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Composition of Coronal Mass Ejections

Zurbuchen, T. H. and Weberg, M. and von Steiger, R. and Mewaldt, R. A. and Lepri, S. T. and Antiochos, S. K. (2016) Composition of Coronal Mass Ejections. Astrophysical Journal, 826 (1). Art. No. 10. ISSN 0004-637X. doi:10.3847/0004-637X/826/1/10.

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We analyze the physical origin of plasmas that are ejected from the solar corona. To address this issue, we perform a comprehensive analysis of the elemental composition of interplanetary coronal mass ejections (ICMEs) using recently released elemental composition data for Fe, Mg, Si, S, C, N, Ne, and He as compared to O and H. We find that ICMEs exhibit a systematic abundance increase of elements with first ionization potential (FIP) < 10 eV, as well as a significant increase of Ne as compared to quasi-stationary solar wind. ICME plasmas have a stronger FIP effect than slow wind, which indicates either that an FIP process is active during the ICME ejection or that a different type of solar plasma is injected into ICMEs. The observed FIP fractionation is largest during times when the Fe ionic charge states are elevated above Q_(Fe) > 12.0. For ICMEs with elevated charge states, the FIP effect is enhanced by 70% over that of the slow wind. We argue that the compositionally hot parts of ICMEs are active region loops that do not normally have access to the heliosphere through the processes that give rise to solar wind. We also discuss the implications of this result for solar energetic particles accelerated during solar eruptions and for the origin of the slow wind itself.

Item Type:Article
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Mewaldt, R. A.0000-0003-2178-9111
Additional Information:© 2016 The American Astronomical Society. Received 2016 January 18; revised 2016 April 27; accepted 2016 May 4; published 2016 July 14. We acknowledge the work of the ACE SWICS team and particularly Paul Shearer for their dedication to producing high-quality compositional data. T.H.Z. acknowledges the hospitality of the staff of the International Space Science Institute where much of this work was performed. This work was supported, in part, by NASA grants NNX13AH66G, NNH13ZDA001N, and NNX11A075G, and the Catholic University of America contract 362496-Sub1.
Funding AgencyGrant Number
Catholic University of America362496-Sub1
Subject Keywords:acceleration of particles – solar wind – Sun: abundances – Sun: coronal mass ejections (CMEs)
Issue or Number:1
Record Number:CaltechAUTHORS:20160916-154106257
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Official Citation:T. H. Zurbuchen et al 2016 ApJ 826 10
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:70409
Deposited By: Tony Diaz
Deposited On:20 Sep 2016 02:00
Last Modified:11 Nov 2021 04:28

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