra is the relative MTT of 150% or greater (area under the curve, 0.827; 95% confidence interval, 0.826-0.827), whereas the parameter that most accurately describes the infarct core is the relative DT of + 2.0 seconds or greater (area under the curve, 0.879; 95% confidence interval, 0.878-0.879). The optimal parameters to define the infarct core and the penumbra are relative DT (≥+ 2.0 seconds) and relative MTT (≥ 150%).

  16. A Revised Collection of Sunspot Group Numbers

    CERN Document Server

    Vaquero, J M; Carrasco, V M S; Clette, F; Lefèvre, L; Gallego, M C; Arlt, R; Aparicio, A J P; Richard, J -G; Howe, R

    2016-01-01

    We describe a revised collection of the number of sunspot groups from 1610 to the present. This new collection is based on the work of Hoyt and Schatten (Solar Phys. 179, 189, 1998). The main changes are the elimination of a considerable number of observations during the Maunder Minimum (hereafter, MM) and the inclusion of several long series of observations. Numerous minor changes are also described. Moreover, we have calculated the active-day percentage during the MM from this new collection as a reliable index of the solar activity. Thus, the level of solar activity obtained in this work is greater than the level obtained using the original Hoyt and Schatten data, although it remains compatible with a grand minimum of solar activity. The new collection is available in digital format.

  17. Formation of Moving Magnetic Features and Penumbral Magnetic Fields with Hinode/SOT

    CERN Document Server

    Kubo, Masahito; Shimizu, Toshifumi; Tsuneta, Saku; Suematsu, Yoshinori; Katsukawa, Yukio; Nagata, Shin'ichi; Tarbell, Theodore D; Shine, Richard A; Title, Alan M; Frank, Zoe A; Lites, Bruce W; Elmore, David

    2007-01-01

    Vector magnetic fields of moving magnetic features (MMFs) are well observed with the Solar Optical Telescope (SOT) aboard the Hinode satellite. We focus on the evolution of three MMFs with the SOT in this study. We found that an MMF having relatively vertical fields with polarity same as the sunspot is detached from the penumbra around the granules appeared in the outer penumbra. This suggests that granular motions in the outer penumbra are responsible for the disintegration of the sunspot. Two MMFs with polarity opposite to the sunspot are located around the outer edge of horizontal fields extending from the penumbra. This is an evidence that the MMFs with polarity opposite to the sunspot are prolongation of penumbral horizontal fields. Radshifts larger than sonic velocity in the photosphere are detected for some of the MMFs with polarity opposite to the sunspot.

  18. Rapid Sunspot Displacement Associated with Solar Eruptions

    Science.gov (United States)

    Liu, Chang; Deng, N.; Wang, H.

    2010-05-01

    Many observational and modeling studies of solar eruptions merely treat photosphere as the lower boundary and assume no significant changes of magnetic fields anchoring there to occur during flares/CMEs. With increasing evidence of photospheric magnetic fields variations resulting from energy release in the upper atmosphere, Hudson, Fisher and Welsch (2008, ASP, 383, 221) proposed that the photosphere and even solar interior would respond in a back-reaction process to the coronal magnetic field restructuring. Inspired by this concept, we analyzed white-light images obtained with TRACE and report here rapid and permanent perturbation in the position of delta spot umbrae associated with five X-class flares. Our main results are the following: (1) The centroids of umbrae with opposite magnetic polarities undergo relative as well as overall displacement on the order of 1E3 km after flares/CMEs. (2) The estimated total kinetic energy associated with these motions (Ek) is on the order of 1E29 ergs and appears to correlate with the 6 mHZ seismic energy (Es) derived by the Monash group. (3) There appears correlation between both the Ek and Es corresponding to the velocity of CMEs. We suggest that: (1) sunspot displacement provides a direct observational evidence of the photospheric back-reaction and could potentially serve as an alternative excitation mechanism of seismic waves; (2) These could provide rational support to the back-reaction mechanism in the sense that its magnitude might be related to how violent the coronal magnetic field is disrupted. For selected events with good multiwavelength coverage, we also analyze in detail spatial as well as temporal relationship among the sunspot displacement, magnetic field changes, seismic sources, hard X-ray emissions, and overall flaring condition. This work is supported by NSF grants ATM 08-19662 and ATM 07-45744, and NASA grants NNX 08AQ90G, NNX 07AH78G, and NNX 08AQ32G.

  19. Theoretical modeling of propagation of magneto-acoustic waves in magnetic regions below sunspots

    CERN Document Server

    Khomenko, E; Collados, M; Parchevsky, K; Olshevsky, V

    2008-01-01

    We use 2D numerical simulations and eikonal approximation to study properties of magneto-acoustic gravity waves traveling below the solar surface through the magnetic structure of sunspots. We consider a series of magnetostatic models of sunspots of different magnetic field strengths, from the deep interior to the chromosphere. The purpose of these studies is to quantify the effect of the magnetic field on local helioseismology measurements. Waves are excited by a sub-photospheric source located in the region beta slightly larger than 1. Time-distance diagrams and travel times are calculated for various frequency intervals and compared to the non-magnetic case. The results confirm that the observed time-distance helioseismology signals in sunspot regions correspond to fast MHD waves. The slow MHD waves form a distinctly different pattern in the time-distance diagram, which has not been detected in observations. The numerical results are in good agreement with the solution in the short-wavelength (eikonal) app...

  20. Oscillatory Response of the Solar Chromosphere to a Strong Downflow above a Sunspot

    CERN Document Server

    Kwak, Hannah; Song, Donguk; Kim, Yeon-Han; Lim, Eun-Kyung; Madjarska, Maria S

    2016-01-01

    We report three-minute oscillations in the solar chromosphere driven by a strong downflow event in a sunspot. We used the Fast Imaging Solar Spectrograph of the 1.6 m New Solar Telescope and the Interface Region Imaging Spectrograph (IRIS). The strong downflow event is identified in the chromospheric and transition region lines above the sunspot umbra. After the event, oscillations occur at the same region. The amplitude of the Doppler velocity oscillations is 2 km/s, and gradually decreases with time. In addition, the period of the oscillations gradually increases from 2.7 minutes to 3.3 minutes. In the IRIS 1330 slit-jaw images, we identify a transient brightening near the footpoint of the downflow detected in the Ha+0.5A image. The characteristics of the downflowing material are consistent with those of sunspot plumes. Based on our findings, we suggest that the gravitationally stratified atmosphere came to oscillate with three minute period in response to the impulsive downflow event as was theoretically i...

  1. Oscillations Above Sunspots and Faculae: Height Stratification and Relation to Coronal Fan Structure

    CERN Document Server

    Kobanov, N I; Chelpanov, A A

    2014-01-01

    Oscillation properties in two sunspots and two facular regions are studied using Solar Dynamics Observatory (SDO) data and ground-based observations in the SiI 10827 and HeI 10830 lines. The aim is to study different-frequency spatial distribution characteristics above sunspots and faculae and their dependence on magnetic-field features and to detect the oscillations that reach the corona from the deep photosphere most effectively. We used Fast-Fourier-Transform and frequency filtration of the intensity and Doppler-velocity variations with Morlet wavelet to trace the wave propagating from the photosphere to the chromosphere and corona. Spatial distribution of low-frequency (1-2 mHz) oscillations outlines well the fan-loop structures in the corona (the Fe IX 171 line) above sunspots and faculae. High-frequency oscillations (5-7 mHz) are concentrated in fragments inside the photospheric umbra boundaries and close to facular-region centers. This implies that the upper parts of most coronal loops, which transfer ...

  2. Properties of sunspot umbrae observed in Cycle 24

    CERN Document Server

    Kiess, Christoph; Schmidt, Wolfgang

    2014-01-01

    We analyzed the size, intensity, and magnetic field strength of sunspot umbrae to compare the present cycle 24 with the previous one. We used data of the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory and selected all sunspots between May 2010 and October 2012, using one image per day. We created two subsets of this data with a manual tracking algorithm, both without duplication. One is containing each sunspot (910 umbrae within 488 spots) and was used to analyze the distribution of umbral areas, selected with an automated thresholding method. The other one contains 205 fully evolved sunspots. We find nonlinear relations between umbral minimum intensity and size and between maximum magnetic field strength and size. The field strength scales linear with the intensity and the umbral size scales roughly linear with the total magnetic flux, while the size and field strength level off with stronger flux. When separated in hemisphere and averaged temporally, the southern umbrae show a tempo...

  3. Flare forecasting based on sunspot-groups characteristics

    National Research Council Canada - National Science Library

    Contarino, Lidia; Zuccarello, Francesca; Romano, Paolo; Spadaro, Daniele; Guglielmino, Salvatore L; Battiato, Viviana

    2009-01-01

    ... accurate flare forecasting. In order to give a contribution to this aspect, we focused our attention on the characteristics that must be fulfilled by sunspot-groups in order to be flare-productive...

  4. Velocity fields in and around sunspots at the highest resolution

    CERN Document Server

    Denker, Carsten

    2010-01-01

    The flows in and around sunspots are rich in detail. Starting with the Evershed flow along low-lying flow channels, which are cospatial with the horizontal penumbral magnetic fields, Evershed clouds may continue this motion at the periphery of the sunspot as moving magnetic features in the sunspot moat. Besides these well-ordered flows, peculiar motions are found in complex sunspots, where they contribute to the build-up or relaxation of magnetic shear. In principle, the three-dimensional structure of these velocity fields can be captured. The line-of-sight component of the velocity vector is accessible with spectroscopic measurements, whereas local correlation or feature tracking techniques provide the means to assess horizontal proper motions. The next generation of ground-based solar telescopes will provide spectropolarimetric data resolving solar fine structure with sizes below 50 km. Thus, these new telescopes with advanced post-focus instruments act as a "zoom lens" to study the intricate surface flows ...

  5. Search for Possible Connections of Sunspot Features and Torsional Waves

    CERN Document Server

    Muraközy, J

    2014-01-01

    The torsional oscillation is a well established observational fact and there are theoretical attempts for its description but no final solution has yet been accepted. One of the possible candidates for its cause is the presence of sunspots modifying the streaming conditions. The present work focuses on the temporally varying latitudinal distribution of several sunspot features, such as the spot sizes and spot numbers. These features are different faces of the butterfly diagram. In fact some weak spatial correlations can be recognized.

  6. Long-term variations in sunspot magnetic field - area relation

    CERN Document Server

    Nagovitsyn, Yury A; Osipova, Aleksandra A

    2016-01-01

    Using observations of sunspot magnetic field strengths (H) from the Crimean Astrophysical Observatory (CrAO) and area (S) of sunspots from the Kislovodsk Mountain Astronomical Station of Pulkovo Observatory, we investigate the changes in the relation between H and S over the period of about two solar cycles (1994-2013). The data were fitted by H = A + B log S, where A = (778+/-46) and B = (778+/-25). We show that the correlation between H and S varies with the phase of solar cycle, and $A$ coefficient decreases significantly after year 2001, while B coefficient does not change significantly. Furthermore, our data confirm the presence of two distinct populations in distribution of sunspots (small sunspots with weaker field strength and large sunspots with stronger field). We show that relative contribution of each component to the distribution of sunspots by their area changes with the phase of solar cycle and on longer-then-cycle periods. We interpret these changes as a signature of a long-term (centennial) v...

  7. Long Term Sunspot Cycle Phase Coherence with Periodic Phase Disruptions

    CERN Document Server

    Pease, Gerald E

    2016-01-01

    In 1965 Paul D. Jose published his discovery that both the motion of the Sun about the center of mass of the solar system and periods comprised of eight Hale magnetic sunspot cycles with a mean period of ~22.375 years have a matching periodicity of ~179 years. We have investigated the implied link between solar barycentric torque cycles and sunspot cycles and have found that the unsigned solar torque values from 1610 to 2058 are consistently phase and magnitude coherent in ~179 year Jose Cycles. We are able to show that there is also a surprisingly high degree of sunspot cycle phase coherence for times of minima in addition to magnitude correlation of peaks between the nine Schwabe sunspot cycles of 1878 through 1976 (SC12 through SC20) and those of 1699 through 1797 (SC[-5] through SC4). We further identify subsequent subcycles of predominantly non-coherent sunspot cycle phase. In addition we have analyzed the empirical solar motion triggers of both sunspot cycle phase coherence and phase coherence disruptio...

  8. The association between sunspot magnetic fields and superpenumbral fibrils

    CERN Document Server

    Louis, Rohan E; Kuckein, Christoph; Gomory, Peter; Puschmann, Klaus G; Denker, Carsten

    2013-01-01

    Spectropolarimetric observations of a sunspot were carried out with the Tenerife Infrared Polarimeter at Observatorio del Teide, Tenerife, Spain. Maps of the physical parameters were obtained from an inversion of the Stokes profiles observed in the infrared Fe i line at 15648 angstrom. The regular sunspot consisted of a light bridge which separated the two umbral cores of the same polarity. One of the arms of the light bridge formed an extension of a penumbral filament which comprised weak and highly inclined magnetic fields. In addition, the Stokes V profiles in this filament had an opposite sign as the sunspot and some resembled Stokes Q or U. This penumbral filament terminated abruptly into another at the edge of the sunspot, where the latter was relatively vertical by about 30 degrees. Chromospheric H-alpha and He 304 angstrom filtergrams revealed three superpenumbral fibrils on the limb-side of the sunspot, in which one fibril extended into the sunspot and was oriented along the highly inclined penumbral...

  9. WIN55,212-2 protects oligodendrocyte precursor cells in stroke penumbra following permanent focal cerebral ischemia in rats

    Institute of Scientific and Technical Information of China (English)

    Jing SUN; Yin-quan FANG; Hong REN; Tao CHEN; Jing-jing GUO; Jun YAN; Shu SONG; Lu-yong ZHANG; Hong LIAO

    2013-01-01

    Aim:To explore whether the synthetic cannabinoid receptor agonist WIN55,212-2 could protect oligodendrocyte precursor cells (OPCs)in stroke penumbra,thereby providing neuroprotection following permanent focal cerebral ischemia in rats.Methods:Adult male SD rats were subjected to permanent middle cerebral artery occlusion (p-MCAO).The animals were administered WIN55,212-2 at 2 h,and sacrificed at 24 h after the ischemic insult.The infarct volumes and brain swelling were assessed.The expression of cannabinoid receptor type 1 (CB1) in the stroke penumbra was examined using Western blot assay.The pathological changes and proliferation of neural glial antigen 2-positive OPCs (NG2+ cells) in the stroke penumbra were studied using immunohistochemistry staining.Results:p-MCAO significantly increased the expression of CB1 within the stroke penumbra with the highest level appearing at 2 h following the ischemic insult.Administration of WIN55,212-2 (9 mg/kg,iv) significantly attenuated the brain swelling,and reduced the infarct volume as well as the number of tau-immunoreactive NG2+ cells (tau-1+/NG2+ cells) in the stroke penumbra.Moreover,WIN55,212-2 significantly promoted the proliferation of NG2+ cells in the stroke penumbra and in the ipsilateral subventricular zone at 24 h following the ischemic insult.Administration of the selective CB1 antagonist rimonabant (1 mg/kg,iv) partially blocked the effects caused by WIN55,212-2.Conclusion:Tau-1 is expressed in NG2+ cells following permanent focal cerebral ischemic injury.Treatment with WIN55,212-2 reduces the number of tau-1+/NG2+ cells and promotes NG2+ cell proliferation in the stroke penumbra,which are mediated partially via CB1 and may contribute to its neuroprotective effects.

  10. Multi-layer Study of Wave Propagation in Sunspots

    Science.gov (United States)

    Felipe, T.; Khomenko, E.; Collados, M.; Beck, C.

    2010-10-01

    We analyze the propagation of waves in sunspots from the photosphere to the chromosphere using time series of co-spatial Ca II H intensity spectra (including its line blends) and polarimetric spectra of Si I λ10,827 and the He I λ10,830 multiplet. From the Doppler shifts of these lines we retrieve the variation of the velocity along the line of sight at several heights. Phase spectra are used to obtain the relation between the oscillatory signals. Our analysis reveals standing waves at frequencies lower than 4 mHz and a continuous propagation of waves at higher frequencies, which steepen into shocks in the chromosphere when approaching the formation height of the Ca II H core. The observed nonlinearities are weaker in Ca II H than in He I lines. Our analysis suggests that the Ca II H core forms at a lower height than the He I λ10,830 line: a time delay of about 20 s is measured between the Doppler signal detected at both wavelengths. We fit a model of linear slow magnetoacoustic wave propagation in a stratified atmosphere with radiative losses according to Newton's cooling law to the phase spectra and derive the difference in the formation height of the spectral lines. We show that the linear model describes well the wave propagation up to the formation height of Ca II H, where nonlinearities start to become very important.

  11. Multi-layer study of wave propagation in sunspots

    CERN Document Server

    Felipe, T; Collados, M; Beck, C

    2010-01-01

    We analyze the propagation of waves in sunspots from the photosphere to the chromosphere using time series of co-spatial Ca II H intensity spectra (including its line blends) and polarimetric spectra of Si I 10827 and the He I 10830 multiplet. From the Doppler shifts of these lines we retrieve the variation of the velocity along the line-of-sight at several heights. Phase spectra are used to obtain the relation between the oscillatory signals. Our analysis reveals standing waves at frequencies lower than 4 mHz and a continuous propagation of waves at higher frequencies, which steepen into shocks in the chromosphere when approaching the formation height of the Ca II H core. The observed non-linearities are weaker in Ca II H than in He I lines. Our analysis suggests that the Ca II H core forms at a lower height than the He I 10830 line: a time delay of about 20 s is measured between the Doppler signal detected at both wavelengths. We fit a model of linear slow magnetoacoustic wave propagation in a stratified at...

  12. Skin Cancer, Irradiation, and Sunspots: The Solar Cycle Effect

    Directory of Open Access Journals (Sweden)

    Edward Valachovic

    2014-01-01

    Full Text Available Skin cancer is diagnosed in more than 2 million individuals annually in the United States. It is strongly associated with ultraviolet exposure, with melanoma risk doubling after five or more sunburns. Solar activity, characterized by features such as irradiance and sunspots, undergoes an 11-year solar cycle. This fingerprint frequency accounts for relatively small variation on Earth when compared to other uncorrelated time scales such as daily and seasonal cycles. Kolmogorov-Zurbenko filters, applied to the solar cycle and skin cancer data, separate the components of different time scales to detect weaker long term signals and investigate the relationships between long term trends. Analyses of crosscorrelations reveal epidemiologically consistent latencies between variables which can then be used for regression analysis to calculate a coefficient of influence. This method reveals that strong numerical associations, with correlations >0.5, exist between these small but distinct long term trends in the solar cycle and skin cancer. This improves modeling skin cancer trends on long time scales despite the stronger variation in other time scales and the destructive presence of noise.

  13. Endoplasmic reticulum stress-induced apoptosis in the penumbra aggravates secondary damage in rats with traumatic brain injur y

    Institute of Scientific and Technical Information of China (English)

    Guo-zhu Sun; Fen-fei Gao; Zong-mao Zhao; Hai Sun; Wei Xu; Li-wei Wu; Yong-chang He

    2016-01-01

    Neuronal apoptosis is mediated by intrinsic and extrinsic signaling pathways such as the membrane-mediated, mitochondrial, and endo-plasmic reticulum stress pathways. Few studies have examined the endoplasmic reticulum-mediated apoptosis pathway in the penumbra after traumatic brain injury, and it remains unclear whether endoplasmic reticulum stress can activate the caspase-12-dependent apoptotic pathway in the traumatic penumbra. Here, we established rat models of lfuid percussion-induced traumatic brain injury and found that protein expression of caspase-12, caspase-3 and the endoplasmic reticulum stress marker 78 kDa glucose-regulated protein increased in the traumatic penumbra 6 hours after injury and peaked at 24 hours. Furthermore, numbers of terminal deoxynucleotidyl transferase-mediat-ed dUTP nick end labeling-positive cells in the traumatic penumbra also reached peak levels 24 hours after injury. These ifndings suggest that caspase-12-mediated endoplasmic reticulum-related apoptosis is activated in the traumatic penumbra, and may play an important role in the pathophysiology of secondary brain injury.

  14. Origins of the Wolf Sunspot Number Series: Geomagnetic Underpinning

    Science.gov (United States)

    Cliver, E. W.; Svalgaard, L.

    2007-12-01

    The Wolf or International sunspot number (SSN) series is based on the work of Swiss astronomer Rudolf Wolf (1816-1893). Following the discovery of the sunspot cycle by Schwabe in 1843, Wolf culled sunspot counts from journals and observatory reports and combined them with his own observations to produce a SSN series that extended from 1700-1893. Thereafter the SSN record has been maintained by the Zurich Observatory and, since 1981, by the Royal Observatory of Belgium. The 1700-1893 SSN record constructed by Wolf has not been modified since his death. Here we show that Wolf's SSNs were not based solely on reports of sunspots but were calibrated by reference to geomagnetic range observations which closely track the sunspot number. Nor were these corrections small; for example Wolf multiplied the long series (1749-1796) of sunspot counts obtained by Staudacher by factors of 2.0 and 1.25, in turn, to obtain the numbers in use today. It is not surprising then that a competing SSN series obtained by Hoyt and Schatten based on group sunspot numbers is different, generally lower than that of Wolf. Comparison of the International number with current magnetic range observations indicates that, as Wolf found, the magnetic range (specifically, the average annual Y-component of mid-latitude stations) can be used as an independent check on the validity and stability of the SSN series. Moreover, the geomagnetic range series, which in itself is a long-term proxy of solar EUV emission, can be used to resolve discrepancies between the Wolf and Group SSN series during the 19th century.

  15. Independence, Intervention and Great Power Patronage: Kosovo, Georgia and the Contemporary Self-Determination Penumbra

    Directory of Open Access Journals (Sweden)

    Aidan Hehir

    2009-01-01

    Full Text Available This article contends that despite the increased currency of self-determination in contemporary international political debate the issue remains highly ambiguous and problematic. Two situation in 2008 - Kosovo’s declaration of independence and Russia’s recognition of South Ossetia and Abkhazia – brought this issue to the top of the international agenda and yet neither case has clarified the self-determination penumbra. The issue remains the preserve of political expediency rather than objective legal doctrine. This article assesses the evolution of independence Kosovo highlighting the highly contingent nature of this case and the conditional nature of Kosovo’s “independence”

  16. Investigation of a Sunspot Complex by Helioseismology

    CERN Document Server

    Kosovichev, A G

    2011-01-01

    Sunspot regions often form complexes of activity that may live for several solar rotations, and represent a major component of the Sun's magnetic activity. It had been suggested that the close appearance of active regions in space and time might be related to common subsurface roots, or "nests" of activity. EUV images show that the active regions are magnetically connected in the corona, but subsurface connections have not been established. We investigate the subsurface structure and dynamics of a large complex of activity, NOAA 10987-10989, observed during the SOHO/MDI Dynamics run in March-April 2008, which was a part of the Whole Heliospheric Interval (WHI) campaign. The active regions in this complex appeared in a narrow latitudinal range, probably representing a subsurface toroidal flux tube. We use the MDI full-disk Dopplergrams to measure perturbations of travel times of acoustic waves traveling to various depths by using time-distance helioseismology, and obtain sound-speed and flow maps by inversion ...

  17. What causes geomagnetic activity during sunspot minimum

    CERN Document Server

    Kirov, Boian; Georgieva, Katya; Obridko, Vladimir

    2014-01-01

    The average geomagnetic activity during sunspot minimum has been continuously decreasing in the last four cycles. The geomagnetic activity is caused by both interplanetary disturbances - coronal mass ejections and high speed solar wind streams, and the background solar wind over which these disturbances ride. We show that the geomagnetic activity in cycle minimum does not depend on the number and parameters of coronal mass ejections or high speed solar wind streams, but on the background solar wind. The background solar wind has two components: slower and faster. The source of the slower component is the heliospheric current sheet, and of the faster one the polar coronal holes. It is supposed that the geomagnetic activity in cycle minimum is determined by the thickness of the heliospheric current sheet which is related to the portions of time the Earth spends in slow and in fast solar wind. We demonstrate that it is also determined by the parameters of these two components of the background solar wind which v...

  18. Comparison of sunspot properties in cycles 23 and 24

    Science.gov (United States)

    Rezaei, Reza; Schmidt, Wolfgang; Beck, Christian

    Sunspots form by coalescence of small-scale magnetic elements and pores in magnetic flux emergence areas. By observing recently formed sunspots just after their initial growth and before substantial decay, one samples a magnetic signal which has been least disturbed by granulation. Properties of the emergence events have a direct impact on the results. Failed active regions, e.g. the ones which cannot form a sunspot, are a clear example: in several cases, they would harbor enough magnetic flux to form a small sunspot but fail to do so. Another way to evaluate secular variations of flux emergence events is to quantify long-term trends of sunspot properties. The 11-year solar magnetic activity cycle has been known for centuries. During this time the activity level changed dramatically from the Maunder minimum (1650-1700) to the Modern maximum in mid 20-th century. The extended minimum of the last solar cycle alerted solar physicist about possible long-term variation in the solar magnetic activity. While some argue that the Sun was unusually active in mid 20-th century, others find it unusually inactive now. This caused speculations whether the solar activity cycle is overlaid with a long-term decline that may lead to another grand minimum in the near future. Some extrapolations predicted that there will be no sunspots in the next cycle. Detailed observations of sunspot properties were performed only in the last few cycles. Such spectropolarimetric observations enable us to accurately derive the magnetic field strengths of spots and their physical properties. We present measurements of sunspot intensity, area, and magnetic field strength and compare the present cycle 24 with the previous one. We analyze a sample of about 400 sunspots observed from 1999 until 2014 with the Tenerife Infrared Polarimeter at the German Vacuum Tower Telescope as well as with the Facility Infrared Spectropolarimeter of the Dunn Solar Telescope of the NSO. The magnetic field strength is

  19. SOHO sees right through the Sun, and finds sunspots on the far side

    Science.gov (United States)

    2000-03-01

    The story is told today in the journal Science by Charles Lindsey of Tucson, Arizona, and Doug Braun of Boulder, Colorado. They realised that the analytical witchcraft called helioseismic holography might open a window right through the Sun. And the technique worked when they used it to decode waves seen on the visible surface by one of SOHO's instruments, the Michelson Doppler Imager, or MDI. "We've known for ten years that in theory we could make the Sun transparent all the way to the far side," said Charles Lindsey. "But we needed observations of exceptional quality. In the end we got them, from MDI on SOHO." For more than 100 years scientists have been aware that groups of dark sunspots on the Sun's visible face are often the scene of flares and other eruptions. Nowadays they watch the Sun more closely than ever, because modern systems are much more vulnerable to solar disturbances than old-style technology was. The experts can still be taken by surprise, because the Sun turns on its axis. A large group of previously hidden sunspots can suddenly swing into view on the eastern (left-hand) edge of the Sun. It may already be blazing away with menacing eruptions. With a far-side preview of sunspots, nasty shocks for the space weather forecasters may now be avoidable. Last year, French and Finnish scientists used SWAN, another instrument on SOHO, to detect activity on the far side. They saw an ultraviolet glow lighting up gas in the Solar System beyond the Sun, and moving across the sky like a lighthouse beam as the Sun rotated. The method used by Lindsey and Braun with MDI data is completely different, and it pinpoints the source of the activity on the far side. Solar seismology chalks up another success Detection of sound waves reverberating through the Sun opened its gassy interior for investigation, in much the same way as seismologists learned to explore the Earth's rocky interior with earthquake waves. Using special telescopes on the ground and in space

  20. Helioseismic holography of simulated sunspots: magnetic and thermal contributions to travel times

    CERN Document Server

    Felipe, T; Crouch, A D; Birch, A C

    2016-01-01

    Wave propagation through sunspots involves conversion between waves of acoustic and magnetic character. In addition, the thermal structure of sunspots is very different than that of the quiet Sun. As a consequence, the interpretation of local helioseismic measurements of sunspots has long been a challenge. With the aim of understanding these measurements, we carry out numerical simulations of wave propagation through sunspots. Helioseismic holography measurements made from the resulting simulated wavefields show qualitative agreement with observations of real sunspots. We use additional numerical experiments to determine, separately, the influence of the thermal structure of the sunspot and the direct effect of the sunspot magnetic field. We use the ray approximation to show that the travel-time shifts in the thermal (non-magnetic) sunspot model are primarily produced by changes in the wave path due to the Wilson depression rather than variations in the wave speed. This shows that inversions for the subsurfac...

  1. The Relative Phase Asynchronization between Sunspot Numbers and Polar Faculae

    Indian Academy of Sciences (India)

    L. H. Deng; J. Y. Song; Y. Y. Xiang; Y. K. Tang

    2011-09-01

    The monthly sunspot numbers compiled by Temmer et al. and the monthly polar faculae from observations of the National Astronomical Observatory of Japan, for the interval of March 1954 to March 1996, are used to investigate the phase relationship between polar faculae and sunspot activity for total solar disk and for both hemispheres in solar cycles 19, 20, 21 and 22. We found that (1) the polar faculae begin earlier than sunspot activity, and the phase difference exhibits a consistent behaviour for different hemispheres in each of the solar cycles, implying that this phenomenon should not be regarded as a stochastic fluctuation; (2) the inverse correlation between polar faculae and sunspot numbers is not only a long-term behaviour, but also exists in short time range; (3) the polar faculae show leads of about 50–71 months relative to sunspot numbers, and the phase difference between them varies with solar cycle; (4) the phase difference value in the northern hemisphere differs from that in the southern hemisphere in a solar cycle, which means that phase difference also existed between the two hemispheres. Moreover, the phase difference between the two hemispheres exhibits a periodical behaviour. Our results seem to support the finding of Hiremath (2010).

  2. Phase analysis of sunspot group numbers on both solar hemispheres

    Institute of Scientific and Technical Information of China (English)

    Lin-Hua Deng; Zhong-Quan Qu; Xiao-Li Yan; Kai-Rang Wang

    2013-01-01

    Cross-correlation analysis and wavelet transform methods are proposed to investigate the phase relationship between the monthly sunspot group numbers in the solar northern and southern hemispheres.It is found that (1) the monthly sunspot group numbers in the northern hemisphere begin two months earlier than those in the southern one,which should lead to phase asynchrony between them but with a slight effect; (2) the Schwabe cycle length for the monthly sunspot group numbers in the two hemispheres obviously differs from each other,and the mean Schwabe cycle length of the monthly sunspot group numbers in the northern hemisphere is slightly larger than that in the southern one; (3) the monthly sunspot group numbers in the northern hemisphere precede those in the southern hemisphere during the years of about 1874-1927,after which,the southern hemisphere leads the northern hemisphere in the years 1928-1964,and then the northern hemisphere leads in time till the present.

  3. The revised Brussels-Locarno Sunspot Number (1981-2015)

    CERN Document Server

    Clette, Frédéric; Cagnotti, Marco; Cortesi, Sergio; Bulling, Andreas

    2015-01-01

    In 1981, the production of the international Sunspot Number moved from the Z\\"{u}rich Observatory to the Royal Observatory of Belgium, marking a very important transition in the history of the Sunspot Number. Those recent decades are particularly important for linking recent modern solar indices and fluxes and the past Sunspot Number series. However, large variations have been recently identified in the scale of the Sunspot Number between 1981 and the present. Here, we reconstruct a new average Sunspot Number series $S_N$ using long-duration stations between 1981 and 2015. We also extend this reconstruction using long-time series from 35 stations over 1945-2015, which includes the 1981 transition. In both reconstructions, we also derive a parallel Group Number series $G_N$. Our results confirm the variable trends of the Locarno pilot station. We also verify the scale of the resulting 1981-2015 correction factor relative to the preceding period 1945--1980. By comparing the new $S_N$ and $G_N$ series, we find t...

  4. Sunspot latitudes during the Maunder Minimum: a machine-readable catalogue from previous studies

    OpenAIRE

    J. M. Vaquero; Nogales, J. M.; Sánchez-Bajo, F.

    2015-01-01

    The Maunder Minimum (1645-1715 approximately) was a period of very low solar activity and a strong hemispheric asymmetry, with most of sunspots in the southern hemisphere. In this paper, two data sets of sunspot latitudes during the Maunder minimum have been recovered for the international scientific community. The first data set is constituted by latitudes of sunspots appearing in the catalogue published by Gustav Sp\\"orer nearly 130 years ago. The second data set is based on the sunspot lat...

  5. A mismatch between the abnormalities in diffusion- and susceptibility-weighted magnetic resonance imaging may represent an acute ischemic penumbra with misery perfusion.

    Science.gov (United States)

    Fujioka, Masayuki; Okuchi, Kazuo; Iwamura, Asami; Taoka, Toshiaki; Siesjö, Bo K

    2013-11-01

    Susceptibility-weighted imaging (SWI) has recently attracted attention for its ability to investigate acute stroke pathophysiology. SWI detects an increased ratio of deoxyhemoglobin to oxyhemoglobin in cerebral venous compartments, which can illustrate cerebral misery perfusion with a compensatory increase of oxygen extraction fraction in the hypoperfused brain. In this study we make the first case report of blunt cervical trauma leading to a stroke, demonstrating the disparity between diffusion-weighted imaging (DWI) and SWI changes, or DWI-SWI mismatch, in the acute ischemic brain. The area of mismatch between a smaller DWI cytotoxic edema and a larger SWI misery perfusion in our patient matured into a complete infarction with time. The DWI-SWI mismatch may signify the presence of an ischemic penumbra, and provide information about viability of the brain tissue at risk of potential infarction if without early reperfusion.

  6. Development and morphology of leading-following parts of sunspot groups

    CERN Document Server

    Muraközy, J; Ludmány, A

    2014-01-01

    The detailed sunspot catalogues, the DPD and SDD allow to study the leading and following parts of sunspot groups separately. We examine the equilibrium distance of the two parts, the speed of removal, the asymmetry of compactness and the area growth. The distributions of positive and negative tilts of sunspot groups are also examined.

  7. The irregularities of the sunspot cycle and their theoretical modelling

    CERN Document Server

    Choudhuri, Arnab Rai

    2013-01-01

    The 11-year sunspot cycle has many irregularities, the most promi- nent amongst them being the grand minima when sunspots may not be seen for several cycles. After summarizing the relevant observational data about the irregularities, we introduce the flux transport dynamo model, the currently most successful theoretical model for explaining the 11-year sunspot cycle. Then we analyze the respective roles of nonlinearities and random fluctuations in creating the irregularities. We also discuss how it has recently been realized that the fluctuations in meridional circula- tion also can be a source of irregularities. We end by pointing out that fluctuations in the poloidal field generation and fluctuations in meridional circulation together can explain the occurrences of grand minima.

  8. Evershed clouds as precursors of moving magnetic features around sunspots

    CERN Document Server

    Solana, D C; Beck, C; Del Toro-Iniesta, Jose Carlos

    2006-01-01

    The relation between the Evershed flow and moving magnetic features (MMFs) is studied using high-cadence, simultaneous spectropolarimetric measurements of a sunspot in visible (630.2 nm) and near-infrared (1565 nm) lines. Doppler velocities, magnetograms, and total linear polarization maps are calculated from the observed Stokes profiles. We follow the temporal evolution of two Evershed clouds that move radially outward along the same penumbral filament. Eventually, the clouds cross the visible border of the spot and enter the moat region, where they become MMFs. The flux patch farther from the sunspot has the same polarity of the spot, while the MMF closer to it has opposite polarity and exhibits abnormal circular polarization profiles. Our results provide strong evidence that at least some MMFs are the continuation of the penumbral Evershed flow into the moat. This, in turn, suggests that MMFs are magnetically connected to sunspots.

  9. Signatures of running penumbral waves in sunspot photospheres

    CERN Document Server

    Löhner-Böttcher, Johannes

    2015-01-01

    The highly dynamic atmosphere above sunspots exhibits a wealth of magnetohydrodynamic (MHD) waves. Recent studies suggest a coupled nature of the most prominent phenomena: umbral flashes (UFs) and running penumbral waves (RPWs). From an observational point of view, we perform a height-dependent study of RPWs, compare their wave characteristics and aim to track down these so far only chromospherically observed phenomena to photospheric layers to prove the upward propagating field-guided nature of RPWs. We analyze a time series (58\\,min) of multi-wavelength observations of an isolated circular sunspot (NOAA11823) taken at high spatial and temporal resolution in spectroscopic mode with the Interferometric BIdimensional Spectro-polarimeter (IBIS/DST). By means of a multi-layer intensity sampling, velocity comparisons, wavelet power analysis and sectorial studies of time-slices, we retrieve the power distribution, characteristic periodicities and propagation characteristics of sunspot waves at photospheric and chr...

  10. Cycle dependence of the longitudinal-latitudinal sunspot motion correlations

    CERN Document Server

    Muraközy, J; 10.1051/0004-6361:20078456

    2010-01-01

    aims: It is well known that the azimuthal and meridional shifts of sunspots are correlated and that the correlation exhibits a latitudinal distribution, which is expected due to the Coriolis effect. We study the temporal behaviour of this latitudinal distribution. methods: We analyze the daily positions of sunspot groups, provided by the Debrecen Photoheliographic Data and the Greenwich Photoheliographic Results and correlation values, which were mapped in 5 deg latitudinal bins. The latitudinal distributions were examined for each year. results: We derive a sunspot-motion correlation that exhibits a Coriolis-type latitudinal distribution on long timescales, which are typical for the yearly distributions; at cycle maximum, however, unexpected distortions can occur. conclusions: The causes of the weakening of the Coriolis-pattern remain unclear. Possible relations of the phenomenon to the Gnevyshev-gap, the polarity reversal of the main magnetic field, and some mid-period fluctuations are discussed.

  11. Study of sunspot group morphological variations leading to flaring events

    CERN Document Server

    Korsos, M B; Ludmany, A

    2014-01-01

    It is widely assumed that the most probable sites of flare occurrences are the locations of high horizontal magnetic field gradients in the active regions. Instead of magnetograms the present work checks this assumption by using sunspot data, the targeted phenomenon is the pre-flare behaviour of the strong horizontal gradients of the magnetic field at the location of the flare. The empirical basis of the work is the SDD (SOHO/MDI-Debrecen sunspot Data) sunspot catalogue. Case studies of two active regions and five X-flares have been carried out to find possible candidates for pre-flare signatures. It has been found that the following properties of the temporal variations of horizontal magnetic field gradient are promising for flare forecast: the speed of its growth, its maximal value, its decrease after the maximum until the flare and the rate of its fluctuation.

  12. Three-dimensional structure of a sunspot light bridge

    CERN Document Server

    Felipe, T; Khomenko, E; Kuckein, C; Ramos, A Asensio; Balthasar, H; Berkefeld, T; Denker, C; Feller, A; Franz, M; Hofmann, A; Kiess, C; Lagg, A; Nicklas, H; Suárez, D Orozco; Yabar, A Pastor; Rezaei, R; Schlichenmaier, R; Schmidt, D; Schmidt, W; Sigwarth, M; Sobotka, M; Solanki, S K; Soltau, D; Staude, J; Strassmeier, K G; Volkmer, R; von der Lühe, O; Waldmann, T

    2016-01-01

    Active regions are the most prominent manifestations of solar magnetic fields; their generation and dissipation are fundamental problems in solar physics. Light bridges are commonly present during sunspot decay, but a comprehensive picture of their role in the removal of photospheric magnetic field is still missing. We study the three dimensional configuration of a sunspot and in particular its light bridge during one of the last stages of its decay. We present the magnetic and thermodynamical stratification inferred from full Stokes inversions of the photospheric Si I 10827 \\AA\\ and Ca I 10839 \\AA\\ lines obtained with the GREGOR Infrared Spectrograph of the GREGOR telescope at Observatorio del Teide, Tenerife, Spain. The analysis is complemented by a study of continuum images covering the disk passage of the active region, which are provided by the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory. The sunspot shows a light bridge with penumbral continuum intensity that separates the c...

  13. The Revised Brussels-Locarno Sunspot Number (1981 - 2015)

    Science.gov (United States)

    Clette, Frédéric; Lefèvre, Laure; Cagnotti, Marco; Cortesi, Sergio; Bulling, Andreas

    2016-04-01

    In 1981, the production of the international sunspot number moved from the Zürich Observatory to the Royal Observatory of Belgium, with a new pilot station: the Specola Solare Ticinese Observatory in Locarno, Switzerland. This marked a profound transition in the history of the sunspot number. Those recent decades are particularly important as they provide the link between recent modern solar indices and the entire sunspot-number series extending back to the eighteenth century. However, large variations have recently been identified in the scale of the sunspot number during this recent time period. Here, we refine the determination of those recent inhomogeneities by reconstructing a new average sunspot-number series [ SN] from a subset of long-duration stations between 1981 and 2015. We also extend this reconstruction by gathering long time series from 35 stations over 1945 - 2015, thus straddling the critical 1981 transition. In both reconstructions, we also derive a parallel group number series [ GN] built by the same method from exactly the same data set. Our results confirm the variable trends associated with drifts of the Locarno pilot station, which start only in 1983. They lead to a fully uniform SN-series over the entire 1945 - 2015 interval. By comparing the new SN- and GN-series, we find that a constant quadratic relation exists between those two indices over Cycles 19 to 23. Comparisons with a few other solar indices additionally validate this and reveal some possible undetected problems in those series. Using this new reference SN, we find that observing stations are surprisingly grouped among distinct subsets that share similar personal k-scaling coefficients. These various results also open the way to implementing a more advanced method for producing the sunspot number in the future.

  14. The Revised Brussels-Locarno Sunspot Number (1981 - 2015)

    Science.gov (United States)

    Clette, Frédéric; Lefèvre, Laure; Cagnotti, Marco; Cortesi, Sergio; Bulling, Andreas

    2016-11-01

    In 1981, the production of the international sunspot number moved from the Zürich Observatory to the Royal Observatory of Belgium, with a new pilot station: the Specola Solare Ticinese Observatory in Locarno, Switzerland. This marked a profound transition in the history of the sunspot number. Those recent decades are particularly important as they provide the link between recent modern solar indices and the entire sunspot-number series extending back to the eighteenth century. However, large variations have recently been identified in the scale of the sunspot number during this recent time period. Here, we refine the determination of those recent inhomogeneities by reconstructing a new average sunspot-number series [SN] from a subset of long-duration stations between 1981 and 2015. We also extend this reconstruction by gathering long time series from 35 stations over 1945 - 2015, thus straddling the critical 1981 transition. In both reconstructions, we also derive a parallel group number series [GN] built by the same method from exactly the same data set. Our results confirm the variable trends associated with drifts of the Locarno pilot station, which start only in 1983. They lead to a fully uniform SN-series over the entire 1945 - 2015 interval. By comparing the new SN- and GN-series, we find that a constant quadratic relation exists between those two indices over Cycles 19 to 23. Comparisons with a few other solar indices additionally validate this and reveal some possible undetected problems in those series. Using this new reference SN, we find that observing stations are surprisingly grouped among distinct subsets that share similar personal k-scaling coefficients. These various results also open the way to implementing a more advanced method for producing the sunspot number in the future.

  15. A new look at sunspot formation using theory and observations

    Science.gov (United States)

    Losada, I. R.; Warnecke, J.; Glogowski, K.; Roth, M.; Brandenburg, A.; Kleeorin, N.; Rogachevskii, I.

    2017-10-01

    Sunspots are of basic interest in the study of the Sun. Their relevance ranges from them being an activity indicator of magnetic fields to being the place where coronal mass ejections and flares erupt. They are therefore also an important ingredient of space weather. Their formation, however, is still an unresolved problem in solar physics. Observations utilize just 2D surface information near the spot, but it is debatable how to infer deep structures and properties from local helioseismology. For a long time, it was believed that flux tubes rising from the bottom of the convection zone are the origin of the bipolar sunspot structure seen on the solar surface. However, this theory has been challenged, in particular recently by new surface observation, helioseismic inversions, and numerical models of convective dynamos. In this article we discuss another theoretical approach to the formation of sunspots: the negative effective magnetic pressure instability. This is a large-scale instability, in which the total (kinetic plus magnetic) turbulent pressure can be suppressed in the presence of a weak large-scale magnetic field, leading to a converging downflow, which eventually concentrates the magnetic field within it. Numerical simulations of forced stratified turbulence have been able to produce strong super-equipartition flux concentrations, similar to sunspots at the solar surface. In this framework, sunspots would only form close to the surface due to the instability constraints on stratification and rotation. Additionally, we present some ideas from local helioseismology, where we plan to use the Hankel analysis to study the pre-emergence phase of a sunspot and to constrain its deep structure and formation mechanism.

  16. Normalization of sunspot cycles and eigen mode analysis

    Institute of Scientific and Technical Information of China (English)

    徐文耀

    2002-01-01

    The smoothed monthly sunspot numbers of the previous 22 complete sunspot cycles are normalized in time domain, and then an eigen mode analysis is carried out to draw the principle factors (or components) in the cycles. The results show that the main characteristics of the solar cycles can be described fairly well by the first 5 eigen modes. The obtained eigen modes are used to predict the declining phase of cycle 23 on the basis of the data prior to its maximum. The prediction indicates that cycle 23 will last for 127 months to December 2006, with the minimum of 6.2.

  17. Is solar neutrino capture rate correlated with sunspot number?

    Science.gov (United States)

    Bahcall, J. N.; Field, G. B.; Press, W. H.

    1987-01-01

    The statistical significance of the apparent correlation between sunspots and the observed neutrino rate is quantified. It is shown that the correlation depends almost entirely upon four low neutrino capture rates near the beginning of 1980. A calculation based on standard electroweak theory and neutrino production processes demonstrates that a correlation, if real, would be extremely puzzling on energetic grounds alone. It is concluded that measurements with the Cl-37 detector during the next sunspot cycle will be needed to show that there is a physical correlation, since the existing data are not statistically significant at a definitive level.

  18. Creating a sunspot database at the Solar Observatory of Ica National University in Perú

    Science.gov (United States)

    Martínez-Meneses, Lurdes

    2012-07-01

    We describe the database and the method used to analyze the sunspot data recorded at the Solar Observatory of the University of Ica in Peru. The parameters that are measured include the relative sunspot number (R), the sunspot area, their positions on the disk, and an estimate of the constant (k) included in R. Sunspots in the database are classified following the Zurich Classification System. From these observations, the active region area, the sunspot rotation speed, and other active regions properties can be estimated.

  19. Helioseismic Holography of Simulated Sunspots: Magnetic and Thermal Contributions to Travel Times

    Science.gov (United States)

    Felipe, T.; Braun, D. C.; Crouch, A. D.; Birch, A. C.

    2016-10-01

    Wave propagation through sunspots involves conversion between waves of acoustic and magnetic character. In addition, the thermal structure of sunspots is very different than that of the quiet Sun. As a consequence, the interpretation of local helioseismic measurements of sunspots has long been a challenge. With the aim of understanding these measurements, we carry out numerical simulations of wave propagation through sunspots. Helioseismic holography measurements made from the resulting simulated wavefields show qualitative agreement with observations of real sunspots. We use additional numerical experiments to determine, separately, the influence of the thermal structure of the sunspot and the direct effect of the sunspot magnetic field. We use the ray approximation to show that the travel-time shifts in the thermal (non-magnetic) sunspot model are primarily produced by changes in the wave path due to the Wilson depression rather than variations in the wave speed. This shows that inversions for the subsurface structure of sunspots must account for local changes in the density. In some ranges of horizontal phase speed and frequency there is agreement (within the noise level in the simulations) between the travel times measured in the full magnetic sunspot model and the thermal model. If this conclusion proves to be robust for a wide range of models, it would suggest a path toward inversions for sunspot structure.

  20. VizieR Online Data Catalog: Sunspot areas and tilt angles (Senthamizh Pavai+, 2015)

    Science.gov (United States)

    Senthamizh Pavai, V.; Arlt, R.; Dasi-Espuig, M.; Krivova, N.; Solanki, S.

    2015-11-01

    We present sunspot positions and areas from historical observations of sunspots by Samuel Heinrich Schwabe from Dessau, Germany. He has recorded his observations of sunspots from 1825-1867 as drawings in small circles of about 5cm diameter (representing the solar disk). Even though he has used quite a number of telescopes for his observations, the majority of the full-disk drawings were made with a 3-1/2-foot telescope from Fraunhofer. His observing log books are stored in the library of the Royal Astronomical Society in London. Those drawings were digitized photographically with a resolution of 2912x4378 pixels per page. The sizes and positions of the sunspots were measured using a dozen of circular mouse cursor shapes with different diameters. The sunspot sizes in Schwabe's drawings are not to scale and need to be converted into physical sunspot areas. We employed a statistical approach assuming that the area distribution of sunspots was the same in the 19th century as it was in the 20th century. Umbral areas for about 130,000 sunspots observed by Schwabe were obtained, as well as the tilt angles of sunspot groups assuming them to be bipolar (two or more spots). There is, of course, no polarity information in the observations. Both an updated sunspot database and a tilt angle database are available at http://www.aip.de/Members/rarlt/ sunspots for further study. (2 data files).

  1. Numerical Simulation of Excitation and Propagation of Helioseismic MHD Waves in Magnetostatic Models of Sunspots

    CERN Document Server

    Parchevsky, K; Khomenko, E; Olshevsky, V; Collados, M

    2010-01-01

    We present comparison of numerical simulations of propagation of MHD waves,excited by subphotospheric perturbations, in two different ("deep" and "shallow") magnetostatic models of the sunspots. The "deep" sunspot model distorts both the shape of the wavefront and its amplitude stronger than the "shallow" model. For both sunspot models, the surface gravity waves (f-mode) are affected by the sunspots stronger than the acoustic p-modes. The wave amplitude inside the sunspot depends on the photospheric strength of the magnetic field and the distance of the source from the sunspot axis. For the source located at 9 Mm from the center of the sunspot, the wave amplitude increases when the wavefront passes through the central part of the sunspot. For the source distance of 12 Mm, the wave amplitude inside the sunspot is always smaller than outside. For the same source distance from the sunspot center but for the models with different strength of the magnetic field, the wave amplitude inside the sunspot increases with...

  2. VizieR Online Data Catalog: Scheiner drawing sunspot areas and tilt angles (Arlt+, 2016)

    Science.gov (United States)

    Arlt, R.; Senthamizh Pavai, V.; Schmiel, C.; Spada, F.

    2016-09-01

    Christoph Scheiner and his collaborators observed the sunspots from 1611-1631 at five different locations of Rome in Italy, Ingolstadt in Germany, Douai (Duacum in Latin) in France, Freiburg im Breisgau, Germany and Vienna, Austria. However, most of his published drawings were made in Rome. These sunspot drawings are important because they can tell us how the solar activity declined to a very low-activity phase which lasted for nearly five decades. The three sources used for the sunspot data extraction are Scheiner (1630rour.book.....S, Rosa Ursina sive solis), Scheiner (1651ppsm.book.....S, Prodromus pro sole mobili et terra stabili contra Academicum Florentinum Galilaeum a Galilaeis), and Reeves & Van Helden (2010, On sunspots. Galileo Galilei and Christoph Scheiner (University of Chicago Press)). The suspot drawings show the sunspot groups traversing the solar disk in a single full-disk drawing. The positions and areas of the sunspots were measured using 13 circular cursor shapes with different diameters. Umbral areas for 8167 sunspots and tilt angles for 697 manually selected, supposedly bipolar groups were obtained from Scheiner's sunspot drawings. The database does not contain spotless days. There is, of course, no polarity information in the sunspot drawings, so the tilt angles are actually pseudo-tilt angles. Both an updated sunspot database and a tilt angle database may be available at http://www.aip.de/Members/rarlt/sunspots for further study. (2 data files).

  3. A Normalized Sunspot-Area Series Starting in 1832: an Update

    CERN Document Server

    Carrasco, V M S; Gallego, M C; Sánchez-Bajo, F

    2016-01-01

    A new normalized sunspot-area series has been reconstructed from the series obtained by the Royal Greenwich Observatory and other contemporary institutions for the period 1874 - 2008 and the area series compiled by De la Rue, Stewart, and Loewy from 1832 to 1868. Since the two sets of series do not overlap in time, we used as a link between them the new version of sunspot index number (Version 2) published by SILSO (Sunspot Index and Long-term Solar Observations). We also present a spectral analysis of the normalized area series in search of periodicities beyond the well-known solar cycle of 11 years and a study of the Waldmeier effect in the new version of sunspot-number and the sunspot-area series presented in this study. We conclude that while this effect is significant in the new series of sunspot number, it has a weak relationship with the sunspot-area series.

  4. On the formation of a stable penumbra in a region of flux emergence in the Sun

    CERN Document Server

    Murabito, M; Guglielmino, S L; Zuccarello, F

    2016-01-01

    We studied the formation of the first penumbral sector around a pore in the following polarity of the Active Region (AR) NOAA 11490. We used a high spatial, spectral, and temporal resolution data set acquired by the Interferometric BIdimensional Spectrometer operating at the NSO/Dunn Solar Telescope as well as data taken by the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory satellite. On the side towards the leading polarity, elongated granules in the photosphere and an arch filament system (AFS) in the chromosphere are present, while the magnetic field shows a sea-serpent configuration, indicating a region of magnetic flux emergence. We found that the formation of a stable penumbra in the following polarity of the AR begins in the area facing the opposite polarity located below the AFS in the flux emergence region, differently from what found by Schlichenmaier and colleaguestbf. Moreover, during the formation of the first penumbral sector, the area characterized by magnetic flux dens...

  5. Sunspot Groups as Tracers of Sub-Surface Processes

    Indian Academy of Sciences (India)

    Μ. Η. Gokhale

    2000-09-01

    Data on sunspot groups have been quite useful for obtaining clues to several processes on global and local scales within the sun which lead to emergence of toroidal magnetic flux above the sun's surface. I present here a report on such studies carried out at Indian Institute of Astrophysics during the last decade or so.

  6. In-depth survey of sunspot and active region catalogs

    Science.gov (United States)

    Lefèvre, Laure; Clette, Frédéric; Baranyi, Tunde

    2011-08-01

    When consulting detailed photospheric catalogs for solar activity studies spanning long time intervals, solar physicists face multiple limitations in the existing catalogs: finite or fragmented time coverage, limited time overlap between catalogs and even more importantly, a mismatch in contents and conventions. In view of a study of new sunspot-based activity indices, we have conducted a comprehensive survey of existing catalogs. In a first approach, we illustrate how the information from parallel catalogs can be merged to form a much more comprehensive record of sunspot groups. For this, we use the unique Debrecen Photoheliographic Data (DPD), which is already a composite of several ground observatories and SOHO data, and the USAF/Mount Wilson catalog from the Solar Optical Observing Network (SOON). We also describe our semi-interactive cross-identification method, which was needed to match the non-overlapping solar active region nomenclature, the most critical and subtle step when working with multiple catalogs. This effort, focused here first on the last two solar cycles, should lead to a better central database collecting all available sunspot group parameters to address future solar cycle studies beyond the traditional sunspot index time series Ri.

  7. Prediction of Sunspot Cycles by Data Assimilation Method

    CERN Document Server

    Kitiashvili, I N

    2008-01-01

    Despite the known general properties of the solar cycles, a reliable the forecast of the 11-year sunspot number variations is still a problem. The difficulties are caused by the apparent chaotic behavior of the sunspot numbers from cycle to cycle and by the influence of variations of turbulent dynamo processes, which are far from understanding. For predicting the solar cycle properties we make an initial attempt to use the Ensemble Kalman Filter (EnKF), a data assimilation method, which takes into account uncertainties of a dynamo model and measurements, and allows to estimate future observational data. We present the results of forecasting the solar cycles obtained by the EnKF method in application to a low-mode nonlinear dynamical system, modeling the solar alpha-Omega dynamo process with variable magnetic helicity. Calculations of the predictions for previous sunspot cycles show good agreement (with error 10%) with actual data. This forecast model predicts that the next sunspot cycle will be significant by...

  8. Sunspot Cycle 24: Smallest Cycle in 100 Years?

    Science.gov (United States)

    2005-01-11

    and H. B. Hathaway, D. H., R. M. Wilson, and E. J. Reichmann (1994), The shape of Snodgrass (1988), The extended solar activity cycle, Nature, 333...748, the sunspot cycle, Sol. Phys., 151, 177. doi:10.1038/333748a0. Hathaway, D. H., R. M. Wilson, and E. J. Reichmann (2002), Group sun- spot numbers

  9. Tests of Sunspot Number Sequences: 1. Using Ionosonde Data

    CERN Document Server

    Lockwood, M; Owens, M J; Barnard, L; Willis, D M

    2016-01-01

    More than 70 years ago it was recognised that ionospheric F2-layer critical frequencies $foF2$ had a strong relationship to sunspot number. Using historic datasets from the Slough and Washington ionosondes, we evaluate the best statistical fits of $foF2$ to sunspot numbers (at each Universal Time [UT] separately) in order to search for drifts and abrupt changes in the fit residuals over Solar Cycles 17 - 21. Polynomial fits are made both with and without allowance for the white-light facular area, which has been reported as being associated with cycle-to-cycle changes in the sunspot number - $foF2$ relationship. Over the interval studied here, the ISN, $R$, the backbone group number $Rbb$, and the corrected number $Rc$ largely differ in their allowance for the 'Waldmeier discontinuity' around 1945 (the correction factor for which for $R$, $Rbb$ and $Rc$ is, respectively, zero, effectively over 20%, and explicitly 11.6%). It is shown that for Solar Cycles 18 - 21, all three sunspot data sequences perform well,...

  10. A solar eruption driven by rapid sunspot rotation

    CERN Document Server

    Ruan, Guiping; Wang, Shuo; Zhang, Hongqi; Li, Gang; Jing, Ju; Su, Jiangtao; Li, Xing; Xu, Haiqing; Du, Guohui; Wang, Haimin

    2014-01-01

    We present the observation of a major solar eruption that is associated with fast sunspot rotation. The event includes a sigmoidal filament eruption, a coronal mass ejection, and a GOES X2.1 flare from NOAA active region 11283. The filament and some overlying arcades were partially rooted in a sunspot. The sunspot rotated at $\\sim$10$^\\circ$ per hour rate during a period of 6 hours prior to the eruption. In this period, the filament was found to rise gradually along with the sunspot rotation. Based on the HMI observation, for an area along the polarity inversion line underneath the filament, we found gradual pre-eruption decreases of both the mean strength of the photospheric horizontal field ($B_h$) and the mean inclination angle between the vector magnetic field and the local radial (or vertical) direction. These observations are consistent with the pre-eruption gradual rising of the filament-associated magnetic structure. In addition, according to the Non-Linear Force-Free-Field reconstruction of the coron...

  11. Sunspot rotation. I. A consequence of flux emergence

    CERN Document Server

    Sturrock, Z; Archontis, V; McNeill, C M

    2015-01-01

    Context. Solar eruptions and high flare activity often accompany the rapid rotation of sunspots. The study of sunspot rotation and the mechanisms driving this motion are therefore key to our understanding of how the solar atmosphere attains the conditions necessary for large energy release. Aims. We aim to demonstrate and investigate the rotation of sunspots in a 3D numerical experiment of the emergence of a magnetic flux tube as it rises through the solar interior and emerges into the atmosphere. Furthermore, we seek to show that the sub-photospheric twist stored in the interior is injected into the solar atmosphere by means of a definitive rotation of the sunspots. Methods. A numerical experiment is performed to solve the 3D resistive magnetohydrodynamic (MHD) equations using a Lagrangian-Remap code. We track the emergence of a toroidal flux tube as it rises through the solar interior and emerges into the atmosphere investigating various quantities related to both the magnetic field and plasma. Results. Thr...

  12. Improved SOT (Hinode mission) high resolution solar imaging observations: 2—Photometric properties of sunspot umbral dots

    Science.gov (United States)

    Goodarzi, H.; Koutchmy, S.; Adjabshirizadeh, A.

    2016-11-01

    The origin and evolution of solar sunspots in deep photospheric layers are not yet well understood. The case of a quasi-symmetric single mature sunspot near the solar centre is selected for analysis. We use the best available observations of the partial Sun free of turbulent Earth atmospheric effects from the Solar Optical Telescope (SOT) onboard the Hinode spacecraft, after greatly improving the resolution with an optimum Max-likelihood deconvolution with the Point Spread Function (PSF) deduced in a preceding paper. For several different images both the smearing due to the instrumental diffraction effects (PSF core) and the large angle stray light are removed. The selected iterative processing depends on both the signal/noise ratio and on the desired contrast of the ultimate details under examination. The photometric properties of bright umbral dots (BUDs) are deduced from corrected frames. Calibrated isophote maps are provided to show the intensity variations around each UD across the background umbra and the surrounding photospheric field, including the penumbra. We deduce the typical photometrical properties of bright UDs that populate the whole umbral surface down to sub-pixel scales of 0.05448''. The analysis demonstrates the basic heterogeneous nature of the umbra, similar to a network of minute bright and dark round or elongated cells with a spacing of order of 0.35''. For the first time a complete and detailed map of the color index and temperature deduced from the analysis of deeply corrected continuum images is provided, showing that tiny bright UDs can reach photospheric temperatures and even higher for the peripheral BUDs. In the umbra, there are some very dark small regions with temperatures as low as 3100 K. Close links seemingly exist with bright UDs. Central BUDs and peripheral BUDs are found to have similar properties but significantly different contrast values. Photometric analysis shows a large dispersion that reflects the broad range of

  13. IRIS Observation of a Sunspot and the Surrounding Plage Region

    Science.gov (United States)

    TIAN, H.; DeLuca, E. E.; Mcintosh, S. W.; Reeves, K. K.; McKillop, S.; Weber, M.; Saar, S.; Golub, L.; Testa, P.

    2013-12-01

    NASA's IRIS mission is providing high-cadence and high-resolution observations of the solar transition region and chromosphere. We present preliminary results from IRIS observation of a sunspot and the surrounding plage region. The major findings in this observation can be summarized as following: (1) The slit jaw images in the filters of 1400Å and 1330Å reveal the presence of many rapidly evolving fibril-like structures in the transition region for the first time. These thin and long structures mainly reside in the plage region. They could be strands of low-lying cool transition region loops or the transition region counterpart of chromospheric spicules. (2) The C II and Mg II line profiles are almost Gaussian in the sunspot umbra and clearly exhibit a deep reversal at the line center in the plage region, suggesting a greatly reduced opacity in the sunspot atmosphere. (3) Bidirectional jets are frequently occurring mainly in the plage region immediately outside the sunspot throughout the observation. Triple or double Gaussian fit to the line profiles of Si IV suggests a velocity as high as 100 km/s. These velocity values are of the same order of the Alfven speed in the transition region. (4)Three-minute oscillation is clearly present in the sunspot umbra. The oscillation is identified in not only the slit jaw images of 2796Å, 1400Å and 1330Å, but also in spectra of the bright Mg II, C II and Si IV lines. Strong non-linearity is clearly seen in the intensity and Doppler shift oscillations. Interestingly, the obvious increase of the line width only occurs at the times of largest blue shift. The correlated change of the intensity and Doppler shift suggests an upward propagating magneto-acoustic shock wave.

  14. Scattering Matrix for the Interaction between Solar Acoustic Waves and Sunspots. I. Measurements

    Science.gov (United States)

    Yang, Ming-Hsu; Chou, Dean-Yi; Zhao, Hui

    2017-01-01

    Assessing the interaction between solar acoustic waves and sunspots is a scattering problem. The scattering matrix elements are the most commonly used measured quantities to describe scattering problems. We use the wavefunctions of scattered waves of NOAAs 11084 and 11092 measured in the previous study to compute the scattering matrix elements, with plane waves as the basis. The measured scattered wavefunction is from the incident wave of radial order n to the wave of another radial order n‧, for n=0{--}5. For a time-independent sunspot, there is no mode mixing between different frequencies. An incident mode is scattered into various modes with different wavenumbers but the same frequency. Working in the frequency domain, we have the individual incident plane-wave mode, which is scattered into various plane-wave modes with the same frequency. This allows us to compute the scattering matrix element between two plane-wave modes for each frequency. Each scattering matrix element is a complex number, representing the transition from the incident mode to another mode. The amplitudes of diagonal elements are larger than those of the off-diagonal elements. The amplitude and phase of the off-diagonal elements are detectable only for n-1≤slant n\\prime ≤slant n+1 and -3{{Δ }}k≤slant δ {k}x≤slant 3{{Δ }}k, where δ {k}x is the change in the transverse component of the wavenumber and Δk = 0.035 rad Mm‑1.

  15. On signal-noise decomposition of timeseries using the continuous wavelet transform Application to sunspot index

    CERN Document Server

    Polygiannakis, J; Moussas, X

    2003-01-01

    We show that the continuous wavelet transform can provide a unique decomposition of a timeseries in to 'signal-like' and 'noise-like' components: From the overall wavelet spectrum two mutually independent skeleton spectra can be extracted, allowing the separate detection and monitoring in even non-stationary timeseries of the evolution of (a) both stable but also transient, evolving periodicities, such as the output of low dimensional dynamical systems and (b) scale-invariant structures, such as discontinuities, self-similar structures or noise. An indicative application to the monthly-averaged sunspot index reveals, apart from the well-known 11-year periodicity, 3 of its harmonics, the 2-year periodicity (quasi-biennial oscillation, QBO) and several more (some of which detected previously in various solar, earth-solar connection and climate indices), here proposed being just harmonics of the QBO, in all supporting the double-cycle solar magnetic dynamo model (Benevolenskaya, 1998, 2000). The scale maximal sp...

  16. Identification of possible intense historical geomagnetic storms using combined sunspot and auroral observations from East Asia

    Directory of Open Access Journals (Sweden)

    D. M. Willis

    2005-03-01

    Full Text Available Comprehensive catalogues of ancient sunspot and auroral observations from East Asia are used to identify possible intense historical geomagnetic storms in the interval 210 BC-AD 1918. There are about 270 entries in the sunspot catalogue and about 1150 entries in the auroral catalogue. Special databases have been constructed in which the scientific information in these two catalogues is placed in specified fields. For the purposes of this study, an historical geomagnetic storm is defined in terms of an auroral observation that is apparently associated with a particular sunspot observation, in the sense that the auroral observation occurred within several days of the sunspot observation. More precisely, a selection criterion is formulated for the automatic identification of such geomagnetic storms, using the oriental records stored in the sunspot and auroral databases. The selection criterion is based on specific assumptions about the duration of sunspot visibility with the unaided eye, the likely range of heliographic longitudes of an energetic solar feature, and the likely range of transit times for ejected solar plasma to travel from the Sun to the Earth. This selection criterion results in the identification of nineteen putative historical geomagnetic storms, although two of these storms are spurious in the sense that there are two examples of a single sunspot observation being associated with two different auroral observations separated by more than half a (synodic solar rotation period. The literary and scientific reliabilities of the East Asian sunspot and auroral records that define the nineteen historical geomagnetic storms are discussed in detail in a set of appendices. A possible time sequence of events is presented for each geomagnetic storm, including possible dates for both the central meridian passage of the sunspot and the occurrence of the energetic solar feature, as well as likely transit times for the ejected solar plasma

  17. Leakage-Penumbra effect in intensity modulated radiation therapy step-and-shoot dose delivery

    Institute of Scientific and Technical Information of China (English)

    Grigor N Grigorov; James CL Chow

    2016-01-01

    AIM: To study the leakage-penumbra(LP) effect with a proposed correction method for the step-and-shoot intensity modulated radiation therapy(IMRT).METHODS: Leakage-penumbra dose profiles from 10 randomly selected prostate IMRT plans were studied. The IMRT plans were delivered by a Varian 21 EX linear accelerator equipped with a 120-leaf multileaf collimator(MLC). For each treatment plan created by the Pinnacle3 treatment planning system,a 3-dimensional LP dose distribution generated by 5 coplanar photon beams,starting from 0o with equal separation of 72 o,was investigated. For each photon beam used in the stepand-shoot IMRT plans,the first beam segment was set to have the largest area in the MLC leaf-sequencing,and was equal to the planning target volume(PTV). The overshoot effect(OSE) and the segment positional errors were measured using a solid water phantom with Kodak(TL and X-OMAT V) radiographic films. Film dosimetric analysis and calibration were carried out using a film scanner(Vidar VXR-16). The LP dose profiles were determined by eliminating the OSE and segment positional errors with specific individual irradiations. RESULTS: A non-uniformly distributed leaf LP dose ranging from 3% to 5% of the beam dose was measured in clinical IMRT beams. An overdose at the gap between neighboring segments,represented as dose peaks of up to 10% of the total BP,was measured. The LP effect increased the dose to the PTV and surrounding critical tissues. In addition,the effectdepends on the number of beams and segments for each beam. Segment positional error was less than the maximum tolerance of 1 mm under a dose rate of 600 monitor units per minute in the treatment plans. The OSE varying with the dose rate was observed in all photon beams,and the effect increased from 1 to 1.3 Gy per treatment of the rectal intersection. As the dosimetric impacts from the LP effect and OSE may increase the rectal post-radiation effects,a correction of LP was proposed and demonstrated for

  18. Modeling the Longitudinal Asymmetry in Sunspot Emergence -- the Role of the Wilson Depression

    CERN Document Server

    Watson, Fraser; Dalla, Silvia; Marshall, Stephen; 10.1007/s11207-009-9420-z

    2009-01-01

    The distributions of sunspot longitude at first appearance and at disappearance display an east-west asymmetry that results from a reduction in visibility as one moves from disk centre to the limb. To first order, this is explicable in terms of simple geometrical foreshortening. However, the centre-to-limb visibility variation is much larger than that predicted by foreshortening. Sunspot visibility is also known to be affected by the Wilson effect: the apparent dish shape of the sunspot photosphere caused by the temperature-dependent variation of the geometrical position of the tau=1 layer. In this article we investigate the role of the Wilson effect on the sunspot appearance distributions, deducing a mean depth for the umbral tau=1 layer of 500 to 1500 km. This is based on the comparison of observations of sunspot longitude distribution and Monte Carlo simulations of sunspot appearance using different models for spot growth rate, growth time and depth of Wilson depression.

  19. Modelling the Longitudinal Asymmetry in Sunspot Emergence: The Role of the Wilson Depression

    Science.gov (United States)

    Watson, F.; Fletcher, L.; Dalla, S.; Marshall, S.

    2009-11-01

    The distributions of sunspot longitude at first appearance and at disappearance display an east-west asymmetry that results from a reduction in visibility as one moves from disk centre to the limb. To first order, this is explicable in terms of simple geometrical foreshortening. However, the centre-to-limb visibility variation is much larger than that predicted by foreshortening. Sunspot visibility is also known to be affected by the Wilson effect: the apparent ‘dish’ shape of the sunspot photosphere caused by the temperature-dependent variation of the geometrical position of the τ=1 layer. In this article we investigate the role of the Wilson effect on the sunspot appearance distributions, deducing a mean depth for the umbral τ=1 layer of 500 - 1500 km. This is based on the comparison of observations of sunspot longitude distribution and Monte Carlo simulations of sunspot appearance using different models for spot growth rate, growth time and depth of Wilson depression.

  20. Sunspot rotation and magnetic transients associated with flares in NOAA AR 11429

    Science.gov (United States)

    Zheng, Jian-Chuan; Yang, Zhi-Liang; Guo, Jian-Peng; Guo, Kai-Ming; Huang, Hui; Song, Xuan; Wan, Wei-Xing

    2017-08-01

    We analyze sunspot rotation and magnetic transients in NOAA AR 11429 during two X-class (X5.4 and X1.3) flares using data from the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory. A large leading sunspot with positive magnetic polarity rotated counterclockwise. As expected, the rotation was significantly affected by the two flares. Magnetic transients induced by the flares were clearly evident in the sunspots with negative polarity. They were moving across the sunspots with speed of order 3 - 7 km s-1. Furthermore, the trend of magnetic flux evolution in these sunspots exhibited changes associated with the flares. These results may shed light on understanding the evolution of sunspots.

  1. Predicting Maximum Sunspot Number in Solar Cycle 24

    Indian Academy of Sciences (India)

    Nipa J Bhatt; Rajmal Jain; Malini Aggarwal

    2009-03-01

    A few prediction methods have been developed based on the precursor technique which is found to be successful for forecasting the solar activity. Considering the geomagnetic activity aa indices during the descending phase of the preceding solar cycle as the precursor, we predict the maximum amplitude of annual mean sunspot number in cycle 24 to be 111 ± 21. This suggests that the maximum amplitude of the upcoming cycle 24 will be less than cycles 21–22. Further, we have estimated the annual mean geomagnetic activity aa index for the solar maximum year in cycle 24 to be 20.6 ± 4.7 and the average of the annual mean sunspot number during the descending phase of cycle 24 is estimated to be 48 ± 16.8.

  2. Sunspot seismology: accounting for magnetohydrodynamic wave processes using imaging spectropolarimetry

    CERN Document Server

    Rajaguru, S P

    2012-01-01

    The effects of acoustic wave absorption, mode conversion and transmission by a sunspot on the helioseismic inferences are widely discussed, but yet accounting for them has proved difficult for lack of a consistent framework within helioseismic modelling. Here, following a discussion of problems and issues that the near-surface magnetohydrodynamics hosts through a complex interplay of radiative transfer, measurement issues, and MHD wave processes, I present some possibilities entirely from observational analyses based on imaging spectropolarimetry. In particular, I present some results on wave evolution as a function of observation height and inclination of magnetic field to the vertical, derived from a high-cadence imaging spectropolarimetric observation of a sunspot and its surroundings using the instrument IBIS (NSO/Sac Peak, USA). These observations were made in magnetically sensitive (Fe I 6173 A) and insensitive (Fe I 7090 A) upper photospheric absorption lines. Wave travel time contributions from within...

  3. Evidence for low dimensional chaos in sunspot cycles

    Science.gov (United States)

    Letellier, C.; Aguirre, L. A.; Maquet, J.; Gilmore, R.

    2006-04-01

    Sunspot cycles are widely used for investigating solar activity. In 1953 Bracewell argued that it is sometimes desirable to introduce the inversion of the magnetic field polarity, and that can be done with a sign change at the beginning of each cycle. It will be shown in this paper that, for topological reasons, this so-called Bracewell index is inappropriate and that the symmetry must be introduced in a more rigorous way by a coordinate transformation. The resulting symmetric dynamics is then favourably compared with a symmetrized phase portrait reconstructed from the z-variable of the Rössler system. Such a link with this latter variable - which is known to be a poor observable of the underlying dynamics - could explain the general difficulty encountered in finding evidence of low-dimensional dynamics in sunspot data.

  4. Uncertainties in the Sunspot Numbers: Estimation and Implications

    CERN Document Server

    de Wit, Thierry Dudok; Clette, Frédéric

    2016-01-01

    Sunspot number series are subject to various uncertainties, which are still poorly known. The need for their better understanding was recently highlighted by the major makeover of the international Sunspot Number [Clette et al., Space Science Reviews, 2014]. We present the first thorough estimation of these uncertainties, which behave as Poisson-like random variables with a multiplicative coefficient that is time- and observatory-dependent. We provide a simple expression for these uncertainties, and reveal how their evolution in time coincides with changes in the observations, and processing of the data. Knowing their value is essential for properly building composites out of multiple observations, and for preserving the stability of the composites in time.

  5. Recurrence plots of sunspots, solar flux and irradiance

    CERN Document Server

    Sparavigna, Amelia

    2008-01-01

    The paper shows the recurrence and cross recurrence plots of three time series, concerning data of the solar activity. The data are the sunspot number and the values of solar radio flux at 10.7 cm and of solar total irradiance, which are known as highly correlated. To compare the series, the radio flux and irradiance values are monthly averaged. Recurrence plots display the oscillating behaviour with remarkable features. Moreover, cross recurrence plots help in identifying time lags between the sunspot number maximum and the maximum of radio or irradiance signals, in circumstances where the data values are highly dispersed. Image processing is useful too, in enhancing the monitoring. An interesting behaviour is displayed by cross recurrence plots of irradiance, which are not symmetric with respect to the line of identity.

  6. Low Dimensional Chaos from the Group Sunspot Numbers

    Institute of Scientific and Technical Information of China (English)

    Qi-Xiu Li; Ke-Jun Li

    2007-01-01

    We examine the nonlinear dynamical properties of the monthly smoothed group sunspot number Rg and find that the solar activity underlying the time series of Rg is globally governed by a low-dimensional chaotic attractor.This finding is consistent with the nonlinear study results of the monthly Wolf sunspot numbers.We estimate the maximal Lyaponuv exponent (MLE) for the Rg series to be positive and to equal approximately 0.0187±0.0023 (month-1).Thus,the Lyaponuv time or predictability time of the chaotic motion is obtained to be about 4.46±0.5 years.which is slightly different with the predictability time obtained from Rz.However,they both indicate that solar activity forecast should be done only for a short to medium term due to the intrinsic complexity of the time behavior concerned.

  7. Directional Time-Distance Probing of Model Sunspot Atmospheres

    CERN Document Server

    Moradi, H; Przybylski, D; Shelyag, S

    2015-01-01

    A crucial feature not widely accounted for in local helioseismology is that surface magnetic regions actually open a window from the interior into the solar atmosphere, and that the seismic waves leak through this window, reflect high in the atmosphere, and then re-enter the interior to rejoin the seismic wave field normally confined there. In a series of recent numerical studies using translation invariant atmospheres, we utilised a "directional time-distance helioseismology" measurement scheme to study the implications of the returning fast and Alfv\\'en waves higher up in the solar atmosphere on the seismology at the photosphere (Cally & Moradi 2013; Moradi & Cally 2014). In this study, we extend our directional time-distance analysis to more realistic sunspot-like atmospheres to better understand the direct effects of the magnetic field on helioseismic travel-time measurements in sunspots. In line with our previous findings, we uncover a distinct frequency-dependant directional behaviour in the tra...

  8. ON THE SOURCE OF PROPAGATING SLOW MAGNETOACOUSTIC WAVES IN SUNSPOTS

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, S. Krishna; Jess, D. B. [Astrophysics Research Centre, School of Mathematics and Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Khomenko, Elena, E-mail: krishna.prasad@qub.ac.uk [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain)

    2015-10-10

    Recent high-resolution observations of sunspot oscillations using simultaneously operated ground- and space-based telescopes reveal the intrinsic connection between different layers of the solar atmosphere. However, it is not clear whether these oscillations are externally driven or generated in situ. We address this question by using observations of propagating slow magnetoacoustic waves along a coronal fan loop system. In addition to the generally observed decreases in oscillation amplitudes with distance, the observed wave amplitudes are also found to be modulated with time, with similar variations observed throughout the propagation path of the wave train. Employing multi-wavelength and multi-instrument data, we study the amplitude variations with time as the waves propagate through different layers of the solar atmosphere. By comparing the amplitude modulation period in different layers, we find that slow magnetoacoustic waves observed in sunspots are externally driven by photospheric p-modes, which propagate upward into the corona before becoming dissipated.

  9. Spectropolarimetrically accurate magnetohydrostatic sunspot model for forward modelling in helioseismology

    CERN Document Server

    Przybylski, D; Cally, P S

    2015-01-01

    We present a technique to construct a spectropolarimetrically accurate magneto-hydrostatic model of a large-scale solar magnetic field concentration, mimicking a sunspot. Using the constructed model we perform a simulation of acoustic wave propagation, conversion and absorption in the solar interior and photosphere with the sunspot embedded into it. With the $6173\\mathrm{\\AA}$ magnetically sensitive photospheric absorption line of neutral iron, we calculate observable quantities such as continuum intensities, Doppler velocities, as well as full Stokes vector for the simulation at various positions at the solar disk, and analyse the influence of non-locality of radiative transport in the solar photosphere on helioseismic measurements. Bisector shapes were used to perform multi-height observations. The differences in acoustic power at different heights within the line formation region at different positions at the solar disk were simulated and characterised. An increase in acoustic power in the simulated observ...

  10. Molecular Diagnostics of the Internal Structure of Starspots and Sunspots

    Science.gov (United States)

    Afram, N.; Berdyugina, S. V.; Fluri, D. M.; Solanki, S. K.; Lagg, A.; Petit, P.; Arnaud, J.

    2006-12-01

    We have analyzed the usefulness of molecules as a diagnostic tool for studying solar and stellar magnetism with the molecular Zeeman and Paschen-Back effects. In the first part we concentrate on molecules that are observed in sunspots such as MgH and TiO. We present calculated molecular line profiles obtained by assuming magnetic fields of 2-3 kG and compare these synthetic Stokes profiles with spectro-polarimetric observations in sunspots. The good agreement between the theory and observations allows us to turn our attention in the second part to starspots to gain insight into their internal structure. We investigate the temperature range in which the selected molecules can serve as indicators for magnetic fields on highly active cool stars and compare synthetic Stokes profiles with our recent observations.

  11. Sunspot and starspot lifetimes in a turbulent erosion model

    CERN Document Server

    Litvinenko, Yuri E

    2016-01-01

    Quantitative models of sunspot and starspot decay predict the timescale of magnetic diffusion and may yield important constraints in stellar dynamo models. Motivated by recent measurements of starspot lifetimes, we investigate the disintegration of a magnetic flux tube by nonlinear diffusion. Previous theoretical studies are extended by considering two physically motivated functional forms for the nonlinear diffusion coefficient $D$: an inverse power-law dependence $D \\propto B^{-\

  12. The solar magnetic field since 1700: I. Characteristics of sunspot group emergence and reconstruction of the butterfly diagram

    CERN Document Server

    Jiang, Jie; Schmitt, Dieter; Schuessler, Manfred

    2011-01-01

    We use the historic record of sunspot groups compiled by the Royal Greenwich Observatory together with the sunspot number to derive the statistical properties of sunspot group emergence in dependence of cycle phase and strength. In particular we discuss the latitude, longitude, area and tilt angle of sunspot groups as functions of the cycle strength and of time during the solar cycle. Using these empirical characteristics the time-latitude diagram of sunspot group emergence (butterfly diagram) is reconstructed from 1700 onward on the basis of the Wolf and group sunspot numbers. This reconstruction will be useful in studies of the long-term evolution of the Sun's magnetic field.

  13. WIN55,212-2 protects oligodendrocyte precursor cells in stroke penumbra following permanent focal cerebral ischemia in rats

    OpenAIRE

    SUN, JING; Fang, Yin-quan; Ren, Hong; Tao CHEN; Guo, Jing-Jing; Yan, Jun; SONG, SHU; Zhang, Lu-yong; Liao, Hong

    2012-01-01

    Aim: To explore whether the synthetic cannabinoid receptor agonist WIN55,212-2 could protect oligodendrocyte precursor cells (OPCs) in stroke penumbra, thereby providing neuroprotection following permanent focal cerebral ischemia in rats. Methods: Adult male SD rats were subjected to permanent middle cerebral artery occlusion (p-MCAO). The animals were administered WIN55,212-2 at 2 h, and sacrificed at 24 h after the ischemic insult. The infarct volumes and brain swelling were assessed. The e...

  14. Weather variability, sunspots, and the blooms of cyanobacteria.

    Science.gov (United States)

    Hu, Wenbiao; Connell, Des; Mengersen, Kerrie; Tong, Shilu

    2009-03-01

    The roles of weather variability and sunspots in the occurrence of cyanobacteria blooms, were investigated using cyanobacteria cell data collected from the Fred Haigh Dam, Queensland, Australia. Time series generalized linear model and classification and regression tree (CART) model were used in the analysis. Data on notified cell numbers of cyanobacteria and weather variables over the periods 2001 and 2005 were provided by the Australian Department of Natural Resources and Water, and Australian Bureau of Meteorology, respectively. The results indicate that monthly minimum temperature (relative risk [RR]: 1.13, 95% confidence interval [CI]: 1.02-1.25) and rainfall (RR: 1.11; 95% CI: 1.03-1.20) had a positive association, but relative humidity (RR: 0.94; 95% CI: 0.91-0.98) and wind speed (RR: 0.90; 95% CI: 0.82-0.98) were negatively associated with the cyanobacterial numbers, after adjustment for seasonality and auto-correlation. The CART model showed that the cyanobacteria numbers were best described by an interaction between minimum temperature, relative humidity, and sunspot numbers. When minimum temperature exceeded 18 degrees C and relative humidity was under 66%, the number of cyanobacterial cells rose by 2.15-fold. We conclude that weather variability and sunspot activity may affect cyanobacteria blooms in dams.

  15. Photospheric Origin of Three-minute Oscillations in a Sunspot

    Science.gov (United States)

    Chae, Jongchul; Lee, Jeongwoo; Cho, Kyuhyoun; Song, Donguk; Cho, Kyungsuk; Yurchyshyn, Vasyl

    2017-02-01

    The origin of the three-minute oscillations of intensity and velocity observed in the chromosphere of sunspot umbrae is still unclear. We investigated the spatio-spectral properties of the 3 minute oscillations of velocity in the photosphere of a sunspot umbra as well as those in the low chromosphere using the spectral data of the Ni i λ5436, Fe i λ5435, and Na i D2 λ5890 lines taken by the Fast Imaging Solar Spectrograph of the 1.6 m New Solar Telescope at the Big Bear Solar Observatory. As a result, we found a local enhancement of the 3 minute oscillation power in the vicinities of a light bridge (LB) and numerous umbral dots (UDs) in the photosphere. These 3 minute oscillations occurred independently of the 5 minute oscillations. Through wavelet analysis, we determined the amplitudes and phases of the 3 minute oscillations at the formation heights of the spectral lines, and they were found to be consistent with the upwardly propagating slow magnetoacoustic waves in the photosphere with energy flux large enough to explain the chromospheric oscillations. Our results suggest that the 3 minute chromospheric oscillations in this sunspot may have been generated by magnetoconvection occurring in the LB and UDs.

  16. Sunspot Observations of Rudolf Wolf from 1849 - 1893

    Science.gov (United States)

    Friedli, Thomas K.

    2016-06-01

    The sunspot observations of Rudolf Wolf form the core of the Wolf series of sunspot relative numbers, or Wolf numbers, since his observations define the original scale of the series and also the main course of solar activity from 1849 to 1893. Unfortunately, the raw data for the years 1856 to 1869 were never published in full detail. The heritage group of the Rudolf Wolf Society in Switzerland digitized parts of the hitherto unpublished original source book of the Wolf series and put it on its website www.wolfinstitute.ch. Now, the Wolf numbers from 1849 to 1876, as provided by the World Data Center for Solar Index and Long-term Solar Observations (WDC-SILSO), can be reconstructed in every detail, since the source book contains all the raw sunspot group and individual spot numbers as well as the implemented calibration and interpolation methods. Thus, the observations made by Rudolf Wolf with the 83/1320 mm Fraunhofer refractor and with the 40/700 mm Parisian refractor as well as those made by Heinrich Schwabe can be identified and separated now. In this article, we describe Wolf's instruments and methods of observation. An inspection of the source book and other published sources reveals that the calibration factor of the 40/700 mm Parisian refractor should probably be lowered. Since no appropriate comparison observations are available, the scale transfer from Heinrich Schwabe to Rudolf Wolf has to be analyzed further.

  17. A Multi-Instrument Analysis of Sunspot Umbrae

    CERN Document Server

    Watson, Fraser T; Livingston, William C

    2015-01-01

    The recent solar minimum and rise phase of solar cycle 24 have been unlike any period since the early 1900s. This article examines some of the properties of sunspot umbrae over the last 17 years with three different instruments on the ground and in space: MDI, HMI and BABO. The distribution of magnetic fields and their evolution over time is shown and reveals that the field distribution in cycle 24 is fundamentally different from that in cycle 23. The annual average umbral magnetic field is then examined for the 17 year observation period and shows a small decrease of 375 Gauss in sunspot magnetic fields over the period 1996 to 2013, but the mean intensity of sunspot umbrae does not vary significantly over this time. A possible issue with sample sizes in a previous study is then explored to explain disagreements in data from two of the source instruments. All three instruments show that the relationship between umbral magnetic fields and umbral intensity agrees with past studies in that the umbral intensity d...

  18. CLINICAL STUDY OF ISCHEMIC PENUMBRA REGION IN BRAIN ELECTRICAL ACTIVITY MAPPING

    Institute of Scientific and Technical Information of China (English)

    Liu Qingrui; Liu Mingshun; Gu Lanjie; Mei Fengjun

    2000-01-01

    Department of Neurology, Fourth Affiliated Hospital. Hebei Medical University, Shijiazhuang ABSTRACT OBJETIVE To study features and clinical usage of ischemic penumbra region(IPR) in brain electrical activity mapping(BEAM).BACKGROUND To explore the functional improvement index of IPR untraumaticly. METH0DS 69 patients with acute cerebral infarction were divided into two groups according to different therapeutic time window--early treatment group( 32 cases, treatment in 12 hours)and contral group (37 cases, treatment in 12-72 hours).They were analysed in BEAM pre-and post-treatment Results: BEAM showed that the power of infarcted core was decreased and IPR became smaller in slow waves significantly after treatment in early treatment group and this change was in good agreement with improvement of clinical functions and SPECT DISCUSSION The key to treat acute cerebral infarction was to improve functions of IPR as 8oos as possible, BEAM could show the location and size of IPR. CONCLUSION BEAM was one of important index in evaluating the function of IPR.

  19. Wings of the butterfly: Sunspot groups for 1826-2015

    Science.gov (United States)

    Leussu, R.; Usoskin, I. G.; Senthamizh Pavai, V.; Diercke, A.; Arlt, R.; Denker, C.; Mursula, K.

    2017-03-01

    The spatio-temporal evolution of sunspot activity, the so-called Maunder butterfly diagram, has been continously available since 1874 using data from the Royal Greenwich Observatory, extended by SOON network data after 1976. Here we present a new extended butterfly diagram of sunspot group occurrence since 1826, using the recently digitized data from Schwabe (1826-1867) and Spörer (1866-1880). The wings of the diagram are separated using a recently developed method based on an analysis of long gaps in sunspot group occurrence in different latitude bands. We define characteristic latitudes, corresponding to the start, end, and the largest extent of the wings (the F, L, and H latitudes). The H latitudes (30°-45°) are highly significantly correlated with the strength of the wings (quantified by the total sum of the monthly numbers of sunspot groups). The F latitudes (20°-30°) depict a weak tendency, especially in the southern hemisphere, to follow the wing strength. The L latitudes (2°-10°) show no clear relation to the wing strength. Overall, stronger cycle wings tend to start at higher latitudes and have a greater wing extent. A strong (5-6)-cycle periodic oscillation is found in the start and end times of the wings and in the overlap and gaps between successive wings of one hemisphere. While the average wing overlap is zero in the southern hemisphere, it is two to three months in the north. A marginally significant oscillation of about ten solar cycles is found in the asymmetry of the L latitudes. The new long database of butterfly wings provides new observational constraints to solar dynamo models that discuss the spatio-temporal distribution of sunspot occurrence over the solar cycle and longer. Digital data for Fig. 1 are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/599/A131

  20. Magnetic and Thermal Contributions to Helioseismic Travel times in Simulated Sunspots

    Science.gov (United States)

    Braun, Douglas; Felipe, Tobias; Birch, Aaron; Crouch, Ashley D.

    2016-05-01

    The interpretation of local helioseismic measurements of sunspots has long been a challenge, since waves propagating through sunspots are potentially affected by both mode conversion and changes in the thermal structure of the spots. We carry out numerical simulations of wave propagation through a variety of models which alternately isolate either the thermal or magnetic structure of the sunspot or include both of these. We find that helioseismic holography measurements made from the resulting simulated wavefields show qualitative agreement with observations of real sunspots. Using insight from ray theory, we find that travel-time shifts in the thermal (non-magnetic) sunspot model are primarily produced by changes in the wave path due to the Wilson depression rather than variations in the wave speed. This shows that inversions for the subsurface structure of sunspots must account for local changes in the density. In some ranges of horizontal phase speed and frequency there is agreement (within the noise level of the measurements) between the travel times measured in the full magnetic sunspot model and the thermal model. If this conclusion proves to be robust for a wide range of models, it suggests a path towards inversions for sunspot structure. This research has been funded by the Spanish MINECO through grant AYA2014-55078-P, by the NASA Heliophysics Division through NNX14AD42G and NNH12CF23C, and the NSF Solar Terrestrial program through AGS-1127327.

  1. Cross Recurrence Plots Analysis of the North-South Sunspot Activities

    Science.gov (United States)

    Ponyavin, Dmitri I.; Zolotova, Nadejda V.

    A new technique of nonlinear interrelations between time series developed by Marwan & Kurths, (2002) has been applied to the sunspot data. By using this tools we have investigated synchronization and phase difference in annual sunspot areas -- time series available for Northern and Southern Hemispheres of the Sun.

  2. A Standard Law for the Equatorward Drift of the Sunspot Zones

    Science.gov (United States)

    Hathaway, David H.

    2012-01-01

    The latitudinal location of the sunspot zones in each hemisphere is determined by calculating the centroid position of sunspot areas for each solar rotation from May 1874 to June 2012. When these centroid positions are plotted and analyzed as functions of time from each sunspot cycle maximum there appears to be systematic differences in the positions and equatorward drift rates as a function of sunspot cycle amplitude. If, instead, these centroid positions are plotted and analyzed as functions of time from each sunspot cycle minimum then most of the differences in the positions and equatorward drift rates disappear. The differences that remain disappear entirely if curve fitting is used to determine the starting times (which vary by as much as 8 months from the times of minima). The sunspot zone latitudes and equatorward drift measured relative to this starting time follow a standard path for all cycles with no dependence upon cycle strength or hemispheric dominance. Although Cycle 23 was peculiar in its length and the strength of the polar fields it produced, it too shows no significant variation from this standard. This standard law, and the lack of variation with sunspot cycle characteristics, is consistent with Dynamo Wave mechanisms but not consistent with current Flux Transport Dynamo models for the equatorward drift of the sunspot zones.

  3. 70 years of Sunspot Observations at Kanzelh\\"ohe Observatory: systematic study of parameters affecting the derivation of the relative sunspot number

    CERN Document Server

    Pötzi, Werner; Temmer, Manuela; Baumgartner, Dietmar; Freislich, Heinrich; Strutzmann, Heinz

    2015-01-01

    Kanzelh\\"ohe Observatory (KSO) was founded during World War II by the "Deutsche Luftwaffe" (German Airforces) as one station of a network of observatories, which should provide information on solar activity in order to better assess the actual conditions of the Earth's ionosphere in terms of radio wave propagation. The solar observations began in 1943 with photographs of the photosphere, drawings of sunspots, plage regions and faculae, as well as patrol observations of the solar corona. At the beginning all data was sent to Freiburg (Germany). After WWII international cooperation was established and the data was sent to Zurich, Paris, Moscow and Greenwich. Relative sunspot numbers are derived since 1944. The agreement between relative sunspot numbers derived at KSO and the new International Sunspot Number (ISN) \\citep{SIDC} lies within $\\sim10\\%$. However, revisiting the historical data, we also find periods with larger deviations. The reasons for the deviations were twofold: (1) On the one hand a major instr...

  4. The Discontinuity Circa 1885 in the Group Sunspot Number

    Science.gov (United States)

    Cliver, E. W.; Ling, A. G.

    2016-11-01

    On average, the international sunspot number (RI) is 44 % higher than the group sunspot number (RG) from 1885 to the beginning of the RI series in 1700. This is the principal difference between RI and RG. Here we show that this difference is primarily due to an inhomogeneity in the Royal Greenwich Observatory (RGO) record of sunspot groups (1874 - 1976) used to derive observer normalization factors (called k-factors) for RG. Specifically, annual RGO group counts increase relative to those of Wolfer and other long-term observers from 1876 - 1915. A secondary contributing cause is that the k-factors for observers who began observing before 1884 and overlapped with RGO for any years during 1874 - 1883 were not based on direct comparison with RGO but were calculated using one or more intermediary or additional observers. We introduce R_{GC} by rectifying the RGO group counts from 1874 - 1915 and basing k-factors on direct comparison with RGO across the 1885 discontinuity, which brings the RG and RI series into reasonable agreement for the 1841 - 1885 interval (after correcting RI for an inhomogeneity from 1849 - 1867 (to give R_{IC})). Comparison with an independently derived backbone-based reconstruction of RG (R_{BB}) indicates that R_{GC} over-corrects R_{BB} by 4 % on average from 1841 - 1925. Our analysis suggests that the maxima of Cycles 10 (in 1860), 12 (1883/1884), and 13 (1893) in the R_{IC} series are too low by ≈ 10 %.

  5. Comparison of New and Old Sunspot Number Time Series

    Science.gov (United States)

    Cliver, E. W.

    2016-11-01

    Four new sunspot number time series have been published in this Topical Issue: a backbone-based group number in Svalgaard and Schatten ( Solar Phys., 2016; referred to here as SS, 1610 - present), a group number series in Usoskin et al. ( Solar Phys., 2016; UEA, 1749 - present) that employs active day fractions from which it derives an observational threshold in group spot area as a measure of observer merit, a provisional group number series in Cliver and Ling ( Solar Phys., 2016; CL, 1841 - 1976) that removed flaws in the Hoyt and Schatten ( Solar Phys. 179, 189, 1998a; 181, 491, 1998b) normalization scheme for the original relative group sunspot number (RG, 1610 - 1995), and a corrected Wolf (international, RI) number in Clette and Lefèvre ( Solar Phys., 2016; SN, 1700 - present). Despite quite different construction methods, the four new series agree well after about 1900. Before 1900, however, the UEA time series is lower than SS, CL, and SN, particularly so before about 1885. Overall, the UEA series most closely resembles the original RG series. Comparison of the UEA and SS series with a new solar wind B time series (Owens et al. in J. Geophys. Res., 2016; 1845 - present) indicates that the UEA time series is too low before 1900. We point out incongruities in the Usoskin et al. ( Solar Phys., 2016) observer normalization scheme and present evidence that this method under-estimates group counts before 1900. In general, a correction factor time series, obtained by dividing an annual group count series by the corresponding yearly averages of raw group counts for all observers, can be used to assess the reliability of new sunspot number reconstructions.

  6. Distribution of electric currents in sunspots from photosphere to corona

    Energy Technology Data Exchange (ETDEWEB)

    Gosain, Sanjay [National Solar Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Démoulin, Pascal [Observatoire de Paris, LESIA, UMR 8109 (CNRS), F-92195 Meudon Principal Cedex (France); López Fuentes, Marcelo [Instituto de Astronomía y Física del Espacio (IAFE), UBA-CONICET, CC. 67, Suc. 28 Buenos Aires 1428 (Argentina)

    2014-09-20

    We present a study of two regular sunspots that exhibit nearly uniform twist from the photosphere to the corona. We derive the twist parameter in the corona and in the chromosphere by minimizing the difference between the extrapolated linear force-free field model field lines and the observed intensity structures in the extreme-ultraviolet images of the Sun. The chromospheric structures appear more twisted than the coronal structures by a factor of two. Further, we derive the vertical component of electric current density, j{sub z} , using vector magnetograms from the Hinode Solar Optical Telescope (SOT). The spatial distribution of j{sub z} has a zebra pattern of strong positive and negative values owing to the penumbral fibril structure resolved by Hinode/SOT. This zebra pattern is due to the derivative of the horizontal magnetic field across the thin fibrils; therefore, it is strong and masks weaker currents that might be present, for example, as a result of the twist of the sunspot. We decompose j{sub z} into the contribution due to the derivatives along and across the direction of the horizontal field, which follows the fibril orientation closely. The map of the tangential component has more distributed currents that are coherent with the chromospheric and coronal twisted structures. Moreover, it allows us to map and identify the direct and return currents in the sunspots. Finally, this decomposition of j{sub z} is general and can be applied to any vector magnetogram in order to better identify the weaker large-scale currents that are associated with coronal twisted/sheared structures.

  7. Small-scale magnetic flux emergence in a sunspot light bridge

    Science.gov (United States)

    Louis, Rohan E.; Bellot Rubio, Luis R.; de la Cruz Rodríguez, Jaime; Socas-Navarro, Héctor; Ortiz, Ada

    2015-12-01

    Context. Light bridges are convective intrusions in sunspots that often show enhanced chromospheric activity. Aims: We seek to determine the nature of flux emergence in a light bridge and the processes related to its evolution in the solar atmosphere. Methods: We analyse a sequence of high-resolution spectropolarimetric observations of a sunspot taken at the Swedish 1-m Solar Telescope. The data consist of spectral scans of the photospheric Fe i line pair at 630 nm and the chromospheric Ca ii 854.2 nm line. Bisectors were used to construct Dopplergrams from the Fe i 630.15 nm measurements. We employed LTE and non-LTE inversions to derive maps of physical parameters in the photosphere and chromosphere, respectively. Results: We observe the onset of blueshifts of about 2 km s-1 near the entrance of a granular light bridge on the limbward side of the spot. The blueshifts lie immediately next to a strongly redshifted patch that appeared six minutes earlier. Both patches can be seen for 25 min until the end of the sequence. The blueshifts coincide with an elongated emerging granule, while the redshifts appear at the end of the granule. In the photosphere, the development of the blueshifts is accompanied by a simultaneous increase in field strength of about 400 G. The field inclination increases by some 25°, becoming nearly horizontal. At the position of the redshifts, the magnetic field is equally horizontal but of opposite polarity. An intense brightening is seen in the Ca ii filtergrams over the blueshifts and redshifts, about 17 min after their detection in the photosphere. The brightening is due to emission in the blue wing of the Ca ii 854.2 nm line, close to its knee. Non-LTE inversions reveal that this kind of asymmetric emission is caused by a temperature enhancement of ~700 K between -5.0 ≤ log τ ≤ -3.0 and a blueshift of 3 km s-1 at log τ = -2.3 that decreases to zero at log τ = -6.0 Conclusions: The photospheric blueshifts and redshifts observed in a

  8. Measurements of sunspot group tilt angles for solar cycles 19-24

    Science.gov (United States)

    Isik, Seda; Isik, Emre

    2016-07-01

    The tilt angle of a sunspot group is a critical quantity in the surface transport magnetic flux on global scales, playing a role in the solar dynamo. To investigate Joy's law for four cycles, we measured the tilt angles of sunspot groups for solar cycles 19-24. We have developed an IDL routine, which allows the user to interactively select and measure sunspot positions and areas on the solar disc, using the sunspot drawing database of Kandilli Observatory. The method is similar to that used by others in the literature, with the exception that sunspot groups were identified manually, which has improved the accuracy of the tilt angles. We present cycle averages of the tilt angle and compare the results with the existing data in the literature.

  9. Indirect comparison of Debrecen and Greenwich daily sums of sunspot areas

    CERN Document Server

    Baranyi, T; Coffey, H E

    2013-01-01

    Sunspot area data play an important role in the studies of solar activity and its long-term variations. In order to reveal real long-term solar variations precise homogeneous sunspot area databases should be used. However, the measured areas may be burdened with systematic deviations, which may vary in time. Thus, there is a need to investigate the long-term variation of sunspot area datasets and to determine the time-dependent cross-calibration factors. In this study, we investigate the time-dependent differences between the available long-term sunspot databases. Using the results, we estimate the correction factor to calibrate the corrected daily sunspot areas of Debrecen Photoheliographic Data (DPD) to the same data of Greenwich Photoheliographic Results (GPR) by using the overlapping Kislovodsk and Pulkovo data. We give the correction factor as GPR=1.08(\\pm 0.11)*DPD

  10. Digitization of sunspot drawings by Sp\\"orer made in 1861-1894

    CERN Document Server

    Diercke, Andrea; Denker, Carsten

    2014-01-01

    Most of our knowledge about the Sun's activity cycle arises from sunspot observations over the last centuries since telescopes have been used for astronomy. The German astronomer Gustav Sp\\"orer observed almost daily the Sun from 1861 until the beginning of 1894 and assembled a 33-year collection of sunspot data covering a total of 445 solar rotation periods. These sunspot drawings were carefully placed on an equidistant grid of heliographic longitude and latitude for each rotation period, which were then copied to copper plates for a lithographic reproduction of the drawings in astronomical journals. In this article, we describe in detail the process of capturing these data as digital images, correcting for various effects of the aging print materials, and preparing the data for contemporary scientific analysis based on advanced image processing techniques. With the processed data we create a butterfly diagram aggregating sunspot areas, and we present methods to measure the size of sunspots (umbra and penumb...

  11. Spot cycle reconstruction: an empirical tool - Application to the sunspot cycle

    CERN Document Server

    Santos, A R G; Avelino, P P; Campante, T L

    2015-01-01

    The increasing interest in understanding stellar magnetic activity cycles is a strong motivation for the development of parameterised starspot models which may be constrained observationally. In this work we develop an empirical tool for the stochastic reconstruction of sunspot cycles, using the average solar properties as a reference. The synthetic sunspot cycle is compared with the sunspot data extracted from the National Geophysical Data Center, in particular using the Kolmogorov-Smirnov test. This tool yields synthetic spot group records, including date, area, latitude, longitude, rotation rate of the solar surface at the group's latitude, and an identification number. Comparison of the stochastic reconstructions with the daily sunspot records (from the National Geophysical Data Center) confirms that our empirical model is able to successfully reproduce the main properties of the solar sunspot cycle. As a by-product of this work, we show that the Gnevyshev-Waldmeier rule, which describes the spots' area-l...

  12. The causality between the rapid rotation of a sunspot and an X3.4 flare

    Institute of Scientific and Technical Information of China (English)

    Xiao-Li Yan; Zhong-Quan Qu; Cheng-Lin Xu; Zhi-Ke Xue; De-Fang Kong

    2009-01-01

    Using multi-wavelength data of Hinode, the rapid rotation of a sunspot in ac-tive region NOAA 10930 is studied in detail. We found extraordinary counterclockwise rotation of the sunspot with positive polarity before an X3.4 flare. From a series of vector magnetograms, it is found that magnetic force lines are highly sheared along the neu-tral line accompanying the sunspot rotation. Furthermore, it is also found that sheared loops and an inverse S-shaped magnetic loop in the corona formed gradually after the sunspot rotation. The X3.4 flare can be reasonably regarded as a result of this movement. A detailed analysis provides evidence that sunspot rotation leads to magnetic field linestwisting in the photosphere. The twist is then transported into the corona and triggers flares.

  13. Sunspot latitudes during the Maunder Minimum: a machine-readable catalogue from previous studies

    CERN Document Server

    Vaquero, J M; Sánchez-Bajo, F

    2015-01-01

    The Maunder Minimum (1645-1715 approximately) was a period of very low solar activity and a strong hemispheric asymmetry, with most of sunspots in the southern hemisphere. In this paper, two data sets of sunspot latitudes during the Maunder minimum have been recovered for the international scientific community. The first data set is constituted by latitudes of sunspots appearing in the catalogue published by Gustav Sp\\"orer nearly 130 years ago. The second data set is based on the sunspot latitudes displayed in the butterfly diagram for the Maunder Minimum which was published by Ribes and Nesme-Ribes almost 20 years ago. We have calculated the asymmetry index using these data sets confirming a strong hemispherical asymmetry in this period. A machine-readable version of this catalogue with both data sets is available in the Historical Archive of Sunspot Observations (http://haso.unex.es) and in the appendix of this article.

  14. Transplanted bone marrow stem cells relocate to infarct penumbra and co-express endogenous proliferative and immature neuronal markers in a mouse model of ischemic cerebral stroke

    Directory of Open Access Journals (Sweden)

    Liu Wei

    2010-10-01

    Full Text Available Abstract Background Several studies demonstrate that neurogenesis may be induced or activated following vascular insults, which may be important for neuronal regeneration and functional recovery. Understanding the cellular mechanism underlying stroke-associated neurogenesis is of neurobiological as well as neurological/clinical relevance. The present study attempted to explore potential homing and early development of transplanted bone marrow stem cells in mouse forebrain after focal occlusion of the middle cerebral artery, an experimental model of ischemic stroke. Results Bone marrow stem cells isolated from donor mice were confirmed by analysis of surface antigen profile, and were pre-labeled with a lipophilic fluorescent dye PKH26, and subsequently transfused into recipient mice with middle cerebral artery coagulation. A large number of PKH26-labeled cells were detected surrounding the infarct site, most of which colocalized with immunolabelings for the proliferating cell nuclear antigen (PCNA and some also colocalized with the immature neuronal marker doublecortin (DCX during 1-2 weeks after the bone marrow cells transfusion. Conclusions The present study shows that transplanted bone morrow cells largely relocate to the infarct penumbra in ischemic mouse cerebrum. These transplanted bone marrow cells appear to undergo a process of in situ proliferation and develop into putative cortical interneurons during the early phase of experimental vascular injury.

  15. SCALER MODE OF THE AUGER OBSERVATORY AND SUNSPOTS

    Energy Technology Data Exchange (ETDEWEB)

    Canal, Carlos A. Garcia; Tarutina, Tatiana [Instituto de Fisica La Plata, CCT La Plata, CONICET and Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata CC 67, 1900 La Plata (Argentina); Hojvat, Carlos [Fermilab, P.O. Box 500, Batavia, IL 60510-0500 (United States)

    2012-10-15

    Recent data from the Auger Observatory on low-energy secondary cosmic ray particles are analyzed to study temporal correlations together with data on the daily sunspot numbers and neutron monitor data. Standard spectral analysis demonstrates that the available data show 1/f {sup {beta}} fluctuations with {beta} Almost-Equal-To 1 in the low-frequency range. All data behave like Brownian fluctuations in the high-frequency range. The existence of long-range correlations in the data was confirmed by detrended fluctuation analysis. The real data confirmed the correlation between the scaling exponent of the detrended analysis and the exponent of the spectral analysis.

  16. Sunspot seismic halos generated by fast MHD wave refraction

    CERN Document Server

    Khomenko, E

    2009-01-01

    We suggest an explanation for the high-frequency power excess surrounding active regions known as seismic halos. The idea is based on numerical simulations of magneto-acoustic waves propagation in sunspots. We propose that such an excess can be caused by the additional energy injected by fast mode waves refracted in the higher atmosphere due to the rapid increase of the Alfven speed. Our model qualitatively explains the magnitude of the halo and allows to make some predictions of its behavior that can be checked in future observations.

  17. Sunspot numbers based on historic records in the 1610s: Early telescopic observations by Simon Marius and others

    Science.gov (United States)

    Neuhäuser, R.; Neuhäuser, D. L.

    2016-07-01

    Hoyt & Schatten (1998) claim that Simon Marius would have observed the sun from 1617 Jun 7 to 1618 Dec 31 (Gregorian calendar) all days, except three short gaps in 1618, but would never have detected a sunspot - based on a quotation from Marius in Wolf (1857), but mis-interpreted by Hoyt & Schatten. Marius himself specified in early 1619 that for one and a half year ... rather few or more often no spots could be detected ... which was never observed before (Marius 1619). The generic statement by Marius can be interpreted such that the active day fraction was below 0.5 (but not zero) from fall 1617 to spring 1619 and that it was 1 before fall 1617 (since August 1611). Hoyt & Schatten cite Zinner (1952), who referred to Zinner (1942), where observing dates by Marius since 1611 are given but which were not used by Hoyt & Schatten. We present all relevant texts from Marius where he clearly stated that he observed many spots in different form on and since 1611 Aug 3 (Julian) = Aug 13 (Greg.) (on the first day together with Ahasverus Schmidnerus); 14 spots on 1612 May 30 (Julian) = Jun 9 (Greg.), which is consistent with drawings by Galilei and Jungius for that day, the latter is shown here for the first time; at least one spot on 1611 Oct 3 and/or 11 (Julian), i.e. Oct 13 and/or 21 (Greg.), when he changed his sunspot observing technique; he also mentioned that he has drawn sunspots for 1611 Nov 17 (Julian) = Nov 27 (Greg.); in addition to those clearly datable detections, there is evidence in the texts for regular observations. For all the information that can be compared to other observers, the data from Marius could be confirmed, so that his texts are highly credible. We also correct several shortcomings or apparent errors in the database by Hoyt & Schatten (1998) regarding 1612 (Harriot), 1615 (Saxonius, Tardé), 1616 (Tardé), 1617-1619 (Marius, Riccioli/Argoli), and Malapert (for 1618, 1620, and 1621). Furthermore, Schmidnerus, Cysat, David & Johann Fabricius

  18. Penumbra pattern assessment in acute stroke patients: comparison of quantitative and non-quantitative methods in whole brain CT perfusion.

    Directory of Open Access Journals (Sweden)

    Kolja M Thierfelder

    Full Text Available BACKGROUND AND PURPOSE: While penumbra assessment has become an important part of the clinical decision making for acute stroke patients, there is a lack of studies measuring the reliability and reproducibility of defined assessment techniques in the clinical setting. Our aim was to determine reliability and reproducibility of different types of three-dimensional penumbra assessment methods in stroke patients who underwent whole brain CT perfusion imaging (WB-CTP. MATERIALS AND METHODS: We included 29 patients with a confirmed MCA infarction who underwent initial WB-CTP with a scan coverage of 100 mm in the z-axis. Two blinded and experienced readers assessed the flow-volume-mismatch twice and in two quantitative ways: Performing a volumetric mismatch analysis using OsiriX imaging software (MM(VOL and visual estimation of mismatch (MM(EST. Complementarily, the semiquantitative Alberta Stroke Programme Early CT Score for CT perfusion was used to define mismatch (MM(ASPECTS. A favorable penumbral pattern was defined by a mismatch of ≥ 30% in combination with a cerebral blood flow deficit of ≤ 90 ml and an MM(ASPECTS score of ≥ 1, respectively. Inter- and intrareader agreement was determined by Kappa-values and ICCs. RESULTS: Overall, MM(VOL showed considerably higher inter-/intrareader agreement (ICCs: 0.751/0.843 compared to MM(EST (0.292/0.749. In the subgroup of large (≥ 50 mL perfusion deficits, inter- and intrareader agreement of MM(VOL was excellent (ICCs: 0.961/0.942, while MM(EST interreader agreement was poor (0.415 and intrareader agreement was good (0.919. With respect to penumbra classification, MM(VOL showed the highest agreement (interreader agreement: 25 agreements/4 non-agreements/κ: 0.595; intrareader agreement 27/2/0.833, followed by MM(EST (22/7/0.471; 23/6/0.577, and MM(ASPECTS (18/11/0.133; 21/8/0.340. CONCLUSION: The evaluated approach of volumetric mismatch assessment is superior to pure visual and ASPECTS penumbra

  19. Experimental measurement of radiological penumbra associated with intermediate energy x-rays (1 MV) and small radiosurgery field sizes.

    Science.gov (United States)

    Keller, Brian M; Beachey, David J; Pignol, Jean-Philippe

    2007-10-01

    Stereotactic radiosurgery is used to treat intracranial lesions with a high degree of accuracy. At the present time, x-ray energies at or above Co-60 gamma rays are used. Previous Monte Carlo simulations have demonstrated that intermediate energy x-ray photons or IEPs (defined to be photons in the energy range of 0.2-1.2 MeV), combined with small field sizes, produce a reduced radiological penumbra leading to a sharper dose gradient, improved dose homogeneity and sparing of critical anatomy adjacent to the target volume. This hypothesis is based on the fact that, for small x-ray fields, a dose outside the treatment volume is dictated mainly by the range of electrons set into motion by x-ray photons. The purpose of this work is: (1) to produce intermediate energy x rays using a detuned medical linear accelerator, (2) to characterize the energy of this beam, (3) to measure the radiological penumbra for IEPs and small fields to compare with that produced by 6 MV x rays or Co-60, and (4) to compare these experimental measurements with Monte Carlo computer simulations. The maximum photon energy of our IEP x-ray spectrum was measured to be 1.2 MeV. Gafchromic EBT films (ISP Technologies, Wayne, NJ) were irradiated and read using a novel digital microscopy imaging system with high spatial resolution. Under identical irradiation conditions the measured radiological penumbra widths (80%-20% distance), for field sizes ranging from 0.3 x 0.3 to 4.0 x 4.0 cm2, varied from 0.3-0.77 mm (1.2 MV) and from 1.1-2.1 mm (6 MV). Even more dramatic were the differences found when comparing the 90%-10% or the 95%-5% widths, which are in fact more significant in radiotherapy. Monte Carlo simulations agreed well with the experimental findings. The reduction in radiological penumbra could be substantial for specific clinical situations such as in the treatment of an ocular melanoma abutting the macula or for the treatment of functional disorders such as trigeminal neuralgia (a nonlethal

  20. Sunspots sketches during the solar eclipses of 9th January and 29th December of 1777 in Mexico

    Science.gov (United States)

    Domínguez-Castro, Fernando; Gallego, María Cruz; Vaquero, José Manuel

    2017-06-01

    Two sunspot observations recorded by the Mexican Felipe de Zúñiga y Ontiveros have been revealed from a manuscript. One sunspot group was recorded on 9th January 1777 and four sunspot groups on 29th December 1777. Both records were taken during the observation of solar eclipses from Mexico City and their description also included sketches of the solar disk with sunspots. The sunspot group corresponding to 9th January was also observed by Erasmus Lievog. The observation on 29th December 1777 is the only record corresponding to this date.

  1. A Recount of Sunspot Groups on Staudach's Drawings

    Science.gov (United States)

    Svalgaard, Leif

    2017-01-01

    We have examined the more than 1100 drawings of the solar disk made by the German amateur astronomer Johann Caspar Staudach during 1749 - 1799 and counted the spots on each image. Using the modern perception of how to group spots into active regions, we regrouped the spots as a modern observer would. The resulting number of groups was found to be higher on average by 25 % than the first count of groups performed by Wolf in 1857, which was used by Hoyt and Schatten ( Solar Phys. 181, 491, 1998) in their construction of the group sunspot number. Compared to other observers at the time, Staudach's drawings have a very low average number, about two, of spots per group, possibly indicating an inferior telescope that probably suffered from spherical and chromatic aberration, as would be typical of amateur telescopes of the day. We have initiated an ongoing project aiming at observing sunspots with antique telescopes having similar defects in order to determine the factor necessary to bring the Staudach observations onto a modern scale.

  2. A Recount of Sunspot Groups on Staudach's Drawings

    CERN Document Server

    Svalgaard, Leif

    2015-01-01

    We have examined the more than 1100 drawings of the solar disk made by the German astronomy amateur Johann Caspar Staudach during 1749-1799 and counted the spots on each image. Using the modern perception of how to group spots into active regions we regrouped the spots as a modern observer would. The resulting number of groups was found to be on average 25% higher than the first count of groups performed by Wolf in 1857, and used by Hoyt and Schatten in their construction of the Group Sunspot Number. Compared to other observers at the time, Staudach's drawings have a very low average number, ~2, of spots per group, possibly indicating an inferior telescope likely suffering from spherical and chromatic aberration as would typical of amateur telescopes of the day. We have initiated an ongoing project aiming at observing sunspots with antique telescopes having similar defects in order to determine the factor necessary to bring the Staudach observations onto a modern scale.

  3. Sunspot Pattern Classification using PCA and Neural Networks (Poster)

    Science.gov (United States)

    Rajkumar, T.; Thompson, D. E.; Slater, G. L.

    2005-01-01

    The sunspot classification scheme presented in this paper is considered as a 2-D classification problem on archived datasets, and is not a real-time system. As a first step, it mirrors the Zuerich/McIntosh historical classification system and reproduces classification of sunspot patterns based on preprocessing and neural net training datasets. Ultimately, the project intends to move from more rudimentary schemes, to develop spatial-temporal-spectral classes derived by correlating spatial and temporal variations in various wavelengths to the brightness fluctuation spectrum of the sun in those wavelengths. Once the approach is generalized, then the focus will naturally move from a 2-D to an n-D classification, where "n" includes time and frequency. Here, the 2-D perspective refers both to the actual SOH0 Michelson Doppler Imager (MDI) images that are processed, but also refers to the fact that a 2-D matrix is created from each image during preprocessing. The 2-D matrix is the result of running Principal Component Analysis (PCA) over the selected dataset images, and the resulting matrices and their eigenvalues are the objects that are stored in a database, classified, and compared. These matrices are indexed according to the standard McIntosh classification scheme.

  4. Flocculent flows in the chromospheric canopy of a sunspot

    CERN Document Server

    Vissers, Gregal

    2012-01-01

    High-quality imaging spectroscopy in the H{\\alpha} line, obtained with the CRisp Imaging SpectroPolarimeter (CRISP) at the Swedish 1-m Solar Telescope (SST) at La Palma and covering a small sunspot and its surroundings, are studied. They exhibit ubiquitous flows both along fibrils making up the chromospheric canopy away from the spot and in the superpenumbra. We term these flows "flocculent" to describe their intermittent character, that is morphologically reminiscent of coronal rain. The flocculent flows are investigated further in order to determine their dynamic and morphological properties. For the measurement of their characteristic velocities, accelerations and sizes, we employ a new versatile analysis tool, the CRisp SPectral EXplorer (CRISPEX), which we describe in detail. Absolute velocities on the order of 7.2-82.4 km/s are found, with an average value of 36.5\\pm5.9 km/s and slightly higher typical velocities for features moving towards the sunspot than away. These velocities are much higher than th...

  5. Diagnostics of a subsurface radial outflow from a sunspot

    CERN Document Server

    Braun, D; Lindsey, C; Jefferies, S M

    1996-01-01

    We measure the mean frequencies of acoustic waves propagating toward and away from a sunspot employing a spot-centered Fourier-Hankel decomposition of p-mode amplitudes as measured from a set of observations made at the South Pole in 1991. We demonstrate that there is a significant frequency shift between the inward and outward traveling waves which is consistent with the Doppler effect of a radial outflow from the sunspot. For p-modes of temporal frequencies of 3 mHz it is observed that the frequency shift decreases slightly with spatial frequency, for modes with degree l between 160 to 600. From the l dependence of the frequency shift, we infer that the mean radial outflow within the observed annular region (which extends between 30 and 137 Mm from the spot) increases nearly linearly with depth, reaching a magnitude of about 200 m/s at a depth of 20 Mm. This outflow exhibits properties similar to flows recently reported by Lindsey, et al. (1996) using spatially sensitive local helioseismic techniques.

  6. The lost sunspot cycle: New support from Be10 measurements

    CERN Document Server

    Karoff, C; Knudsen, M F; Olsen, J; Fogtmann-Schulz, A

    2014-01-01

    It has been suggested that the deficit in the number of spots on the surface of the Sun between 1790 and 1830, known as the Dalton minimum, contained an extra cycle that was not identified in the original sunspot record by Wolf. Though this cycle would be shorter and weaker than the average solar cycle, it would shift the magnetic parity of the solar magnetic field of the earlier cycles. This extra cycle is sometimes referred to as the 'lost solar cycle' or 'cycle 4b'. Here we reanalyse Be10 measurements with annual resolution from the NGRIP ice core in Greenland in order to investigate if the hypothesis regarding a lost sunspot cycle is supported by these measurements. Specifically, we make use of the fact that the Galactic cosmic rays, responsible for forming Be10 in the Earth's atmosphere, are affected differently by the open solar magnetic field during even and odd solar cycles. This fact enables us to evaluate if the numbering of cycles earlier than cycle 5 is correct. For the evaluation, we use Bayesian...

  7. Synthetic observations of wave propagation in a sunspot umbra

    Energy Technology Data Exchange (ETDEWEB)

    Felipe, T. [NorthWest Research Associates, Colorado Research Associates, Boulder, CO 80301 (United States); Socas-Navarro, H.; Khomenko, E. [Instituto de Astrofísica de Canarias, C/Vía Láctea, s/n, E-38205 La Laguna, Tenerife (Spain)

    2014-11-01

    Spectropolarimetric temporal series from Fe I λ6301.5 Å and Ca II infrared triplet lines are obtained by applying the Stokes synthesis code NICOLE to a numerical simulation of wave propagation in a sunspot umbra from MANCHA code. The analysis of the phase difference between Doppler velocity and intensity core oscillations of the Fe I λ6301.5 Å line reveals that variations in the intensity are produced by opacity fluctuations rather than intrinsic temperature oscillations, except for frequencies between 5 and 6.5 mHz. On the other hand, the photospheric magnetic field retrieved from the weak field approximation provides the intrinsic magnetic field oscillations associated to wave propagation. Our results suggest that this is due to the low magnetic field gradient of our sunspot model. The Stokes parameters of the chromospheric Ca II infrared triplet lines show striking variations as shock waves travel through the formation height of the lines, including emission self-reversals in the line core and highly abnormal Stokes V profiles. Magnetic field oscillations inferred from the Ca II infrared lines using the weak field approximation appear to be related with the magnetic field strength variation between the photosphere and the chromosphere.

  8. Solar small-scale dynamo and polarity of sunspot groups

    CERN Document Server

    Sokoloff, D; Abramenko, V

    2015-01-01

    In order to clarify a possible role of small-scale dynamo in formation of solar magnetic field, we suggest an observational test for small-scale dynamo action based on statistics of anti-Hale sunspot groups. As we have shown, according to theoretical expectations the small-scale dynamo action has to provide a population of sunspot groups which do not follow the Hale polarity law, and the density of such groups on the time-latitude diagram is expected to be independent on the phase of the solar cycle. Correspondingly, a percentage of the anti-Hale groups is expected to reach its maximum values during solar minima. For several solar cycles, we considered statistics of anti-Hale groups obtained by several scientific teams, including ours, to find that the percentage of anti-Hale groups becomes indeed maximal during a solar minimum. Our interpretation is that this fact may be explained by the small-scale dynamo action inside the solar convective zone.

  9. Solar small-scale dynamo and polarity of sunspot groups

    Science.gov (United States)

    Sokoloff, D.; Khlystova, A.; Abramenko, V.

    2015-08-01

    In order to clarify a possible role of small-scale dynamo in formation of solar magnetic field, we suggest an observational test for small-scale dynamo action based on statistics of anti-Hale sunspot groups. As we have shown, according to theoretical expectations the small-scale dynamo action has to provide a population of sunspot groups which do not follow the Hale polarity law, and the density of such groups on the time-latitude diagram is expected to be independent on the phase of the solar cycle. Correspondingly, a percentage of the anti-Hale groups is expected to reach its maximum values during solar minima. For several solar cycles, we considered statistics of anti-Hale groups obtained by several scientific teams, including ours, to find that the percentage of anti-Hale groups becomes indeed maximal during a solar minimum. Our interpretation is that this fact may be explained by the small-scale dynamo action inside the solar convective zone.

  10. Sunspot and Starspot Lifetimes in a Turbulent Erosion Model

    Science.gov (United States)

    Litvinenko, Yuri E.; Wheatland, M. S.

    2017-01-01

    Quantitative models of sunspot and starspot decay predict the timescale of magnetic diffusion and may yield important constraints in stellar dynamo models. Motivated by recent measurements of starspot lifetimes, we investigate the disintegration of a magnetic flux tube by nonlinear diffusion. Previous theoretical studies are extended by considering two physically motivated functional forms for the nonlinear diffusion coefficient D: an inverse power-law dependence D ∝ B‑ν and a step-function dependence of D on the magnetic field magnitude B. Analytical self-similar solutions are presented for the power-law case, including solutions exhibiting “superfast” diffusion. For the step-function case, the heat-balance integral method yields approximate solutions, valid for moderately suppressed diffusion in the spot. The accuracy of the resulting solutions is confirmed numerically, using a method which provides an accurate description of long-time evolution by imposing boundary conditions at infinite distance from the spot. The new models may allow insight into the differences and similarities between sunspots and starspots.

  11. Long-period oscillations of sunspot magnetic fields by simultaneous observations of the Global Oscillation Network Group and Solar and Heliospheric Observatory/Michelson Doppler imager

    Science.gov (United States)

    Efremov, V. I.; Parfinenko, L. D.; Solov'ev, A. A.; Riehokainen, A.

    2016-12-01

    For the first time, the ultra-low oscillation mode of the sunspot magnetic field strength has been detected with a high degree of confidence by ground-based observations of sunspots with the Global Oscillation Network Group (GONG) network of telescopes. Synchronous series of magnetograms derived from the GONG and Solar and Heliospheric Observatory/Michelson Doppler Imager (SOHO/MDI) have been processed. They were obtained on September 27-30, 2010, for the active region NOAA 11109 with a total duration of 80 h. The periods of magnetic field oscillations found by space data coincide with the periods defined with GONG. This confirms the physical reality of the oscillatory process. The power spectrum contains harmonics with periods of 26 h, 8-10 h, and 3-4 h.

  12. Tests of Sunspot Number Sequences: 2. Using Geomagnetic and Auroral Data

    CERN Document Server

    Lockwood, Mike; Barnard, Luke A; Scott, Chris J; Usoskin, Ilya G; Nevanlinna, Heikki

    2016-01-01

    We compare four sunspot-number data sequences against geomagnetic and terrestrial auroral observations. The comparisons are made for the original SIDC composite of Wolf-Zurich-International sunspot number [$R_{ISNv1}$], the group sunspot number [$R_{G}$] by Hoyt and Schatten (Solar Phys., 1998), the new "backbone" group sunspot number [$R_{BB}$] by Svalgaard and Schatten (Solar Phys., 2016), and the "corrected" sunspot number [$R_{C}$] by Lockwood at al. (J.G.R., 2014). Each sunspot number is fitted with terrestrial observations, or parameters derived from terrestrial observations to be linearly proportional to sunspot number, over a 30-year calibration interval of 1982-2012. The fits are then used to compute test sequences, which extend further back in time and which are compared to $R_{ISNv1}$, $R_{G}$, $R_{BB}$, and $R_{C}$. To study the long-term trends, comparisons are made using averages over whole solar cycles (minimum-to-minimum). The test variations are generated in four ways: i) using the IDV(1d) an...

  13. Sunspot Rotation as a Driver of Major Solar Eruptions in NOAA Active Region 12158

    CERN Document Server

    Vemareddy, P; Ravindra, B

    2016-01-01

    We studied the developing conditions of sigmoid structure under the influence of magnetic non-potential characteristics of a rotating sunspot in the active region (AR) 12158. Vector magnetic field measurements from Helioseismic Magnetic Imager and coronal EUV observations from Atmospheric Imaging Assembly reveal that the erupting inverse-S sigmoid had roots in the location of the rotating sunspot. Sunspot rotates at a rate of 0-5deg/h with increasing trend in the first half followed by a decrease. Time evolution of many non-potential parameters had a well correspondence with the sunspot rotation. The evolution of the AR magnetic structure is approximated by a time series of force free equilibria. The NLFFF magnetic structure around the sunspot manifests the observed sigmoid structure. Field lines from the sunspot periphery constitute the body of the sigmoid and those from interior overly the sigmoid similar to a fluxrope structure. While the sunspot is being rotating, two major CME eruptions occurred in the A...

  14. RE-EXAMINING SUNSPOT TILT ANGLE TO INCLUDE ANTI-HALE STATISTICS

    Energy Technology Data Exchange (ETDEWEB)

    McClintock, B. H. [University of Southern Queensland, Toowoomba, 4350 (Australia); Norton, A. A. [HEPL, Stanford University, Palo Alto, CA 94305 (United States); Li, J., E-mail: u1049686@umail.usq.edu.au, E-mail: aanorton@stanford.edu, E-mail: jli@igpp.ucla.edu [Department of Earth, Planetary, and Space Sciences, University of California at Los Angeles, Los Angeles, CA 90095 (United States)

    2014-12-20

    Sunspot groups and bipolar magnetic regions (BMRs) serve as an observational diagnostic of the solar cycle. We use Debrecen Photohelographic Data (DPD) from 1974-2014 that determined sunspot tilt angles from daily white light observations, and data provided by Li and Ulrich that determined sunspot magnetic tilt angle using Mount Wilson magnetograms from 1974-2012. The magnetograms allowed for BMR tilt angles that were anti-Hale in configuration, so tilt values ranged from 0 to 360° rather than the more common ±90°. We explore the visual representation of magnetic tilt angles on a traditional butterfly diagram by plotting the mean area-weighted latitude of umbral activity in each bipolar sunspot group, including tilt information. The large scatter of tilt angles over the course of a single cycle and hemisphere prevents Joy's law from being visually identified in the tilt-butterfly diagram without further binning. The average latitude of anti-Hale regions does not differ from the average latitude of all regions in both hemispheres. The distribution of anti-Hale sunspot tilt angles are broadly distributed between 0 and 360° with a weak preference for east-west alignment 180° from their expected Joy's law angle. The anti-Hale sunspots display a log-normal size distribution similar to that of all sunspots, indicating no preferred size for anti-Hale sunspots. We report that 8.4% ± 0.8% of all bipolar sunspot regions are misclassified as Hale in traditional catalogs. This percentage is slightly higher for groups within 5° of the equator due to the misalignment of the magnetic and heliographic equators.

  15. Major revision of sunspot number: implication for the ionosphere models

    Science.gov (United States)

    Gulyaeva, Tamara

    2016-07-01

    Recently on 1st July, 2015, a major revision of the historical sunspot number series has been carried out as discussed in [Clette et al., Revisiting the Sunspot Number. A 400-Year Perspective on the Solar Cycle, Space Science Reviews, 186, Issue 1-4, pp. 35-103, 2014). The revised SSN2.0 dataset is provided along with the former SSN1.0 data at http://sidc.oma.be/silso/. The SSN2.0 values exceed the former conventional SSN1.0 data so that new SSNs are greater in many cases than the solar radio flux F10.7 values which pose a problem of SSN2.0 implementation as a driver of the International Reference Ionosphere, IRI, its extension to plasmasphere, IRI-Plas, NeQuick model, Russian Standard Ionosphere, SMI. In particular, the monthly predictions of the F2 layer peak are based on input of the ITU-R (former CCIR) and URSI maps. The CCIR and URSI maps coefficients are available for each month of the year, and for two levels of solar activity: low (SSN = 0) and high (SSN = 100). SSN is the monthly smoothed sunspot number from the SSN1.0 data set used as an index of the level of solar activity. For every SSN different from 0 or 100 the critical frequency foF2 and the M3000F2 radio propagation factor used for the peak height hmF2 production may be evaluated by an interpolation. The ionospheric proxies of the solar activity IG12 index or Global Electron Content GEC12 index, driving the ionospheric models, are also calibrated with the former SSN1.0 data. The paper presents a solar proxy intended to calibrate SSN2.0 data set to fit F10.7 solar radio flux and/or SSN1.0 data series. This study is partly supported by TUBITAK EEEAG 115E915.

  16. 70 Years of Sunspot Observations at the Kanzelhöhe Observatory: Systematic Study of Parameters Affecting the Derivation of the Relative Sunspot Number

    Science.gov (United States)

    Pötzi, Werner; Veronig, Astrid M.; Temmer, Manuela; Baumgartner, Dietmar J.; Freislich, Heinrich; Strutzmann, Heinz

    2016-11-01

    The Kanzelhöhe Observatory (KSO) was founded during World War II by the Deutsche Luftwaffe (German Airforce) as one station of a network of observatories that were set up to provide information on solar activity in order to better assess the actual conditions of the Earth's ionosphere in terms of radio-wave propagation. Solar observations began in 1943 with photographs of the photosphere and drawings of sunspots, plage regions, and faculae, as well as patrol observations of the solar corona. At the beginning, all data were sent to Freiburg (Germany). After WW II, international cooperation was established and the data were sent to Zurich, Paris, Moscow, and Greenwich. Relative sunspot numbers have been derived since 1944. The agreement between relative sunspot numbers derived at KSO and the new International Sunspot Number (ISN) (SILSO World Data Center in International Sunspot Number Monthly Bulletin and online catalogue, 1945 - 2015) lies within {≈} 10 %. However, revisiting the historical data, we also find periods with larger deviations. The reasons for the deviations were twofold: On the one hand, a major instrumental change took place during which the instrument was relocated and modified. On the other hand, a period of frequent replacements of personnel caused significant deviations; this clearly shows the importance of experienced observers. In the long term, the instrumental improvements led to better image quality. Additionally, we find a long-term trend towards better seeing conditions that began in 2000.

  17. 70 Years of Sunspot Observations at the Kanzelhöhe Observatory: Systematic Study of Parameters Affecting the Derivation of the Relative Sunspot Number

    Science.gov (United States)

    Pötzi, Werner; Veronig, Astrid M.; Temmer, Manuela; Baumgartner, Dietmar J.; Freislich, Heinrich; Strutzmann, Heinz

    2016-03-01

    The Kanzelhöhe Observatory (KSO) was founded during World War II by the Deutsche Luftwaffe (German Airforce) as one station of a network of observatories that were set up to provide information on solar activity in order to better assess the actual conditions of the Earth's ionosphere in terms of radio-wave propagation. Solar observations began in 1943 with photographs of the photosphere and drawings of sunspots, plage regions, and faculae, as well as patrol observations of the solar corona. At the beginning, all data were sent to Freiburg (Germany). After WW II, international cooperation was established and the data were sent to Zurich, Paris, Moscow, and Greenwich. Relative sunspot numbers have been derived since 1944. The agreement between relative sunspot numbers derived at KSO and the new International Sunspot Number (ISN) (SILSO World Data Center in International Sunspot Number Monthly Bulletin and online catalogue, 1945 - 2015) lies within {≈} 10 %. However, revisiting the historical data, we also find periods with larger deviations. The reasons for the deviations were twofold: On the one hand, a major instrumental change took place during which the instrument was relocated and modified. On the other hand, a period of frequent replacements of personnel caused significant deviations; this clearly shows the importance of experienced observers. In the long term, the instrumental improvements led to better image quality. Additionally, we find a long-term trend towards better seeing conditions that began in 2000.

  18. Vigorous convection in a sunspot granular light bridge

    CERN Document Server

    Lagg, Andreas; van Noort, Michiel; Danilovic, Sanja

    2014-01-01

    Light bridges are the most prominent manifestation of convection in sunspots. The brightest representatives are granular light bridges composed of features that appear to be similar to granules. An in-depth study of the convective motions, temperature stratification, and magnetic field vector in and around light bridge granules is presented with the aim of identifying similarities and differences to typical quiet-Sun granules. Spectropolarimetric data from the Hinode Solar Optical Telescope were analyzed using a spatially coupled inversion technique to retrieve the stratified atmospheric parameters of light bridge and quiet-Sun granules. Central hot upflows surrounded by cooler fast downflows reaching 10 km/s clearly establish the convective nature of the light bridge granules. The inner part of these granules in the near surface layers is field free and is covered by a cusp-like magnetic field configuration. We observe hints of field reversals at the location of the fast downflows. The quiet-Sun granules in ...

  19. Sunspot Umbral Oscillations: Results from SOHO JOP097

    Science.gov (United States)

    O'Shea, E.; Muglach, K.; Fleck, B.

    2003-10-01

    We present results of an ongoing analysis of time series data, which were obtained in the context of the Joint Observing Program (JOP) 97 of the year 2000. This JOP included the Coronal Diagnostic Spectrometer (CDS) and the Michelson Doppler Imager (MDI) instrument, both part of SOHO, the TRACE satellite and various ground based observatories. We show evidence for apparently upwardly propagating in a sunspot umbra which we suggest are due to magnetoacoustic waves. These waves manifest themselves as oscillations in lines ranging in temperature from the upper photosphere/chromosphere to the corona. To our knowledge this is the first time umbral oscillations have been conclusively seen in coronal lines. This research is part of the European Solar Magnetometry Network (ESMN) supported by the EU through the TMR programme.

  20. DIAS effective sunspot number as an indicator of the ionospheric activity level over Europe

    National Research Council Canada - National Science Library

    Tsagouri, Ioanna; Zolesi, Bruno; Cander, Ljiljana R; Belehaki, Anna

    2010-01-01

    DIAS (European Digital Upper Atmosphere Server) effective sunspot number — R12eff was recently introduced as a proxy of the ionospheric conditions over Europe for regional ionospheric mapping purposes...

  1. On the contribution of sunspots to the observed frequency shifts of solar acoustic modes

    CERN Document Server

    Santos, A R G; Avelino, P P; Chaplin, W J; Campante, T L

    2016-01-01

    Activity-related variations in the solar oscillation properties have been known for 30 years. However, the relative importance of the different contributions to the observed variations is not yet fully understood. Our goal is to estimate the relative contribution from sunspots to the observed activity-related variations in the frequencies of the acoustic modes. We use a variational principle to relate the phase differences induced by sunspots on the acoustic waves to the corresponding changes in the frequencies of the global acoustic oscillations. From the sunspot properties (area and latitude as a function of time), we are able to estimate the spot-induced frequency shifts. These are then combined with a smooth frequency shift component, associated with long-term solar-cycle variations, and the results compared with the frequency shifts derived from the Global Oscillation Network Group (GONG) data. The result of this comparison is consistent with a sunspot contribution to the observed frequency shifts of rou...

  2. The Impact of the Revised Sunspot Record on Solar Irradiance Reconstructions

    CERN Document Server

    Kopp, G; Lean, J; Wu, C J

    2016-01-01

    Reliable historical records of total solar irradiance (TSI) are needed for climate change attribution and research to assess the extent to which long-term variations in the Sun's radiant energy incident on the Earth may exacerbate (or mitigate) the more dominant warming in recent centuries due to increasing concentrations of greenhouse gases. We investigate potential impacts of the new Sunspot Index and Long-term Solar Observations (SILSO) sunspot-number time series on model reconstructions of TSI. In contemporary TSI records, variations on time scales longer than about a day are dominated by the opposing effects of sunspot darkening and facular brightening. These two surface magnetic features, retrieved either from direct observations or from solar activity proxies, are combined in TSI models to reproduce the current TSI observational record. Indices that manifest solar-surface magnetic activity, in particular the sunspot-number record, then enable the reconstruction of historical TSI. Revisions to the sunsp...

  3. Magneto-acoustic waves in sunspots: first results from a new 3D nonlinear magnetohydrodynamic code

    CERN Document Server

    Felipe, T; Collados, M

    2010-01-01

    Waves observed in the photosphere and chromosphere of sunspots show complex dynamics and spatial patterns. The interpretation of high-resolution sunspot wave observations requires modeling of three-dimensional non-linear wave propagation and mode transformation in the sunspot upper layers in realistic spot model atmospheres. Here we present the first results of such modeling. We have developed a 3D non-linear numerical code specially designed to calculate the response of magnetic structures in equilibrium to an arbitrary perturbation. The code solves the 3D nonlinear MHD equations for perturbations; it is stabilized by hyper-diffusivity terms and is fully parallelized. The robustness of the code is demonstrated by a number of standard tests. We analyze several simulations of a sunspot perturbed by pulses of different periods at subphotospheric level, from short periods, introduced for academic purposes, to longer and realistic periods of three and five minutes. We present a detailed description of the three-d...

  4. Long-Term Sunspot Number Prediction based on EMD Analysis and AR Model

    Institute of Scientific and Technical Information of China (English)

    Tong Xu; Jian Wu; Zhen-Sen Wu; Qiang Li

    2008-01-01

    The Empirical Mode Decomposition (EMD) and Auto-Regressive model (AR) are applied to a long-term prediction of sunspot numbers. With the sample data of sunspot numbers from 1848 to 1992, the method is evaluated by examining the measured data of the solar cycle 23 with the prediction: different time scale components are obtained by the EMD method and multi-step predicted values are combined to reconstruct the sunspot number time series. The result is remarkably good in comparison to the predictions made by the solar dynamo and precursor approaches for cycle 23. Sunspot numbers of the coming solar cycle 24 are obtained with the data from 1848 to 2007, the maximum amplitude of the next solar cycle is predicted to be about 112 in 2011-2012.

  5. Does Building a Relative Sunspot Number Make Sense? A Qualified 'Yes'

    CERN Document Server

    Svalgaard, Leif

    2015-01-01

    Recent research has demonstrated that the number of sunspots per group ('active region') has been decreasing over the last two or three solar cycles and that the classical Relative Sunspot Number (SSN) no longer is a good representation of solar magnetic activity such as revealed by e.g. the F10.7 cm microwave flux. The SSN is derived under the assumption that the number of spots per group is constant (in fact, nominally equal to 10). When this is no longer the case (the ratio is approaching 5, only half of its nominal value) the question arises how to construct a sunspot number series that takes that into account. We propose to harmonize the SSN with the sunspot Group Count that has been shown to follow F10.7 very well, but also to include the day-to-day variations of the spot count in order to preserve both long-term and short-term variability.

  6. Sunspot Numbers and Areas from the Madrid Astronomical Observatory (1876-1986)

    CERN Document Server

    Aparicio, A J P; Carrasco, V M S; Gallego, M C

    2014-01-01

    The solar program of the Astronomical Observatory of Madrid started in 1876. For ten solar cycles, observations were made in this institution to determine sunspot numbers and areas. The program was completed in 1986. The resulting data have been published in various Spanish scientific publications. The metadata allowed four periods of this program (with different observers and instruments) to be identified. In the present work, the published data were retrieved and digitized. Their subsequent analysis showed that most of these data can be considered reliable given their very high correlation with international reference indices (International Sunspot Number, Group Sunspot Number, and Sunspot Area). An abrupt change emerged in the spots/groups ratio in 1946 which lasted until 1972.

  7. Influence of the lifetime parameter on the rotation rate of sunspots

    Science.gov (United States)

    Zuccarello, F.

    1993-05-01

    Recent investigations on the photospheric angular velocity pattern have shown that young and short- living tracers show rotation rates higher than those determined both by older tracers and by photospheric plasma. As a direct relationship between the age of the tracer and the angular velocity determination has been found (Zappalà & Zuccarello 1991), it seemed very interesting to investigate whether also the "lifetime" parameter might have a role on angular velocity determinations. We have therefore analyzed the sunspot-group data reported in the Greenwich Photoheliographic Results during the 1874-1976 period. 9000 objects were selected as young sunspot-groups (YSG) and, using the lifetime parameter as selecting rule, we could catalogue 4463 objects having a lifetime between 2 and 10 d. The rotation rate of these objects as a function of their lifetime was calculated and the results obtained may be summarized in the following main points: 1. Independently of their lifetime, sunspots rotate during the first 2-3 days of life in the photosphere, at a higher rate than that of recurrent sunspots. 2. Sunspots with a lifetime ranging from 2 to 8 d are more efficiently decelerated than YSG, while 11-day living sunspots are less efficiently decelerated. 3. Sunspots in the equatorial belt (0-10°) having a lifetime comparable to that of supergranule cells, rotate slower than the cells themselves. 4. The angular velocity measured during the last day of life is lower both than that of YSG and than that deduced by sunspots which disappear the day after. These results have been analyzed in the scenario of the sunspots cluster model ( 1987). According to the conclusions drawn, the initial higher angular velocity of young and short-living sunspots is not a function of the cluster "aggregation capability"; the rate of rise of the merging level through the convection zone is influenced by (or influences) the ability of the cluster to keep coalesced; finally, when the merging level

  8. Rapid changes of sunspot structure associated with solar eruptions

    Science.gov (United States)

    Wang, Haimin; Liu, Chang

    2011-08-01

    In this paper we summarize the studies of flare-related changes of photospheric magnetic fields. When vector magnetograms are available, we always find an increase of transverse field at the polarity inversion line (PIL). We also discuss 1 minute cadence line-of-sight MDI magnetogram observations, which usually show prominent changes of magnetic flux contained in the flaring δ spot region. The observed limb-ward flux increases while disk-ward flux decreases rapidly and irreversibly after flares. These observations provides evidences, either direct or indirect, for the theory and prediction of Hudson, Fisher & Welsch (2008) that the photospheric magnetic fields would respond to coronal field restructuring and turn to a more horizontal state near the PIL after eruptions. From the white-light observations, we find that at flaring PIL, the structure becomes darker after an eruption, while the peripheral penumbrae decay. Using high-resolution Hinode data, we find evidence that only dark fibrils in the ``uncombed'' penumbral structure disappear while the bright grains evolve to G-band bright points after flares.

  9. Should We Try to Re-Construct the American Relative Sunspot Index (Ra)? (Abstract)

    Science.gov (United States)

    Howe, R.

    2016-06-01

    (Abstract only) The new correction of the international sunspot number (ISN), called the Sunspot Number Version 2.0, led by Frédéric Clette (Director of the World Data Centre [WDC]-SILSO), Ed Cliver (National Solar Observatory), and Leif Svalgaard (Stanford University), nullifies the claim that there has been a Modern Grand Maximum. This comes from the International Astronomical Union (IAU) press release, August 2015 (http://www.iau.org/news/pressreleases/detail/iau1508/).

  10. Sunspot Rotation as a Driver of Major Solar Eruptions in the NOAA Active Region 12158

    Science.gov (United States)

    Vemareddy, P.; Cheng, X.; Ravindra, B.

    2016-09-01

    We studied the development conditions of sigmoid structure under the influence of the magnetic non-potential characteristics of a rotating sunspot in the active region (AR) 12158. Vector magnetic field measurements from the Helioseismic Magnetic Imager and coronal EUV observations from the Atmospheric Imaging Assembly reveal that the erupting inverse-S sigmoid had roots at the location of the rotating sunspot. The sunspot rotates at a rate of 0°-5° h-1 with increasing trend in the first half followed by a decrease. The time evolution of many non-potential parameters had a good correspondence with the sunspot rotation. The evolution of the AR magnetic structure is approximated by a time series of force-free equilibria. The non-linear force-free field magnetic structure around the sunspot manifests the observed sigmoid structure. Field lines from the sunspot periphery constitute the body of the sigmoid and those from the interior overlie the sigmoid, similar to a flux rope structure. While the sunspot was rotating, two major coronal mass ejection eruptions occurred in the AR. During the first (second) event, the coronal current concentrations were enhanced (degraded), consistent with the photospheric net vertical current; however, magnetic energy was released during both cases. The analysis results suggest that the magnetic connections of the sigmoid are driven by the slow motion of sunspot rotation, which transforms to a highly twisted flux rope structure in a dynamical scenario. Exceeding the critical twist in the flux rope probably leads to the loss of equilibrium, thus triggering the onset of the two eruptions.

  11. An Analysis of the Sunspot Groups and Flares of Solar Cycle 23

    Science.gov (United States)

    2012-05-07

    for compact interior. The classes AXX, BXO , BXI, CRO, HSX, HAX, HRX, and HHX have a negligibly small probability of producing an Hα flare. Sunspot...to DRO, HHX, CHO, CRI, and CRO in this study and to FAO, FAC, AXX, BXO , and HRX in Kildahl (1980). While there is good agreement between the two...simplest classes AXX, BXO and CRO accounted for a nearly 28% decrease in total sunspot contribution. Figure 5 indicates that these categories are

  12. Modeling of Sunspot Numbers by a Modified Binary Mixture of Laplace Distribution Functions

    Science.gov (United States)

    Sabarinath, A.; Anilkumar, A. K.

    2008-07-01

    This paper presents a new approach for describing the shape of 11-year sunspot cycles by considering the monthly averaged values. This paper also brings out a prediction model based on the analysis of 22 sunspot cycles from the year 1749 onward. It is found that the shape of the sunspot cycles with monthly averaged values can be described by a functional form of modified binary mixture of Laplace density functions, modified suitably by introducing two additional parameters in the standard functional form. The six parameters, namely two locations, two scales, and two area parameters, characterize this model. The nature of the estimated parameters for the sunspot cycles from 1749 onward has been analyzed and finally we arrived at a sufficient set of the parameters for the proposed model. It is seen that this model picks up the sunspot peaks more closely than any other model without losing the match at other places at the same time. The goodness of fit for the proposed model is also computed with the Hathaway Wilson Reichmann overline{χ} measure, which shows, on average, that the fitted model passes within 0.47 standard deviations of the actual averaged monthly sunspot numbers.

  13. Dynamics in Sunspot Umbra as Seen in New Solar Telescope and Interface Region Imaging Spectrograph Data

    CERN Document Server

    Yurchyshyn, Vasyl; Kilcik, Ali

    2014-01-01

    We analyse sunspot oscillations using Interface Region Imaging Spectrograph (IRIS) slit-jaw and spectral data and narrow-band chromospheric images from the New Solar Telescope (NST) for the main sunspot in NOAA AR 11836. We report that the difference between the shock arrival times as measured the Mg II k 2796.35\\AA\\ and Si IV 1393.76\\AA\\ line formation levels changes during the observed period and peak-to-peak delays may range from 40~s to zero. The intensity of chromospheric shocks also displays a long term (about 20~min) variations. NST's high spatial resolution \\ha\\ data allowed us to conclude that in this sunspot umbral flashes (UFs) appeared in the form of narrow bright lanes stretched along the light bridges and around clusters of umbral bright points. Time series also suggested that UFs preferred to appear on the sunspot-center side of light bridges, which may indicate the existence of a compact sub-photospheric driver of sunspot oscillations. The sunspot's umbra as seen in the IRIS chromospheric and ...

  14. The unusual minimum of sunspot cycle 23 a consequence of Sun's meridional plasma flow variations

    CERN Document Server

    Nandy, Dibyendu; Martens, Petrus C H; 10.1038/nature09786

    2013-01-01

    Direct observations over the past four centuries show that the number of sunspots observed on the Sun's surface vary periodically, going through successive maxima and minima. Following sunspot cycle 23, the Sun went into a prolonged minimum characterized by a very weak polar magnetic field and an unusually large number of days without sunspots. Sunspots are strongly magnetized regions and are generated by a dynamo mechanism which recreates the solar polar field mediated via plasma flows. Here we report results from kinematic dynamo simulations which demonstrate that a fast meridional flow in the early half of a cycle, followed by a slower flow in the latter half, reproduces both the characteristics of the minimum of sunspot cycle 23 - a large number of spotless days and a relatively weak polar field. Our model predicts that, in general, very deep minima are associated with weak polar fields. Sunspots govern the solar radiative energy and radio flux, and in conjunction with the polar field, modulate the solar ...

  15. Detección de Zonas de Penumbra y Visibilidad a los Flujos Electromagnéticos en Campos Abiertos

    Directory of Open Access Journals (Sweden)

    Jairo Madrigal-Argáez

    2007-12-01

    Full Text Available This article exhibits a computational procedure that allows, on a Terrain Elevation Map (TEM of a geographic region of interest, are as that are in line with direct impact of energy flows generated from point sources located. This presents visually, the geographical are as of visibility and penumbras of electromagnetic radiation of punctual sources. In developing of the exercise ha ve be en covered two aspects: the first produces a 3D geometric model that represents the topographic profile of geographical regions, based on the available databases as a result ofthe project SRTM (NGA and NASA[8]. The second, proposed a model of propagation for a radiation so urce wave in the space free of charge and sources in homogeneous and isotropic regions, according to the solution of Maxwell to the propagation of electromagnetic waves and in accordance with the law and Snell and techniques of Ray-Tracing (RT.

  16. Blood flow and vascular reactivity in collaterally perfused brain tissue. Evidence of an ischemic penumbra in patients with acute stroke

    DEFF Research Database (Denmark)

    Olsen, T S; Larsen, B; Herning, M;

    1983-01-01

    ischemic low flow areas were a constant finding in the collaterally perfused tissue. In 6 of the patients, the collaterally perfused part of the brain had low flow values comparable to those of an "ischemic penumbra" (viable, but functionally depressed brain tissue due to inadequate perfusion......In a group of 48 patients with completed stroke, 8 patients had viable collaterally perfused brain tissue which was accessible for rCBF recordings with a two dimensional technique. All 8 had deep subcortical infarcts on CT-scan, and angiographic occlusion of the arteries normally supplying...... the infarcted territory. The brain tissue overlying the deep infarcts appeared normal on CT-scan and was supplied by collateral circulation. rCBF was measured in all within 72 hours after the stroke. The intra-carotid Xe-133 injection method and a 254 multidetector camera were used to study rCBF. Relatively...

  17. Delay-sensitive and delay-insensitive deconvolution perfusion-CT: similar ischemic core and penumbra volumes if appropriate threshold selected for each

    Energy Technology Data Exchange (ETDEWEB)

    Man, Fengyuan [Capital Medical University, Department of Radiology, Beijing Tongren Hospital, Beijing (China); University of Virginia, Department of Radiology, Neuroradiology Division, Charlottesville, VA (United States); Patrie, James T.; Xin, Wenjun [University of Virginia, Department of Public Health Sciences, Charlottesville, VA (United States); Zhu, Guangming [University of Virginia, Department of Radiology, Neuroradiology Division, Charlottesville, VA (United States); Military General Hospital of Beijing PLA, Department of Neurology, Beijing (China); Hou, Qinghua [University of Virginia, Department of Radiology, Neuroradiology Division, Charlottesville, VA (United States); The Second Affiliated Hospital of Guangzhou Medical University, Department of Neurology, Guangzhou (China); Michel, Patrik; Eskandari, Ashraf [Centre Hospitalier Universitaire Vaudois, Department of Neurology, Lausanne (Switzerland); Jovin, Tudor [University of Pittsburgh, Department of Neurology, Pittsburgh, PA (United States); Xian, Junfang; Wang, Zhenchang [Capital Medical University, Department of Radiology, Beijing Tongren Hospital, Beijing (China); Wintermark, Max [University of Virginia, Department of Radiology, Neuroradiology Division, Charlottesville, VA (United States); Centre Hospitalier Universitaire Vaudois, Department of Radiology, Lausanne (Switzerland); Stanford University, Department of Radiology, Neuroradiology Division, Stanford, CA (United States)

    2015-03-07

    Perfusion-CT (PCT) processing involves deconvolution, a mathematical operation that computes the perfusion parameters from the PCT time density curves and an arterial curve. Delay-sensitive deconvolution does not correct for arrival delay of contrast, whereas delay-insensitive deconvolution does. The goal of this study was to compare delay-sensitive and delay-insensitive deconvolution PCT in terms of delineation of the ischemic core and penumbra. We retrospectively identified 100 patients with acute ischemic stroke who underwent admission PCT and CT angiography (CTA), a follow-up vascular study to determine recanalization status, and a follow-up noncontrast head CT (NCT) or MRI to calculate final infarct volume. PCT datasets were processed twice, once using delay-sensitive deconvolution and once using delay-insensitive deconvolution. Regions of interest (ROIs) were drawn, and cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) in these ROIs were recorded and compared. Volume and geographic distribution of ischemic core and penumbra using both deconvolution methods were also recorded and compared. MTT and CBF values are affected by the deconvolution method used (p < 0.05), while CBV values remain unchanged. Optimal thresholds to delineate ischemic core and penumbra are different for delay-sensitive (145 % MTT, CBV 2 ml x 100 g{sup -1} x min{sup -1}) and delay-insensitive deconvolution (135 % MTT, CBV 2 ml x 100 g{sup -1} x min{sup -1} for delay-insensitive deconvolution). When applying these different thresholds, however, the predicted ischemic core (p = 0.366) and penumbra (p = 0.405) were similar with both methods. Both delay-sensitive and delay-insensitive deconvolution methods are appropriate for PCT processing in acute ischemic stroke patients. The predicted ischemic core and penumbra are similar with both methods when using different sets of thresholds, specific for each deconvolution method. (orig.)

  18. A solar flare disturbing a light wall above a sunspot light bridge

    CERN Document Server

    Hou, Yijun; Li, Ting; Yang, Shuhong; Li, Leping; Li, Xiaohong

    2016-01-01

    With the high-resolution data from the Interface Region Imaging Spectrograph, we detect a light wall above a sunspot light bridge in the NOAA active region (AR) 12403. In the 1330 A slit-jaw images, the light wall is brighter than the ambient areas while the wall top and base are much brighter than the wall body, and it keeps oscillating above the light bridge. A C8.0 flare caused by a filament activation occurred in this AR with the peak at 02:52 UT on 2015 August 28, and the flare's one ribbon overlapped the light bridge which was the observational base of the light wall. Consequently, the oscillation of the light wall was evidently disturbed. The mean projective oscillation amplitude of the light wall increased from 0.5 Mm to 1.6 Mm before the flare, and decreased to 0.6 Mm after the flare. We suggest that the light wall shares a group of magnetic field lines with the flare loops, which undergo a magnetic reconnection process, and they constitute a coupled system. When the magnetic field lines are pushed u...

  19. The Impact of the Revised Sunspot Record on Solar Irradiance Reconstructions

    Science.gov (United States)

    Kopp, G.; Krivova, N.; Wu, C. J.; Lean, J.

    2016-11-01

    Reliable historical records of the total solar irradiance (TSI) are needed to assess the extent to which long-term variations in the Sun's radiant energy that is incident upon Earth may exacerbate (or mitigate) the more dominant warming in recent centuries that is due to increasing concentrations of greenhouse gases. We investigate the effects that the new Sunspot Index and Long-term Solar Observations (SILSO) sunspot-number time series may have on model reconstructions of the TSI. In contemporary TSI records, variations on timescales longer than about a day are dominated by the opposing effects of sunspot darkening and facular brightening. These two surface magnetic features, retrieved either from direct observations or from solar-activity proxies, are combined in TSI models to reproduce the current TSI observational record. Indices that manifest solar-surface magnetic activity, in particular the sunspot-number record, then enable reconstructing historical TSI. Revisions of the sunspot-number record therefore affect the magnitude and temporal structure of TSI variability on centennial timescales according to the model reconstruction methods that are employed. We estimate the effects of the new SILSO record on two widely used TSI reconstructions, namely the NRLTSI2 and the SATIRE models. We find that the SILSO record has little effect on either model after 1885, but leads to solar-cycle fluctuations with greater amplitude in the TSI reconstructions prior. This suggests that many eighteenth- and nineteenth-century cycles could be similar in amplitude to those of the current Modern Maximum. TSI records based on the revised sunspot data do not suggest a significant change in Maunder Minimum TSI values, and from comparing this era to the present, we find only very small potential differences in the estimated solar contributions to the climate with this new sunspot record.

  20. Presence of C2 molecular Lines in Sunspot Umbral Spectra

    Science.gov (United States)

    Sriramachandran, P.; Sindhan, R.; Ramaswamy, S.; Shanmugavel, R.

    2016-10-01

    The C2 molecule is well known for its astrophysical importance. The radiative transition parameters that include Franck-Condon (FC) factor, r-centroid, electronic transition moment, Einstein coefficient, absorption band oscillator strength, effective temperatures and radiative life time have been estimated for the Swan band (d3Πg -a3Πu) system of C2 molecule for experimentally observed vibrational levels using RKR (Rydberg-Klein-Rees) potential energy curve. The lifetime for the d3Πg state of C2 molecule was found to be 82.36 ns for the v‧ = 0 level. A reliable numerical integration method has been used to solve the radial Schrödinger equation for the vibrational wave functions of upper and lower electronic states based on the latest available spectroscopic data and known wavelengths. The estimated radiative transition parameters are tabulated. The effective vibrational temperature of Swan band system of C2 molecule is found agreed with the effective rotational temperature from photosphere spectrum. Hence, the radiative transition parameters and effective temperatures help us to ascertain the presence of C2 molecule in the interstellar medium, photosphere and sunspots.

  1. Analysis of the vector magnetic fields of complex sunspots

    Science.gov (United States)

    Patty, S. R.

    1981-01-01

    An analysis of the vector magnetic field in the delta-configurations of two complex sunspot groups is presented, noting several characteristics identified in the delta-configurations. The observations of regions 2469 (S12E80) and 2470 (S21E83) took place in May, 1980 with a vector magnetograph, verified by optical viewing. Longitudinal magnetic field plots located the delta-configurations in relation to the transverse field neutral line. It is shown that data on the polarization yields qualitative information on the magnetic field strengths, while the azimuth of the transverse field can be obtained from the relative intensities of linear polarization measurements aligned with respect to the magnetograph analyses axis at 0 and 90 deg, and at the plus and minus 45 deg positions. Details of the longitudinal fields are discussed. A strong, sheared transverse field component is found to be a signature of strong delta. A weak delta is accompanied by a weak longitudinal gradient with an unsheared transverse component of variable strength.

  2. Chromospheric Plasma Ejections in a Light Bridge of a Sunspot

    Science.gov (United States)

    Song, Donguk; Chae, Jongchul; Yurchyshyn, Vasyl; Lim, Eun-Kyung; Cho, Kyung-Suk; Yang, Heesu; Cho, Kyuhyoun; Kwak, Hannah

    2017-02-01

    It is well-known that light bridges (LBs) inside a sunspot produce small-scale plasma ejections and transient brightenings in the chromosphere, but the nature and origin of such phenomena are still unclear. Utilizing the high-spatial and high-temporal resolution spectral data taken with the Fast Imaging Solar Spectrograph and the TiO 7057 Å broadband filter images installed at the 1.6 m New Solar Telescope of Big Bear Solar Observatory, we report arcsecond-scale chromospheric plasma ejections (1.″7) inside a LB. Interestingly, the ejections are found to be a manifestation of upwardly propagating shock waves as evidenced by the sawtooth patterns seen in the temporal-spectral plots of the Ca ii 8542 Å and Hα intensities. We also found a fine-scale photospheric pattern (1″) diverging with a speed of about 2 km s‑1 two minutes before the plasma ejections, which seems to be a manifestation of magnetic flux emergence. As a response to the plasma ejections, the corona displayed small-scale transient brightenings. Based on our findings, we suggest that the shock waves can be excited by the local disturbance caused by magnetic reconnection between the emerging flux inside the LB and the adjacent umbral magnetic field. The disturbance generates slow-mode waves, which soon develop into shock waves, and manifest themselves as the arcsecond-scale plasma ejections. It also appears that the dissipation of mechanical energy in the shock waves can heat the local corona.

  3. Correlation Between Sunspot Number and ca II K Emission Index

    CERN Document Server

    Bertello, Luca; Tlatov, Andrey; Singh, Jagdev

    2016-01-01

    Long-term synoptic observations in the resonance line of Ca II K constitute a fundamental database for a variety of retrospective analyses of the state of the solar magnetism. Synoptic Ca II K observations began in late 1904 at the Kodaikanal Observatory, in India. In early 1970s, the National Solar Observatory (NSO) at Sacramento Peak (USA) started a new program of daily Sun-as-a-star observations in the Ca II K line. Today the NSO is continuing these observations through its Synoptic Optical Long-term Investigations of the Sun (SOLIS) facility. These different data sets can be combined into a single disk-integrated Ca II K index time series that describes the average properties of the chromospheric emission over several solar cycles. We present such a Ca II K composite and discuss its correlation with the new entirely revised sunspot number data series. For this preliminary investigation, the scaling factor between pairs of time series was determined assuming a simple linear model for the relationship betwe...

  4. Correlation Between Sunspot Number and Ca ii K Emission Index

    Science.gov (United States)

    Bertello, Luca; Pevtsov, Alexei; Tlatov, Andrey; Singh, Jagdev

    2016-11-01

    Long-term synoptic observations in the resonance line of Ca ii K constitute a fundamental database for a variety of retrospective analyses of the state of the solar magnetism. Synoptic Ca ii K observations began in late 1904 at the Kodaikanal Observatory in India. In the early 1970s, the National Solar Observatory (NSO) at Sacramento Peak (USA) started a new program of daily Sun-as-a-star observations in the Ca ii K line. Today the NSO is continuing these observations through its Synoptic Optical Long-term Investigations of the Sun (SOLIS) facility. These different data sets can be combined into a single disk-integrated Ca ii K index time series that describes the average properties of the chromospheric emission over several solar cycles. We present such a Ca ii K composite and discuss its correlation with the new entirely revised sunspot number data series. For this preliminary investigation, the scaling factor between pairs of time series was determined assuming a simple linear model for the relationship between the monthly mean values during the duration of overlapping observations.

  5. Identification of Beryllium Hydride Isotopomer Lines in Sunspot Umbral Spectra

    Directory of Open Access Journals (Sweden)

    Shanmugavel, R.

    2008-06-01

    Full Text Available A high resolution spectrum of FTS sunspot umbra of NSO/Kitt Peak was used to conduct a search for the molecular absorption lines due to BeH, BeD and BeT isotopomers. Analysis led to estimates of identification of the molecular lines of bands A - X (0,0, (1,1 and (2,2 for BeH, A - X (0,0, (1,1, (2,2 and (3,3 for BeD and of A - X (0,0, (1,1 and (2,2 for BeT. Among the identified lines, those which are well resolved were selected for measurements to calculate equivalent widths. The values of effective rotational temperature T were estimated for bands A - X(1,1 and (2,2 of BeH, A - X(1,1 of BeD and A - X(2,2 of BeT to be 4228K, 4057K, 3941K and 3243K respectively.

  6. Enhancement of a sunspot light wall with external disturbances

    CERN Document Server

    Yang, Shuhong; Erdélyi, Robert

    2016-01-01

    Based on the \\emph{Interface Region Imaging Spectrograph} observations, we study the response of a solar sunspot light wall to external disturbances. A flare occurrence near the light wall caused material to erupt from the lower solar atmosphere into the corona. Some material falls back to the solar surface, and hits the light bridge (i.e., the base of the light wall), then sudden brightenings appear at the wall base followed by the rise of wall top, leading to an increase of the wall height. Once the brightness of the wall base fades, the height of the light wall begins to decrease. Five hours later, another nearby flare takes place, a bright channel is formed that extends from the flare towards the light bridge. Although no obvious material flow along the bright channel is found, some ejected material is conjectured to reach the light bridge. Subsequently, the wall base brightens and the wall height begins to increase again. Once more, when the brightness of the wall base decays, the wall top fluctuates to ...

  7. Efficacy of a coaxial system with a compliant balloon catheter for navigation of the Penumbra reperfusion catheter in tortuous arteries: technique and case experience.

    Science.gov (United States)

    Takahira, Kazuki; Kataoka, Taketo; Ogino, Tatsuya; Endo, Hideki; Nakamura, Hirohiko

    2017-04-01

    OBJECTIVE The authors describe a method by which they easily and atraumatically navigate a large-bore reperfusion catheter of the Penumbra system to an embolus by using a coaxial system with a compliant balloon catheter in patients with tortuous arteries. METHODS A retrospective review of the prospective endovascular database was performed to identify cases in which a coaxial system with a compliant balloon catheter (Scepter C, MicroVention/Terumo; or TransForm C, Stryker Neurovascular) and a large-bore reperfusion catheter of the Penumbra system (Penumbra, Inc.) was used. The authors achieved a stable guiding sheath position and delivered the coaxial system with a compliant balloon catheter and a large-bore reperfusion catheter. Then, the balloon was inflated somewhat when the distal tip of the balloon was slightly advanced from the tip of the reperfusion catheter, and together the coaxial system was advanced to an embolus over a 0.014-in guidewire, even around the corner. When the distal tip of the balloon catheter reached the embolus, the authors deflated the balloon and navigated the large-bore reperfusion catheter to the embolus. Finally, the aspiration of the embolus with the Penumbra MAX pump was begun. RESULTS Between May 2014 and September 2015, the authors used this technique in 17 cases: 16 cases of middle cerebral artery occlusion (including 5 cases of internal carotid artery occlusion) and 1 case of basilar artery occlusion (age range 36-88 years, mean age 74.7 years, 13 men). For the reperfusion catheter of the Penumbra system, the 5MAX ACE was used in 15 cases, and the 5MAX was used in 2 cases. As a compliant balloon catheter, the Scepter C was used in 16 cases, and the TransForm C was used in 1 case. The technique was successful in 16 cases (94.1%). No parent artery dissections were noted in any cases. Catheter-induced vasospasm was noted in 1 case, but the vasospasm was transient. CONCLUSIONS A coaxial system with a compliant balloon catheter can

  8. LDRD final report on enhanced edge detection techniques for manufacturing quality control and materials characterization

    Energy Technology Data Exchange (ETDEWEB)

    Osbourn, G.C.

    1997-01-01

    Detecting object boundaries in the presence of cast shadows is a difficult task for machine vision systems. A new edge detector is presented which responds to shadow penumbras and abrupt object edges with distinguishable signals. The detector requires the use of spatially extended light sources and sufficient video resolution to resolve the shadow penumbras of interest. Detection of high frequency noise is suppressed without requiring image-dependent adjustment of signal thresholds. The ability of the edge operator to distinguish shadow penumbras from abrupt object boundaries while suppressing responses to high frequency noise and texture is illustrated with idealized shadow and object edge intensity profiles. Selective detection of object boundaries in a video scene with a cast shadow has also been demonstrated with this operator.

  9. Statistical Study on Personal Reduction Coefficients of Sunspot Numbers Since 1981

    Science.gov (United States)

    Cho, Il-Hyun; Bong, Su-Chan; Cho, Kyung-Suk; Lee, Jaejin; Kim, Rok-Soon; Park, Young-Deuk; Kim, Yeon-Han

    2014-12-01

    Using sunspot number data from 270 historical stations for the period 1981-2013, we investigate their personal reduction coefficients ($) statistically. Chang & Oh (2012) perform a simulation showing that the k varies with the solar cycle. We try to verify their results using observational data. For this, a weighted mean and weighted standard deviation of monthly sunspot number are used to estimate the error from observed data. We find that the observed error (noise) is much smaller than that used in the simulation. Thus no distinct k-variation with the solar cycle is observed contrary to the simulation. In addition, the probability distribution of k is determined to be non-Gaussian with a fat-tail on the right side. This result implies that the relative sunspot number after 1981 might be overestimated since the mean value of k is less than that of the Gaussian distribution.

  10. He I vector magnetic field maps of a sunspot and its superpenumbral fine-structure

    CERN Document Server

    Schad, T A; Lin, H; Tritschler, A

    2015-01-01

    Advanced inversions of high-resolution spectropolarimetric observations of the He I triplet at 1083 nm are used to generate unique maps of the chromospheric magnetic field vector across a sunspot and its superpenumbral canopy. The observations were acquired by the Facility Infrared Spectropolarimeter (FIRS) at the Dunn Solar Telescope (DST) on 29 January 2012. Multiple atmospheric models are employed in the inversions, as superpenumbral Stokes profiles are dominated by atomic-level polarization while sunspot profiles are Zeeman-dominated but also exhibit signatures perhaps induced by symmetry breaking effects of the radiation field incident on the chromospheric material. We derive the equilibrium magnetic structure of a sunspot in the chromosphere, and further show that the superpenumbral magnetic field does not appear finely structured, unlike the observed intensity structure. This suggests fibrils are not concentrations of magnetic flux but rather distinguished by individualized thermalization. We also dire...

  11. Relationship between geomagnetic classes’ activity phases and their occurrence during the sunspot cycle

    Directory of Open Access Journals (Sweden)

    Frédéric Ouattara

    2009-06-01

    Full Text Available Four well known geomagnetic classes of activity such as quiet days activity, fluctuating activity, recurrent activity
    and shock activity time occurrences have been determined not only by using time profile of sunspot number
    Rz but also by using aa index values.
    We show that recurrent wind stream activity and fluctuating activity occur in opposite phase and slow solar wind
    activity during minimum phase and shock activity at the maximum phase.
    It emerges from this study that fluctuating activity precedes the sunspot cycle by π/2 and the latter also precedes
    recurrent activity by π/2. Thus in the majority the activities do not happen at random; the sunspot cycle starts
    with quiet days activity, continues with fluctuating activity and during its maximum phase arrives shock activity.
    The descending phase is characterized by the manifestation of recurrent wind stream activity.

  12. Tracing sunspot groups to determine angular momentum transfer on the Sun

    CERN Document Server

    Sudar, D; Ruždjak, D; Brajša, R; Wöohl, H

    2014-01-01

    The goal of this paper is to investigate Reynolds stresses and to check if it is plausible that they are responsible for angular momentum transfer toward the solar equator. We also analysed meridional velocity, rotation velocity residuals and correlation between the velocities. We used sunspot groups position measurements from GPR (Greenwich Photographic Result) and SOON/USAF/NOAA (Solar Observing Optical Network/United States Air Force/National Oceanic and Atmospheric Administration) databases covering the period from 1878 until 2011. In order to calculate velocities we used daily motion of sunspot groups. The sample was also limited to $\\pm$58\\degr in Central Meridian Distance (CMD) in order to avoid solar limb effects. We mainly investigated velocity patterns depending on solar cycle phase and latitude. We found that meridional motion of sunspot groups is toward the centre of activity from all available latitudes and in all phases of the solar cycle. The range of meridional velocities is $\\pm10$ m s$^{-1}$...

  13. Absorption of acoustic waves by sunspots. II - Resonance absorption in axisymmetric fibril models

    Science.gov (United States)

    Rosenthal, C. S.

    1992-01-01

    Analytical calculations of acoustic waves scattered by sunspots which concentrate on the absorption at the magnetohydrodynamic Alfven resonance are extended to the case of a flux-tube embedded in a uniform atmosphere. The model is based on a flux-tubes of varying radius that are highly structured, translationally invariant, and axisymmetric. The absorbed fractional energy is determined for different flux-densities and subphotospheric locations with attention given to the effects of twist. When the flux is highly concentrated into annuli efficient absorption is possible even when the mean magnetic flux density is low. The model demonstrates low absorption at low azimuthal orders even in the presence of twist which generally increases the range of wave numbers over which efficient absorption can occur. Resonance absorption is concluded to be an efficient mechanism in monolithic sunspots, fibril sunspots, and plage fields.

  14. On the Role of Rotating Sunspots in the Activity of Solar Active Region NOAA 11158

    CERN Document Server

    Vemareddy, P; Maurya, R A

    2012-01-01

    We study the role of rotating sunspots in relation to the evolution of various physical parameters characterizing the non-potentiality of the active region NOAA 11158 and its eruptive events using the magnetic field data from the Helioseismic and Magnetic Imager (HMI) and multi-wavelength observations from the Atmospheric Imaging Assembly (AIA) on board Solar Dynamics Observatory (SDO). From the evolutionary study of HMI intensity and AIA channels, it is observed that the AR consists of two major rotating sunspots one connected to flare-prone region and another with CME. The constructed space-time intensity maps reveal that the sunspots exhibited peak rotation rates coinciding with the occurrence of the major eruptive events. Further, temporal profiles of twist parameters, viz., average shear angle, $\\alpha_{\\rm av}$, $\\alpha_{\\rm best}$, derived from HMI vector magnetograms and the rate of helicity injection, obtained from the horizontal flux motions of HMI line-of-sight magnetograms, corresponded well with ...

  15. Observation of a reversal of rotation in a sunspot during a solar flare.

    Science.gov (United States)

    Bi, Yi; Jiang, Yunchun; Yang, Jiayan; Hong, Junchao; Li, Haidong; Yang, Bo; Xu, Zhe

    2016-12-13

    The abrupt motion of the photospheric flux during a solar flare is thought to be a back reaction caused by the coronal field reconfiguration. However, the type of motion pattern and the physical mechanism responsible for the back reaction has been uncertain. Here we show that the direction of a sunspot's rotation is reversed during an X1.6 flare using observations from the Helioseismic and Magnetic Imager. A magnetic field extrapolation model shows that the corresponding coronal magnetic field shrinks with increasing magnetic twist density. This suggests that the abrupt reversal of rotation in the sunspot may be driven by a Lorentz torque that is produced by the gradient of twist density from the solar corona to the solar interior. These results support the view that the abrupt reversal in the rotation of the sunspot is a dynamic process responding to shrinkage of the coronal magnetic field during the flare.

  16. On the Force-Freeness of the Photospheric Sunspot Magnetic Fields as Observed from Hinode (SOT/SP)

    CERN Document Server

    Tiwari, Sanjiv Kumar

    2011-01-01

    A magnetic field is force-free if there is no interaction between the magnetic field and plasma in surrounding atmosphere i.e., electric currents are aligned with the magnetic field, giving rise to zero Lorentz force. Computation of various magnetic parameters such as magnetic energy, gradient of twist of sunspot fields and any kind of extrapolations, heavily hinge on the force-free approximation of the photospheric sunspot magnetic fields. Thus it is important to inspect the force-freeness of sunspot fields. The force-freeness of sunspot magnetic fields has been examined earlier by some researchers ending with incoherent results. Accurate photospheric vector field measurements with high spatial resolution are required to inspect the force-free nature of sunspots. We use several such vector magnetograms obtained from the Solar Optical Telescope/Spectro-Polarimeter aboard the Hinode. Both necessary and sufficient conditions for force-freeness are examined by checking global and local nature of magnetic forces ...

  17. The solar rotation in the period 1853-1870 from the sunspot catalogues of Carrington, Peters, and de la Rue

    CERN Document Server

    Casas, Ricard

    2014-01-01

    R. C. Carrington, C. H. F. Peters, and W. de la Rue observed the sunspots in the second half of the 19th century, determining their heliographic positions between 1853 and 1870, before the establishment of the solar program of the Royal Greenwich Observatory. The large tables of sunspot positions included in the catalogues published by these observers have recently been converted to a machine readable format. The present work analyses this data by calculating the sunspot group velocities for each observer. These results are then fitted with a differential rotation law to compare the data of the three observers with each other and with the results published by other authors. Finally, a study is made of the possible relationship between the sunspot group areas as determined by de la Rue and the corresponding sunspot group velocities.

  18. Mixing intensity modulated electron and photon beams: combining a steep dose fall-off at depth with sharp and depth-independent penumbras and flat beam profiles.

    Science.gov (United States)

    Korevaar, E W; Heijmen, B J; Woudstra, E; Huizenga, H; Brahme, A

    1999-09-01

    For application in radiotherapy, intensity modulated high-energy electron and photon beams were mixed to create dose distributions that feature: (a) a steep dose fall-off at larger depths, similar to pure electron beams, (b) flat beam profiles and sharp and depth-independent beam penumbras, as in photon beams, and (c) a selectable skin dose that is lower than for pure electron beams. To determine the required electron and photon beam fluence profiles, an inverse treatment planning algorithm was used. Mixed beams were realized at a MM50 racetrack microtron (Scanditronix Medical AB, Sweden), and evaluated by the dose distributions measured in a water phantom. The multileaf collimator of the MM50 was used in a static mode to shape overlapping electron beam segments, and the dynamic multileaf collimation mode was used to realize the intensity modulated photon beam profiles. Examples of mixed beams were generated at electron energies of up to 40 MeV. The intensity modulated electron beam component consists of two overlapping concentric fields with optimized field sizes, yielding broad, fairly depth-independent overall beam penumbras. The matched intensity modulated photon beam component has high fluence peaks at the field edges to sharpen this penumbra. The combination of the electron and the photon beams yields dose distributions with the characteristics (a)-(c) mentioned above.

  19. 脑梗塞患者缺血半暗带的PET检查%PET Measurement of Ischemic Penumbra in Patients with Cerebral Infarction

    Institute of Scientific and Technical Information of China (English)

    刘建辉

    2001-01-01

    The role of positron emission tomography(PET) for measurement of ischemic penumbra in acute ischemic cerebrovascular diseases are reviewed.With PET,not only the location and size of penumbra can be discovered in the early stage,but also the existent status of the living tissue and its prognosis can be judeged.PET is a new,effective measuring means in the screening of the candidates for early therapy in ischemic cerebrovascular diseases and clinical study of ischemia penumbra.%对正电子发射计算机断层显像(Positron emission tomography,PET)在缺血性脑血管病早期缺血半暗带判定中的作用进行了综述。PET不但能早期发现半暗带的部位及大小,而且可以判定其中存活组织的生存状态,并能预测其转归,为缺血性脑血管病早期治疗对象的筛选及缺血半暗带的研究提供了一种新的、有效的检查手段。

  20. False ischaemic penumbras in CT perfusion in patients with carotid artery stenosis and changes following angioplasty and stenting.

    Science.gov (United States)

    Mosqueira, A J; Pumar, J M; Arias, S; Rodríguez-Yáñez, M; Blanco Ulla, M; Vázquez Herrero, F; Castillo, J

    2017-08-30

    Carotid artery stenosis influences CT perfusion (CTP) studies, sometimes manifesting as a false ischaemic penumbra (FIP). This study aims to estimate the incidence of FIP in patients with carotid artery stenosis, establish their relationship with the degree of stenosis, and measure quantitative and qualitative changes in CTP after carotid angioplasty and stenting (CAS). Between October 2013 and June 2015, we prospectively selected 26 patients with carotid stenosis who underwent CAS, with CTP being performed 2-10 days before and after CAS. Sixteen patients had unilateral stenosis (11 in the subgroup displaying < 90% stenosis and 5 in the subgroup with ≥ 90% stenosis) and 10 patients had bilateral stenosis. The incidence of FIP in patients with carotid artery stenosis was 38.5%. Risk of FIP increased in direct relation to degree of stenosis, with a relative risk of 11 in the subgroup with ≥ 90% stenosis with respect to the subgroup displaying < 90% stenosis (95% CI, 1.7-71.3; P=.0005). There were statistically significant changes in the parameters CBF, TTP, MTT, and Tmax CTP, which reverted after angioplasty. No significant changes were found in CBV. Carotid artery stenosis involves changes in CTP parameters. Patients with ≥ 90% stenosis carry a high risk of FIP; CTP studies may therefore be misinterpreted in these cases. Changes in CTP parameters are reverted after CAS. Copyright © 2017 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.

  1. A Solar Flare Disturbing a Light Wall above a Sunspot Light Bridge

    Science.gov (United States)

    Hou, Yijun; Zhang, Jun; Li, Ting; Yang, Shuhong; Li, Leping; Li, Xiaohong

    2016-10-01

    With the high-resolution data from the Interface Region Imaging Spectrograph, we detect a light wall above a sunspot light bridge in the NOAA active region (AR) 12403. In the 1330 Å slit-jaw images, the light wall is brighter than the ambient areas while the wall top and base are much brighter than the wall body, and it keeps oscillating above the light bridge. A C8.0 flare caused by a filament activation occurred in this AR with the peak at 02:52 UT on 2015 August 28, and the flare’s one ribbon overlapped the light bridge, which was the observational base of the light wall. Consequently, the oscillation of the light wall was evidently disturbed. The mean projective oscillation amplitude of the light wall increased from 0.5 to 1.6 Mm before the flare and decreased to 0.6 Mm after the flare. We suggest that the light wall shares a group of magnetic field lines with the flare loops, which undergo a magnetic reconnection process, and they constitute a coupled system. When the magnetic field lines are pushed upward at the pre-flare stage, the light wall turns to the vertical direction, resulting in the increase of the light wall’s projective oscillation amplitude. After the magnetic reconnection takes place, a group of new field lines with smaller scales are formed underneath the reconnection site, and the light wall inclines. Thus, the projective amplitude notably decrease at the post-flare stage.

  2. Salient Features of the New Sunspot Number Time Series

    Science.gov (United States)

    Ahluwalia, H. S.; Ygbuhay, R. C.

    2016-12-01

    Recently Clette et al. (Space Sci. Rev. 186, 35, 2014) completed the first revision of the international sunspot number SSN(V2) since its creation by Wolf in 1849 SSN(V1) starting in 1700 and ending in May 2015. The yearly values of SSN(V2) are larger than those of SSN(V1) but the secular trend in their timelines both exhibit a gradual descent after Cycle 21 minimum resulting in greatly reduced activity for Cycle 24. It has two peaks; one in 2012 due to activity in the north hemisphere (NH) and the other in 2014 due to excess activity in the south hemisphere (SH). The N-S excess of hemispheric SSNs is examined for 1950 - 2014, in relation to the time variations of the solar polar field for 1976 - 2015, covering five complete solar cycles (19 - 23) and parts of the bordering two (18, 24). We find that SH tends to become progressively more active in the declining phase of the cycles reaching an extreme value that gave rise to a second higher peak in October 2014 in the smoothed SSNs accompanied by a strong solar polar field in SH. There may be a Gleissberg cyclicity in the asymmetric solar dynamo operation. The continuing descent of the secular trend in SSNs implies that we may be near a Dalton-level grand minimum. The low activity spell may last well past 2060, accompanied by a stable but reduced level of the space weather/climate. Fourier spectrum of the time domain of SSNs shows no evidence of the 208 year/cycle (ypc) (DeVries/Suess cycle) seen in the cosmogenic radionuclide ({}^{10}Be) concentration in the polar ice cores and {}^{14}C record in trees indicating that 208 ypc peak may be of non-solar origin. It may arise from the climate process(es) that change(s) the way radionuclides are deposited on polar ice. It should be noted that we only have {˜} 400 years of SSN data, so it is possible that DeVries/Suess cycle is really driven by the Sun but for now we do not have any evidence of that; there is no known physical process linking 208 ypc to solar dynamo

  3. Chromatic Shadow Detection and Tracking for Moving Foreground Segmentation

    DEFF Research Database (Denmark)

    Huerta, Ivan; Holte, Michael Boelstoft; Moeslund, Thomas B.

    2015-01-01

    Advanced segmentation techniques in the surveillance domain deal with shadows to avoid distortions when detecting moving objects. Most approaches for shadow detection are still typically restricted to penumbra shadows and cannot cope well with umbra shadows. Consequently, umbra shadow regions...... are usually detected as part of moving objects, thus affecting the performance of the final detection. In this paper we address the detection of both penumbra and umbra shadow regions. First, a novel bottom-up approach is presented based on gradient and colour models, which successfully discriminates between...... chromatic moving cast shadow regions and those regions detected as moving objects. In essence, those regions corresponding to potential shadows are detected based on edge partitioning and colour statistics. Subsequently (i) temporal similarities between textures and (ii) spatial similarities between...

  4. δ-SUNSPOT FORMATION IN SIMULATION OF ACTIVE-REGION-SCALE FLUX EMERGENCE

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Fang; Fan, Yuhong [High Altitude Observatory, National Center for Atmospheric Research, 3090 Center Green Drive, Boulder, CO 80301 (United States)

    2015-06-10

    δ-sunspots, with highly complex magnetic structures, are very productive in energetic eruptive events, such as X-class flares and homologous eruptions. We here study the formation of such complex magnetic structures by numerical simulations of magnetic flux emergence from the convection zone into the corona in an active-region-scale domain. In our simulation, two pairs of bipolar sunspots form on the surface, originating from two buoyant segments of a single subsurface twisted flux rope, following the approach of Toriumi et al. Expansion and rotation of the emerging fields in the two bipoles drive the two opposite polarities into each other with apparent rotating motion, producing a compact δ-sunspot with a sharp polarity inversion line. The formation of the δ-sunspot in such a realistic-scale domain produces emerging patterns similar to those formed in observations, e.g., the inverted polarity against Hale's law, the curvilinear motion of the spot, and strong transverse field with highly sheared magnetic and velocity fields at the polarity inversion line (PIL). Strong current builds up at the PIL, giving rise to reconnection, which produces a complex coronal magnetic connectivity with non-potential fields in the δ-spot overlaid by more relaxed fields connecting the two polarities at the two ends.

  5. Dependence of time derivative of horizontal geomagnetic field on sunspot number and aa index

    National Research Council Canada - National Science Library

    Falayi, Elijah O; Rabiu, Babatunde A

    2013-01-01

    This work investigated an interrelationship between the monthly means of time derivatives of horizontal geomagnetic field, dH/dt, sunspot number, R z , and aa index for the period of substorms (from −90 to −1800 nT...

  6. A method to predict amplitude and date of maximum sunspot number

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A method to predict the amplitude and date of the maximum sunspot number is introduced. The regression analysis of the relationship between the variation rate of monthly sunspot numbers in the initial stage of solar cycles and both of the maximum and the time-length of ascending period of the cycle showed that they are closely correlative. In general, the maximum will be larger and the ascending period will be shorter when the rate is larger. The rate of sunspot numbers in the initial 2 years of the 23rd cycle is thus analyzed based on these grounds and the maximum of the cycle is predicted. For the smoothed monthly sunspot numbers, the maximum will be about 139.2±18.8 and the time-length of ascending period will be about 3.31±0.42 years, that is to say, the maximum will appear around the spring of the year 2000. For the mean monthly ones, the maximum will be near 170.1±22.9 and the time-length of ascending period will be about 3.42±0.46 years, that is to say, the appearing date of the maximum will be later.

  7. Re-examining Sunspot Tilt Angle to Include Anti-Hale Statistics

    CERN Document Server

    McClintock, Bruce H; Li, Jing

    2014-01-01

    Sunspot groups and bipolar magnetic regions (BMRs) serve as an observational diagnostic of the solar cycle. We use Debrecen Photohelographic Data (DPD) from 1974-2014 that determined sunspot tilt angles from daily white light observations, and data provided by Li & Ulrich that determined sunspot magnetic tilt angle using Mount Wilson magnetograms from 1974-2012. The magnetograms allowed for BMR tilt angles that were anti-Hale in configuration, so tilt values ranged from 0 to 360{\\deg} rather than the more common $\\pm$ 90{\\deg}. We explore the visual representation of magnetic tilt angles on a traditional butterfly diagram by plotting the mean area-weighted latitude of umbral activity in each bipolar sunspot group, including tilt information. The large scatter of tilt angles over the course of a single cycle and hemisphere prevents Joy's law from being visually identified in the tilt-butterfly diagram without further binning. The average latitude of anti-Hale regions does not differ from the average latitu...

  8. Sensitivity of sunspot area to the tidal effect of planet Mercury during solar cycle 23

    CERN Document Server

    Edmonds, Ian

    2014-01-01

    We present evidence that the allowed periods of equatorially trapped Rossby wave modes on the Sun coincide closely with the 88 day period and 176 day sub harmonic period of Mercury and evidence of Rossby waves on the Sun at the same periods. To test the hypothesis that Rossby waves trigger the emergence of sunspots we use band pass filtering to obtain the 88 day period and 176 day period components of hemispherical sunspot area and compare the variations to the tidal height variation on the surface of the Sun due to Mercury. We find that the two components of hemispherical sunspot area occur in several episodes or activations of duration 2 to 6 years during each solar cycle. When the activations are discrete the variation of the 88 day and 176 day period components are phase coherent with the tidal height variation and a 180 degree phase change is evident between successive activations. We use this result to demonstrate that Rieger type quasi-periodicities in sunspot activity are, in most reported cases, peri...

  9. An Early Sunspot Catalog by Miguel Aguilar for the Period 1914 - 1920

    Science.gov (United States)

    Lefèvre, L.; Aparicio, A. J. P.; Gallego, M. C.; Vaquero, J. M.

    2016-11-01

    We provide a source of detailed solar parameters spanning the years 1914 - 1920. Although various catalogs containing information on sunspots and sunspot groups have been available for almost 150 years, the contents and conventions can vary greatly from one source to another. Thus, the availability of multiple sources is very important to assess the relative uncertainties in the identified quantities. We provide here a machine-readable version of the sunspot catalog made by M. Aguilar from 1914 to 1920. We show and explain the structure and possible errors found in this catalog. We also try to understand the specific differences of this catalog, i.e. explain the shortcomings and benefits of this catalog versus other available sources of solar information. This catalog, combined with the Valencia catalog, presents a valuable source of comparison with the Royal Greenwich Observatory (RGO or GPR for Greenwich Photoheliographic Results) data, and it helps shed more light on the link between the RGO classification and the more modern classifications of sunspot groups found in the Zürich or McIntosh classifications. We also extend the work started by Carrasco et al. ( Solar Phys. 290, 1445, 2015) on the mapping of Cortie types.

  10. A wavelet analysis of the relationship between Loess Plateau erosion and sunspots

    NARCIS (Netherlands)

    Gao, P.; Geissen, V.; Temme, A.J.A.M.; Ritsema, C.J.; Mu, X.; Wang, F.

    2014-01-01

    The Chinese Loess Plateau is one of the most rapidly eroding regions in the world. The purpose of this study is to find out to which extent soil erosion on the Loess Plateau is driven by sunspot activity. We analyzed the relation between annual sediment discharge (from 1919 to 2010) from the Loess P

  11. COMPARISON OF CHAOTIC AND FRACTAL PROPERTIES OF POLAR FACULAE WITH SUNSPOT ACTIVITY

    Energy Technology Data Exchange (ETDEWEB)

    Deng, L. H.; Xiang, Y. Y.; Dun, G. T. [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650216 (China); Li, B., E-mail: wooden@escience.cn [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, School of Space Science and Physics, Shandong University at Weihai, Weihai 264209 (China)

    2016-01-15

    The solar magnetic activity is governed by a complex dynamo mechanism and exhibits a nonlinear dissipation behavior in nature. The chaotic and fractal properties of solar time series are of great importance to understanding the solar dynamo actions, especially with regard to the nonlinear dynamo theories. In the present work, several nonlinear analysis approaches are proposed to investigate the nonlinear dynamical behavior of the polar faculae and sunspot activity for the time interval from 1951 August to 1998 December. The following prominent results are found: (1) both the high- and the low-latitude solar activity are governed by a three-dimensional chaotic attractor, and the chaotic behavior of polar faculae is the most complex, followed by that of the sunspot areas, and then the sunspot numbers; (2) both the high- and low-latitude solar activity exhibit a high degree of persistent behavior, and their fractal nature is due to such long-range correlation; (3) the solar magnetic activity cycle is predictable in nature, but the high-accuracy prediction should only be done for short- to mid-term due to its intrinsically dynamical complexity. With the help of the Babcock–Leighton dynamo model, we suggest that the nonlinear coupling of the polar magnetic fields with strong active-region fields exhibits a complex manner, causing the statistical similarities and differences between the polar faculae and the sunspot-related indicators.

  12. Formation of δ-Sunspot in Simulations of Active-Region-Scale Flux Emergence

    Science.gov (United States)

    Fang, Fang; Fan, Yuhong

    2015-04-01

    δ-sunspots, with highly complex magnetic structures, are very productive in energetic eruptive events, such as X-class flares and homologous eruptions. We here study the formation of such complex magnetic structures by numerical simulations of magnetic flux emergence from the convection zone into the corona in an active-region-scale domain. In our simulation, two pairs of bipolar sunspots form on the surface, originating from two buoyant segments of a single subsurface twisted flux rope. Expansion and rotation of the emerging fields in the two bipoles drive the two opposite polarities into each other with apparent rotating motion, producing a compact δ-sunspot with a sharp polarity inversion line. The formation of the δ-sunspot in such a realistic-scale domain produces emerging pattherns similar to those formed in observations, e.g. the inverted polarity against Hale’s law, the curvilinear motion of the spot, strong transverse field with highly sheared magnetic and velocity fields at the PIL. Strong current builds up at the PIL, giving rise to reconnection, which produces a complex coronal magnetic connectivity with non-potential fields in the -spot overlaid by more relaxed fields connecting the two polarities at the two ends.

  13. $\\delta$-Sunspot Formation in Simulation of Active-Region-Scale Flux Emergence

    CERN Document Server

    Fang, Fang

    2015-01-01

    $\\delta$-sunspots, with highly complex magnetic structures, are very productive in energetic eruptive events, such as X-class flares and homologous eruptions. We here study the formation of such complex magnetic structures by numerical simulations of magnetic flux emergence from the convection zone into the corona in an active-region-scale domain. In our simulation, two pairs of bipolar sunspots form on the surface, originating from two buoyant segments of a single subsurface twisted flux rope, following the approach of Toriumi et al. (2014). Expansion and rotation of the emerging fields in the two bipoles drive the two opposite polarities into each other with apparent rotating motion, producing a compact $\\delta$-sunspot with a sharp polarity inversion line. The formation of the $\\delta$-sunspot in such a realistic-scale domain produces emerging patterns similar to those formed in observations, e.g. the inverted polarity against Hale's law, the curvilinear motion of the spot, strong transverse field with hig...

  14. Helioseismic Observations of the Structure and Dynamics of a Rotating Sunspot Beneath the Solar Surface

    Science.gov (United States)

    Zhao, Junwei; Kosovichev, Alexander G.

    2003-01-01

    Time-distance helioseismology is applied to study the subphotospheric structures and dynamics of an unusually fast-rotating sunspot observed by the Michelson Doppler Imager on bead SOH0 in 2000 August. The subsurface sound speed structures and velocity fields are obtained for the sunspot region at different depths from 0 to 12 Mm. By comparing the subsurface sound speed variations with the surface magnetic field, we find evidence for structural twists beneath the visible surface of this active region, which may indicate that magnetic twists often seen at the photosphere also exist beneath the photosphere. We also report on the observation of subsurface horizontal vortical flows that extend to a depth of 5 Mm around this rotating sunspot and present evidence that opposite vortical flows may exist below 9 Mm. It is suggested that the vortical flows around this active region may build up a significant amount of magnetic helicity and energy to power solar eruptions. Monte Carlo simulation has been performed to estimate the error propagation, and in addition the sunspot umbra is masked to test the reliability of our inversion results. On the basis of the three-dimensional velocity fields obtained from the time-distance helioseismology inversions, we estimate the subsurface kinetic helicity at different depths for the first time and conclude that it is comparable to the current helicity estimated from vector magnetograms.

  15. Comparison of Chaotic and Fractal Properties of Polar Faculae with Sunspot Activity

    Science.gov (United States)

    Deng, L. H.; Li, B.; Xiang, Y. Y.; Dun, G. T.

    2016-01-01

    The solar magnetic activity is governed by a complex dynamo mechanism and exhibits a nonlinear dissipation behavior in nature. The chaotic and fractal properties of solar time series are of great importance to understanding the solar dynamo actions, especially with regard to the nonlinear dynamo theories. In the present work, several nonlinear analysis approaches are proposed to investigate the nonlinear dynamical behavior of the polar faculae and sunspot activity for the time interval from 1951 August to 1998 December. The following prominent results are found: (1) both the high- and the low-latitude solar activity are governed by a three-dimensional chaotic attractor, and the chaotic behavior of polar faculae is the most complex, followed by that of the sunspot areas, and then the sunspot numbers; (2) both the high- and low-latitude solar activity exhibit a high degree of persistent behavior, and their fractal nature is due to such long-range correlation; (3) the solar magnetic activity cycle is predictable in nature, but the high-accuracy prediction should only be done for short- to mid-term due to its intrinsically dynamical complexity. With the help of the Babcock-Leighton dynamo model, we suggest that the nonlinear coupling of the polar magnetic fields with strong active-region fields exhibits a complex manner, causing the statistical similarities and differences between the polar faculae and the sunspot-related indicators.

  16. A New Approach in Understanding Growth and Decay of the Sunspots

    CERN Document Server

    Hiremath, K M; R, M

    2010-01-01

    From the previous study (Hiremath 2009b; Hiremath 2010), on the genesis of solar cycle and activity phenomena, it is understood that sunspots are formed at different depths by superposition of Alfven wave perturbations of a strong toroidal field structure in the convective envelope and after attaining a critical strength, due to buoyancy, raise toward the surface along the rotational isocontours that have positive (0.7-0.935 $R_{\\odot}$) and negative (0.935-1.0 $R_{\\odot}$) rotational gradients. Owing to physical conditions in these two rotational gradients, from the equation of magnetic induction, sunspot's area growth and decay problem is solved separately. It is found that rate of growth of sunspot's area during its evolution at different depths is function of steady and fluctuating parts of Lorentzian force of the ambient medium, fluctuations in meridional flow velocity, radial variation of rotational gradient and $cot(\\vartheta)$ (where $\\vartheta$ is co-latitude). While rate of decay of sunspot's area a...

  17. Bimodal Distribution of Area-Weighted Latitude of Sunspots And Solar North-South Asymmetry

    CERN Document Server

    Chang, Heon-Young

    2011-01-01

    We study the latitudinal distribution of sunspots observed from 1874 to 2009 using the center-of-latitude (COL). We calculate COL by taking the area-weighted mean latitude of sunspots for each calendar month. We then form the latitudinal distribution of COL for the sunspots appearing in the northern and southern hemispheres separately, and in both hemispheres with unsigned and signed latitudes, respectively. We repeat the analysis with subsets which are divided based on the criterion of which hemisphere is dominant for a given solar cycle. Our primary findings are as follows: (1) COL is not monotonically decreasing with time in each cycle. Small humps can be seen (or short plateaus) around every solar maxima. (2) The distribution of COL resulting from each hemisphere is bimodal, which can well be represented by the double Gaussian function. (3) As far as the primary component of the double Gaussian function is concerned, for a given data subset, the distributions due to the sunspots appearing in two different...

  18. Relationships between solar activity and climate change. [sunspot cycle effects on lower atmosphere

    Science.gov (United States)

    Roberts, W. O.

    1974-01-01

    Recurrent droughts are related to the double sunspot cycle. It is suggested that high solar activity generally increases meridional circulations and blocking patterns at high and intermediate latitudes, especially in winter. This effect is related to the sudden formation of cirrus clouds during strong geomagnetic activity that originates in the solar corpuscular emission.

  19. Penumbra Stroke System as an "add-on" for the treatment of large vessel occlusive disease following thrombolysis: first results.

    Science.gov (United States)

    Struffert, Tobias; Köhrmann, Martin; Engelhorn, Tobias; Nowe, Tim; Richter, Gregor; Schellinger, Peter D; Schwab, Stefan; Doerfler, Arnd

    2009-09-01

    The Penumbra Stroke System (PSS) was cleared for use in patients with ischemic stroke by the FDA in January 2008. We describe our experience of using this new system in acute large vessel occlusive disease following thrombolysis. Fifteen consecutive patients (mean age 60 years) suffering from acute ischemic stroke were treated with the PSS after intravenous or intra-arterial standard treatment with tissue plasminogen activator (n = 14) or ReoPro (n = 1). All patients presented with TIMI 3 before use of the PSS. Carotid stenting (n = 3) and intracranial balloon angioplasty or stenting (n = 2) were performed if indicated. Neurological evaluation was performed using the NIHSS score and the mRS score. Initial median NIHSS score in 12 patients with occlusions in the anterior circulation was 15; three patients with basilar artery occlusion presented with coma. Median symptom to procedure start time was 151 min. In the anterior circulation, 9 of the 12 target vessels were recanalised successfully (TIMI 2 and 3). The rate of patients with independent clinical outcome (mRS

  20. Are secular correlations between sunspots, geomagnetic activity, and global temperature significant?

    Science.gov (United States)

    Love, J.J.; Mursula, K.; Tsai, V.C.; Perkins, D.M.

    2011-01-01

    Recent studies have led to speculation that solar-terrestrial interaction, measured by sunspot number and geomagnetic activity, has played an important role in global temperature change over the past century or so. We treat this possibility as an hypothesis for testing. We examine the statistical significance of cross-correlations between sunspot number, geomagnetic activity, and global surface temperature for the years 1868-2008, solar cycles 11-23. The data contain substantial autocorrelation and nonstationarity, properties that are incompatible with standard measures of cross-correlational significance, but which can be largely removed by averaging over solar cycles and first-difference detrending. Treated data show an expected statistically- significant correlation between sunspot number and geomagnetic activity, Pearson p correlations between global temperature and sunspot number (geomagnetic activity) are not significant, p = 0.9954, (p = 0.8171). In other words, straightforward analysis does not support widely-cited suggestions that these data record a prominent role for solar-terrestrial interaction in global climate change. With respect to the sunspot-number, geomagnetic-activity, and global-temperature data, three alternative hypotheses remain difficult to reject: (1) the role of solar-terrestrial interaction in recent climate change is contained wholly in long-term trends and not in any shorter-term secular variation, or, (2) an anthropogenic signal is hiding correlation between solar-terrestrial variables and global temperature, or, (3) the null hypothesis, recent climate change has not been influenced by solar-terrestrial interaction. ?? 2011 by the American Geophysical Union.

  1. Sunspot positions, areas, and group tilt angles for 1611-1631 from observations by Christoph Scheiner

    Science.gov (United States)

    Arlt, R.; Senthamizh Pavai, V.; Schmiel, C.; Spada, F.

    2016-11-01

    Aims: Digital images of observations printed in the books Rosa Ursina sive solis and Prodromus pro sole mobili by Christoph Scheiner, as well as the drawings from Scheiner's letters to Marcus Welser, are analysed to obtain information on the positions and sizes of sunspots that appeared before the Maunder minimum. Methods: In most cases, the given orientation of the ecliptic is used to set up the heliographic coordinate system for the drawings. Positions and sizes are measured manually on screen. Very early drawings have no indication of their orientation. A rotational matching using common spots of adjacent days is used in some cases, while in other cases, the assumption that images were aligned with a zenith-horizon coordinate system appeared to be the most probable. Results: In total, 8167 sunspots were measured. A distribution of sunspot latitudes versus time (butterfly diagram) is obtained for Scheiner's observations. The observations of 1611 are very inaccurate, the drawings of 1612 have at least an indication of their orientation, while the remaining part of the spot positions from 1618-1631 have good to very good accuracy. We also computed 697 tilt angles of apparently bipolar sunspot groups observed in the period 1618-1631. We find that the average tilt angle of nearly 4 degrees is not significantly different from 20th-century values. Data on the sunspot position and area are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/595/A104

  2. An Assessment of Sunspot Number Data Composites over 1845-2014

    Science.gov (United States)

    Lockwood, M.; Owens, M. J.; Barnard, L.; Usoskin, I. G.

    2016-06-01

    New sunspot data composites, some of which are radically different in the character of their long-term variation, are evaluated over the interval 1845-2014. The method commonly used to calibrate historic sunspot data, relative to modern-day data, is “daisy-chaining,” whereby calibration is passed from one data subset to the neighboring one, usually using regressions of the data subsets for the intervals of their overlap. Recent studies have illustrated serious pitfalls in these regressions, and the resulting errors can be compounded by their repeated use as the data sequence is extended back in time. Hence, the recent composite data series by Usoskin et al., R UEA, is a very important advance because it avoids regressions, daisy-chaining, and other common, but invalid, assumptions: this is achieved by comparing the statistics of “active-day” fractions to those for a single reference data set. We study six sunspot data series, including R UEA and the new “backbone” data series (R BB, recently generated by Svalgaard & Schatten by employing both regression and daisy-chaining). We show that all six can be used with a continuity model to reproduce the main features of the open solar flux variation for 1845-2014, as reconstructed from geomagnetic activity data. However, some differences can be identified that are consistent with tests using a basket of other proxies for solar magnetic fields. Using data from a variety of sunspot observers, we illustrate problems with the method employed in generating R BB that cause it to increasingly overestimate sunspot numbers going back in time, and we recommend using R UEA because it employs more robust procedures that avoid such problems.

  3. Three-dimensional magnetic structure of a sunspot: Comparison of the photosphere and upper chromosphere

    Science.gov (United States)

    Joshi, Jayant; Lagg, Andreas; Hirzberger, Johann; Solanki, Sami K.

    2017-08-01

    Aims: We investigate the magnetic field of a sunspot in the upper chromosphere and compare it to the photospheric properties of the field. Methods: We observed the main leading sunspot of the active region NOAA 11124 during two days with the Tenerife Infrared Polarimeter-2 (TIP-2) mounted at the German Vacuum Tower Telescope (VTT). Through inversion of Stokes spectra of the He i triplet at 10 830 Å, we obtained the magnetic field vector of the upper chromosphere. For comparison with the photosphere, we applied height-dependent inversions of the Si i 10 827.1 Å and Ca i 10 833.4 Å lines. Results: We found that the umbral magnetic field strength in the upper chromosphere is lower by a factor of 1.30-1.65 compared to the photosphere. The magnetic field strength of the umbra decreases from the photosphere toward the upper chromosphere by an average rate of 0.5-0.9 G km-1. The difference in the magnetic field strength between both atmospheric layers steadily decreases from the sunspot center to the outer boundary of the sunspot; the field, in particular its horizontal component, is stronger in the chromopshere outside the spot and this is suggestive of a magnetic canopy. The sunspot displays a twist that on average is similar in the two layers. However, the differential twist between the photosphere and chromosphere increases rapidly toward the outer penumbral boundary. The magnetic field vector is more horizontal with respect to the solar surface by roughly 5-20° in the photosphere compared to the upper chromosphere. Above a lightbridge, the chromospheric magnetic field is equally strong as that in the umbra, whereas the field of the lightbridge is weaker than its surroundings in the photosphere by roughly 1 kG. This suggests a cusp-like magnetic field structure above the lightbridge.

  4. Mode transformation and frequency change with height in 3D numerical simulations of magneto-acoustic wave propagation in sunspots

    CERN Document Server

    Felipe, T; Collados, M

    2010-01-01

    Three-dimensional numerical simulations of magnetoacoustic wave propagation are performed in a sunspot atmosphere with a computational domain covering from the photosphere to the chromosphere. The wave source, with properties resembling the solar spectrum, is located at different distances from the axis of the sunspot for each simulation. These results are compared with the theory of mode transformation and also with observational features. Simulations show that the dominant oscillation frequency in the chromosphere decreases with the radial distance from the sunspot axis. The energy flux of the different wave modes involved, including de Alfv\\'en mode, is evaluated and discussed.

  5. ON THE FORCE-FREE NATURE OF PHOTOSPHERIC SUNSPOT MAGNETIC FIELDS AS OBSERVED FROM HINODE (SOT/SP)

    Energy Technology Data Exchange (ETDEWEB)

    Tiwari, Sanjiv Kumar, E-mail: tiwari@mps.mpg.de [Udaipur Solar Observatory, Physical Research Laboratory, Dewali, Bari Road, Udaipur 313 001 (India)

    2012-01-01

    A magnetic field is force-free if there is no interaction between it and the plasma in the surrounding atmosphere, i.e., electric currents are aligned with the magnetic field, giving rise to zero Lorentz force. The computation of various magnetic parameters, such as magnetic energy (using the virial theorem), gradient of twist of sunspot magnetic fields (computed from the force-free parameter {alpha}), and any kind of extrapolation, heavily hinges on the force-free approximation of the photospheric sunspot magnetic fields. Thus, it is of vital importance to inspect the force-free behavior of sunspot magnetic fields. The force-free nature of sunspot magnetic fields has been examined earlier by some researchers, ending with incoherent results. Accurate photospheric vector field measurements with high spatial resolution are required to inspect the force-free nature of sunspots. For this purpose, we use several vector magnetograms of high spatial resolution obtained from the Solar Optical Telescope/Spectro-Polarimeter on board Hinode. Both the necessary and sufficient conditions for force-free nature are examined by checking the global and local nature of equilibrium magnetic forces over sunspots. We find that sunspot magnetic fields are not very far from the force-free configuration, although they are not completely force-free on the photosphere. The umbral and inner penumbral fields are more force-free than the middle and outer penumbral fields. During their evolution, sunspot magnetic fields are found to maintain their proximity to force-free field behavior. Although a dependence of net Lorentz force components is seen on the evolutionary stages of the sunspots, we do not find a systematic relationship between the nature of sunspot magnetic fields and the associated flare activity. Further, we examine whether the fields at the photosphere follow linear or nonlinear force-free conditions. After examining this in various complex and simple sunspots, we conclude that

  6. Thermospheric density model biases at the 23rd sunspot maximum

    Science.gov (United States)

    Pardini, C.; Moe, K.; Anselmo, L.

    2012-07-01

    Uncertainties in the neutral density estimation are the major source of aerodynamic drag errors and one of the main limiting factors in the accuracy of the orbit prediction and determination process at low altitudes. Massive efforts have been made over the years to constantly improve the existing operational density models, or to create even more precise and sophisticated tools. Special attention has also been paid to research more appropriate solar and geomagnetic indices. However, the operational models still suffer from weakness. Even if a number of studies have been carried out in the last few years to define the performance improvements, further critical assessments are necessary to evaluate and compare the models at different altitudes and solar activity conditions. Taking advantage of the results of a previous study, an investigation of thermospheric density model biases during the last sunspot maximum (October 1999 - December 2002) was carried out by analyzing the semi-major axis decay of four satellites: Cosmos 2265, Cosmos 2332, SNOE and Clementine. Six thermospheric density models, widely used in spacecraft operations, were analyzed: JR-71, MSISE-90, NRLMSISE-00, GOST-2004, JB2006 and JB2008. During the time span considered, for each satellite and atmospheric density model, a fitted drag coefficient was solved for and then compared with the calculated physical drag coefficient. It was therefore possible to derive the average density biases of the thermospheric models during the maximum of the 23rd solar cycle. Below 500 km, all the models overestimated the average atmospheric density by amounts varying between +7% and +20%. This was an inevitable consequence of constructing thermospheric models from density data obtained by assuming a fixed drag coefficient, independent of altitude. Because the uncertainty affecting the drag coefficient measurements was about 3% at both 200 km and 480 km of altitude, the calculated air density biases below 500 km were

  7. Analisis Klaster K-Means dari Data Luas Grup Sunspot dan Data Grup Sunspot Klasifikasi Mc.Intosh yang membangkitkan Flare Soft X-Ray dan H-alpha

    Directory of Open Access Journals (Sweden)

    Siti Jumaroh

    2015-12-01

    Full Text Available Analisis klaster merupakan teknik interpendensi yang mengelompokkan suatu objek berdasarkan kemiripan dan kedekatan jarak antar objek. Pengelompokan objek dengan jumlah banyak membutuhkan waktu yang lama. Salah satu analisis klaster yang dapat digunakan dalam situasi ini adalah analisis klaster non hierarki, yaitu K-means. Pada artikel ini mengelompokkan data luas grup sunspot dan data grup sunspot klasifikasi Mc.Intosh yang membangkitkan flare soft X-Ray dan Hα. Untuk mengetahui luas grup sunspot dan grup sunspot klasifikasi Mc.Intosh yang berpeluang membangkitkan flare soft X-Ray dan Hα dengan intensitas ledakan yang tinggi dan rendah. Berdasarkan hasil analisis, diperoleh dua klaster yaitu klaster pertama yang tergolong mampu membangkitkan flare Soft X-Ray dan Hα dengan intensitas yang tinggi. Sedangkan klaster kedua yang tergolong mampu membangkitkan flare Soft X-Ray dan Hα dengan intensitas yang rendah

  8. Deciphering Solar Magnetic Activity I: On The Relationship Between The Sunspot Cycle And The Evolution Of Small Magnetic Features

    CERN Document Server

    McIntosh, Scott W; Leamon, Robert J; Davey, Alisdair R; Howe, Rachel; Krista, Larisza D; Malanushenko, Anna V; Cirtain, Jonathan W; Gurman, Joseph B; Thompson, Michael J

    2014-01-01

    Sunspots are a canonical marker of the Sun's internal magnetic field which flips polarity every ~22-years. The principal variation of sunspots, an ~11-year variation in number, modulates the amount of magnetic field that pierces the solar surface and drives significant variations in our Star's radiative, particulate and eruptive output over that period. This paper presents observations from the Solar and Heliospheric Observatory and Solar Dynamics Observatory indicating that the 11-year sunspot variation is intrinsically tied it to the spatio-temporal overlap of the activity bands belonging to the 22-year magnetic activity cycle. Using a systematic analysis of ubiquitous coronal brightpoints, and the magnetic scale on which they appear to form, we show that the landmarks of sunspot cycle 23 can be explained by considering the evolution and interaction of the overlapping activity bands of the longer scale variability.

  9. Deciphering solar magnetic activity. I. On the relationship between the sunspot cycle and the evolution of small magnetic features

    Energy Technology Data Exchange (ETDEWEB)

    McIntosh, Scott W.; Wang, Xin; Markel, Robert S.; Thompson, Michael J. [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307 (United States); Leamon, Robert J.; Malanushenko, Anna V. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Davey, Alisdair R. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Howe, Rachel [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom); Krista, Larisza D. [Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80205 (United States); Cirtain, Jonathan W. [Marshall Space Flight Center, Code ZP13, Huntsville, AL 35812 (United States); Gurman, Joseph B.; Pesnell, William D., E-mail: mscott@ucar.edu [Solar Physics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2014-09-01

    Sunspots are a canonical marker of the Sun's internal magnetic field which flips polarity every ∼22 yr. The principal variation of sunspots, an ∼11 yr variation, modulates the amount of the magnetic field that pierces the solar surface and drives significant variations in our star's radiative, particulate, and eruptive output over that period. This paper presents observations from the Solar and Heliospheric Observatory and Solar Dynamics Observatory indicating that the 11 yr sunspot variation is intrinsically tied to the spatio-temporal overlap of the activity bands belonging to the 22 yr magnetic activity cycle. Using a systematic analysis of ubiquitous coronal brightpoints and the magnetic scale on which they appear to form, we show that the landmarks of sunspot cycle 23 can be explained by considering the evolution and interaction of the overlapping activity bands of the longer-scale variability.

  10. Characteristics of latitude distribution of sunspots and their links to solar activity in pre-Greenwich data

    CERN Document Server

    Ivanov, V G

    2016-01-01

    We study and compare characteristics of sunspot group latitude distribution in two catalogs: the extended Greenwich (1874--2014) and Schwabe ones (1825--1867). We demonstrate that both datasets reveal similar links between latitude and amplitude characteristics of the 11-year cycle: the latitude dispersion correlates with the current activity and the mean latitude of sunspots in the cycle's maximum is proportional to its amplitude, It agrees with conclusions that we made in previous papers for the Greenwich catalog. We show that the latitude properties of sunspot distribution are much more stable against loss of observational data than traditional amplitude indices of activity. Therefore, the found links can be used for estimates of quality of observations and independent normalizing of activity levels in a gappy pre-Greenwich data. We demonstrate it using the Schwabe catalog as an example. In addition, we show that the first part of the Schwabe data probably contains errors in determination of sunspot latitu...

  11. A small collection of sunspot drawings made in the Royal Astronomical Observatory of the Spanish Navy in 1884

    Science.gov (United States)

    Galaviz, P.; Vaquero, J. M.; Gallego, M. C.; Sánchez-Bajo, F.

    2016-12-01

    In this paper we analyze a small collection of sunspot drawings made at the Astronomical Observatory of the Spanish Navy in the period from April 1, 1884 to August 18, 1884. We calculate the area and the heliographic coordinates of the observed sunspots. From these coordinates, we obtain the solar rotation rate in this period. Finally, we compare our results with the data recorded by the Royal Greenwich Observatory.

  12. Deciphering Solar Magnetic Activity I: On The Relationship Between The Sunspot Cycle And The Evolution Of Small Magnetic Features

    OpenAIRE

    McIntosh, Scott W.; Wang, Xin; Leamon, Robert J.; Howe, Rachel; Krista, Larisza D.; Malanushenko, Anna V.; Cirtain, Jonathan W.; Gurman, Joseph B.; Thompson, Michael J

    2014-01-01

    Sunspots are a canonical marker of the Sun's internal magnetic field which flips polarity every ~22-years. The principal variation of sunspots, an ~11-year variation in number, modulates the amount of magnetic field that pierces the solar surface and drives significant variations in our Star's radiative, particulate and eruptive output over that period. This paper presents observations from the Solar and Heliospheric Observatory and Solar Dynamics Observatory indicating that the 11-year sunsp...

  13. North-south asymmetry in small and large sunspot group activity and violation of even-odd solar cycle rule

    Science.gov (United States)

    Javaraiah, J.

    2016-07-01

    According to Gnevyshev-Ohl (G-O) rule an odd-numbered cycle is stronger than its preceding even-numbered cycle. In the modern time the cycle pair (22, 23) violated this rule. By using the combined Greenwich Photoheliographic Results (GPR) and Solar Optical Observing Network (SOON) sunspot group data during the period 1874-2015, and Debrecen Photoheliographic Data (DPD) of sunspot groups during the period 1974-2015, here we have found that the solar cycle pair (22, 23) violated the G-O rule because, besides during cycle 23 a large deficiency of small sunspot groups in both the northern and the southern hemispheres, during cycle 22 a large abundance of small sunspot groups in the southern hemisphere. In the case of large and small sunspot groups the cycle pair (22, 23) violated the G-O rule in the northern and southern hemispheres, respectively, suggesting the north-south asymmetry in solar activity has a significant contribution in the violation of G-O rule. The amplitude of solar cycle 24 is smaller than that of solar cycle 23. However, Coronal Mass Ejections (CMEs) rate in the rising phases of the cycles 23 and 24 are almost same (even slightly large in cycle 24). From both the SOON and the DPD sunspot group data here we have also found that on the average the ratio of the number (counts) of large sunspot groups to the number of small sunspot groups is larger in the rising phase of cycle 24 than that in the corresponding phase of cycle 23. We suggest this could be a potential reason for the aforesaid discrepancy in the CME rates during the rising phases of cycles 23 and 24. These results have significant implication on solar cycle mechanism.

  14. Sunspot numbers based on historic records in the 1610s - early telescopic observations by Simon Marius and others

    CERN Document Server

    Neuhaeuser, Ralph

    2016-01-01

    Hoyt & Schatten (1998) claim that Simon Marius would have observed the sun from 1617 Jun 7 to 1618 Dec 31 (Gregorian calendar) all days, except three short gaps in 1618, but would never have detected a sunspot -- based on a quotation from Marius in Wolf (1857), but misinterpreted by Hoyt & Schatten. Marius himself specified in early 1619 that "for one and a half year ... rather few or more often no spots could be detected ... which was never observed before" (Marius 1619). The generic statement by Marius can be interpreted such that the active day fraction was below 0.5 (but not zero) from fall 1617 to spring 1619 and that it was 1 before fall 1617 (since August 1611). Hoyt & Schatten cite Zinner (1952), who referred to Zinner (1942), where observing dates by Marius since 1611 are given, but which were not used by Hoyt & Schatten. We present all relevant texts from Marius where he clearly stated that he observed many spots in different form on and since 1611 Aug 3 (Julian) = Aug 13 (Greg.) (on...

  15. Hinode Observation of the Magnetic Fields in a Sunspot Light Bridge Accompanied by Long-Lasting Chromospheric Plasma Ejections

    Science.gov (United States)

    Shimizu, Toshifumi; Katsukawa, Yukio; Kubo, Masahito; Lites, Bruce W.; Ichimoto, Kiyoshi; Suematsu, Yoshinori; Tsuneta, Saku; Nagata, Shin'ichi; Shine, Richard A.; Tarbell, Theodore D.

    2009-05-01

    We present high-resolution magnetic field measurements of a sunspot light bridge (LB) that produced chromospheric plasma ejections intermittently and recurrently for more than 1 day. The observations were carried out with the Hinode Solar Optical Telescope on 2007 April 29 and 30. The spectro-polarimeter reveals obliquely oriented magnetic fields with vertical electric current density higher than 100 mA m-2 along the LB. The observations suggest that current-carrying highly twisted magnetic flux tubes are trapped below a cusp-shaped magnetic structure along the LB. The presence of trapped current-carrying flux tubes is essential for causing long-lasting chromospheric plasma ejections at the interface with pre-existing vertically oriented umbral fields. A bidirectional jet was clearly detected, suggesting magnetic reconnections occurring at very low altitudes, slightly above the height where the vector magnetic fields are measured. Moreover, we found another strong vertical electric current on the interface between the current-carrying flux tube and pre-existing umbral field, which might be a direct detection of the currents flowing in the current sheet formed at the magnetic reconnection sites.

  16. Re-evaluation of Predictive Models in Light of New Data: Sunspot Number Version 2.0

    Science.gov (United States)

    Gkana, A.; Zachilas, L.

    2016-10-01

    The original version of the Zürich sunspot number (Sunspot Number Version 1.0) has been revised by an entirely new series (Sunspot Number Version 2.0). We re-evaluate the performance of our previously proposed models for predicting solar activity in the light of the revised data. We perform new monthly and yearly predictions using the Sunspot Number Version 2.0 as input data and compare them with our original predictions (using the Sunspot Number Version 1.0 series as input data). We show that our previously proposed models are still able to produce quite accurate solar-activity predictions despite the full revision of the Zürich Sunspot Number, indicating that there is no significant degradation in their performance. Extending our new monthly predictions (July 2013 - August 2015) by 50 time-steps (months) ahead in time (from September 2015 to October 2019), we provide evidence that we are heading into a period of dramatically low solar activity. Finally, our new future long-term predictions endorse our previous claim that a prolonged solar activity minimum is expected to occur, lasting up to the year ≈ 2100.

  17. Time-variation of the near 5-month period of sunspot numbers

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The variation of the near 5-month period of sunspot numbers is discussed on the basis of the wavelet transform of the daily sunspot number series in the 14th-22nd solar cycles. The result shows that the period exists in every cycle and its energy density (amplitude) is comparatively large in the peak section of the cycle. In the distinct cycle, the length and intensity of the period is different, which means that the period varies with time. The near 25-day period is also analyzed and it is found to be time- variable and even not very stable in the peak section of the cycle. The variations of the two periods show that the near 5-month period should not be simply regarded as the multiples of the near 25-day period.

  18. Image patch analysis of sunspots and active regions. I. Intrinsic dimension and correlation analysis

    CERN Document Server

    Moon, Kevin R; Delouille, Veronique; De Visscher, Ruben; Watson, Fraser; Hero, Alfred O

    2015-01-01

    Complexity of an active region is related to its flare-productivity. Mount Wilson or McIntosh sunspot classifications measure such complexity but in a categorical way, and may therefore not use all the information present in the observations. Moreover, such categorical schemes hinder a systematic study of an active region's evolution for example. We propose fine-scale quantitative descriptors for an active region's complexity and relate them to the Mount Wilson classification. We analyze the local correlation structure within continuum and magnetogram data, as well as the cross-correlation between continuum and magnetogram data. We compute the intrinsic dimension, partial correlation, and canonical correlation analysis (CCA) of image patches of continuum and magnetogram active region images taken from the SOHO-MDI instrument. We use masks of sunspots derived from continuum as well as larger masks of magnetic active regions derived from the magnetogram to analyze separately the core part of an active region fr...

  19. Has global warming modified the relationship between sunspot numbers and global temperatures?

    CERN Document Server

    Kristoufek, Ladislav

    2016-01-01

    We study time evolution of the relationship between sunspot numbers and global temperatures between 1880 and 2016 using wavelet coherence framework. The results suggest that the relationship is stable in time. Changes in the sunspot numbers precede changes in the temperatures by more than two years as suggested by the wavelet phase differences. This leading position of the sun activity is stable in time as well. However, the relationship has been disturbed by increasing $CO_2$ emissions since 1960s. Without controlling for the effect of possible global warming, or more precisely the positive connection between increasing $CO_2$ emissions and the global temperatures, the findings would have been quite different. Combination of the cointegration analysis and wavelet coherence framework has enabled uncovering a hidden relationship between the solar activity and global temperatures, and possibly explaining equivocal results in the topical literature.

  20. Chromospheric Sunspot Oscillations in H-alpha and Ca II 8542A

    CERN Document Server

    Maurya, Ram Ajor; Park, Hyungmin; Yang, Heesu; Song, Donguk; Cho, Kyuhyoun

    2013-01-01

    We study chromospheric oscillations including umbral flashes and running penumbral waves in a sunspot of active region (AR) using scanning spectroscopy in H-alpha and Ca II 8542A, with the Fast Imaging Solar Spectrograph (FISS) at the 1.6 meter New Solar Telescope at Big Bear Solar Observatory. A bisector method is applied to spectral observations to construct chromospheric Doppler velocity maps. Temporal sequence analysis of these shows enhanced high-frequency oscillations inside the sunspot umbra in both lines. Their peak frequency gradually decreases outward from the umbra. The oscillation power is found to be associated with magnetic-field strength and inclination, with different relationships in different frequency bands.

  1. Evolution of a Long-lived Sunspot Group and Its Associated Solar-terrestrial Events

    Institute of Scientific and Technical Information of China (English)

    Gui-Qing Zhang; Li-Rong Tian

    2005-01-01

    A long-lived sunspot group (AR 9604) on the south hemisphere that lasted five solar rotations and produced some strong bursts is analyzed. The focus is on its evolving features. Its whole life was successfully maintained by four Emerging Flux Regions (EFRs). Apart from the one that lasted only a short time and did not produce any bursts, the other three EFRs have the following common features: (1) A positive writhe of magnetic flux tubes and a twist of the field lines of the same sign, indicating kink instability. (2) A clockwise rotation and a high tilt because the writhe was right-handed. (3) A compact "island δ" structure of the sunspot group indicating concentrated kink instability. Since magnetic reconnection easily occurs at the kinked point of a very kink-unstable flux tube, these features should be the inducement of the strong bursts.

  2. Has global warming modified the relationship between sunspot numbers and global temperatures?

    Science.gov (United States)

    Kristoufek, Ladislav

    2017-02-01

    We study time evolution of the relationship between sunspot numbers and global temperatures between 1880 and 2016 using wavelet coherence framework. The results suggest that the relationship is stable in time. Changes in the sunspot numbers precede changes in the temperatures by more than two years as suggested by the wavelet phase differences. This leading position of the sun activity is stable in time as well. However, the relationship has been disturbed by increasing CO2 emissions since 1960s. Without controlling for the effect of possible global warming, or more precisely the positive connection between increasing CO2 emissions and the global temperatures, the findings would have been quite different. Combination of the cointegration analysis and wavelet coherence framework has enabled uncovering a hidden relationship between the solar activity and global temperatures, and possibly explaining equivocal results in the topical literature.

  3. Suppression of Heating of Coronal Loops Rooted in Opposite Polarity Sunspot Umbrae

    Science.gov (United States)

    Tiwari, Sanjiv K.; Thalmann, Julia K.; Moore, Ronald L.; Panesar, Navdeep K.; Winebarger, Amy R.

    2016-01-01

    EUV observations of active region (AR) coronae reveal the presence of loops at different temperatures. To understand the mechanisms that result in hotter or cooler loops, we study a typical bipolar AR, near solar disk center, which has moderate overall magnetic twist and at least one fully developed sunspot of each polarity. From AIA 193 and 94 Å images we identify many clearly discernible coronal loops that connect plage or a sunspot of one polarity to an opposite-­polarity plage region. The AIA 94 Å images show dim regions in the umbrae of the spots. To see which coronal loops are rooted in a dim umbral area, we performed a non-linear force-free field (NLFFF) modeling using photospheric vector magnetic field measurements obtained with the Heliosesmic Magnetic Imager (HMI) onboard SDO. The NLFFF model, validated by comparison of calculated model field lines with observed loops in AIA 193 and 94 Å, specifies the photospheric roots of the model field lines. Some model coronal magnetic field lines arch from the dim umbral area of the positive-polarity sunspot to the dim umbral area of a negative-polarity sunspot. Because these coronal loops are not visible in any of the coronal EUV and X-ray images of the AR, we conclude they are the coolest loops in the AR. This result suggests that the loops connecting opposite polarity umbrae are the least heated because the field in umbrae is so strong that the convective braiding of the field is strongly suppressed.

  4. The Sun's Meridional Flow and Its Role in Magnetic Flux Transport and the Sunspot Cycle

    Science.gov (United States)

    Hathaway, D. H.; Upton, L.

    2014-12-01

    The Sun's meridional flow can be measured with a variety of measurement techniques including, but not limited to: direct Doppler, magnetic feature tracking, velocity feature tracking, time-distance helioseismology, and ring-diagram analysis. Direct Doppler gives information on the flow in the photosphere while the other measurement techniques provide information about the flow at some depth or range of depths in the Sun's convection zone. These various measurement methods now provide a converging (but not yet fully converged) picture of the meridional flow as a function of latitude, depth, and time. This converging picture has a flow which is poleward from the equator all the way to pole in the near surface layers, has an equatorward return flow beginning at a depth of about 50 Mm, and has another poleward branch deeper in the convection zone. The poleward flow in the near surface layers varies systematically in strength and latitudinal structure with the phase of the sunspot cycle and from one cycle to the next. This near surface meridional flow is observed to play a significant role in the poleward transport of the magnetic flux that emerges at the surface in the form of bipolar active regions. Variations in the strength and structure of the meridional flow introduce variations in the strength of the Sun's polar fields, which in turn introduce variations in the size of subsequent sunspot cycles. The polar fields at the end of cycle 23 (2008-2009) were much weaker than the polar fields at the end of the previous cycles. This led to the production of the weakest sunspot cycle in 100 years - cycle 24. Surprisingly, we find that the variations we observed in the meridional flow during cycle 23 led to stronger polar fields than would have been produced otherwise. This suggests that variations in the meridional flow can be one mechanism for modulating the sizes of sunspot cycles - helping to keep them from getting too big or too small.

  5. On the Source of Propagating Slow Magneto-acoustic Waves in Sunspots

    OpenAIRE

    S. Krishna Prasad; Jess, D. B.; Khomenko, Elena

    2015-01-01

    Recent high-resolution observations of sunspot oscillations using simultaneously operated ground- and space-based telescopes reveal the intrinsic connection between different layers of the solar atmosphere. However, it is not clear whether these oscillations are externally driven or generated in-situ. We address this question by using observations of propagating slow magneto-acoustic waves along a coronal fan loop system. In addition to the generally observed decreases in oscillation amplitud...

  6. ON THE ROLE OF ROTATING SUNSPOTS IN THE ACTIVITY OF SOLAR ACTIVE REGION NOAA 11158

    Energy Technology Data Exchange (ETDEWEB)

    Vemareddy, P.; Ambastha, A. [Udaipur Solar Observatory, Physical Research Laboratory, Udaipur-313001 (India); Maurya, R. A., E-mail: vema@prl.res.in, E-mail: ambastha@prl.res.in, E-mail: ramajor@astro.snu.ac.kr [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of)

    2012-12-10

    We study the role of rotating sunspots in relation to the evolution of various physical parameters characterizing the non-potentiality of the active region (AR) NOAA 11158 and its eruptive events using the magnetic field data from the Helioseismic and Magnetic Imager (HMI) and multi-wavelength observations from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory. From the evolutionary study of HMI intensity and AIA channels, it is observed that the AR consists of two major rotating sunspots, one connected to a flare-prone region and another with coronal mass ejection (CME). The constructed space-time intensity maps reveal that the sunspots exhibited peak rotation rates coinciding with the occurrence of major eruptive events. Further, temporal profiles of twist parameters, namely, average shear angle, {alpha}{sub av}, {alpha}{sub best}, derived from HMI vector magnetograms, and the rate of helicity injection, obtained from the horizontal flux motions of HMI line-of-sight magnetograms, correspond well with the rotational profile of the sunspot in the CME-prone region, giving predominant evidence of rotational motion causing magnetic non-potentiality. Moreover, the mean value of free energy from the virial theorem calculated at the photospheric level shows a clear step-down decrease at the onset time of the flares revealing unambiguous evidence of energy release intermittently that is stored by flux emergence and/or motions in pre-flare phases. Additionally, distribution of helicity injection is homogeneous in the CME-prone region while in the flare-prone region it is not and often changes sign. This study provides a clear picture that both proper and rotational motions of the observed fluxes played significant roles in enhancing the magnetic non-potentiality of the AR by injecting helicity, twisting the magnetic fields and thereby increasing the free energy, leading to favorable conditions for the observed transient activity.

  7. Image patch analysis of sunspots and active regions. I. Intrinsic dimension and correlation analysis

    Science.gov (United States)

    Moon, Kevin R.; Li, Jimmy J.; Delouille, Véronique; De Visscher, Ruben; Watson, Fraser; Hero, Alfred O.

    2016-01-01

    Context. The flare productivity of an active region is observed to be related to its spatial complexity. Mount Wilson or McIntosh sunspot classifications measure such complexity but in a categorical way, and may therefore not use all the information present in the observations. Moreover, such categorical schemes hinder a systematic study of an active region's evolution for example. Aims: We propose fine-scale quantitative descriptors for an active region's complexity and relate them to the Mount Wilson classification. We analyze the local correlation structure within continuum and magnetogram data, as well as the cross-correlation between continuum and magnetogram data. Methods: We compute the intrinsic dimension, partial correlation, and canonical correlation analysis (CCA) of image patches of continuum and magnetogram active region images taken from the SOHO-MDI instrument. We use masks of sunspots derived from continuum as well as larger masks of magnetic active regions derived from magnetogram to analyze separately the core part of an active region from its surrounding part. Results: We find relationships between the complexity of an active region as measured by its Mount Wilson classification and the intrinsic dimension of its image patches. Partial correlation patterns exhibit approximately a third-order Markov structure. CCA reveals different patterns of correlation between continuum and magnetogram within the sunspots and in the region surrounding the sunspots. Conclusions: Intrinsic dimension has the potential to distinguish simple from complex active regions. These results also pave the way for patch-based dictionary learning with a view toward automatic clustering of active regions.

  8. Angular dependence of the facular-sunspot coverage relation as derived by MDI magnetograms

    CERN Document Server

    Criscuoli, Serena

    2016-01-01

    Previous studies have shown that the variation over the solar magnetic activity cycle of the area of facular/network features identified on broad band and narrow band imagery is positively correlated with the sunspot area and number, the relation between the area coverages being described as either linear or quadratic. On the other hand, the temporal variation of the spatial distributions of faculae, network and sunspots follows patterns that are less obviously correlated, so that we expect the relation that describes variation of the area coverage of different types of magnetic features to vary with the position over the disk. In this work we employ MDI full-disk magnetograms acquired during Cycle 23 and at the beginning of Cycle 24 to investigate the relation between the coverage of magnetic elements characterized by different amounts of magnetic flux and located at different angular distances from disk center with the sunspot number. In agreement with some previous studies we find that daily data are best ...

  9. GCR intensity during the sunspot maximum phase and the inversion of the heliospheric magnetic field

    CERN Document Server

    Krainev, M; Kalinin, M; Svirzhevskaya, A; Svirzhevsky, N

    2015-01-01

    The maximum phase of the solar cycle is characterized by several interesting features in the solar activity, heliospheric characteristics and the galactic cosmic ray (GCR) intensity. Recently the maximum phase of the current solar cycle (SC) 24, in many relations anomalous when compared with solar cycles of the second half of the 20-th century, came to the end. The corresponding phase in the GCR intensity cycle is also in progress. In this paper we study different aspects of the sunspot, heliospheric and GCR behavior around this phase. Our main conclusions are as follows: 1) The maximum phase of the sunspot SC 24 ended in 06.2014, the development of the sunspot cycle being similar to those of SC 14, 15 (the Glaisberg minimum). The maximum phase of SC 24 in the GCR intensity is still in progress. 2) The inversion of the heliospheric magnetic field consists of three stages, characterized by the appearance of the global heliospheric current sheet (HCS), connecting all longitudes. In two transition dipole stages ...

  10. Leading and following sunspots: their magnetic properties and ultra-violet emission above them

    CERN Document Server

    Zagainova, Iu S; Obridko, V N

    2015-01-01

    Using SDO/HMI and SDO/AIA data for sunspot groups of the 24th solar cycle, we analyzed magnetic properties and He II 304 emission in leading and following sunspots separately. Simultaneous examination of umbral magnetic properties and atmospheric characteristics above the umbrae draws on average differences in He II 304 contrast over the umbrae of leading and following spots we discovered earlier for solar cycle 23 sunspot groups based on SOHO data as well as on the hypothetical relationship between contrast asymmetry and magnetic field asymmetry in umbrae. We use a more accurate and faster algorithm for solving the pi-uncertainty problem of the transverse magnetic field direction in this research producing new results on differences in magnetic field properties between magneto-conjugated leaders and followers. We found that, in ~78% of the cases, the minimum (over the umbra area) angle between the magnetic field line and the normal to the solar surface, a_min, is smaller in the leading spots, so the magnetic...

  11. Sunspot positions and sizes for 1825-1867 from the observations by Samuel Heinrich Schwabe

    CERN Document Server

    Arlt, R; Giese, N; Mursula, K; Usoskin, I G

    2013-01-01

    Samuel Heinrich Schwabe made 8486 drawings of the solar disk with sunspots in the period from November 5, 1825 to December 29, 1867. We have measured sunspot sizes and heliographic positions on digitized images of these drawings. A total of about 135,000 measurements of individual sunspots are available in a data base. Positions are accurate to about 5% of the solar radius or to about three degrees in heliographic coordinates in the solar disk center. Sizes were given in 12 classes as estimated visually with circular cursor shapes on the screen. Most of the drawings show a coordinate grid aligned with the celestial coordinate system. A subset of 1168 drawings have no indication of their orientation. We have used a Bayesian estimator to infer the orientations of the drawings as well as the average heliographic spot positions from a chain of drawings of several days, using the rotation profile of the present Sun. The data base also includes all information available from Schwabe on spotless days.

  12. Sunspot positions and sizes for 1825-1867 from the observations by Samuel Heinrich Schwabe

    Science.gov (United States)

    Arlt, R.; Leussu, R.; Giese, N.; Mursula, K.; Usoskin, I. G.

    2013-08-01

    Samuel Heinrich Schwabe made 8486 drawings of the solar disc with sunspots in the period from 1825 November 5 to 1867 December 29. We have measured sunspot sizes and heliographic positions on digitized images of these drawings. A total of about 135 000 measurements of individual sunspots are available in a data base. Positions are accurate to about 5 per cent of the solar radius or to about 3° in heliographic coordinates in the solar-disc centre. Sizes were given in 12 classes as estimated visually with circular cursor shapes on the screen. Most of the drawings show a coordinate grid aligned with the celestial coordinate system. A subset of 1168 drawings have no indication of their orientation. We have used a Bayesian estimator to infer the orientations of the drawings as well as the average heliographic spot positions from a chain of drawings of several days, using the rotation profile of the present Sun. The data base also includes all information available from Schwabe on spotless days.

  13. An Assessment of Sunspot Number Data Composites over 1845-2014

    CERN Document Server

    Lockwood, Mike; Barnard, Luke A; Usoskin, Ilya G

    2016-01-01

    New sunspot data composites, some of which are radically different in the character of their long-term variation, are evaluated over the interval 1845-2014. The method commonly used to calibrate historic sunspot data, relative to modern-day data, is "daisy-chaining", whereby calibration is passed from one data subset to the neighbouring one, usually using regressions of the data subsets for the intervals of their overlap. Recent studies have illustrated serious pitfalls in these regressions and the resulting errors can be compounded by their repeated use as the data sequence is extended back in time. Hence the recent composite data series by Usoskin et al. (2016), $R_{UEA}$, is a very important advance because it avoids regressions, daisy-chaining and other common, but invalid, assumptions: this is achieved by comparing the statistics of "active day" fractions to those for a single reference dataset. We study six sunspot data series including $R_{UEA}$ and the new "backbone" data series $R_{BB}$, recently gen...

  14. Tilt Angle and Footpoint Separation of Small and Large Bipolar Sunspot Regions Observed with HMI

    Science.gov (United States)

    McClintock, B. H.; Norton, A. A.

    2016-02-01

    We investigate bipolar sunspot regions and how tilt angle and footpoint separation vary during emergence and decay. The Helioseismic and Magnetic Imager on board the Solar Dynamic Observatory collects data at a higher cadence than historical records and allows for a detailed analysis of regions over their lifetimes. We sample the umbral tilt angle, footpoint separation, and umbral area of 235 bipolar sunspot regions in Helioseismic and Magnetic Imager—Debrecen Data with an hourly cadence. We use the time when the umbral area peaks as time zero to distinguish between the emergence and decay periods of each region and we limit our analysis of tilt and separation behavior over time to within ±96 hr of time zero. Tilt angle evolution is distinctly different for regions with small (≈30 MSH), midsize (≈50 MSH), and large (≈110 MSH) maximum umbral areas, with 45 and 90 MSH being useful divisions for separating the groups. At the peak umbral area, we determine median tilt angles for small (7.°6), midsize (5.°9), and large (9.°3) regions. Within ±48 hr of the time of peak umbral area, large regions steadily increase in tilt angle, midsize regions are nearly constant, and small regions show evidence of negative tilt during emergence. A period of growth in footpoint separation occurs over a 72-hr period for all of the regions from roughly 40 to 70 Mm. The smallest bipoles (Jaramillo et al. (2015) results that the sunspots appear to be two distinct populations.

  15. Magneto-acoustic wave energy from numerical simulations of an observed sunspot umbra

    CERN Document Server

    Felipe, T; Collados, M

    2011-01-01

    We aim at reproducing the height dependence of sunspot wave signatures obtained from spectropolarimetric observations through 3D MHD numerical simulations. A magneto-static sunspot model based on the properties of the observed sunspot is constructed and perturbed at the photosphere introducing the fluctuations measured with the \\SiI\\ $\\lambda$ 10827 \\AA\\ line. The results of the simulations are compared with the oscillations observed simultaneously at different heights from the \\HeI\\ $\\lambda$ 10830 \\AA\\ line, the \\CaIIH\\ core and the \\FeI\\ blends in the wings of the \\CaIIH\\ line. The simulations show a remarkable agreement with the observations. They reproduce the velocity maps and power spectra at the formation heights of the observed lines, as well as the phase and amplification spectra between several pair of lines. We find that the stronger shocks at the chromosphere are accompanied with a delay between the observed signal and the simulated one at the corresponding height, indicating that shocks shift th...

  16. f-mode interaction with models of sunspot: near-field scattering and multifrequency effects

    Science.gov (United States)

    Daiffallah, Khalil

    2016-07-01

    We use numerical simulations to investigate the interaction of an f-mode wave packet with small and large models of a sunspot in a stratified atmosphere. While a loose cluster model has been largely studied before, we focus in this study on the scattering from an ensemble of tightly compact tubes. We showed that the small compact cluster produces a slight distorted scattered wave field in the transverse direction, which can be attributed to the simultaneous oscillations of the pairs of tubes within the cluster aligned in a perpendicular direction to the incoming wave. However, no signature of a multiple-scattering regime has been observed from this model, while it has been clearly observable for the large compact cluster model. Furthermore, we pointed out the importance of the geometrical shape of the monolithic model on the interaction of f-mode waves with a sunspot in a high-frequency range (ν = 5 mHz). These results are a contribution to the observational effort to distinguish seismically between different configurations of magnetic flux tubes within sunspots and plage.

  17. Looking for granulation and periodicity imprints in the sunspot time series

    CERN Document Server

    Lopes, Ilidio

    2015-01-01

    The sunspot activity is the end result of the cyclic destruction and regeneration of magnetic fields by the dynamo action. We propose a new method to analyze the daily sunspot areas data recorded since 1874. By computing the power spectral density of daily data series using the Mexican hat wavelet, we found a power spectrum with a well-defined shape, characterized by three features. The first term is the 22 yr solar magnetic cycle, estimated in our work to be of 18.43 yr. The second term is related to the daily volatility of sunspots. This term is most likely produced by the turbulent motions linked to the solar granulation. The last term corresponds to a periodic source associated with the solar magnetic activity, for which the maximum of power spectral density occurs at 22.67 days. This value is part of the 22-27 day periodicity region that shows an above-average intensity in the power spectra. The origin of this 22.67 day periodic process is not clearly identified, and there is a possibility that it can be...

  18. Angular Dependence of the Facular-Sunspot Coverage Relation as Derived by MDI Magnetograms

    Science.gov (United States)

    Criscuoli, S.

    2016-08-01

    Previous studies have shown that the variation over the solar magnetic activity cycle of the area of facular/network features identified from broad-band and narrow-band imagery is positively correlated with the sunspot area and number, the relation being described as either linear or quadratic. On the other hand, the temporal variation of the spatial distributions of faculae, network and sunspots follows patterns that are less obviously correlated, so that we expect the relation that describes variation of the area coverage of different types of magnetic features to vary with the position over the disk. In this work we employ Michelson Doppler Interferometer (MDI) full-disk magnetograms acquired during solar cycle 23 and at the beginning of cycle 24 to investigate the relation between the coverage of magnetic elements characterized by different amounts of magnetic flux and located at different angular distances from disk center with the sunspot number. In agreement with some previous studies we find that daily data are best described by a quadratic function while data averaged over six months are best described by a linear function. In both cases the coefficients of the fits show large dependence on the position over the disk and the magnetic flux. We also find that toward disk center six-month averaged data show asymmetries between the ascending and the descending phases. The implications for solar irradiance modeling are discussed.

  19. Flaring Rates and the Evolution of Sunspot Group McIntosh Classifications

    CERN Document Server

    McCloskey, Aoife E; Bloomfield, D Shaun

    2016-01-01

    Sunspot groups are the main source of solar flares, with the energy to power them being supplied by magnetic-field evolution (e.g. flux emergence or twisting/shearing). To date, few studies have investigated the statistical relation between sunspot-group evolution and flaring, with none considering evolution in the McIntosh classification scheme. Here we present a statistical analysis of sunspot groups from Solar Cycle 22, focusing on 24-hour changes in the three McIntosh classification components. Evolution-dependent >C1.0, >M1.0, and >X1.0 flaring rates are calculated, leading to the following results: (i) flaring rates become increasingly higher for greater degrees of upward evolution through the McIntosh classes, with the opposite found for downward evolution; (ii) the highest flaring rates are found for upward evolution from larger, more complex, classes (e.g. Zurich D- and E-classes evolving upward to F-class produce >C1.0 rates of 2.66 +/- 0.28 and 2.31 +/- 0.09 flares per 24 hours, respectively); (iii...

  20. Sunspot positions, areas, and group tilt angles for 1611-1631 from observations by Christoph Scheiner

    CERN Document Server

    Arlt, R; Schmiel, C; Spada, F

    2016-01-01

    Digital images of the observations printed in the books "Rosa Ursina sive solis" and "Prodromus pro sole mobili" by Christoph Scheiner as well as the drawings from Scheiner's letters to Marcus Welser are analysed in order to obtain information on positions and sizes of sunspots that appeared before the Maunder minimum. In most cases, the given orientation of the ecliptic is used to set up the heliographic coordinate system for the drawings. Positions and sizes are measured manually on the screen. Very early drawings have no indication of their orientation. A rotational matching using common spots of adjacent days is used in some cases, while in other cases, the assumption of images being aligned with a zenith-horizon coordinate system appeared to be the most probable. In total, 8167 sunspots were measured. A distribution of sunspot latitudes versus time (butterfly diagram) is obtained for Scheiner's observations. The observations of 1611 are very inaccurate, the drawings of 1612 have at least an indication of...

  1. SMALL-SCALE AND GLOBAL DYNAMOS AND THE AREA AND FLUX DISTRIBUTIONS OF ACTIVE REGIONS, SUNSPOT GROUPS, AND SUNSPOTS: A MULTI-DATABASE STUDY

    Energy Technology Data Exchange (ETDEWEB)

    Muñoz-Jaramillo, Andrés; Windmueller, John C.; Amouzou, Ernest C.; Longcope, Dana W. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Senkpeil, Ryan R. [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Tlatov, Andrey G. [Kislovodsk Mountain Astronomical Station of the Pulkovo Observatory, Kislovodsk 357700 (Russian Federation); Nagovitsyn, Yury A. [Pulkovo Astronomical Observatory, Russian Academy of Sciences, St. Petersburg 196140 (Russian Federation); Pevtsov, Alexei A. [National Solar Observatory, Sunspot, NM 88349 (United States); Chapman, Gary A.; Cookson, Angela M. [San Fernando Observatory, Department of Physics and Astronomy, California State University Northridge, Northridge, CA 91330 (United States); Yeates, Anthony R. [Department of Mathematical Sciences, Durham University, South Road, Durham DH1 3LE (United Kingdom); Watson, Fraser T. [National Solar Observatory, Tucson, AZ 85719 (United States); Balmaceda, Laura A. [Institute for Astronomical, Terrestrial and Space Sciences (ICATE-CONICET), San Juan (Argentina); DeLuca, Edward E. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Martens, Petrus C. H., E-mail: munoz@solar.physics.montana.edu [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303 (United States)

    2015-02-10

    In this work, we take advantage of 11 different sunspot group, sunspot, and active region databases to characterize the area and flux distributions of photospheric magnetic structures. We find that, when taken separately, different databases are better fitted by different distributions (as has been reported previously in the literature). However, we find that all our databases can be reconciled by the simple application of a proportionality constant, and that, in reality, different databases are sampling different parts of a composite distribution. This composite distribution is made up by linear combination of Weibull and log-normal distributions—where a pure Weibull (log-normal) characterizes the distribution of structures with fluxes below (above) 10{sup 21}Mx (10{sup 22}Mx). Additionally, we demonstrate that the Weibull distribution shows the expected linear behavior of a power-law distribution (when extended to smaller fluxes), making our results compatible with the results of Parnell et al. We propose that this is evidence of two separate mechanisms giving rise to visible structures on the photosphere: one directly connected to the global component of the dynamo (and the generation of bipolar active regions), and the other with the small-scale component of the dynamo (and the fragmentation of magnetic structures due to their interaction with turbulent convection)

  2. North-south asymmetry in small and large sunspot group activity and violation of even-odd solar cycle rule

    CERN Document Server

    Javaraiah, J

    2016-01-01

    According to Gnevyshev-Ohl (G-O) rule an odd-numbered cycle is stronger than its preceding even-numbered cycle. In the modern time the cycle pair (22, 23) violated this rule. By using the combined Greenwich Photoheliographic Results (GPR) and Solar Optical Observing Network (SOON) sunspot group data during the period 1874-2015, and Debrecen Photoheliographic Data (DPD) of sunspot groups during the period 1974-2015, here we have found that the solar cycle pair (22, 23) violated the G-O rule because, besides during cycle 23 a large deficiency of small sunspot groups in both the northern and the southern hemispheres, during cycle 22 a large abundance of small sunspot groups in the southern hemisphere. In the case of large and small sunspot groups the cycle pair (22, 23) violated the G-O rule in the northern and southern hemispheres, respectively, suggesting the north-south asymmetry in solar activity has a significant contribution in the violation of G-O rule. The amplitude of solar cycle 24 is smaller than that...

  3. Records of sunspot and aurora during CE 960-1279 in the Chinese chronicle of the Song dynasty

    CERN Document Server

    Hayakawa, Hisashi; Kawamura, Akito D; Isobe, Hiroaki

    2015-01-01

    Records of sunspots and aurora observations in pre-telescopic historical documents can provide useful information about solar activity in the past. This is also true for extreme space weather events, as they may have been recorded as large sunspots observed by the naked eye or as low-latitude auroras. In this paper, we present the results of a comprehensive survey of records of sunspots and auroras in the Songshi, a Chinese formal chronicle spanning the tenth to the thirteenth century. This chronicle contains a record of continuous observations with well-formatted reports conducted as a policy of the government. A brief comparison of the frequency of observations of sunspots and auroras and the observations of radioisotopes as an indicator of the solar activity during corresponding periods is provided. This paper is the first step of our project in which we survey and compile the records of sunspots and aurora in historical documents from various locations and languages, ultimately providing it to the science...

  4. The presence of large sunspots near the central solar meridian at the times of modern Japanese auroral observations

    Directory of Open Access Journals (Sweden)

    D. M. Willis

    2006-10-01

    Full Text Available The validity of a technique developed by the authors to identify historical occurrences of intense geomagnetic storms, which is based on finding approximately coincident observations of sunspots and aurorae recorded in East Asian histories, is corroborated using more modern sunspot and auroral observations. Scientific observations of aurorae in Japan during the interval 1957–2004 are used to identify geomagnetic storms that are sufficiently intense to produce auroral displays at low geomagnetic latitudes. By examining white-light images of the Sun obtained by the Royal Greenwich Observatory, the Big Bear Solar Observatory, the Debrecen Heliophysical Observatory and the Solar and Heliospheric Observatory spacecraft, it is found that a sunspot large enough to be seen with the unaided eye by an "experienced" observer was located reasonably close to the central solar meridian immediately before all but one of the 30 distinct Japanese auroral events, which represents a 97% success rate. Even an "average" observer would probably have been able to see a sunspot with the unaided eye before 24 of these 30 events, which represents an 80% success rate. This corroboration of the validity of the technique used to identify historical occurences of intense geomagnetic storms is important because early unaided-eye observations of sunspots and aurorae provide the only possible means of identifying individual historical geomagnetic storms during the greater part of the past two millennia.

  5. Forced arterial suction thrombectomy with the penumbra reperfusion catheter in acute basilar artery occlusion: a retrospective comparison study in 2 Korean university hospitals.

    Science.gov (United States)

    Eom, Y-I; Hwang, Y-H; Hong, J M; Choi, J W; Lim, Y C; Kang, D-H; Kim, Y-W; Kim, Y-S; Kim, S Y; Lee, J S

    2014-12-01

    A performance of forced arterial suction thrombectomy was not reported for the treatment of acute basilar artery occlusion. This study compared revascularization performance between intra-arterial fibrinolytic treatment and forced arterial suction thrombectomy with a Penumbra reperfusion catheter in patients with acute basilar artery occlusion. Fifty-seven patients with acute basilar artery occlusion were treated with intra-arterial fibrinolysis (n = 25) or forced arterial suction thrombectomy (n = 32). Baseline characteristics, successful revascularization rate, and clinical outcomes were compared between the groups. Baseline characteristics, the frequency of patients receiving intravenous recombinant tissue plasminogen activator, and mean time interval between symptom onset and femoral puncture did not differ between groups. The forced arterial suction thrombectomy group had a shorter procedure duration (75.5 minutes versus 113.3 minutes, P = .016) and higher successful revascularization rate (88% versus 60%, P = .017) than the fibrinolysis group. Fair outcome, indicated by a modified Rankin Scale 0-3, at 3 months was achieved in 34% of patients undergoing forced arterial suction thrombectomy and 8% of patients undergoing fibrinolysis (P = .019), and the mortality rate was significantly higher in the fibrinolysis group (25% versus 68%, P = .001). Multiple logistic regression analysis identified the forced arterial suction thrombectomy method as an independent predictor of fair outcome with adjustment for age, sex, initial NIHSS score, and the use of intravenous recombinant tissue plasminogen activator (odds ratio, 7.768; 95% CI, 1.246-48.416; P = .028). In acute basilar artery occlusion, forced arterial suction thrombectomy demonstrated a higher revascularization rate and improved clinical outcome compared with traditional intra-arterial fibrinolysis. Further clinical trials with the newer Penumbra catheter are warranted. © 2014 by American Journal of

  6. SU-E-T-604: Penumbra Characteristics of a New InCiseâ„¢ Multileaf Collimator of CyberKnife M6â„¢ System

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, M; Jang, S; Ozhasoglu, C; Lalonde, R; Heron, D; Huq, M [University of Pittsburgh Medical Center, Pittsburgh, PA (United States)

    2015-06-15

    Purpose: The InCise™ Multileaf Collimator (MLC) of CyberKnife M6™ System has been released recently. The purpose of this study was to explore the dosimetric characteristics of the new MLC. In particular, the penumbra characteristics of MLC fields at varying locations are evaluated. Methods: EBT3-based film measurements were performed with varying MLC fields ranging from 7.5 mm to 27.5 mm. Seventeen regions of interests (ROIs) were identified for irradiation. These are regions located at the central area (denoted as reference field), at the left/right edge areas of reference open field, at an intermediate location between central and edge area. Single beam treatment plans were designed by using the MultiPlan and was delivered using the Blue Phantom. Gafchromic films were irradiated at 1.5 cm depth in the Blue Phantom and analyzed using the Film Pro software. Variation of maximum dose, penumbra of MLC-defined fields, and symmetry/flatness were calculated as a function of locations of MLC fields. Results: The InCise™ MLC System showed relatively consistent dose distribution and penumbra size with varying locations of MLC fields. The measured maximum dose varied within 5 % at different locations compared to that at the central location and agreed with the calculated data well within 2%. The measured penumbrae were in the range of 2.9 mm and 3.7 mm and were relatively consistent regardless of locations. However, dose profiles in the out-of-field and in-field regions varied with locations and field sizes. Strong variation was seen for all fields located at 55 mm away from the central field. The MLC leakage map showed that the leakage is dependent on position. Conclusion: The size of penumbra and normalized maximum dose for MLC-defined fields were consistent in different regions of MLC. However, dose profiles in the out-field region varied with locations and field sizes.

  7. On Solar Granulations, Limb Darkening, and Sunspots: Brief Insights in Remembrance of Father Angelo Secchi

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2011-07-01

    Full Text Available Father Angelo Secchi used the existence of solar granulation as a central line of rea- soning when he advanced that the Sun was a gaseous body with a photosphere contain- ing incandescent particulate matter (Secchi A. Sulla Struttura della Fotosfera Solare. Bullettino Meteorologico dell’Osservatorio del Collegio Romano , 30 November 1864, v.3(11, 1–3. Secchi saw the granules as condensed matter emitting the photospheric spectrum, while the darkened intergranular lanes conveyed the presence of a gaseous solar interior. Secchi also considered the nature of sunspots and limb darkening. In the context of modern solar models, opacity arguments currently account for the emis- sive properties of the photosphere. Optical depth is thought to explain limb darkening. Both temperature variations and magnetic fields are invoked to justify the weakened emissivities of sunspots, even though the presence of static magnetic fields in materi- als is not usually associated with modified emissivity. Conversely, within the context of a liquid metallic hydrogen solar model, the appearance of granules, limb darkening, and sunspots can be elegantly understood through the varying directional emissivity of condensed matter. A single explanation is applicable to all three phenomena. Granular contrast can be directly associated with the generation of limb darkening. Depending on size, granules can be analyzed by considering Kolmogoroff’s formulations and B ́ enard convection, respectively, both of which were observed using incompressible liquids, not gases. Granules follow the 2-dimensional space filling laws of Aboav-Weiner and Lewis. Their adherence to these structural laws provides supportive evidence that the granular surface of the Sun represents elements which can only be constructed from condensed matter. A gaseous Sun cannot be confined to a 2-dimensional framework. Mesogranules, supergranules, and giant cells constitute additional entities which further

  8. The formation of an inverse S-shaped active-region filament driven by sunspot motion and magnetic reconnection

    CERN Document Server

    Yan, X L; Guo, Q L; Xue, Z K; Wang, J C; Yang, L H

    2016-01-01

    We present a detailed study of the formation of an inverse S-shaped filament prior to its eruption in active region NOAA 11884 from October 31 to November 2, 2013. In the initial stage, clockwise rotation of a small positive sunspot around the main negative trailing sunspot formed a curved filament. Then the small sunspot cancelled with negative magnetic flux to create a longer active-region filament with an inverse S-shape. At the cancellation site a brightening was observed in UV and EUV images and bright material was transferred to the filament. Later the filament erupted after cancellation of two opposite polarities under the upper part of the filament. Nonlinear force-free field (NLFFF) extrapolation of vector photospheric fields suggests that the filament may have a twisted structure, but this cannot be confirmed from the current observations.

  9. MHD simulations of formation and eruption of a magnetic flux rope in an active region with a delta-sunspot

    Science.gov (United States)

    Yokoyama, Takaaki; Oi, Yoshiaki; Toriumi, Shin

    2017-08-01

    Active regions holding a delta-sunspot are known to produce the largest class of solar flares. How, where, and when such large flares occur above a delta-sunspot are still under debate. For studying this, 3D MHD simulations of the emergence of a subsurface flux tube at two locations in a simulation box modeling the convection zone to the corona were conducted. We found that a flux rope is formed as a consequence of magnetic reconnection of two bipolar loops and sunspot rotation caused by the twist of the subsurface flux tube. Moreover, the flux rope stops ascending when the initial background is not magnetized, whereas it rises up to the upper boundary when a reconnection favorably oriented pre-existing field is introduced to the initial background.

  10. Assessment of different sunspot number series using the cosmogenic isotope 44Ti in meteorites

    Science.gov (United States)

    Asvestari, Eleanna; Usoskin, Ilya G.; Kovaltsov, Gennady A.; Owens, Mathew J.; Krivova, Natalie A.; Rubinetti, Sara; Taricco, Carla

    2017-01-01

    Many sunspot number series exist suggesting different levels of solar activity during the past centuries. Their reliability can be assessed only by comparing them with alternative indirect proxies. We test different sunspot number series against the updated record of cosmogenic radionuclide 44Ti measured in meteorites. Two bounding scenarios of solar activity changes have been considered: the HH-scenario (based on the series by Svalgaard and Schatten, 2016) in particular predicting moderate activity during the Maunder minimum; and the LL-scenario (based on the RG series by Lockwood et al., 2014b) predicting moderate activity for the 18-19th centuries and the very low activity level for the Maunder minimum. For each scenario, the magnetic open solar flux, the heliospheric modulation potential and the expected production of 44Ti were computed. The calculated production rates were compared with the corresponding measurements of 44Ti activity in stony meteorites fallen since 1766. The analysis reveals that the LL-scenario is fully consistent with the measured 44Ti data, in particular recovering the observed secular trend between the 17th century and the Modern grand maximum. On the contrary, the HH-scenario appears significantly inconsistent with the data, mostly due the moderate level of activity during the Maunder minimum. It is concluded that the HH-scenario sunspot number reconstruction significantly overestimates solar activity prior to the mid-18th century, especially during the Maunder minimum. The exact level of solar activity after 1750 cannot be distinguished with this method, since both H- and L- scenarios appear statistically consistent with the data.

  11. LOOKING FOR GRANULATION AND PERIODICITY IMPRINTS IN THE SUNSPOT TIME SERIES

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, Ilídio [Centro Multidisciplinar de Astrofísica, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Silva, Hugo G., E-mail: ilidio.lopes@tecnico.ulisboa.pt, E-mail: hgsilva@uevora.pt [Departamento de Física, ECT, Instituto de Ciências da Terra, Universidade de Évora, Rua Romão Ramalho 59, 7002-554 Évora (Portugal)

    2015-05-10

    The sunspot activity is the end result of the cyclic destruction and regeneration of magnetic fields by the dynamo action. We propose a new method to analyze the daily sunspot areas data recorded since 1874. By computing the power spectral density of daily data series using the Mexican hat wavelet, we found a power spectrum with a well-defined shape, characterized by three features. The first term is the 22 yr solar magnetic cycle, estimated in our work to be 18.43 yr. The second term is related to the daily volatility of sunspots. This term is most likely produced by the turbulent motions linked to the solar granulation. The last term corresponds to a periodic source associated with the solar magnetic activity, for which the maximum power spectral density occurs at 22.67 days. This value is part of the 22–27 day periodicity region that shows an above-average intensity in the power spectra. The origin of this 22.67 day periodic process is not clearly identified, and there is a possibility that it can be produced by convective flows inside the star. The study clearly shows a north–south asymmetry. The 18.43 yr periodical source is correlated between the two hemispheres, but the 22.67 day one is not correlated. It is shown that toward the large timescales an excess occurs in the northern hemisphere, especially near the previous two periodic sources. To further investigate the 22.67 day periodicity, we made a Lomb–Scargle spectral analysis. The study suggests that this periodicity is distinct from others found nearby.

  12. TILT ANGLE AND FOOTPOINT SEPARATION OF SMALL AND LARGE BIPOLAR SUNSPOT REGIONS OBSERVED WITH HMI

    Energy Technology Data Exchange (ETDEWEB)

    McClintock, B. H. [University of Southern Queensland, Toowoomba, 4350 (Australia); Norton, A. A., E-mail: u1049686@umail.usq.edu.au, E-mail: aanorton@stanford.edu [HEPL, Stanford University, Palo Alto, CA 94305 (United States)

    2016-02-10

    We investigate bipolar sunspot regions and how tilt angle and footpoint separation vary during emergence and decay. The Helioseismic and Magnetic Imager on board the Solar Dynamic Observatory collects data at a higher cadence than historical records and allows for a detailed analysis of regions over their lifetimes. We sample the umbral tilt angle, footpoint separation, and umbral area of 235 bipolar sunspot regions in Helioseismic and Magnetic Imager—Debrecen Data with an hourly cadence. We use the time when the umbral area peaks as time zero to distinguish between the emergence and decay periods of each region and we limit our analysis of tilt and separation behavior over time to within ±96 hr of time zero. Tilt angle evolution is distinctly different for regions with small (≈30 MSH), midsize (≈50 MSH), and large (≈110 MSH) maximum umbral areas, with 45 and 90 MSH being useful divisions for separating the groups. At the peak umbral area, we determine median tilt angles for small (7.°6), midsize (5.°9), and large (9.°3) regions. Within ±48 hr of the time of peak umbral area, large regions steadily increase in tilt angle, midsize regions are nearly constant, and small regions show evidence of negative tilt during emergence. A period of growth in footpoint separation occurs over a 72-hr period for all of the regions from roughly 40 to 70 Mm. The smallest bipoles (<9 MSH) are outliers in that they do not obey Joy's law and have a much smaller footpoint separation. We confirm the Muñoz-Jaramillo et al. results that the sunspots appear to be two distinct populations.

  13. STOCHASTIC DESCRIPTION OF THE HIGH-FREQUENCY CONTENT OF DAILY SUNSPOTS AND EVIDENCE FOR REGIME CHANGES

    Energy Technology Data Exchange (ETDEWEB)

    Shapoval, A. [Financial University under the Government of the Russian Federation, Leningradsky pr. 49, Moscow (Russian Federation); Le Mouël, J.-L.; Courtillot, V. [Institute de Physique du Globe, Sorbonne Paris Cité, Paris (France); Shnirman, M. [Institute of Earthquake Prediction Theory and Mathematical Geophysics, Profsoyuznaya 84/32, 117997 Moscow (Russian Federation)

    2015-01-20

    The irregularity index λ is applied to the high-frequency content of daily sunspot numbers ISSN. This λ is a modification of the standard maximal Lyapunov exponent. It is computed here as a function of embedding dimension m, within four-year time windows centered at the maxima of Schwabe cycles. The λ(m) curves form separate clusters (pre-1923 and post-1933). This supports a regime transition and narrows its occurrence to cycle 16, preceding the growth of activity leading to the Modern Maximum. The two regimes are reproduced by a simple autoregressive process AR(1), with the mean of Poisson noise undergoing 11 yr modulation. The autocorrelation a of the process (linked to sunspot lifetime) is a ≈ 0.8 for 1850-1923 and ≈0.95 for 1933-2013. The AR(1) model suggests that groups of spots appear with a Poisson rate and disappear at a constant rate. We further applied the irregularity index to the daily sunspot group number series for the northern and southern hemispheres, provided by the Greenwich Royal Observatory (RGO), in order to study a possible desynchronization. Correlations between the north and south λ(m) curves vary quite strongly with time and indeed show desynchronization. This may reflect a slow change in the dimension of an underlying dynamical system. The ISSN and RGO series of group numbers do not imply an identical mechanism, but both uncover a regime change at a similar time. Computation of the irregularity index near the maximum of cycle 24 will help in checking whether yet another regime change is under way.

  14. Transition of the Sunspot Number from Zurich to Brussels in 1980: A Personal Perspective

    Science.gov (United States)

    Stenflo, J. O.

    2016-11-01

    The Swiss Federal Observatory, which had been founded in 1863 by Rudolf Wolf, was dissolved in connection with the retirement of Max Waldmeier in 1979. The determination of the Zurich sunpot number, which had been a cornerstone activity of the observatory, was then discontinued by ETH Zurich. A smooth transition of the responsibility for the sunspot number from Zurich to Brussels was achieved in 1980, however, through which it was possible to avoid a discontinuity in this important time series. Here we describe the circumstances that led to the termination in Zurich, how Brussels was chosen for the succession, and how the transfer was accomplished.

  15. Solar Polarimetry - from Turbulent Magnetic Fields to Sunspots

    Science.gov (United States)

    Kleint, Lucia

    2016-07-01

    Polarimetric measurements are essential to investigate the solar magnetic field. Scattering polarization and the Hanle effect allow us to probe the turbulent magnetic field and the still open questions of its strength and variability. Directed magnetic fields can be detected via the Zeeman effect. To derive their orientation and strength, so-called inversion codes are used, which iteratively modify a model atmosphere and calculate the resulting polarization profiles that are then compared to the observations. While photospheric polarimetry is well-established, chromospheric polarimetry is still in its infancy, especially because it requires a treatment in non-LTE, making it a complex non-linear problem. But some of the most important open questions concern the strength and geometry of the chromospheric magnetic field. In this talk, I will review different polarimetric analysis techniques and recent advances in magnetic field measurements going from the small scales of turbulent magnetic fields to changes of magnetic fields in an active region during flares.

  16. Non-parametric Data Analysis of Low-latitude Auroras and Naked-eye Sunspots in the Medieval Epoch

    Science.gov (United States)

    Bekli, Mohamed Reda; Zougab, Nabil; Belabbas, Abdelmoumene; Chadou, Ilhem

    2017-04-01

    We have studied solar activity by analyzing naked-eye sunspot observations and aurorae borealis observed at latitudes below 45°. We focused on the medieval epoch by considering the non-telescopic observations of sunspots from AD 974 to 1278 and aurorae borealis from AD 965 to 1273 that are reported in several Far East historical sources, primarily in China and Korea. After setting selection rules, we analyzed the distribution of these individual events following the months of the Gregorian calendar. In December, an unusual peak is observed with data recorded in both China and Japan, but not within Korean data.

  17. A closer look at a coronal loop rooted in a sunspot umbra

    CERN Document Server

    Chitta, L P; Young, P R

    2015-01-01

    Extreme UV (EUV) and X-ray loops in the solar corona connect regions of enhanced magnetic activity, but usually they are not rooted in the dark umbrae of sunspots. This is because there the strong magnetic field suppresses convection and thus the Poynting flux of magnetic energy into the upper atmosphere is not significant within the umbra, as long as there are no light bridges, umbral dots. Here we report a rare observation of a coronal loop rooted in the dark umbra of a sunspot without any traces of light bridges or umbral dots. We used the slit-jaw images and spectroscopic data from the IRIS and concentrate on the line profiles of O IV and Si IV that show persistent strong redshifted components in the loop rooted in the umbra. Using the ratios of O IV, we can estimate the density and thus investigate the mass flux. The coronal context and temperature diagnostics of these observations is provided through the EUV channels of the AIA. The coronal loop, embedded within cooler downflows, is hosting supersonic d...

  18. Time Distributions of Large and Small Sunspot Groups Over Four Solar Cycles

    CERN Document Server

    Kilcik, A; Abramenko, V; Goode, P R; Ozguc, A; Rozelot, J P; Cao, W; 10.1088/0004-637X/731/1/30

    2011-01-01

    Here we analyze solar activity by focusing on time variations of the number of sunspot groups (SGs) as a function of their modified Zurich class. We analyzed data for solar cycles 2023 by using Rome (cycles 2021) and Learmonth Solar Observatory (cycles 2223) SG numbers. All SGs recorded during these time intervals were separated into two groups. The first group includes small SGs (A, B, C, H, and J classes by Zurich classification) and the second group consists of large SGs (D, E, F, and G classes). We then calculated small and large SG numbers from their daily mean numbers as observed on the solar disk during a given month. We report that the time variations of small and large SG numbers are asymmetric except for the solar cycle 22. In general large SG numbers appear to reach their maximum in the middle of the solar cycle (phase 0.450.5), while the international sunspot numbers and the small SG numbers generally peak much earlier (solar cycle phase 0.290.35). Moreover, the 10.7 cm solar radio flux, the facul...

  19. Are intermediate range periodicities in sunspot area associated with planetary motion?

    CERN Document Server

    Edmonds, Ian

    2016-01-01

    Rieger quasi-periodicities have been reported numerous times. However, no accepted explanation of the quasi-periodicities has emerged. We examine the possibility that the some of the reported periodicities are associated with a Mercury to Sun interaction of base period 88 days. To test this idea we filter the daily sunspot area record with band pass filters centred on the 88 day period and 176 day sub harmonic period of Mercury. We observed that the time variation of the amplitude of the components was comprised of episodes that varied in duration from 1.5 to 4 years, with successive episodes usually overlapping in time but, for significant intervals in the record, the episodes were discrete, i.e. not overlapping. The time variation of the filtered components was compared with the time variation of the tidal effect of Mercury. We were able to show that when episodes were discrete the time variation of the component of sunspot area during the episode was either in-phase or in anti-phase with the tidal effect. ...

  20. Narrow-line-width UV Bursts in the Transition Region above Sunspots Observed by IRIS

    Science.gov (United States)

    Hou, Zhenyong; Huang, Zhenghua; Xia, Lidong; Li, Bo; Madjarska, Maria S.; Fu, Hui; Mou, Chaozhou; Xie, Haixia

    2016-10-01

    Various small-scale structures abound in the solar atmosphere above active regions, playing an important role in the dynamics and evolution therein. We report on a new class of small-scale transition region structures in active regions, characterized by strong emissions but extremely narrow Si iv line profiles as found in observations taken with the Interface Region Imaging Spectrograph (IRIS). Tentatively named as narrow-line-width UV bursts (NUBs), these structures are located above sunspots and comprise one or multiple compact bright cores at sub-arcsecond scales. We found six NUBs in two data sets (a raster and a sit-and-stare data set). Among these, four events are short-lived with a duration of ∼10 minutes, while two last for more than 36 minutes. All NUBs have Doppler shifts of 15–18 km s‑1, while the NUB found in sit-and-stare data possesses an additional component at ∼50 km s‑1 found only in the C ii and Mg ii lines. Given that these events are found to play a role in the local dynamics, it is important to further investigate the physical mechanisms that generate these phenomena and their role in the mass transport in sunspots.

  1. Prediction of the smoothed monthly mean sunspot numbers for solar cycle 24

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The prediction for the smoothed monthly mean sunspot numbers (hereafter SMSNs) of solar cycle 23, which was given with a similar cycle method proposed by us at the beginning time of cycle 23, is analyzed and verified in this paper. Using our predicted maximum SMSN and the ascending length for solar cycle 24, and as- suming their relative errors to be respectively 20% and ± 7 months, solar cycles 2, 4, 8, 11, 17, 20 and 23 are selected to be the similar cycles to cycle 24. The selected solar cycles are divided into two groups. The first group consists of all the selected cycles; while the second group consists of only cycles 11, 17, 20 and 23. Two SMSN time profiles then may be obtained, respectively, for the two similar cycle groups. No significant difference is found between the two predicted time profiles. Consid- ering the latest observed sunspot number so far available for cycle 23 and the pre- dictions for the minimum SMSN of cycle 24, a date calibration is done for the ob- tained time profiles, and thus, SMSNs for 127 months of cycle 24, from October 2007 to April 2018, are predicted.

  2. Prediction of the smoothed monthly mean sunspot numbers for solar cycle 24

    Institute of Scientific and Technical Information of China (English)

    WANG JiaLong; MIAO Juan; LIU SiQing; GONG JianCun; ZHU CuiLian

    2008-01-01

    The prediction for the smoothed monthly mean sunspot numbers (hereafter SMSNs) of solar cycle 23,which was given with a similar cycle method proposed by us at the beginning time of cycle 23,is analyzed and verified in this paper.Using our predicted maximum SMSN and the ascending length for solar cycle 24,and assuming their relative errors to be respectively 20% and ± 7 months,solar cycles 2,4,8,11,17,20 and 23 are selected to be the similar cycles to cycle 24.The selected solar cycles are divided into two groups.The first group consists of all the selected cycles; while the second group consists of only cycles 11,17,20 and 23.Two SMSN time profiles then may be obtained,respectively,for the two similar cycle groups.No significant difference is found between the two predicted time profiles.Considering the latest observed sunspot number so far available for cycle 23 and the predictions for the minimum SMSN of cycle 24,a date calibration is done for the obtained time profiles,and thus,SMSNs for 127 months of cycle 24,from October 2007 to April 2018,are predicted.

  3. Comparison of Debrecen and Mount Wilson/Kodaikanal sunspot group tilt angles and the Joy's law

    CERN Document Server

    Baranyi, T

    2014-01-01

    The study of active region tilt angles and their variations in different time scales plays an important role in revealing the subsurface dynamics of magnetic flux ropes and in understanding the dynamo mechanism. In order to reveal the exact characteristics of tilt angles, precise long-term tilt angle data bases are needed. However, there are only a few different data sets at present, which are difficult to be compared and cross-calibrate because of their substantial deviations. In this paper, we describe new tilt angle data bases derived from the Debrecen Photoheliographic Data ($DPD$) (1974--) and from the SOHO/MDI-Debrecen Data ($SDD$) (1996-2010) sunspot catalogues. We compare them with the traditional sunspot group tilt angle data bases of Mount Wilson Observatory (1917-85) and Kodaikanal Solar Observatory (1906-87) and we analyse the deviations. Various methods and filters are investigated which may improve the sample of data and may help deriving better results based on combined data. As a demonstration...

  4. Comparison of Debrecen and Mount Wilson/Kodaikanal sunspot group tilt angles and the Joy's law

    Science.gov (United States)

    Baranyi, T.

    2015-02-01

    The study of active region tilt angles and their variations in different time-scales plays an important role in revealing the subsurface dynamics of magnetic flux ropes and in understanding the dynamo mechanism. In order to reveal the exact characteristics of tilt angles, precise long-term tilt angle data bases are needed. However, there are only a few different data sets at present, which are difficult to be compared and cross-calibrate because of their substantial deviations. In this paper, we describe new tilt angle data bases derived from the Debrecen Photoheliographic Data (DPD) (1974-) and from the SOHO/MDI-Debrecen Data (SDD) (1996-2010) sunspot catalogues. We compare them with the traditional sunspot group tilt angle data bases of Mount Wilson Observatory (1917-85) and Kodaikanal Solar Observatory (1906-87) and we analyse the deviations. Various methods and filters are investigated which may improve the sample of data and may help in deriving better results based on combined data. As a demonstration of the enhanced quality of the improved data set a refined diagram of Joy's law is presented.

  5. Magneto-acoustic waves in sunspots from observations and numerical simulations

    CERN Document Server

    Felipe, T; Collados, M; Beck, C

    2010-01-01

    We study the propagation of waves from the photosphere to the chromosphere of sunspots. From time series of cospatial Ca II H (including its line blends) intensity spectra and polarimetric spectra of Si I 1082.7 nm and He I 1083.0 nm we retrieve the line-of-sight velocity at several heights. The analysis of the phase difference and amplification spectra shows standing waves for frequencies below 4 mHz and propagating waves for higher frequencies, and allows us to infer the temperature and height where the lines are formed. Using these observational data, we have constructed a model of sunspot, and we have introduced the velocity measured with the photospheric Si I 1082.7 nm line as a driver. The numerically propagated wave pattern fits reasonably well with the observed using the lines formed at higher layers, and the simulations reproduce many of the observed features. The observed waves are slow MHD waves propagating longitudinally along field lines.

  6. The mutual attraction of magnetic knots. [solar hydromagnetic instability in sunspot regions

    Science.gov (United States)

    Parker, E. N.

    1978-01-01

    It is observed that the magnetic knots associated with active regions on the sun have an attraction for each other during the formative period of the active regions, when new magnetic flux is coming to the surface. The attraction disappears when new flux ceases to rise through the surface. Then the magnetic spots and knots tend to come apart, leading to disintegration of the sunspots previously formed. The dissolution of the fields is to be expected, as a consequence of the magnetic repulsion of knots of like polarity and as a consequence of the hydromagnetic exchange instability. The purpose of this paper is to show that the mutual attraction of knots during the formative stages of a sunspot region may be understood as the mutual hydrodynamic attraction of the rising flux tubes. Two rising tubes attract each other, as a consequence of the wake of the leading tube when one is moving behind the other, and as a consequence of the Bernoulli effect when rising side by side.

  7. A New Calibrated Sunspot Group Series Since 1749: Statistics of Active Day Fractions

    CERN Document Server

    Usoskin, I G; Lockwood, M; Mursula, K; Owens, M; Solanki, S K

    2015-01-01

    Although the sunspot-number series have existed since the mid-19th century, they are still the subject of intense debate, with the largest uncertainty being related to the "calibration" of the visual acuity of individual observers in the past. Daisy-chain regression methods are applied to inter-calibrate the observers which may lead to significant bias and error accumulation. Here we present a novel method to calibrate the visual acuity of the key observers to the reference data set of Royal Greenwich Observatory sunspot groups for the period 1900-1976, using the statistics of the active-day fraction. For each observer we independently evaluate their observational thresholds [S_S] defined such that the observer is assumed to miss all of the groups with an area smaller than S_S and report all the groups larger than S_S. Next, using a Monte-Carlo method we construct, from the reference data set, a correction matrix for each observer. The correction matrices are significantly non-linear and cannot be approximate...

  8. Tilt Angle and Footpoint Separation of Small and Large Bipolar Sunspot Regions Observed with HMI

    CERN Document Server

    McClintock, Bruce H

    2016-01-01

    We investigate bipolar sunspot regions and how tilt angle and footpoint separation vary during emergence and decay. The Helioseismic and Magnetic Imager on board the Solar Dynamic Observatory collects data at a higher cadence than historical records and allows for a detailed analysis of regions over their lifetimes. We sample the umbral tilt angle, footpoint separation, and umbral area of 235 bipolar sunspot regions in Helioseismic and Magnetic Imager - Debrecen Data (HMIDD) with an hourly cadence. We use the time when the umbral area peaks as time zero to distinguish between the emergence and decay periods of each region and we limit our analysis of tilt and separation behavior over time to within +/-96 hours of time zero. Tilt angle evolution is distinctly different for regions with small (~30 MSH), midsize (~50 MSH), and large (~110 MSH) maximum umbral areas, with 45 and 90 MSH being useful divisions in separating the groups. At the peak umbral area, we determine median tilt angles for small (7.6 degrees),...

  9. Magnetic field measurements in sunspots using spectral lines with different Lande factors

    Science.gov (United States)

    Lozitsky, V.; Osipov, S.

    2017-06-01

    Results of direct measurements of magnetic fields in sunspots are presented. Observations were carried out in June-July 2015 on Horizontal Solar Telescope AtsU-5 of Main Astronomical Observatory of National Academy of Science of Ukraine. Magnetic fields were measured by the Zeeman splitting of some spectral lines of FeI, MnI and NiI placed nearly FeI 5434.5 Å and FeI 6093.66 Å Effective Lande factors of these lines, geff, are in range from -0.22 - 2.14. Significant differences were found both for lines with different and closest values of geff. In some places of sunspots, FeI 5434.5 Å line (geff = -0.014) displays a realible splitting which corresponds to magnetic field strengths up to 2.5 kG. In all cases under study, FeI 6094.419 Å line with negative Lande factor (geff = -0.22) has the sign of splitting as a line with positive Lande factor (geff > 0). The possible reasons of this effect are discussed.

  10. The Frequency-dependent Damping of Slow Magnetoacoustic Waves in a Sunspot Umbral Atmosphere

    Science.gov (United States)

    Krishna Prasad, S.; Jess, D. B.; Van Doorsselaere, T.; Verth, G.; Morton, R. J.; Fedun, V.; Erdélyi, R.; Christian, D. J.

    2017-09-01

    High spatial and temporal resolution images of a sunspot, obtained simultaneously in multiple optical and UV wavelengths, are employed to study the propagation and damping characteristics of slow magnetoacoustic waves up to transition region heights. Power spectra are generated from intensity oscillations in sunspot umbra, across multiple atmospheric heights, for frequencies up to a few hundred mHz. It is observed that the power spectra display a power-law dependence over the entire frequency range, with a significant enhancement around 5.5 mHz found for the chromospheric channels. The phase difference spectra reveal a cutoff frequency near 3 mHz, up to which the oscillations are evanescent, while those with higher frequencies propagate upward. The power-law index appears to increase with atmospheric height. Also, shorter damping lengths are observed for oscillations with higher frequencies suggesting frequency-dependent damping. Using the relative amplitudes of the 5.5 mHz (3 minute) oscillations, we estimate the energy flux at different heights, which seems to decay gradually from the photosphere, in agreement with recent numerical simulations. Furthermore, a comparison of power spectra across the umbral radius highlights an enhancement of high-frequency waves near the umbral center, which does not seem to be related to magnetic field inclination angle effects.

  11. Values of Kp Indices, Ap Indices, Cp Indices, C9 Indices, Sunspot Number, and 10.7 cm Flux

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data file consists of Kp indices, Ap indices, Cp indices, C9 indices, sunspot number, and 10.7 cm flux. The most often requested parameter of this file are the...

  12. Comparisons of Apparent Diffusion Coefficient Values in Penumbra, Infarct, and Normal Brain Regions in Acute Ischemic Stroke: Confirmatory Data Using Bootstrap Confidence Intervals, Analysis of Variance, and Analysis of Means.

    Science.gov (United States)

    Lopez-Mejia, Mariana; Roldan-Valadez, Ernesto

    2016-03-01

    There is no consensus about apparent diffusion coefficient (ADC) values in acute stroke regions that could be used by clinicians in a day-to-day clinical practice; regional measures using confidence intervals (CIs) and a graphic representation of means are scarce in the literature. Our aim in this study was to compare ADC values in infarct, penumbra, and normal brain regions in patients with acute ischemic stroke (AIS). This is a retrospective study of 100 magnetic resonance imaging data sets from AIS patients. ADC values were measured in the infarct, penumbra, and normal regions. Three hundred measurements underwent 1-way analysis of variance, analysis of means, and calculation of 95% and 84% CIs. There was a statistically significant difference at the P level less than .025 in ADC values for the 3 regions (F[2, 297] = 168.039, P ≤ .001), with no overlap of the CIs for the means among the regions: normal brain (mean [M] = .847, standard deviation [SD] = .103, 95% CI: .825-.866), infarct (M = .533, SD = .157, 95% CI: .501-.563), and penumbra (M = .764, SD = .110, 95% CI: .740-.787). ADC values might be used as reference data in acute stroke-specific populations; CIs would provide radiologists and clinicians with additional quantitative tools to evaluate penumbra, infarct, and normal brain tissue and to tailor follow-up and treatment options for selected patients. Copyright © 2016 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  13. Simulation study of two major events in the heliosphere during the present sunspot cycle

    Energy Technology Data Exchange (ETDEWEB)

    Akasofu, S.I.; Fillius, W.; Sun, W.; Fry, C.; Dryer, M.

    1985-01-01

    The two major disturbances in the heliosphere during the present sunspot cycle, the event of June to August, 1982, and the event of April to June, 1978, are simulated by the method developed by Hakamada and Akasofu (1982). Specifically, an attempt was made to simulate the effects of six major flares from three active regions in June and July, 1982, and April and May, 1978. A comparison of the results with the solar wind observations at Pioneer 12 (approximately 0.8 au), ISEE-3 (approximately 1 au), Pioneer 11 (approximately 7 to 13 au) and Pioneer 10 (approximately 16 to 28 au) suggests that some major flares occurred behind the disk of the sun during the two periods. The method provides qualitatively some information as to how such a series of intense solar flares can greatly disturb both the inner and outer heliospheres. A long lasting effect on cosmic rays is discussed in conjunction with the disturbed heliosphere.

  14. Small-scale Magnetic Field Diagnostics outside Sunspots: Comparison of Different Methods

    Indian Academy of Sciences (India)

    D. N. Rachkovsky; T. T. Tsap; V. G. Lozitsky

    2005-12-01

    We analyse different observational data related to the problem of intrinsic magnetic field strength in small-scale fluxtubes outside sunspots. We conclude that the kG range of fluxtube fields follows from not only classical line ratio method, but also from other old and new techniques. For the quiet regions on the Sun, the most probable mode of such fields has a magnetic field strength of 1.2–1.5 kG assuming the rectangular field profile. To best interpret the observations, a weak background field between fluxtubes should be assumed, and its magnetic field strength is expected to increase with the filling factor of fluxtubes. The alternative point of view about subkilogauss fluxtube fields is critically examined, and possible sources of different conclusions are presented.

  15. The long sunspot cycle 23 predicts a significant temperature decrease in cycle 24

    CERN Document Server

    Solheim, Jan-Erik; Humlum, Ole

    2012-01-01

    Relations between the length of a sunspot cycle and the average temperature in the same and the next cycle are calculated for a number of meteorological stations in Norway and in the North Atlantic region. No significant trend is found between the length of a cycle and the average temperature in the same cycle, but a significant negative trend is found between the length of a cycle and the temperature in the next cycle. This provides a tool to predict an average temperature decrease of at least 1.0 "C from solar cycle 23 to 24 for the stations and areas analyzed. We find for the Norwegian local stations investigated that 25-56% of the temperature increase the last 150 years may be attributed to the Sun. For 3 North Atlantic stations we get 63-72% solar contribution. This points to the Atlantic currents as reinforcing a solar signal.

  16. Sunspot Cycle 24 and the Advent of Dalton-Like Minimum

    Directory of Open Access Journals (Sweden)

    H. S. Ahluwalia

    2012-01-01

    Full Text Available Ahluwalia and Jackiewicz (2011 have predicted that sunspot cycle 24 will be only half as active as cycle 23, reaching its peak in May 2013±6 months. Here, we discuss the timeline for cycle 24 since its onset in December, 2008 and compare it to the timelines for the last ten cycles (14 to 23 of the 20th century; cycle 24 is rising the slowest. We speculate that cycle 24 may herald the onset of a Dalton-like minimum in the 21st century. The implications of this outcome on global temperature change and ensuing socioeconomic and political scenarios are discussed, on the basis of the historical record.

  17. A mechanism for the dependence of sunspot group tilt angles on cycle strength

    CERN Document Server

    Işık, Emre

    2015-01-01

    The average tilt angle of sunspot groups emerging throughout the solar cycle determines the net magnetic flux crossing the equator, which is correlated with the strength of the subsequent cycle. I suggest that a deep-seated, non-local process can account for the observed cycle-dependent changes in the average tilt angle. Motivated by helioseismic observations indicating cycle-scale variations in the sound speed near the base of the convection zone, I determined the effect of a thermally perturbed overshoot region on the stability of flux tubes and on the tilt angles of emerging flux loops. I found that 5-20 K of cooling is sufficient for emerging flux loops to reproduce the reported amplitude of cycle-averaged tilt angle variations, suggesting that it is a plausible effect responsible for the nonlinearity of the solar activity cycle.

  18. Solar wind and coronal structure near sunspot minimum - Pioneer and SMM observations from 1985-1987

    Science.gov (United States)

    Mihalov, J. D.; Barnes, A.; Hundhausen, A. J.; Smith, E. J.

    1990-01-01

    Changes in solar wind speed and magnetic polarity observed at the Pioneer spacecraft are discussed here in terms of the changing magnetic geometry implied by SMM coronagraph observations over the period 1985-1987. The pattern of recurrent solar wind streams, the long-term average speed, and the sector polarity of the interplanetary magnetic field all changed in a manner suggesting both a temporal variation, and a changing dependence on heliographic latitude. Coronal observations during this epoch show a systematic variation in coronal structure and the magnetic structure imposed on the expanding solar wind. These observations suggest interpretation of the solar wind speed variations in terms of the familiar model where the speed increases with distance from a nearly flat interplanetary current sheet, and where this current sheet becomes aligned with the solar equatorial plane as sunspot minimum approaches, but deviates rapidly from that orientation after minimum.

  19. Photospheric high-frequency acoustic power excess in sunspot umbra: signature of magneto-acoustic modes

    Directory of Open Access Journals (Sweden)

    S. Zharkov

    2013-08-01

    Full Text Available We present observational evidence for the presence of MHD (magnetohydrodynamic waves in the solar photosphere deduced from SOHO/MDI (Solar and Heliospheric Observatory/Michelson Doppler Imager Dopplergram velocity observations. The magneto-acoustic perturbations are observed as acoustic power enhancement in the sunspot umbra at high-frequency bands in the velocity component perpendicular to the magnetic field. We use numerical modelling of wave propagation through localised non-uniform magnetic field concentration along with the same filtering procedure as applied to the observations to identify the observed waves. Guided by the results of the numerical simulations we classify the observed oscillations as magneto-acoustic waves excited by the trapped sub-photospheric acoustic waves. We consider the potential application of the presented method as a diagnostic tool for magnetohelioseismology.

  20. Spectropolarimetric investigation of the propagation of magnetoacoustic waves and shock formation in sunspot atmospheres

    CERN Document Server

    Centeno, R; Collados, M; Bueno, Javier Trujillo; Centeno, Rebecca; Collados, Manuel

    2006-01-01

    Velocity oscillations in sunspot umbrae have been measured simultaneously in two spectral lines: the photospheric Silicon I 10827 A line and the chromospheric Helium I 10830 A multiplet. From the full Stokes inversion of temporal series of spectropolarimetric observations we retrieved, among other parameters, the line of sight velocity temporal variations at photospheric and chromospheric heights. Chromospheric velocity oscillations show a three minute period with a clear sawtooth shape typical of propagating shock wave fronts. Photospheric velocity oscillations have basically a five minute period, although the power spectrum also shows a secondary peak in the three minute band which has proven to be predecessor for its chromospheric counterpart. The derived phase spectra yield a value of the atmospheric cut-off frequency around 4 mHz and give evidence for the upward propagation of higher frequency oscillation modes. The phase spectrum has been reproduced with a simple model of linear vertical propagation of ...

  1. Heritage of Konkoly's Solar Observations: the Debrecen Photoheliograph Programme and the Debrecen Sunspot Databases

    CERN Document Server

    Baranyi, T; Ludmány, A

    2016-01-01

    The primary task of the Debrecen Heliophysical Observatory (DHO) was to produce the detailed and reliable photographic documentation of the solar photospheric activity since 1958. This long-term effort resulted in various solar catalogues based on ground-based and space-borne observations. The DHO hosts solar-image databases containing heritages of two former Hungarian observatories. One of the sets of drawings was observed between 1872 and 1891 at the \\'Ogyalla Observatory (now Hurbanovo, Slovakia) founded by Mikl\\'os Konkoly-Thege (1842--1916). We briefly summarize the history of the events that resulted in the longest photographic sunspot database available at the DHO at present, and we show the basic role of Dr. Mikl\\'os Konkoly-Thege in this achievement.

  2. A deep-seated mechanism for cycle-dependent sunspot group tilt angles

    Science.gov (United States)

    Isik, Emre

    2016-07-01

    The cycle-averaged tilt angle of sunspot groups is an important quantity in determining the magnetic flux diffusing across the equator, which is highly correlated with the strength of the next cycle. This quantity has recently been reported to be anti-correlated with the strength of the solar cycle. I suggest that a deep-seated thermodynamic cycle can be responsible for the observed correlation. Motivated by helioseismic indications, I calculate the effect of cooling of the convective overshoot region on the stability and dynamics of thin, unstable flux tubes. I find that only 5-20 K of cooling in the layer can explain the observed range of tilt angle fluctuations among different cycles. This mechanism can play a role in the nonlinear saturation and amplitude fluctuations of the solar dynamo.

  3. Local helioseismic and spectroscopic analyses of interactions between acoustic waves and a sunspot

    CERN Document Server

    Rajaguru, S P; Sankarasubramanian, K; Couvidat, S; 10.1088/2041-8205/721/2/L86

    2010-01-01

    Using a high cadence imaging spectropolarimetric observation of a sunspot and its surroundings in magnetically sensitive (FeI 6173 A) and insensitive (FeI 7090 A) upper photospheric absorption lines, we map the instantaneous wave phases and helioseismic travel times as a function of observation height and inclination of magnetic field to the vertical. We confirm the magnetic inclination angle dependent transmission of incident acoustic waves into upward propagating waves, and derive (1) proof that helioseismic travel times receive direction dependent contributions from such waves and hence cause errors in conventional flow inferences, (2) evidences for acoustic wave sources beneath the umbral photosphere, and (3) significant differences in travel times measured from the chosen magnetically sensitive and insensitive spectral lines.

  4. Monthly sunspot number time series analysis and its modeling through autoregressive artificial neural network

    CERN Document Server

    Chattopadhyay, Goutami; 10.1140/epjp/i2012-12043-9

    2012-01-01

    This study reports a statistical analysis of monthly sunspot number time series and observes non homogeneity and asymmetry within it. Using Mann-Kendall test a linear trend is revealed. After identifying stationarity within the time series we generate autoregressive AR(p) and autoregressive moving average (ARMA(p,q)). Based on minimization of AIC we find 3 and 1 as the best values of p and q respectively. In the next phase, autoregressive neural network (AR-NN(3)) is generated by training a generalized feedforward neural network (GFNN). Assessing the model performances by means of Willmott's index of second order and coefficient of determination, the performance of AR-NN(3) is identified to be better than AR(3) and ARMA(3,1).

  5. Long-term Modulation of Cosmic Ray Intensity in relation to Sunspot Numbers and Tilt Angle

    Indian Academy of Sciences (India)

    Meera Gupta; V. K. Mishra; A. P. Mishra

    2006-12-01

    A detailed correlative analysis between sunspot numbers (SSN) and tilt angle (TA) with cosmic ray intensity (CRI) in the neutron monitor energy range has been performed for the solar cycles 21, 22 and 23. It is found that solar activity parameters (SSN and TA) are highly (positive) correlated with each other and have inverse correlation with cosmic ray intensity (CRI). The ‘running cross correlation coefficient’ between cosmic ray intensity and tilt angle has also been calculated and it is found that the correlation is positive during the maxima of odd cycles 21 and 23. Moreover, the time lag analysis between CRI and SSN, and between CRI and TA has also been performed and is supported by hysteresis curves, which are wide for odd cycles and narrow for even cycles.

  6. A new solar signal: Average maximum sunspot magnetic fields independent of activity cycle

    CERN Document Server

    Livingston, William

    2016-01-01

    Over the past five years, 2010-2015, we have observed, in the near infrared (IR), the maximum magnetic field strengths for 4145 sunspot umbrae. Herein we distinguish field strengths from field flux. (Most solar magnetographs measure flux). Maximum field strength in umbrae is co-spatial with the position of umbral minimum brightness (Norton and Gilman, 2004). We measure field strength by the Zeeman splitting of the Fe 15648.5 A spectral line. We show that in the IR no cycle dependence on average maximum field strength (2050 G) has been found +/- 20 Gauss. A similar analysis of 17,450 spots observed by the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory reveal the same cycle independence +/- 0.18 G., or a variance of 0.01%. This is found not to change over the ongoing 2010-2015 minimum to maximum cycle. Conclude the average maximum umbral fields on the Sun are constant with time.

  7. SYSTEMATIC REGULARITY OF HEMISPHERIC SUNSPOT AREAS OVER THE PAST 140 YEARS

    Energy Technology Data Exchange (ETDEWEB)

    Deng, L. H.; Xiang, Y. Y. [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Qu, Z. N. [Department of Physics, School of Science, Sichuan University of Science and Engineering, Zigong 643000 (China); An, J. M., E-mail: znqu@ynao.ac.cn [School of Software Engineering, Chongqing University of Arts and Sciences, Chongqing 402160 (China)

    2016-03-15

    Solar magnetic activity varies with time in the two hemispheres in different ways. The hemispheric interconnection of solar activity phenomena provides an important clue to understanding the dynamical behavior of solar dynamo actions. In this paper, several analysis approaches are proposed to analyze the systematic regularity of hemispheric asynchronism and amplitude asymmetry of long-term sunspot areas during solar cycles 9–24. It is found that, (1) both the hemispheric asynchronism and the amplitude asymmetry of sunspot areas are prevalent behaviors and are not anomalous, but the hemispheric asynchronism exhibits a much more regular behavior than the amplitude asymmetry; (2) the phase-leading hemisphere returns back to the identical hemisphere every 8 solar cycles, and the secular periodic pattern of hemispheric phase differences follows 3 (south leading) + 5 (north leading) solar cycles, which probably corresponds to the Gleissberg cycle; and (3) the pronounced periodicities of (absolute and normalized) asymmetry indices and lines of synchronization (LOSs) are not identical: the significant periodic oscillations are 80.65 ± 6.31, 20.91 ± 0.40, and 13.45 ± 0.16 years for the LOS values, and 51.34 ± 2.48, 8.83/8.69 ± 0.07, and 3.77 ± 0.02 years for the (absolute and normalized) asymmetry indices. The analysis results improve our knowledge on the hemispheric interrelation of solar magnetic activity and may provide valuable constraints for solar dynamo models.

  8. Reconstruction of Subdecadal Changes in Sunspot Numbers Based on the NGRIP 10Be Record

    DEFF Research Database (Denmark)

    Inceoglu, Fadil; Knudsen, Mads Faurschou; Karoff, Christoffer

    2014-01-01

    , to reconstruct both long-term and subdecadal changes in sunspot numbers (SSNs). We compare three different approaches for reconstructing subdecadal-scale changes in SSNs, including a linear approach and two approaches based on the hysteresis effect, i.e. models with ellipse-linear and ellipse relationships......Sunspot observations since 1610 A.D. show that the solar magnetic activity displays long-term changes, from Maunder Minimum-like low-activity states to Modern Maximum-like high-activity episodes, as well as short-term variations, such as the pronounced 11-year periodicity. Information on changes...... the actual solar cycles and the GCR intensity, which is known as the hysteresis effect. In this study, we use the North Greenland Ice Core Project (NGRIP) records of the 10Be flux to reconstruct the solar modulation strength (Φ), which describes the modulation of GCRs throughout the heliosphere...

  9. Doubts about the crucial role of the rising-tube mechanism in the formation of sunspot groups

    CERN Document Server

    Getling, A V; Buchnev, A A

    2014-01-01

    Preliminary processing results are presented for a dataset obtained with the Solar Optical Telescope on the Hinode satellite. The idea of the project is to record, nearly simultaneously, the full velocity and magnetic-field vectors in growing active regions and sunspot groups at a photospheric level and distinguish between the manifestations of two mechanisms of sunspot-group formation --- the rising of an flux tube of a strong magnetic field and the in situ amplification and structuring of magnetic field by convection. A young bipolar subregion developing within AR 11313 was observed on 9--10 October 2011. Filtergrams and Dopplergrams were obtained, and one or two spectropolarimetric fast-mode scans were done. Based on the series of filtergrams, the trajectories of corks are computed, using a technique similar to but more reliable than local correlation tracking, and compared with the magnetic maps. Currently, only the vertical magnetic field and the horizontal flows are used for a qualitative analysis. The ...

  10. $f$-mode interaction with models of sunspot : near-field scattering and multi-frequency effects

    CERN Document Server

    Daiffallah, Khalil

    2016-01-01

    We use numerical simulations to investigate the interaction of an $f$-mode wave packet with small and large models of a sunspot in a stratified atmosphere. While a loose cluster model has been largely studied before, we focus in this study on the scattering from an ensemble of tightly compact tubes. We showed that the small compact cluster produces a slight distorted scattered wave field in the transverse direction, which can be attributed to the simultaneous oscillations of the pairs of tubes within the cluster aligned in a perpendicular direction to the incoming wave. However, no signature of a multiple-scattering regime has been observed from this model, while it has been clearly observable for the large compact cluster model. Furthermore, we pointed out the importance of the geometrical shape of the monolithic model on the interaction of $f$-mode waves with a sunspot in a high frequency range ($\

  11. DETECTION OF FAST-MOVING WAVES PROPAGATING OUTWARD ALONG SUNSPOTS’ RADIAL DIRECTION IN THE PHOTOSPHERE

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Junwei; Chen, Ruizhu [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305-4085 (United States); Hartlep, Thomas [BAER Institute, NASA Ames Research Center, Moffet Field, CA 94043 (United States); Kosovichev, Alexander G. [Department of Physics, New Jersey Institute of Technology, Newark, NJ 07102 (United States)

    2015-08-10

    Helioseismic and magnetohydrodynamic waves are abundant in and above sunspots. Through cross-correlating oscillation signals in the photosphere observed by the Solar Dynamics Observatory/Helioseismic and Magnetic Imager, we reconstruct how waves propagate away from virtual wave sources located inside a sunspot. In addition to the usual helioseismic wave, a fast-moving wave is detected traveling along the sunspot’s radial direction from the umbra to about 15 Mm beyond the sunspot boundary. The wave has a frequency range of 2.5–4.0 mHz with a phase velocity of 45.3 km s{sup −1}, substantially faster than the typical speeds of Alfvén and magnetoacoustic waves in the photosphere. The observed phenomenon is consistent with a scenario of that a magnetoacoustic wave is excited at approximately 5 Mm beneath the sunspot. Its wavefront travels to and sweeps across the photosphere with a speed higher than the local magnetoacoustic speed. The fast-moving wave, if truly excited beneath the sunspot’s surface, will help open a new window for studying the internal structure and dynamics of sunspots.

  12. Differentiation of the infarct core from ischemic penumbra within the first 4.5 hours, using diffusion tensor imaging-derived metrics: A rat model

    Energy Technology Data Exchange (ETDEWEB)

    Kuo, Duen Pang [Dept. of Electrical Engineering, National Taiwan University, Taipei (China); Lu, Chia Feng [Research Center of Translational Imaging, College of Medicine, Taipei Medical University, Taipei (China); Chen, Yung Chieh [Dept. of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei (China); Liou, Michelle [Institute of Statistical Science, Academia Sinica, Taipei (China); Chung, Hsiao Wen [Graduate Institute of Biomedical Electrics and Bioinformatics, National Taiwan University, Taipei (China)

    2017-04-15

    To investigate whether the diffusion tensor imaging-derived metrics are capable of differentiating the ischemic penumbra (IP) from the infarct core (IC), and determining stroke onset within the first 4.5 hours. All procedures were approved by the local animal care committee. Eight of the eleven rats having permanent middle cerebral artery occlusion were included for analyses. Using a 7 tesla magnetic resonance system, the relative cerebral blood flow and apparent diffusion coefficient maps were generated to define IP and IC, half hour after surgery and then every hour, up to 6.5 hours. Relative fractional anisotropy, pure anisotropy (rq) and diffusion magnitude (rL) maps were obtained. One-way analysis of variance, receiver operating characteristic curve and nonlinear regression analyses were performed. The evolutions of tensor metrics were different in ischemic regions (IC and IP) and topographic subtypes (cortical, subcortical gray matter, and white matter). The rL had a significant drop of 40% at 0.5 hour, and remained stagnant up to 6.5 hours. Significant differences (p < 0.05) in rL values were found between IP, IC, and normal tissue for all topographic subtypes. Optimal rL threshold in discriminating IP from IC was about -29%. The evolution of rq showed an exponential decrease in cortical IC, from -26.9% to -47.6%; an rq reduction smaller than 44.6% can be used to predict an acute stroke onset in less than 4.5 hours. Diffusion tensor metrics may potentially help discriminate IP from IC and determine the acute stroke age within the therapeutic time window.

  13. Differentiation of the Infarct Core from Ischemic Penumbra within the First 4.5 Hours, Using Diffusion Tensor Imaging-Derived Metrics: A Rat Model

    Science.gov (United States)

    Kuo, Duen-Pang; Lu, Chia-Feng; Liou, Michelle; Chen, Yung-Chieh; Chung, Hsiao-Wen

    2017-01-01

    Objective To investigate whether the diffusion tensor imaging-derived metrics are capable of differentiating the ischemic penumbra (IP) from the infarct core (IC), and determining stroke onset within the first 4.5 hours. Materials and Methods All procedures were approved by the local animal care committee. Eight of the eleven rats having permanent middle cerebral artery occlusion were included for analyses. Using a 7 tesla magnetic resonance system, the relative cerebral blood flow and apparent diffusion coefficient maps were generated to define IP and IC, half hour after surgery and then every hour, up to 6.5 hours. Relative fractional anisotropy, pure anisotropy (rq) and diffusion magnitude (rL) maps were obtained. One-way analysis of variance, receiver operating characteristic curve and nonlinear regression analyses were performed. Results The evolutions of tensor metrics were different in ischemic regions (IC and IP) and topographic subtypes (cortical, subcortical gray matter, and white matter). The rL had a significant drop of 40% at 0.5 hour, and remained stagnant up to 6.5 hours. Significant differences (p < 0.05) in rL values were found between IP, IC, and normal tissue for all topographic subtypes. Optimal rL threshold in discriminating IP from IC was about -29%. The evolution of rq showed an exponential decrease in cortical IC, from -26.9% to -47.6%; an rq reduction smaller than 44.6% can be used to predict an acute stroke onset in less than 4.5 hours. Conclusion Diffusion tensor metrics may potentially help discriminate IP from IC and determine the acute stroke age within the therapeutic time window. PMID:28246507

  14. Penumbra Stroke System as an ''add-on'' for the treatment of large vessel occlusive disease following thrombolysis: first results

    Energy Technology Data Exchange (ETDEWEB)

    Struffert, Tobias; Engelhorn, Tobias; Richter, Gregor; Doerfler, Arnd [University of Erlangen-Nuremberg, Department of Neuroradiology, Erlangen (Germany); Koehrmann, Martin; Nowe, Tim; Schellinger, Peter D.; Schwab, Stefan [University of Erlangen-Nuremberg, Department of Neurology, Erlangen (Germany)

    2009-09-15

    The Penumbra Stroke System (PSS) was cleared for use in patients with ischemic stroke by the FDA in January 2008. We describe our experience of using this new system in acute large vessel occlusive disease following thrombolysis. Fifteen consecutive patients (mean age 60 years) suffering from acute ischemic stroke were treated with the PSS after intravenous or intra-arterial standard treatment with tissue plasminogen activator (n = 14) or ReoPro (n = 1). All patients presented with TIMI 3 before use of the PSS. Carotid stenting (n = 3) and intracranial balloon angioplasty or stenting (n = 2) were performed if indicated. Neurological evaluation was performed using the NIHSS score and the mRS score. Initial median NIHSS score in 12 patients with occlusions in the anterior circulation was 15; three patients with basilar artery occlusion presented with coma. Median symptom to procedure start time was 151 min. In the anterior circulation, 9 of the 12 target vessels were recanalised successfully (TIMI 2 and 3). The rate of patients with independent clinical outcome (mRS {<=} 2) was 42%. One patient died 5 days after unsuccessful treatment, one after 28 days and one after 85 days owing to heart attack. Basilar artery occlusions could be recanalised in all cases to TIMI 3. The clinical result after 90 days was mRS 4 in two cases and mRS 5 in one case. Symptomatic haemorrhage did not occur. The PSS can safely be used for recanalisation in patients with acute ischemic stroke due to large vessel occlusion, who have already received thrombolysis treatment. The recanalisation rate was 80%. Symptomatic haemorrhage did not occur. Randomized trials may demonstrate that endovascular mechanical thrombectomy improves patient outcome. (orig.)

  15. The presence of large sunspots near the central solar meridian at the times of major geomagnetic storms

    Directory of Open Access Journals (Sweden)

    D. M. Willis

    2009-01-01

    Full Text Available A further study is made of the validity of a technique developed by the authors to identify historical occurrences of intense geomagnetic storms, which is based on finding approximately coincident observations of sunspots and aurorae recorded in East Asian histories. Previously, the validity of this technique was corroborated using scientific observations of aurorae in Japan during the interval 1957–2004 and contemporaneous white-light images of the Sun obtained by the Royal Greenwich Observatory, the Big Bear Solar Observatory, the Debrecen Heliophysical Observatory, and the Solar and Heliospheric Observatory spacecraft. The present investigation utilises a list of major geomagnetic storms in the interval 1868–2008, which is based on the magnitude of the AA* magnetic index, and reconstructed solar images based on the sunspot observations acquired by the Royal Greenwich Observatory during the shorter interval 1874–1976. It is found that a sunspot large enough to be seen with the unaided eye by an "experienced" observer was located reasonably close to the central solar meridian for almost 90% of these major geomagnetic storms. Even an "average" observer would easily achieve a corresponding success rate of 70% and this success rate increases to about 80% if a minority of ambiguous situations are interpreted favourably. The use of information on major geomagnetic storms, rather than modern auroral observations from Japan, provides a less direct corroboration of the technique for identifying historical occurrences of intense geomagnetic storms, if only because major geomagnetic storms do not necessarily produce auroral displays over East Asia. Nevertheless, the present study provides further corroboration of the validity of the original technique for identifying intense geomagnetic storms. This additional corroboration of the original technique is important because early unaided-eye observations of sunspots and aurorae provide the only

  16. Power spectra analysis for world-wide and North Africa historical earthquakes data in relation to sunspots periodicities

    Energy Technology Data Exchange (ETDEWEB)

    Shaltout, M.A.M.; Mesiha, S.L. [National Research Inst. of Astronomy and Geophysics, Helwan (Egypt); Tadros, M.T.Y. [Mansoura Univ., Physics Dept., Mansoura (Egypt)

    1999-07-01

    In the last three decades, the influence of solar activity on earth seismicity is one of the most important subjects in the field of long-term prediction of earthquakes. In the present work, the autocorrelation and power spectra analysis were applied for the sequences of sunspots and earthquakes activity. The used data are the worldwide earthquakes of M {>=} 5, and the sunspots number R{sub 2}, for the period 1903-1985. Both are available from the National Oceanic and Atmospheric Administration NOAA, Boulder, Colorado, U.S.A. Also, we restrict our attention to earthquakes in North Africa with two stations, one at Cairo (Egypt), and the other at Alger (Algeria) of M {>=} 4 for the period (1900-1986). The results indicated the presence of the eleven year cycles of the sunspots into the time of the earthquakes of the North Africa. Also, for the worldwide and North Africa earthquakes data a periodicities ranged between 1.01 and 5.5 years are revealed, which may be linked to a solar activity cycle. (Author)

  17. The "Sun-climate" relationship : III. The solar flares, north-south sunspot arrea asymmetry and climate

    CERN Document Server

    Komitov, Boris

    2010-01-01

    In this last Paper III additional evidences that the solar high energetic particles radiation with energies higher as 100 MeV (the solar cosmic rays SCR) is an very important component for the "Sun- climate" relationship are given (see also Paper I and II). The total solar irradiance (TSI) and the galactic cosmic rays (GCR) variations given an integral climate effect of cooling in sunspot minima and warming in the sunspot maxima. Unlike the both ones the powerful solar corpuscular events plays a cooling climate role during the epochs of their heigh levels. By this one subcenturial global and regional temperature quasi- cyclic changes by duration of approximately 60 years could be track during the last 150 years of instrumental climate observations . It has been also evided in the paper that this subcenturial oscilation is very important in the Group sunspot number (GSN) data series since the Maunder minimum up to the end of 20th century. Thus the solar erruptive activity effect make the total "Sun -climate" r...

  18. Helioseismic holography of simulated sunspots: dependence of the travel time on magnetic field strength and Wilson depression

    Science.gov (United States)

    Felipe, T.; Braun, D. C.; Birch, A. C.

    2017-08-01

    Improving methods for determining the subsurface structure of sunspots from their seismic signature requires a better understanding of the interaction of waves with magnetic field concentrations. We aim to quantify the impact of changes in the internal structure of sunspots on local helioseismic signals. We have numerically simulated the propagation of a stochastic wave field through sunspot models with different properties, accounting for changes in the Wilson depression between 250 and 550 km and in the photospheric umbral magnetic field between 1500 and 3500 G. The results show that travel-time shifts at frequencies above approximately 3.50 mHz (depending on the phase-speed filter) are insensitive to the magnetic field strength. The travel time of these waves is determined exclusively by the Wilson depression and sound-speed perturbation. The travel time of waves with lower frequencies is affected by the direct effect of the magnetic field, although photospheric field strengths below 1500 G do not leave a significant trace on the travel-time measurements. These results could potentially be used to develop simplified travel-time inversion methods.

  19. On the relation between activity-related frequency shifts and the sunspot distribution over the solar cycle 23

    CERN Document Server

    Santos, A R G; Avelino, P P; Chaplin, W J; Campante, T L

    2016-01-01

    The activity-related variations in the solar acoustic frequencies have been known for 30 years. However, the importance of the different contributions is still not well established. With this in mind, we developed an empirical model to estimate the spot-induced frequency shifts, which takes into account the sunspot properties, such as area and latitude. The comparison between the model frequency shifts obtained from the daily sunspot records and those observed suggests that the contribution from a stochastic component to the total frequency shifts is about 30%. The remaining 70% is related to a global, long-term variation. We also propose a new observable to investigate the short- and mid-term variations of the frequency shifts, which is insensitive to the long-term variations contained in the data. On the shortest time scales the variations in the frequency shifts are strongly correlated with the variations in the total area covered by sunspots. However, a significant loss of correlation is still found, whic...

  20. Direct measurement results of the time lag of LOS-velocity oscillations between two heights in solar faculae and sunspots

    CERN Document Server

    Kobanov, Nikolai; Kustov, Arseniy; Chupin, Sergey; Chelpanov, Andrey; 10.1007/s11207-013-0247-2

    2013-01-01

    We present an investigation of line-of-sight (LOS) velocity oscillations in solar faculae and sunspots. To study the phase relations between chromosphere and photosphere oscillations of the LOS velocity, we measured the time lag of the chromospheric signal relative to the photospheric one for several faculae and sunspots in a set of spectral line pairs. The measured time lags are different for different objects. The mean measured delay between the oscillations in the five-minute band in faculae is 50s for the SiI 10827{\\AA}-HeI 10830{\\AA} pair; for the pair FeI 6569{\\AA}-H-alpha 6563{\\AA} the mean delay is 20s; for the pair FeI 4551{\\AA}-BaII 4554{\\AA} the mean delay is 7s; for the pair SiI 8536{\\AA}-CaII 8542{\\AA} the mean delay is 20s. For the oscillations in the three-minute band in sunspot umbrae the mean delay is 55s for the SiI 10827{\\AA}-HeI 10830{\\AA} pair; for the Fe I 6569{\\AA}-H-alpha 6563{\\AA} pair it was not possible to determine the delay; for the FeI 4551{\\AA}-BaII 4554{\\AA} pair the mean delay...

  1. Oscillation Power in Sunspots and Quiet Sun from Hankel Analysis Performed on SDO/HMI and SDO/AIA Data

    CERN Document Server

    Couvidat, Sebastien

    2012-01-01

    The Helioseismic and Magnetic Imager (HMI) and the Atmospheric Imaging Assembly (AIA) instruments onboard the Solar Dynamics Observatory satellite produce Doppler velocity and continuum intensity at 6173 A as well as intensity maps at 1600 A and 1700 A, which can be used for helioseismic studies at different heights in the solar photosphere. We perform a Hankel-Fourier analysis in an annulus centered around sunspots or quiet-Sun regions, to estimate the change in power of waves crossing these regions of interest. We find that there is a dependence of power-reduction coefficients on measurement height in the photosphere: Sunspots reduce the power of outgoing waves with frequencies lower than 4.5 mHz at all heights, but enhance the power of acoustic waves in the range 4.5-5.5 mHz toward chromospheric heights, which is likely the signature of acoustic glories (halos). Maximum power reduction seems to occur near the continuum level and to decrease with altitude. Sunspots also impact the frequencies of outgoing wa...

  2. Reconstruction of Subdecadal Changes in Sunspot Numbers Based on the NGRIP 10Be Record

    Science.gov (United States)

    Inceoglu, F.; Knudsen, M. F.; Karoff, C.; Olsen, J.

    2014-11-01

    Sunspot observations since 1610 A.D. show that the solar magnetic activity displays long-term changes, from Maunder Minimum-like low-activity states to Modern Maximum-like high-activity episodes, as well as short-term variations, such as the pronounced 11-year periodicity. Information on changes in solar activity levels before 1610 relies on proxy records of solar activity stored in natural archives, such as 10Be in ice cores and 14C in tree rings. These cosmogenic radionuclides are produced by the interaction between Galactic cosmic rays (GCRs) and atoms in the Earth's atmosphere; their production rates are anti-correlated with the solar magnetic activity. The GCR intensity displays a distinct 11-year periodicity due to solar modulation of the GCRs in the heliosphere, which is inversely proportional to, but out of phase with, the 11-year solar cycle. This implies a time lag between the actual solar cycles and the GCR intensity, which is known as the hysteresis effect. In this study, we use the North Greenland Ice Core Project (NGRIP) records of the 10Be flux to reconstruct the solar modulation strength (Φ), which describes the modulation of GCRs throughout the heliosphere, to reconstruct both long-term and subdecadal changes in sunspot numbers (SSNs). We compare three different approaches for reconstructing subdecadal-scale changes in SSNs, including a linear approach and two approaches based on the hysteresis effect, i.e. models with ellipse-linear and ellipse relationships between Φ and SSNs. We find that the ellipse approach provides an amplitude-sensitive reconstruction and the highest cross-correlation coefficients in comparison with the ellipse-linear and linear approaches. The long-term trend in the reconstructed SSNs is computed using a physics-based model and agrees well with the other group SSN reconstructions. The new empirical approach, combining a physics-based model with ellipse-modeling of the 11-year cycle, therefore provides a method for

  3. Brief Communication: Correlation of global earthquake rates with temperature and sunspot cycle

    Science.gov (United States)

    Rajesh, R.; Tiwari, R. K.

    2014-04-01

    We studied the complex and non-stationary records of global earthquake employing the robust statistical and spectral techniques to understand the patterns, processes and periodicity. Singular Spectral Analysis (SSA) and correlation methods are used to quantify the nature of principle dynamical processes of global annual earthquake rates. The SSA decomposes the principle component of earthquake rates (first mode), which suggests that there is a linear increase in the yearly earthquake number from 1975 to 2005 accounting for 93% variance and may be identified with the earth's internal dynamical processes. Superimposed on this monotonic trend, there is an 11 years cyclic variation (second and third modes) accounting for 5% variance, which may corresponds to the well-known solar cycle. The remaining 2% higher order fluctuating components appears to be associated with artificial recharge and natural triggering forces (reservoir, tidal triggering etc.). The correlation study indicates that there is strong positive and negative correlation among the global earthquake rates with surface air temperature and sunspot numbers respectively. Interesting coupling mechanisms do exist, in which atmospheric circulations perturbed by the abrupt temperature variability might change the torques/momentum of inertia (earth's angular momentum) of the earth and thereby may offer the required inputs to trigger earthquake activities at the "critical phases".

  4. Brief Communication: Correlation of global earthquake rates with temperature and sunspot cycle

    Directory of Open Access Journals (Sweden)

    R. Rajesh

    2014-04-01

    Full Text Available We studied the complex and non-stationary records of global earthquake employing the robust statistical and spectral techniques to understand the patterns, processes and periodicity. Singular Spectral Analysis (SSA and correlation methods are used to quantify the nature of principle dynamical processes of global annual earthquake rates. The SSA decomposes the principle component of earthquake rates (first mode, which suggests that there is a linear increase in the yearly earthquake number from 1975 to 2005 accounting for 93% variance and may be identified with the earth's internal dynamical processes. Superimposed on this monotonic trend, there is an 11 years cyclic variation (second and third modes accounting for 5% variance, which may corresponds to the well-known solar cycle. The remaining 2% higher order fluctuating components appears to be associated with artificial recharge and natural triggering forces (reservoir, tidal triggering etc.. The correlation study indicates that there is strong positive and negative correlation among the global earthquake rates with surface air temperature and sunspot numbers respectively. Interesting coupling mechanisms do exist, in which atmospheric circulations perturbed by the abrupt temperature variability might change the torques/momentum of inertia (earth's angular momentum of the earth and thereby may offer the required inputs to trigger earthquake activities at the "critical phases".

  5. Variability of sunspot cycle QBO and total ozone over high altitude western Himalayan regions

    Science.gov (United States)

    Ningombam, Shantikumar Singh

    2011-10-01

    Long-term trend of total column ozone at high altitude region in Ladakh is studied, using a total ozone mapping spectrometer and an ozone monitoring instrument during 1979-2008. In the region, total ozone exhibits seasonality with maximum in spring and minimum in autumn. The decreasing trend of total ozone was found as -2.51±0.45% per decade with 95% confidence level in the region. Ozone deficiency in the Ladakh region is strongest (-33.9 DU at Hanle) in May and weakest (-11.5 DU at Hanle) in January-February. In the study, the solar maximum in 1990 is in phase with ozone maximum, while ozone variation lags in phase with the 1980 and 2000 solar maxima. However, a significant correlation between total ozone and sunspot number is achieved in the westerly phase of quasi-biennial oscillation during spring season. Decreasing trend of ozone in the region is correlating well with the cooling rate in the lower stratosphere.

  6. Fan-shaped jets above the light bridge of a sunspot driven by reconnection

    Science.gov (United States)

    Robustini, Carolina; Leenaarts, Jorrit; de la Cruz Rodriguez, Jaime; Rouppe van der Voort, Luc

    2016-05-01

    We report on a fan-shaped set of high-speed jets above a strongly magnetized light bridge (LB) of a sunspot observed in the Hα line. We study the origin, dynamics, and thermal properties of the jets using high-resolution imaging spectroscopy in Hα from the Swedish 1m Solar Telescope and data from the Solar Dynamics Observatory and Hinode. The Hα jets have lengths of 7-38 Mm, are impulsively accelerated to a speed of ~100 km s-1 close to photospheric footpoints in the LB, and exhibit a constant deceleration consistent with solar effective gravity. They are predominantly launched from one edge of the light bridge, and their footpoints appear bright in the Hα wings. Atmospheric Imaging Assembly data indicates elongated brightenings that are nearly co-spatial with the Hα jets. We interpret them as jets of transition region temperatures. The magnetic field in the light bridge has a strength of 0.8-2 kG and it is nearly horizontal. All jet properties are consistent with magnetic reconnection as the driver. Movies associated to Figs. 1 and 2 are available in electronic form at http://www.aanda.org

  7. Kinematics and Magnetic Properties of a Light Bridge in a Decaying Sunspot

    CERN Document Server

    Falco, M; Guglielmino, S L; Romano, P; Zuccarello, F; Criscuoli, S; Cristaldi, A; Ermolli, I; Jafarzadeh, S; van der Voort, L Rouppe

    2016-01-01

    We present the results obtained by analyzing high spatial and spectral resolution data of the solar photosphere acquired by the CRisp Imaging SpectroPolarimeter at the Swedish Solar Telescope on 6 August 2011, relevant to a large sunspot with a light bridge (LB) observed in NOAA AR 11263. These data are complemented by simultaneous Hinode Spectropolarimeter (SP) observation in the Fe I 630.15 nm and 630.25 nm lines. The continuum intensity map shows a discontinuity of the radial distribution of the penumbral filaments in correspondence with the LB, which shows a dark lane (about 0.3" wide and about 8.0" long) along its main axis. The available data were inverted with the Stokes Inversion based on Response functions (SIR) code and physical parameters maps were obtained. The line-of-sight (LOS) velocity of the plasma along the LB derived from the Doppler effect shows motions towards and away from the observer up to 0.6 km/s, which are lower in value than the LOS velocities observed in the neighbouring penumbral...

  8. Bayesian Methods for Reconstructing Sunspot Numbers Before and During the Maunder Minimum

    Science.gov (United States)

    Travaglini, Guido

    2017-01-01

    The Maunder Minimum (MM) was an extended period of reduced solar activity in terms of yearly sunspot numbers (SSN) during 1610 - 1715. The reality of this "grand minimum" is generally accepted in the scientific community, but the statistics of the SSN record suggest a need for data reconstruction. The MM data show a nonstandard distribution compared with the entire SSN signal (1610 - 2014). The pattern does not satisfy the weakly stationary solar dynamo approximation, which characterizes many natural events spanning centuries or even millennia, including the Sun and the stars. Over the entire observation period (1610 - 2014), the reported SSN exhibits statistically significant regime switches, departures from autoregressive stationarity, and growing trends. Reconstruction of the SSN during the pre-MM and MM periods is performed using five novel statistical procedures in support of signal analysis. A Bayesian-Monte Carlo backcast technique is found to be most reliable and produces an SSN signal that meets the weak-stationarity requirement. The computed MM signal for this reconstruction does not show a "grand" minimum or even a "semi-grand" minimum.

  9. Magnetic properties of G-band bright points in a sunspot moat

    CERN Document Server

    Beck, C; Schlichenmaier, R; Suetterlin, P

    2007-01-01

    We present simultaneous spectropolarimetric observations of four visible and three infrared spectral lines from the VTT (Tenerife), together with speckle-reconstructed filtergrams in the G band and the CaII H line core from the DOT (La Palma). After alignment of the data sets, we used the G-band intensity to locate bright points (BPs) in the moat of a regular sunspot. With the cospatial and cotemporal information provided by the polarimetric data, we characterize the magnetic, kinematic, and thermal properties of the BPs. We find that (a) 94 % of the BPs are associated with magnetic fields; (b) their field strengths range between 500 and 1400 G, with a rather flat distribution; (c) the contrast of BPs in the G band depends on the angle between the vector magnetic field and the line of sight; (d) the BPs harbor downflows of magnetized plasma and exhibit Stokes V profiles with large area and amplitude asymmetries; (e) the magnetic interior of BPs is hotter than the immediate field-free surroundings by about 100...

  10. DOES THE VARIATION OF THE SOLAR INTRA-NETWORK HORIZONTAL FIELD FOLLOW THE SUNSPOT CYCLE?

    Energy Technology Data Exchange (ETDEWEB)

    Jin, C. L.; Wang, J. X., E-mail: cljin@nao.cas.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2015-07-01

    The ubiquitousness of the solar inter-network horizontal magnetic field has been revealed by space-borne observations with high spatial resolution and polarization sensitivity. However, no consensus has been achieved on the origin of the horizontal field among solar physicists. For a better understanding, in this study, we analyze the cyclic variation of the inter-network horizontal field by using the spectro-polarimeter observations provided by the Solar Optical Telescope on board Hinode, covering the interval from 2008 April to 2015 February. The method of wavelength integration is adopted to achieve a high signal-to-noise ratio. It is found that from 2008 to 2015 the inter-network horizontal field does not vary when solar activity increases, and the average flux density of the inter-network horizontal field is 87 ± 1 G, In addition, the imbalance between horizontal and vertical fields also keeps invariant within the scope of deviation, i.e., 8.7 ± 0.5, from the solar minimum to maximum of solar cycle 24. This result confirms that the inter-network horizontal field is independent of the sunspot cycle. The revelation favors the idea that a local dynamo is creating and maintaining the solar inter-network horizontal field.

  11. Peacock jets above the light bridge of a sunspot driven by reconnection

    CERN Document Server

    Robustini, Carolina; Rodriguez, Jaime de la Cruz; van der Voort, Luc Rouppe

    2015-01-01

    We report on a fan-shaped set of high-speed jets above the light bridge (LB) of a sunspot observed in the H-alpha line. We study the origin, dynamics and thermal properties of the jets using high-resolution imaging spectroscopy in \\Halpha\\ from the Swedish 1-m Solar Telescope and data from the Atmospheric Imaging Assembly (AIA) at the Solar Dynamics Observatory. The H-alpha jets have lengths of 14-38 Mm, are impulsively accelerated to a speed of ~100 km/s close to photospheric footpoints in the LB, and exhibit a constant deceleration consistent with solar effective gravity. They are launched from one edge of the light bridge, and their footpoints appear bright in the H-alpha wings.AIA data indicates elongated brightenings that are nearly co-spatial with the H-alpha jets. We interpret them as jets of at least transition region temperatures.The photospheric line-of-sight magnetic field in the light bridge is weaker than, and has opposite polarity compared to, the umbra. All measured jet properties are consisten...

  12. INTERFERENCE OF THE RUNNING WAVES AT LIGHT BRIDGES OF A SUNSPOT

    Energy Technology Data Exchange (ETDEWEB)

    Su, J. T.; Priya, T. G.; Yu, S. J.; Zhang, M. [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Ji, K. F. [Kunming University of Science and Technology, Kunming 650093 (China); Banerjee, D. [Indian Institute of Astrophysics, Koramangala Bangalore 560034 (India); Cao, W. D. [Big Bear Solar Observatory, 40386 North Shore Lane, Big Bear City, CA 92314 (United States); Zhao, J. S.; Ji, H. S., E-mail: jt@bao.ac.cn [Purple Mountain Observatory, CAS, Nanjing 210008 (China)

    2016-01-01

    The observations of chromospheric oscillations of two umbral light bridges (LBs) within a sunspot from NOAA Active Region 12127 are presented. It was found that the running umbral waves with periods of 2.2–2.6 minutes underwent very fast damping before approaching umbral boundaries, while those with higher periods (>2.6 minutes) could propagate outside umbrae. On two sides of each LB adjacent to umbrae, the cross-wavelet spectra displayed that the oscillations on them had a common significant power region with dominant frequencies of 2–6 minutes and phase differences of ∼90°. A counterstream of two running umbral waves in the 2–6 minute frequency range propagated toward the LBs, where they encountered each other and gave rise to constructive or even destructive interference on the LBs. In addition, the velocity and density perturbations on the LBs were found in opposite phases suggesting that the perturbations were caused by the downward propagating waves.

  13. Narrow-line-width UV bursts in the transition region above Sunspots observed by IRIS

    CERN Document Server

    Hou, Zhenyong; Xia, Lidong; Li, Bo; Madjarska, Maria S; Fu, Hui; Mou, Chaozhou; Xie, Haixia

    2016-01-01

    Various small-scale structures abound in the solar atmosphere above active regions, playing an important role in the dynamics and evolution therein. We report on a new class of small-scale transition region structures in active regions, characterized by strong emissions but extremely narrow Si IV line profiles as found in observations taken with the Interface Region Imaging Spectrograph (IRIS). Tentatively named as Narrow-line-width UV bursts (NUBs), these structures are located above sunspots and comprise of one or multiple compact bright cores at sub-arcsecond scales. We found six NUBs in two datasets (a raster and a sit-and-stare dataset). Among these, four events are short-living with a duration of $\\sim$10 mins while two last for more than 36 mins. All NUBs have Doppler shifts of 15--18 km/s, while the NUB found in sit-and-stare data possesses an additional component at $\\sim$50 km/s found only in the C II and Mg II lines. Given that these events are found to play a role in the local dynamics, it is impo...

  14. Successful spectral synthesis of Zeeman-split molecular bands in sunspot spectra

    Science.gov (United States)

    Berdyugina, S. V.; Frutiger, C.; Solanki, S. K.; Livingstone, W.

    2000-12-01

    We present the first spectral synthesis of Zeeman-split Stokes profiles of the MgH A2Pi -X2BLAigma green system and TiO gamma -system. The calculations involve different regimes of the molecular Zeeman effect, up to the complete Paschen-Back effect for individual lines. The synthetic spectra are compared with observations of Stokes I and V in sunspot umbrae. We find that although the Stokes I spectra are reasonably reproduced, some lines are obviously still missing from the employed line lists. The Stokes V spectra turn out to be much cleaner since the missing lines do not appear to be Zeeman-split. We thus provide the first good fit to Zeeman-split molecular lines, including profiles with unconventional Stokes V shapes, determined by the Paschen-Back effect. Based on observations from the Canada-France-Hawaii Telescope operated by the National Research Council of Canada, the Centre National de la Recherche Scientifique de France and the University of Hawaii

  15. Performance of the Autoregressive Method in Long-Term Prediction of Sunspot Number

    Science.gov (United States)

    Chae, Jongchul; Kim, Yeon Han

    2017-04-01

    The autoregressive method provides a univariate procedure to predict the future sunspot number (SSN) based on past record. The strength of this method lies in the possibility that from past data it yields the SSN in the future as a function of time. On the other hand, its major limitation comes from the intrinsic complexity of solar magnetic activity that may deviate from the linear stationary process assumption that is the basis of the autoregressive model. By analyzing the residual errors produced by the method, we have obtained the following conclusions: (1) the optimal duration of the past time for the forecast is found to be 8.5 years; (2) the standard error increases with prediction horizon and the errors are mostly systematic ones resulting from the incompleteness of the autoregressive model; (3) there is a tendency that the predicted value is underestimated in the activity rising phase, while it is overestimated in the declining phase; (5) the model prediction of a new Solar Cycle is fairly good when it is similar to the previous one, but is bad when the new cycle is much different from the previous one; (6) a reasonably good prediction of a new cycle can be made using the AR model 1.5 years after the start of the cycle. In addition, we predict the next cycle (Solar Cycle 25) will reach the peak in 2024 at the activity level similar to the current cycle.

  16. Probability Estimates of Solar Proton Doses During Periods of Low Sunspot Number for Short Duration Missions

    Science.gov (United States)

    Atwell, William; Tylka, Allan J.; Dietrich, William F.; Rojdev, Kristina; Matzkind, Courtney

    2016-01-01

    In an earlier paper presented at ICES in 2015, we investigated solar particle event (SPE) radiation exposures (absorbed dose) to small, thinly-shielded spacecraft during a period when the monthly smoothed sunspot number (SSN) was less than 30. Although such months are generally considered "solar-quiet", SPEs observed during these months even include Ground Level Events, the most energetic type of SPE. In this paper, we add to previous study those SPEs that occurred in 1973-2015 when the SSN was greater than 30 but less than 50. Based on the observable energy range of the solar protons, we classify the event as GLEs, sub-GLEs, and sub-sub-GLEs, all of which are potential contributors to the radiation hazard. We use the spectra of these events to construct a probabilistic model of the absorbed dose due to solar protons when SSN < 50 at various confidence levels for various depths of shielding and for various mission durations. We provide plots and tables of solar proton-induced absorbed dose as functions of confidence level, shielding thickness, and mission-duration that will be useful to system designers.

  17. Evidence of mass outflow in the low corona over a large sunspot.

    Science.gov (United States)

    Neupert, W. M.; Brosius, J. W.; Thomas, R. J.; Thompson, W. T.

    1994-04-01

    An extreme ultraviolet imaging spectrograph designed for sounding rocket flight has been used to search for velocity fields in the low solar corona. During a flight in May, 1989, the authors obtained emission line profile measurements along a chord through an active region on the Sun. Relative Doppler velocities were measured in emission lines of Mg IX, Fe XV, and Fe XVI with a sensitivity of 2 - 3 km s-1 at 350 A. The only Doppler shift appreciably greater than this level was observed in the line of Mg IX at 368.1 A over the umbra of the large sunspot. The maximum shift measured at that location corresponded to a velocity toward the observer of 14±3 km s-1 relative to the mean of measurements in that emission line made elsewhere over the active region. The magnetic field in the low corona was aligned to within 10° of the line of sight at the location of maximum Doppler shift. Depending on the magnetic field geometry, this mass outflow could either re-appear as a downflow of material in distant footpoints of closed coronal loops or, if along open field lines, could contribute to the solar wind.

  18. Small-scale magnetic flux emergence in a sunspot light bridge

    CERN Document Server

    Louis, Rohan E; Rodriguez, Jaime de la Cruz; Socas-Navarro, Hector; Ortiz, Ada

    2015-01-01

    We analyse a sequence of high-resolution spectropolarimetric observations of a sunspot taken at the 1-m SST, to determine the nature of flux emergence in a light bridge and the processes related to its evolution in the photosphere and chromosphere. Blueshifts of about 2 km/s are seen near the entrance of a granular light bridge on the limbward side of the spot. They lie next to a strongly redshifted patch that appeared 6 mins earlier. Both patches are seen for 25 mins until the end of the sequence. The blueshifts coincide with an elongated emerging granule, while the redshifts appear at the end of it. In the photosphere, the development of the blueshifts is accompanied by a simultaneous increase in field strength and inclination, with the field becoming nearly horizontal. In the redshifted patch, the magnetic field is equally horizontal but of opposite polarity. An intense brightening is seen in the Ca filtergrams over these features, 17 mins after they emerge in the photosphere. The brightening is due to emi...

  19. Beyond sunspots: Studies using the McIntosh Archive of global solar magnetic field patterns

    Science.gov (United States)

    Gibson, Sarah E.; Webb, David; Hewins, Ian M.; McFadden, Robert H.; Emery, Barbara A.; Denig, William; McIntosh, Patrick S.

    2017-10-01

    In 1964 (Solar Cycle 20; SC 20), Patrick McIntosh began creating hand-drawn synoptic maps of solar magnetic features, based on Hα images. These synoptic maps were unique in that they traced magnetic polarity inversion lines, and connected widely separated filaments, fibril patterns, and plage corridors to reveal the large-scale organization of the solar magnetic field. Coronal hole boundaries were later added to the maps, which were produced, more or less continuously, into 2009 (i.e., the start of SC 24). The result was a record of ~45 years (~570 Carrington rotations), or nearly four complete solar cycles of synoptic maps. We are currently scanning, digitizing and archiving these maps, with the final, searchable versions publicly available at NOAA's National Centers for Environmental Information. In this paper we present preliminary scientific studies using the archived maps from SC 23. We show the global evolution of closed magnetic structures (e.g., sunspots, plage, and filaments) in relation to open magnetic structures (e.g., coronal holes), and examine how both relate to the shifting patterns of large-scale positive and negative polarity regions.

  20. Data Reduction and Related Software for Photographic Observations of Sunspots in the Yunnan Observatories%云南天文台太阳黑子照相观测资料处理和相关软件

    Institute of Scientific and Technical Information of China (English)

    顾啸马; 刘艳霄; 叶惠莲; 林隽

    2015-01-01

    In this paper we present a data-reduction approach and related software for processing data of sunspots obtained from a photographic full-disk solar observation system established by us.When applied to data from our system the approach and software yield fundamental data and parameter values of sunspots, which can serve as the first-hand data to be accumulated and used by solar physicists to study underlying mechanisms of solar activities.The results of our data reduction include those of the relative sunspot numbers. sunspot-group numbers, sunspot locations, sunspot circular areas, sunspot surface areas, sunspot total areas, sunspot classifications, and distances from sunspots ( or sunspot groups) to the solar center.As part of our data reduction we have incorporated a calculation program, which makes it possible to rapidly process daily sunspot data and give values of the mentioned parameters.Our approach may thus completely change the traditional method of manually handling photographic sunspot data, and greatly improve efficiencies of sunspot observation/data processing.It is still necessary for an observer to have certain observational experience and technical skill to use our approach, especially in grouping sunspots and evaluating group numbers.%在建立太阳全日面黑子照相观测系统的基础上对黑子观测资料进行了处理,给出黑子观测的重要数据及相关参数,为太阳物理学家研究太阳活动规律提供和积累最基本的第一手数据。这些数据包括:太阳黑子相对数,南北半球太阳黑子的坐标和黑子群数,太阳黑子的圆面积和球面积等。编写了一个程序,对每天的太阳黑子观测资料进行处理,给出以上物理参数,彻底改变了手工描绘黑子和计算黑子参数的传统方法,同时也提高了黑子资料处理的精度和效率。