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Spectral Properties of He and Heavy Ions in ^3He-rich Solar Flares

Mason, G. M. and Wiedenbeck, M. E. and Miller, J. A. and Mazur, J. E. and Christian, E. R. and Cohen, C. M. S. and Cummings, A. C. and Dwyer, J. R. and Gold, R. E. and Krimigis, S. M. and Leske, R. A. and Mewaldt, R. A. and Slocum, P. L. and Stone, E. C. and von Rosenvinge, T. T. (2002) Spectral Properties of He and Heavy Ions in ^3He-rich Solar Flares. Astrophysical Journal, 574 (2). pp. 1039-1058. ISSN 0004-637X. doi:10.1086/341112.

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Using advanced instrumentation on the ACE spacecraft, we have conducted a survey of solar energetic particle spectra in ^3He-rich events over a broad energy range ~80 keV nucleon^(-1) to 15 MeV nucleon^(-1) during the period 1997 September-2001 March. The spectra of ^4He and heavy ions (C, N, O, Ne, Mg, Si, S, Ca, Fe) were generally similar over this range but often hardened below ~1 MeV nucleon^(-1). In most of the events there was even stronger hardening of the ^3He spectrum below ~1 MeV nucleon^(-1), leading to an energy-dependent ^3He : ^4He ratio. These observations point to unique and distinct properties of ^3He in these events and place new constraints on models that seek to explain enhancements of ^3He and heavy ions using the same mechanisms. In addition to the events with spectra in the form of power laws or double power laws, there is a second class of event in which the low-energy ^3He and Fe spectra are rounded, while the ^4He remains a power law. In these cases ^3He and Fe spectra can be fitted at low energies by a stochastic acceleration model, but this model does not explain the higher energy portions of these spectra, nor the power-law spectral forms of the ^4He. These observations appear to require an additional mechanism, such as acceleration by cascading MHD turbulence. The ^3He enrichment pattern that we observe suggests that all these different spectral features might be due to processes with a common origin but then followed by different acceleration histories.

Item Type:Article
Related URLs:
URLURL TypeDescription
Mason, G. M.0000-0003-2169-9618
Wiedenbeck, M. E.0000-0002-2825-3128
Christian, E. R.0000-0003-2134-3937
Cohen, C. M. S.0000-0002-0978-8127
Cummings, A. C.0000-0002-3840-7696
Krimigis, S. M.0000-0003-2781-2386
Leske, R. A.0000-0002-0156-2414
Mewaldt, R. A.0000-0003-2178-9111
Stone, E. C.0000-0002-2010-5462
Alternate Title:Spectral Properties of He and Heavy Ions in 3He-rich Solar Flares
Additional Information:© 2002 American Astronomical Society. Received 2002 January 2; accepted 2002 April 8. We thank the many individuals at the University of Maryland, Johns Hopkins Applied Physics Laboratory, California Institute of Technology, Jet Propulsion Laboratory, and Goddard Space Flight Center responsible for the construction of the ULEIS and SIS instruments. This work was supported in part by NASA under grant PC 251429 at the University of Maryland and NAG5-6912 at Caltech.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
NASAPC 251429
Subject Keywords:acceleration of particles; cosmic rays; interplanetary medium; solar wind; Sun: abundances; Sun: flares
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Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory2002-02
Issue or Number:2
Record Number:CaltechAUTHORS:20140827-085036707
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Official Citation:Spectral Properties of He and Heavy Ions in 3He-rich Solar Flares G. M. Mason et al. 2002 ApJ 574 1039
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:48961
Deposited By: Ruth Sustaita
Deposited On:27 Aug 2014 17:53
Last Modified:10 Nov 2021 18:38

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