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Probing shock geometry via the charge to mass ratio dependence of heavy ion spectra from multiple spacecraft observations of the 2013 November 4 event

Zhao, Lulu and Li, Gang and Mason, Glenn M. and Cohen, Christina and Mewaldt, Richard A. and Desai, Mihir I. and Ebert, Rob W. and Dayeh, Maher A. (2016) Probing shock geometry via the charge to mass ratio dependence of heavy ion spectra from multiple spacecraft observations of the 2013 November 4 event. Research in Astronomy and Astrophysics, 16 (12). Art. No. 190. ISSN 1674-4527. doi:10.1088/1674-4527/16/12/190.

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In large Solar Energetic Particle (SEP) events, ions can be accelerated at coronal mass ejection (CME)-driven shocks to very high energies. The spectra of heavy ions in many large SEP events show features such as roll-overs or spectral breaks. In some events when the spectra are plotted in terms of energy/nucleon, they can be shifted relative to each other to make the spectral breaks align. The amount of shift is charge to mass ratio (Q/A) dependent and varies from event to event. This can be understood if the spectra of heavy ions are organized by the diffusion coefficients (Cohen et al. 2005). In the work of Li et al. (2009), the Q/A dependence of the scaling is related to shock geometry when the CME-driven shock is close to the Sun. For events where multiple in-situ spacecraft observations exist, one may expect that different spacecraft are connected to different portions of the CME-driven shock that have different shock geometries, therefore yielding different Q/A dependence. In this work, we examine one SEP event which occurred on 2013 November 4. We study the Q/A dependence of the energy scaling for heavy ion spectra using helium, oxygen and iron ions. Observations from STEREO-A, STEREO-B and ACE are examined. We find that the scalings are different for different spacecraft. We suggest that this is because ACE, STEREO-A and STEREO-B are connected to different parts of the shock that have different shock geometries. Our analysis indicates that studying the Q/A scaling of in-situ particle spectra can serve as a powerful tool to remotely examine the shock geometry for large SEP events.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Li, Gang0000-0001-9313-251X
Mason, Glenn M.0000-0003-2169-9618
Cohen, Christina0000-0002-0978-8127
Mewaldt, Richard A.0000-0003-2178-9111
Desai, Mihir I.0000-0002-7318-6008
Ebert, Rob W.0000-0002-2504-4320
Dayeh, Maher A.0000-0001-9323-1200
Additional Information:© 2016 National Astronomical Observatories, Chinese Academy of Sciences and IOP Publishing Ltd. This work is supported at UAH by NSF grants AGS-1135432 and AGS-1622391, NASA grant NNX15AJ93G; at APL by NASA grant NNX13AR20G/115828 (ACE/ULEIS and STEREO/SIT) and NASA subcontract SA4889-26309 from the University of California Berkeley; at Caltech by NNX13A66G, NNX11A075G, and subcontract 00008864 of NNX15AG09G and by NSF grant AGS-1156004; at SwRI partially by NSF grant AGS-1460118.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
Issue or Number:12
Record Number:CaltechAUTHORS:20161129-100031026
Persistent URL:
Official Citation:Lulu Zhao et al 2016 Res. Astron. Astrophys. 16 190
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:72394
Deposited By: Tony Diaz
Deposited On:29 Nov 2016 18:11
Last Modified:11 Nov 2021 05:00

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