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Title: PROPERTIES OF A CORONAL SHOCK WAVE AS A DRIVER OF EARLY SEP ACCELERATION

Abstract

Coronal mass ejectmons (CMEs) are thought to drive collisionless shocks in the solar corona, which in turn have been shown to be capable of accelerating solar energetic particles (SEPs) in minutes. It has been notoriously difficult to extract information about energetic particle spectra in the corona, owing to a lack of in situ measurements. It is possible, however, to combine remote observations with data-driven models in order to deduce coronal shock properties relevant to the local acceleration of SEPs and their heliospheric connectivity to near-Earth space. We present such novel analysis applied to the 2011 May 11 CME event on the western solar limb, focusing on the evolution of the eruption-driven, dome-like shock wave observed by the Atmospheric Imaging Assembly (AIA) EUV telescopes on board the Solar Dynamics Observatory spacecraft. We analyze the shock evolution and estimate its strength using emission measure modeling. We apply a new method combining a geometric model of the shock front with a potential field source surface model to estimate time-dependent field-to-shock angles and heliospheric connectivity during shock passage in the low corona. We find that the shock was weak, with an initial speed of ∼450 km s{sup –1}. It was initially mostly quasi-parallel, but amore » significant portion of it turned quasi-perpendicular later in the event. There was good magnetic connectivity to near-Earth space toward the end of the event as observed by the AIA instrument. The methods used in this analysis hold a significant potential for early characterization of coronal shock waves and forecasting of SEP spectra based on remote observations.« less

Authors:
 [1];  [2];  [3];  [4]
  1. Smithsonian Astrophysical Observatory, Cambridge, MA 02138 (United States)
  2. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  3. Learmonth Solar Observatory, Exmouth, WA 6707 (Australia)
  4. Department of Physics, Cornell University, 109 Clark Hall, Ithaca, NY 14853 (United States)
Publication Date:
OSTI Identifier:
22364372
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 799; 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; ACCELERATION; EMISSION SPECTRA; MASS; POTENTIALS; SHOCK WAVES; SOLAR CORONA; SOLAR SYSTEM EVOLUTION; SUN; TELESCOPES; TIME DEPENDENCE; ULTRAVIOLET RADIATION; VELOCITY

Citation Formats

Kozarev, K. A., Raymond, J. C., Lobzin, V. V., and Hammer, M., E-mail: kkozarev@cfa.harvard.edu. PROPERTIES OF A CORONAL SHOCK WAVE AS A DRIVER OF EARLY SEP ACCELERATION. United States: N. p., 2015. Web. doi:10.1088/0004-637X/799/2/167.
Kozarev, K. A., Raymond, J. C., Lobzin, V. V., & Hammer, M., E-mail: kkozarev@cfa.harvard.edu. PROPERTIES OF A CORONAL SHOCK WAVE AS A DRIVER OF EARLY SEP ACCELERATION. United States. doi:10.1088/0004-637X/799/2/167.
Kozarev, K. A., Raymond, J. C., Lobzin, V. V., and Hammer, M., E-mail: kkozarev@cfa.harvard.edu. 2015. "PROPERTIES OF A CORONAL SHOCK WAVE AS A DRIVER OF EARLY SEP ACCELERATION". United States. doi:10.1088/0004-637X/799/2/167.
@article{osti_22364372,
title = {PROPERTIES OF A CORONAL SHOCK WAVE AS A DRIVER OF EARLY SEP ACCELERATION},
author = {Kozarev, K. A. and Raymond, J. C. and Lobzin, V. V. and Hammer, M., E-mail: kkozarev@cfa.harvard.edu},
abstractNote = {Coronal mass ejectmons (CMEs) are thought to drive collisionless shocks in the solar corona, which in turn have been shown to be capable of accelerating solar energetic particles (SEPs) in minutes. It has been notoriously difficult to extract information about energetic particle spectra in the corona, owing to a lack of in situ measurements. It is possible, however, to combine remote observations with data-driven models in order to deduce coronal shock properties relevant to the local acceleration of SEPs and their heliospheric connectivity to near-Earth space. We present such novel analysis applied to the 2011 May 11 CME event on the western solar limb, focusing on the evolution of the eruption-driven, dome-like shock wave observed by the Atmospheric Imaging Assembly (AIA) EUV telescopes on board the Solar Dynamics Observatory spacecraft. We analyze the shock evolution and estimate its strength using emission measure modeling. We apply a new method combining a geometric model of the shock front with a potential field source surface model to estimate time-dependent field-to-shock angles and heliospheric connectivity during shock passage in the low corona. We find that the shock was weak, with an initial speed of ∼450 km s{sup –1}. It was initially mostly quasi-parallel, but a significant portion of it turned quasi-perpendicular later in the event. There was good magnetic connectivity to near-Earth space toward the end of the event as observed by the AIA instrument. The methods used in this analysis hold a significant potential for early characterization of coronal shock waves and forecasting of SEP spectra based on remote observations.},
doi = {10.1088/0004-637X/799/2/167},
journal = {Astrophysical Journal},
number = 2,
volume = 799,
place = {United States},
year = 2015,
month = 2
}
  • We study the effect of large-scale coronal magnetic field on the electron acceleration at a spherical coronal shock using a test-particle method. The coronal field is approximated by an analytical solution with a streamer-like magnetic field featured by partially open magnetic field and a current sheet at the equator atop the closed region. It shows that the closed field plays the role of a trapping agency of shock-accelerated electrons, allowing for repetitive reflection and acceleration, therefore can greatly enhance the shock-electron acceleration efficiency. It is found that, with an ad hoc pitch-angle scattering, electron injected in the open field atmore » the shock flank can be accelerated to high energies as well. In addition, if the shock is faster or stronger, a relatively harder electron energy spectrum and a larger maximum energy can be achieved.« less
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