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Title: Sunward-propagating Solar Energetic Electrons inside Multiple Interplanetary Flux Ropes

Abstract

On 2013 December 2 and 3, the SEPT and STE instruments on board STEREO-A observed two solar energetic electron events with unusual sunward-directed fluxes. Both events occurred during a time interval showing typical signatures of interplanetary coronal mass ejections (ICMEs). The electron timing and anisotropies, combined with extreme-ultraviolet solar imaging and radio wave spectral observations, are used to confirm the solar origin and the injection times of the energetic electrons. The solar source of the ICME is investigated using remote-sensing observations and a three-dimensional reconstruction technique. In situ plasma and magnetic field data combined with energetic electron observations and a flux-rope model are used to determine the ICME magnetic topology and the interplanetary electron propagation path from the Sun to 1 au. Two consecutive flux ropes crossed the STEREO-A location and each electron event occurred inside a different flux rope. In both cases, the electrons traveled from the solar source to 1 au along the longest legs of the flux ropes still connected to the Sun. During the December 2 event, energetic electrons propagated along the magnetic field, while during the December 3 event they were propagating against the field. As found by previous studies, the energetic electron propagation timesmore » are consistent with a low number of field line rotations N < 5 of the flux rope between the Sun and 1 au. The flux rope model used in this work suggests an even lower number of rotations.« less

Authors:
; ; ;  [1]; ; ;  [2]; ;  [3];  [4];  [5]
  1. Dpto. de Física y Matemáticas, Universidad de Alcalá, E-28871 Alcalá de Henares, Madrid (Spain)
  2. Institut für Experimentelle und Angewandte Physik, University of Kiel, D-24118, Kiel (Germany)
  3. Institute of Physics/Kanzelhöhe Observatory, University of Graz, A-8010 Graz (Austria)
  4. Institut für Astrophysik, Georg-August-Universität Göttingen, D-37077, Göttingen (Germany)
  5. The Johns Hopkins University, Applied Physics Laboratory, Laurel, MD 20723 (United States)
Publication Date:
OSTI Identifier:
22663622
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 840; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANISOTROPY; EMISSION; EXTREME ULTRAVIOLET RADIATION; INJECTION; MAGNETIC FIELDS; MASS; PLASMA; RADIOWAVE RADIATION; REMOTE SENSING; ROTATION; SEASONAL THERMAL ENERGY STORAGE; SUN; TAIL ELECTRONS; THREE-DIMENSIONAL CALCULATIONS; TOPOLOGY

Citation Formats

Gómez-Herrero, Raúl, Hidalgo, Miguel A., Carcaboso, Fernando, Blanco, Juan J., Dresing, Nina, Klassen, Andreas, Heber, Bernd, Temmer, Manuela, Veronig, Astrid, Bučík, Radoslav, and Lario, David, E-mail: raul.gomezh@uah.es. Sunward-propagating Solar Energetic Electrons inside Multiple Interplanetary Flux Ropes. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA6C5C.
Gómez-Herrero, Raúl, Hidalgo, Miguel A., Carcaboso, Fernando, Blanco, Juan J., Dresing, Nina, Klassen, Andreas, Heber, Bernd, Temmer, Manuela, Veronig, Astrid, Bučík, Radoslav, & Lario, David, E-mail: raul.gomezh@uah.es. Sunward-propagating Solar Energetic Electrons inside Multiple Interplanetary Flux Ropes. United States. doi:10.3847/1538-4357/AA6C5C.
Gómez-Herrero, Raúl, Hidalgo, Miguel A., Carcaboso, Fernando, Blanco, Juan J., Dresing, Nina, Klassen, Andreas, Heber, Bernd, Temmer, Manuela, Veronig, Astrid, Bučík, Radoslav, and Lario, David, E-mail: raul.gomezh@uah.es. Wed . "Sunward-propagating Solar Energetic Electrons inside Multiple Interplanetary Flux Ropes". United States. doi:10.3847/1538-4357/AA6C5C.
@article{osti_22663622,
title = {Sunward-propagating Solar Energetic Electrons inside Multiple Interplanetary Flux Ropes},
author = {Gómez-Herrero, Raúl and Hidalgo, Miguel A. and Carcaboso, Fernando and Blanco, Juan J. and Dresing, Nina and Klassen, Andreas and Heber, Bernd and Temmer, Manuela and Veronig, Astrid and Bučík, Radoslav and Lario, David, E-mail: raul.gomezh@uah.es},
abstractNote = {On 2013 December 2 and 3, the SEPT and STE instruments on board STEREO-A observed two solar energetic electron events with unusual sunward-directed fluxes. Both events occurred during a time interval showing typical signatures of interplanetary coronal mass ejections (ICMEs). The electron timing and anisotropies, combined with extreme-ultraviolet solar imaging and radio wave spectral observations, are used to confirm the solar origin and the injection times of the energetic electrons. The solar source of the ICME is investigated using remote-sensing observations and a three-dimensional reconstruction technique. In situ plasma and magnetic field data combined with energetic electron observations and a flux-rope model are used to determine the ICME magnetic topology and the interplanetary electron propagation path from the Sun to 1 au. Two consecutive flux ropes crossed the STEREO-A location and each electron event occurred inside a different flux rope. In both cases, the electrons traveled from the solar source to 1 au along the longest legs of the flux ropes still connected to the Sun. During the December 2 event, energetic electrons propagated along the magnetic field, while during the December 3 event they were propagating against the field. As found by previous studies, the energetic electron propagation times are consistent with a low number of field line rotations N < 5 of the flux rope between the Sun and 1 au. The flux rope model used in this work suggests an even lower number of rotations.},
doi = {10.3847/1538-4357/AA6C5C},
journal = {Astrophysical Journal},
number = 2,
volume = 840,
place = {United States},
year = {Wed May 10 00:00:00 EDT 2017},
month = {Wed May 10 00:00:00 EDT 2017}
}
  • Recent statistical surveys of interplanetary MeV energy nucleon flux anisotropies observed between prompt solar particle events during solar activity minimum have included time blocks of data obtained when the interplanetary magnetic field (IMF) connects the near earth spacecraft to earth's bow shock. The ensemble average nucleon flux anisotropy in the solar wind reference frame obtained on these 'connected' field lines does not accurately represent the unperturbed obtained on field lines free of this magnetic connection. Hourly average observations of interplanetary 0.5- to 1.8-MeV proton fluxes, obtained near earth from 1972 to 1977, are correlated herein with simultaneous measurements of themore » IMF and solar wind plasma. At moderate flux levels during solar activity minimum, indicates that nucleon flow in the solar wind frame is toward the sun and primarily along the IMF, although is directed more sunward than strict field-aligned propagation requires. Cross-field transport is statistically significant and in the direction expected from the large-scale MeV energy nucleon flux distributions throughout the heliosphere. The unperturbed nucleon flow direction relative to the IMF is used to demonstrate and characterize the interaction of MeV energy nuclei with the earth's bow shock and magnetosheath. The result of this interaction is that the mean value of perpendicular to connected field lines is consistent with zero and therefore is not statistically significant. Obstruction of sunward nucleon flow on connected field lines is indicated by the variation of with spacecraft position.« less
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  • Whether a magnetic flux rope is pre-existing or formed in situ in the Sun's atmosphere, there is little doubt that magnetic reconnection is essential to release the flux rope during its ejection. During this process, the question remains: how does magnetic reconnection change the flux-rope structure? In this work, we continue with the original study of Qiu et al. by using a larger sample of flare-coronal mass ejection (CME)-interplanetary CME (ICME) events to compare properties of ICME/magnetic cloud (MC) flux ropes measured at 1 AU and properties of associated solar progenitors including flares, filaments, and CMEs. In particular, the magneticmore » field-line twist distribution within interplanetary magnetic flux ropes is systematically derived and examined. Our analysis shows that, similar to what was found before, for most of these events, the amount of twisted flux per AU in MCs is comparable with the total reconnection flux on the Sun, and the sign of the MC helicity is consistent with the sign of the helicity of the solar source region judged from the geometry of post-flare loops. Remarkably, we find that about half of the 18 magnetic flux ropes, most of them associated with erupting filaments, have a nearly uniform and relatively low twist distribution from the axis to the edge, and the majority of the other flux ropes exhibit very high twist near the axis, up to ≳ 5 turns per AU, which decreases toward the edge. The flux ropes are therefore not linearly force-free. We also conduct detailed case studies showing the contrast of two events with distinct twist distribution in MCs as well as different flare and dimming characteristics in solar source regions, and discuss how reconnection geometry reflected in flare morphology may be related to the structure of the flux rope formed on the Sun.« less