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The first gradual solar energetic particle event with an enhanced ³He abundance on Solar Orbiter

Bucik, R. and Mason, G. M. and Gómez-Herrero, R. and Krupar, V. and Lario, D. and Starkey, M. J. and Ho, G. C. and Rodríguez-Pacheco, J. and Wimmer-Schweingruber, R. F. and Espinosa Lara, F. and Tadesse, T. and Balmaceda, L. and Cohen, C. M. S. and Dayeh, M. A. and Desai, M. I. and Kühl, P. and Nitta, N. V. and Wiedenbeck, M. E. and Xu, Z. G. (2023) The first gradual solar energetic particle event with an enhanced ³He abundance on Solar Orbiter. Astronomy and Astrophysics, 669 . Art. No. A13. ISSN 0004-6361. doi:10.1051/0004-6361/202245037.

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The origin of ³He bundance enhancements in gradual solar energetic particle (SEP) events remains largely unexplained. Two mechanisms have been suggested: the reacceleration of remnant flare material by coronal mass ejection (CME)-driven shocks in interplanetary space, and concomitant activity in the corona. We explore the first gradual SEP event with enhanced 3He abundance that was observed by Solar Orbiter. The event started on 2020 November 24 and was associated with a relatively fast halo CME. During the event, the spacecraft was at 0.9 au from the Sun. The event-averaged ³He/⁴He abundance ratio is 24 times higher than the coronal or solar wind value, and the timing of the ³He intensity was similar to that of other species. We inspected available imaging, radio observations, and the spacecraft magnetic connection to the CME source. The most probable cause of the enhanced ³He ions remaining from a preceding long period of 3He-rich SEPs on 2020 November 17–23.

Item Type:Article
Related URLs:
URLURL TypeDescription
Bucik, R.0000-0001-7381-6949
Mason, G. M.0000-0003-2169-9618
Gómez-Herrero, R.0000-0002-5705-9236
Krupar, V.0000-0001-6185-3945
Lario, D.0000-0002-3176-8704
Starkey, M. J.0000-0001-7514-6571
Ho, G. C.0000-0003-1093-2066
Rodríguez-Pacheco, J.0000-0002-4240-1115
Wimmer-Schweingruber, R. F.0000-0002-7388-173X
Espinosa Lara, F.0000-0001-9039-8822
Balmaceda, L.0000-0003-1162-5498
Cohen, C. M. S.0000-0002-0978-8127
Dayeh, M. A.0000-0001-9323-1200
Desai, M. I.0000-0002-7318-6008
Kühl, P.0000-0002-3758-9272
Nitta, N. V.0000-0001-6119-0221
Wiedenbeck, M. E.0000-0002-2825-3128
Xu, Z. G.0000-0002-9246-996X
Additional Information:© The Authors 2022. Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. R. Bučík was supported by NASA grants 80NSSC21K1316, 80NSSC22K0757 and NASA contract NNN06AA01C. V. Krupar acknowledges the support by NASA under grants 18-2HSWO2182-0010 and 19-HSR-192-0143. Solar Orbiter is a mission of international cooperation between ESA and NASA, operated by ESA. The Suprathermal Ion Spectrograph (SIS) is a European facility instrument funded by ESA. The SIS instrument was constructed by the Johns Hopkins Applied Physics Lab. and CAU Kiel. Post launch operation of SIS at APL is funded by NASA contract NNN06AA01C. The UAH team acknowledges the financial support of the Spanish MINCIN Project PID2019-104863RBI00/AEI/10.13039/501100011033. We thank the German Space Agency, DLR, for the build and support of STEP, EPT, and HET with grants 50OT0901, 50OT1202, 50OT1702, and 50OT2002. Solar Orbiter magnetometer data was provided by Imperial College London and supported by the UK Space Agency. The LASCO C2 CME catalog is generated and maintained at the CDAW Data Center by NASA and The Catholic University of America in cooperation with the Naval Research Laboratory. SOHO is a project of international cooperation between ESA and NASA.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
NASA18-2HSWO2182- 0010
European Space Agency (ESA)UNSPECIFIED
Ministerio de Ciencia e Innovación (MINCIN)PID2019-104863RBI00/AEI/10.13039/501100011033
Deutsches Zentrum für Luft- und Raumfahrt (DLR)50OT0901
Deutsches Zentrum für Luft- und Raumfahrt (DLR)50OT1202
Deutsches Zentrum für Luft- und Raumfahrt (DLR)50OT1702
Deutsches Zentrum für Luft- und Raumfahrt (DLR)50OT2002
United Kingdom Space Agency (UKSA)UNSPECIFIED
Record Number:CaltechAUTHORS:20230209-988069100.7
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:119173
Deposited By: Research Services Depository
Deposited On:15 Mar 2023 00:03
Last Modified:15 Mar 2023 00:03

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