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13 results on '"University College of London [London] (UCL)"'

1. Preface: Probing the Sun Inside and Out

Author

John Leibacher, Louise K. Harra, Lidia van Driel-Gesztelyi, Rachel Howe, Deborah Baker, University College of London [London] (UCL), University of Birmingham, National Solar Observatory, Institut d'astrophysique spatiale (IAS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Physique solaire, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris

Subjects
Physics, Corona (optical phenomenon), Space and Planetary Science, Astronomy, Astronomy and Astrophysics, Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Helicity, Magnetic field, Nanoflares
Abstract

International audience; Not Available

Published
2015

2. On-Orbit Degradation of Solar Instruments

Author

Vincenzo Andretta, Udo Schühle, D. Walton, C. Jeppesen, L. Bradley, Matthieu Kretzschmar, M. Dominique, Abdanour Irbah, Andrew R. Jones, Thomas N. Woods, B. Giordanengo, C. J. Eyles, Werner Schmutz, G. Del Zanna, Gregory J. Ucker, Frédéric Auchère, Francis G. Eparvier, Daniel B. Seaton, Daniel Stephen Brown, Leonid Didkovsky, Don Woodraska, Seth Wieman, Darrell L. Judge, Jean-Philippe Halain, David Berghmans, Mustapha Meftah, Thomas Foujols, S. Mekaoui, Gaël Cessateur, G. Thuillier, Steven Dewitte, I. E. Dammasch, Rachel Hock, D. Gillotay, B. Nicula, Phillip C. Chamberlin, Samuel Gissot, Ali BenMoussa, David Bolsee, Danielle Bewsher, D. R. McMullin, Solar-Terrestrial Centre of Excellence [Brussels] (STCE), Royal Observatory of Belgium [Brussels] (ROB), Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Department of Applied Mathematics and Theoretical Physics (DAMTP), University of Cambridge [UK] (CAM), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut Royal Météorologique de Belgique [Bruxelles] (IRM), European Commission - Joint Research Centre [Ispra] (JRC), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Mullard Space Science Laboratory (MSSL), University College of London [London] (UCL), Grupo de Astronomia y Ciencias del Espacio (GACE), Laboratorio de Procesado de Imagenes [Valencia] (LPI), Universitat de València (UV)-Universitat de València (UV), Space Science and Technology Department [Didcot] (RAL Space), STFC Rutherford Appleton Laboratory (RAL), Science and Technology Facilities Council (STFC)-Science and Technology Facilities Council (STFC), STRATO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Capodimonte (OAC), Istituto Nazionale di Astrofisica (INAF), Jeremiah Horrocks Institute for Mathematics, Physics and Astronomy [Preston], University of Central Lancashire [Preston] (UCLAN), Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), NASA Goddard Space Flight Center (GSFC), University of Southern California (USC), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre Spatial de Liège (CSL), Université de Liège, Air Force Research Laboratory (AFRL), United States Air Force (USAF), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Space Systems Research Corporation (SSRC), Physikalisch-Meteorologisches Observatorium Davos/World Radiation Center (PMOD/WRC), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Institut Royal Météorologique de Belgique [Bruxelles] - Royal Meteorological Institute (IRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES)

Subjects
solar instruments, [PHYS.ASTR.IM]Physics [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], 010504 meteorology & atmospheric sciences, FOS: Physical sciences, Solar mission, Space weather, Space (commercial competition), 7. Clean energy, 01 natural sciences, Space exploration, Degradation, Contamination, Observatory, 0103 physical sciences, Aerospace engineering, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, business.industry, Astronomy and Astrophysics, con- tamination, calibration, space environment, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Orbit (dynamics), Environmental science, Astrophysics - Instrumentation and Methods for Astrophysics, business, Space environment, Degradation (telecommunications)
Abstract

International audience; We present the lessons learned about the degradation observed in several space solar missions, based on contributions at the Workshop about On-Orbit Degradation of Solar and Space Weather Instruments that took place at the Solar Terrestrial Centre of Excellence (Royal Observatory of Belgium) in Brussels on 3 May 2012. The aim of this workshop was to open discussions related to the degradation observed in Sun-observing instruments exposed to the effects of the space environment. This article summarizes the various lessons learned and offers recommendations to reduce or correct expected degradation with the goal of increasing the useful lifespan of future and ongoing space missions.

Published
2013
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3. Twisted Flux Tube Emergence Evidenced in Longitudinal Magnetograms: Magnetic Tongues

Author

Cristina Hemilse Mandrini, Pascal Démoulin, Maria Luisa Luoni, L. van Driel-Gesztelyi, Instituto de Astronomía y Física del Espacio, Universidade de Buenos Aires (IAFE), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Physique solaire, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and University College of London [London] (UCL)

Subjects
Physics, 010504 meteorology & atmospheric sciences, Flux tube, Ciencias Físicas, STRUCTURES [CORONA], Astronomy and Astrophysics, MAGNETIC FIELDS, Astrophysics, 01 natural sciences, Helicity, Magnetic field, Astronomía, Classical mechanics, Space and Planetary Science, Magnetic helicity, MAGNETIC HELICITY, 0103 physical sciences, ACTIVE REGIONS, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, CIENCIAS NATURALES Y EXACTAS, 0105 earth and related environmental sciences
Abstract

Bipolar active regions (ARs) are thought to be formed by twisted flux tubes, as the presence of such twist is theoretically required for a cohesive rise through the whole convective zone. We use longitudinal magnetograms to demonstrate that a clear signature of a global magnetic twist is present, particularly, during the emergence phase when the AR is forming in a much weaker pre-existing magnetic field environment. The twist is characterised by the presence of elongated polarities, called “magnetic tongues”, which originate from the azimuthal magnetic field component. The tongues first extend in size before retracting when the maximum magnetic flux is reached. This implies an apparent rotation of the magnetic bipole. Using a simple half-torus model of an emerging twisted flux tube having a uniform twist profile, we derive how the direction of the polarity inversion line and the elongation of the tongues depend on the global twist in the flux rope. Using a sample of 40 ARs, we verify that the helicity sign, determined from the magnetic polarity distribution pattern, is consistent with the sign derived from the photospheric helicity flux computed from magnetogram time series, as well as from other proxies such as sheared coronal loops, sigmoids, Fil: Luoni, Maria Luisa. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina Fil: Démoulin, Pascal. Centre National de la Recherche Scientifique. Observatoire de Paris; Francia Fil: Mandrini, Cristina Hemilse. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina Fil: van Driel Gesztelyi, Lidia. Centre National de la Recherche Scientifique. Observatoire de Paris; Francia

Published
2011

4. Pre-Flare Flows in the Corona

Author

Sarah A. Matthews, Lucie M. Green, L. van Driel-Gesztelyi, A. J. Wallace, Louise K. Harra, University College of London [London] (UCL), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Physique solaire, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris

Subjects
Physics, Solar flare, 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Astronomy, Astronomy and Astrophysics, Magnetic reconnection, Astrophysics, 01 natural sciences, Instability, Magnetic field, Nanoflares, law.invention, Space and Planetary Science, law, Physics::Space Physics, 0103 physical sciences, Coronal mass ejection, Astrophysics::Solar and Stellar Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, Pressure gradient, Flare
Abstract

International audience; Solar flares take place in regions of strong magnetic fields and are generally accepted to be the result of a resistive instability leading to magnetic reconnection. When new flux emerges into a pre-existing active region it can act as a flare and coronal mass ejection trigger. In this study we observed active region 10955 after the emergence of small-scale additional flux at the magnetic inversion line. We found that flaring began when additional positive flux levels exceeded 1.38×1020 Mx (maxwell), approximately 7 h after the initial flux emergence. We focussed on the pre-flare activity of one B-class flare that occurred on the following day. The earliest indication of activity was a rise in the non-thermal velocity one hour before the flare. 40 min before flaring began, brightenings and pre-flare flows were observed along two loop systems in the corona, involving the new flux and the pre-existing active region loops. We discuss the possibility that reconnection between the new flux and pre-existing loops before the flare drives the flows by either generating slow mode magnetoacoustic waves or a pressure gradient between the newly reconnected loops. The subsequent B-class flare originated from fast reconnection of the same loop systems as the pre-flare flows.

Published
2010

5. Revealing the Fine Structure of Coronal Dimmings and Associated Flows with Hinode/EIS

Author

Louise K. Harra, L. van Driel-Gesztelyi, G. D. R. Attrill, M. J. Wills-Davey, Harvard-Smithsonian Center for Astrophysics, University College of London [London] (UCL), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Physique solaire, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris

Subjects
Physics, 010504 meteorology & atmospheric sciences, Astronomy, Astronomy and Astrophysics, Coronal loop, Astrophysics, 01 natural sciences, 13. Climate action, Space and Planetary Science, Coronal plane, 0103 physical sciences, Outflow, Magnetic cloud, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Recovery phase
Abstract

International audience; We study two CME events on 13 and 14 December 2006 that were associated with large-scale dimmings. We study the eruptions from pre-event on 11 December through the recovery on 15 December, using a combination of Hinode/EIS, SOHO/EIT, SOHO/MDI, and MLSO Halpha data. The GOES X-class flares obscured the core dimmings, but secondary dimmings developed remote from the active region (AR) in both events. The secondary dimmings are found to be formed by a removal of bright coronal material from loops in the plage region to the East of the AR. Using Hinode/EIS data, we find that the outflows associated with the coronal-dimming regions are highly structured. The concentrated outflows are located at the footpoints of coronal loops (which exist before, and are re-established after, the eruptions), and these are correlated with regions of positive magnetic elements. Comparative study of the Hinode/EIS and SOHO/EIT data shows that the reduction in outflow velocity is consistent with the recovery in intensity of the studied regions. We find that concentrated downflows develop during the recovery phase of the dimmings and are also correlated with the same positive magnetic elements that were previously related to outflows. The local behaviour of the flows in and around the dimming regions following the eruptions is found to be dynamic and complex. Despite the global aspects of these events (widespread dimmings, CMEs, coronal waves) being largely homologous, there are significant local variations and distinct differences between the flows associated with the two events. We find that the secondary dimmings recover primarily by re-establishment of the bright coronal loops (the exact configuration changes between the eruptions, which is reflected by the complexity of the flows).

Published
2010

6. A New Model for Propagating Parts of EIT Waves: A Current Shell in a CME

Author

C. Delannée, Jean-François Hochedez, Tibor Torok, Guillaume Aulanier, Observatoire Royal de Belgique (ORB), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Physique solaire, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and University College of London [London] (UCL)

Subjects
Physics, Solar flare, Flux tube, Astronomy and Astrophysics, Plasma, Astrophysics, Magnetic flux, Magnetic field, Space and Planetary Science, Physics::Space Physics, Astrophysics::Solar and Stellar Astrophysics, Magnetohydrodynamics, Electric current, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Current density
Abstract

International audience; EIT waves are observed in EUV as bright fronts. Some of these bright fronts propagate across the solar disk. EIT waves are all associated with a flare and a CME and are commonly interpreted as fast-mode magnetosonic waves. Propagating EIT waves could also be the direct signature of the gradual opening of magnetic field lines during a CME. We quantitatively addressed this alternative interpretation. Using two independent 3D MHD codes, we performed nondimensional numerical simulations of a slowly rotating magnetic bipole, which progressively result in the formation of a twisted magnetic flux tube and its fast expansion, as during a CME. We analyse the origins, the development, and the observability in EUV of the narrow electric currents sheets that appear in the simulations. Both codes give similar results, which we confront with two well-known SOHO/EIT observations of propagating EIT waves (7 April and 12 May 1997), by scaling the vertical magnetic field components of the simulated bipole to the line of sight magnetic field observed by SOHO/MDI and the sign of helicity to the orientation of the soft X-ray sigmoids observed by Yohkoh/SXT. A large-scale and narrow current shell appears around the twisted flux tube in the dynamic phase of its expansion. This current shell is formed by the return currents of the system, which separate the twisted flux tube from the surrounding fields. It intensifies as the flux tube accelerates and it is co-spatial with weak plasma compression. The current density integrated over the altitude has the shape of an ellipse, which expands and rotates when viewed from above, reproducing the generic properties of propagating EIT waves. The timing, orientation, and location of bright and faint patches observed in the two EIT waves are remarkably well reproduced. We conjecture that propagating EIT waves are the observational signature of Joule heating in electric current shells, which separate expanding flux tubes from their surrounding fields during CMEs or plasma compression inside this current shell. We also conjecture that the bright edges of halo CMEs show the plasma compression in these current shells.

Published
2007

7. Are CME-Related Dimmings Always a Simple Signature of Interplanetary Magnetic Cloud Footpoints?

Author

Cristina Hemilse Mandrini, H. A. Elliott, M. S. Nakwacki, Gemma Attrill, Pascal Démoulin, L. van Driel-Gesztelyi, Sergio Dasso, Instituto de Astronomía y Física del Espacio, Universidade de Buenos Aires (IAFE), University College of London [London] (UCL), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Physique solaire, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Southwest Research Institute

Subjects
Astronomía, Physics, INTERPLANETARY [CORONAL MASS EJECTIONS], Space and Planetary Science, Ciencias Físicas, INTERPLANETARY [MAGNETIC FIELD], PHOTOSPHERE [MAGNETIC FIELD], LOW CORONAL SIGNATURES [CORONAL MASS EJECTIONS], Astronomy and Astrophysics, Astrophysics, Magnetic cloud, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], CIENCIAS NATURALES Y EXACTAS
Abstract

Coronal dimmings are often present on both sides of erupting magnetic configurations. It has been suggested that dimmings mark the location of the footpoints of ejected flux ropes and, thus, their magnetic flux can be used as a proxy for the flux involved in the ejection. If so, this quantity can be compared to the flux in the associated interplanetary magnetic cloud to find clues about the origin of the ejected flux rope. In the context of this physical interpretation, we analyze the event, flare, and coronal mass ejection (CME) that occurred in active region 10486 on 28 October 2003. The CME on this day is associated with large-scale dimmings, located on either side of the main flaring region. We combine SOHO/Extreme Ultraviolet Imaging Telescope data and Michelson Doppler Imager magnetic maps to identify and measure the flux in the dimming regions. We model the associated cloud and compute its magnetic flux using in situ observations from the Magnetometer Instrument and the Solar Wind Electron Proton Alpha Monitor aboard the Advance Composition Explorer. We find that the magnetic fluxes of the dimmings and magnetic cloud are incompatible, in contrast to what has been found in previous studies. We conclude that, in certain cases, especially in large-scale events and eruptions that occur in regions that are not isolated from other flux concentrations, the interpretation of dimmings requires a deeper analysis of the global magnetic configuration, since at least a fraction of the dimmed regions is formed by reconnection between the erupting field and the surrounding magnetic structures. Fil: Mandrini, Cristina Hemilse. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina Fil: Nakwacki, Maria Soledad. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina Fil: Attrill, G.. University College London, Mullard Space Science Laboratory; Reino Unido Fil: van Driel Gesztelyi, Lidia. Centre National de la Recherche Scientifique. Observatoire de Paris; Francia Fil: Démoulin, Pascal. Centre National de la Recherche Scientifique. Observatoire de Paris; Francia Fil: Dasso, Sergio Ricardo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina Fil: Elliott, H.. Southwest Research Institute; Estados Unidos

Published
2007

8. A Multiple Flare Scenario where the Classic Long-Duration Flare Was Not the Source of a CME

Author

Cristina Hemilse Mandrini, C. P. Goff, Pascal Démoulin, Louise K. Harra, J. L. Culhane, L. van Driel-Gesztelyi, Karl-Ludwig Klein, Hiroki Kurokawa, Sarah A. Matthews, University College of London [London] (UCL), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Physique solaire, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Instituto de Astronomía y Física del Espacio, Universidade de Buenos Aires (IAFE), and Hida & Kwasan Observatoires, Kyoto University

Subjects
Physics, Flux tube, Solar flare, Ciencias Físicas, Astrophysics::High Energy Astrophysical Phenomena, Astronomy and Astrophysics, Magnetic reconnection, Astrophysics, Helicity, law.invention, Magnetic field, Astronomía, Solar flares, Space and Planetary Science, law, Physics::Space Physics, Coronal mass ejection, Astrophysics::Solar and Stellar Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Short duration, CIENCIAS NATURALES Y EXACTAS, Flare
Abstract

A series of flares (GOES class M, M and C) and a CME were observed in close succession on 20 January 2004 in NOAA 10540. Radio observations, which took the form of types II, III and N bursts, were associated with these events. We use the combined observations from TRACE, EIT, Hα images from Kwasan, MDI magnetograms and GOES to understand the complex development of this event. Contrary to a standard interpretation, we conclude that the first two impulsive flares are part of the CME launch process while the following long-duration event flare represents simply the recovery phase. Observations show that the flare ribbons not only separate but also shift along the magnetic inversion line so that magnetic reconnection progresses stepwise to neighboring flux tubes. We conclude that “tether cutting” reconnection in the sheared arcade progressively transforms it to a twisted flux tube, which becomes unstable, leading to a CME. We interpret the third flare, a long-duration event, as a combination of the classical two-ribbon flare with the relaxation process following forced reconnection between the expanding CME structure and neighboring magnetic fields. Fil: Golf, C. P.. Mullard Space Science Laboratory; Reino Unido Fil: van Driel Gesztelyi, Lidia. Centre National de la Recherche Scientifique. Observatoire de Paris; Francia Fil: Démoulin, Pascal. Centre National de la Recherche Scientifique. Observatoire de Paris; Francia Fil: Culhane, J. L.. Mullard Space Science Laboratory; Reino Unido Fil: Matthews, S. A.. Mullard Space Science Laboratory; Reino Unido Fil: Harra, L. K.. Mullard Space Science Laboratory; Reino Unido Fil: Mandrini, Cristina Hemilse. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina Fil: Klein, K. L.. Centre National de la Recherche Scientifique. Observatoire de Paris; Francia Fil: Kurokawa, H.. Kyoto university; Japón

Published
2007

9. The Gradual Phase of the X17 Flare on October 28, 2003

Author

Brigitte Schmieder, Stephen J. Bradshaw, G. Del Zanna, A. Berlicki, Helen E. Mason, University College of London [London] (UCL), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Physique solaire, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, Wilberforce Road, Astronomical Institute, University of Wroclaw, and Imperial College London

Subjects
Physics, business.industry, Phase (waves), Astronomy and Astrophysics, Astrophysics, law.invention, symbols.namesake, Optics, Space and Planetary Science, law, symbols, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], business, Doppler effect, Flare
Abstract

We present SOHO/CDS observations taken during the gradual phase of the X17 flare that occurred on October 28, 2003. The CDS data are supplemented with TRACE and ground-based observations. The spectral observations allow us to determine velocities from the Doppler shifts measured in the flare loops and in the two ribbon kernels, one hour and a half after the flare peak. Strong downflows (>70 km s−1) are observed along the loop legs at transition-region temperatures. The velocities are close to those expected for free fall. Observations and results from a hydrodynamic simulation are consistent with the heating taking place for a short time near the top of the arcade. Slight upflows are observed in the outer edges of the ribbons (

Published
2006

10. The Sun–Earth Connection near Solar Minimum: Placing it into Context

Author

Barbara A. Emery, Lidia van Driel-Gesztelyi, John Leibacher, Barbara J. Thompson, Mario M. Bisi, Sarah Gibson, Aberystwyth University, NASA/Goddard Space Flight Center (NASA/GSFC), High Altitude Observatory, National Center for Atmospheric Research, National Solar Observatory, Tucson, Institut d'astrophysique spatiale (IAS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Physique solaire, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and University College of London [London] (UCL)

Subjects
Physics, Solar minimum, Space and Planetary Science, business.industry, Astronomy and Astrophysics, Context (language use), Earth (chemistry), Aerospace engineering, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], business, Connection (mathematics)
Abstract

International audience; Not Available

Published
2011

11. Preface

Author

Green, Lucie M., Sakurai, Takashi, van Driel-Gesztelyi, Lidia, University College of London [London] (UCL), National Astronomical Observatory of Japan (NAOJ), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Space and Planetary Science, Astronomy and Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience; Not Available

Published
2012

12. Solar Physics Memoir Series Reinstituted

Author

Lidia van Driel-Gesztelyi, Ed Cliver, Air Force Research Laboratory, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Physique solaire, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and University College of London [London] (UCL)

Subjects
Physics, Series (mathematics), Space and Planetary Science, Memoir, Astronomy, Astronomy and Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Solar physics, Engineering physics
Abstract

International audience; Not Available

Published
2010

13. Preface

Author

Therese A. Kucera, M. L. Kaiser, Lidia van Driel Gesztelyi, E. R. Christian, O. C. St. Cyr, Cristina Hemilse Mandrini, NASA/Goddard Space Flight Center (NASA/GSFC), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), University College of London [London] (UCL), and Instituto de Astronomía y Física del Espacio, Universidade de Buenos Aires (IAFE)

Subjects
Solar minimum, Space and Planetary Science, Environmental science, Astronomy and Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Remote sensing
Abstract

International audience; Not Available

Published
2009

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