A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä
Solar energetic particles injected inside and outside a magnetic cloud
Tekijät: Rodríguez-García, L.; Gómez-Herrero, R.; Dresing, N.; Balmaceda, L. A.; Palmerio, E.; Kouloumvakos, A.; Jebaraj, I. C.; Espinosa Lara, F.; Roco, M.; Palmroos, C.; Warmuth, A.; Nicolaou, G.; Mason, G. M.; Guo, J.; Laitinen, T.; Cernuda, I.; Nieves-Chinchilla, T.; Fedeli, A.; Lee, C. O.; Cohen, C. M. S.; Owen, C. J.; Ho, G. C.; Malandraki, O.; Vainio, R.; Rodríguez-Pacheco, J.
Kustantaja: EDP Sciences
Kustannuspaikka: LES ULIS CEDEX A
Julkaisuvuosi: 2025
Journal: Astronomy and Astrophysics
Tietokannassa oleva lehden nimi: Astronomy & Astrophysics
Lehden akronyymi: ASTRON ASTROPHYS
Artikkelin numero: A64
Vuosikerta: 694
Sivujen määrä: 29
ISSN: 0004-6361
eISSN: 1432-0746
DOI: https://doi.org/10.1051/0004-6361/202452158
Verkko-osoite: https://doi.org/10.1051/0004-6361/202452158
Rinnakkaistallenteen osoite: https://research.utu.fi/converis/portal/detail/Publication/491323270
Context. On 2022 January 20, the Energetic Particle Detector (EPD) on board Solar Orbiter measured a solar energetic particle (SEP) event showing unusual first arriving particles from the anti-Sun direction. Near-Earth spacecraft separated by 17 degrees in longitude to the west of Solar Orbiter measured classic anti-sunward-directed fluxes. STEREO-A and MAVEN, separated by 18 degrees to the east and by 143 degrees to the west of Solar Orbiter, respectively, also observed the event, suggesting that particles spread over at least 160 degrees in the heliosphere.
Aims. The aim of the present study is to investigate how SEPs are accelerated and transported towards Solar Orbiter and near-Earth spacecraft, as well as to examine the influence of a magnetic cloud (MC) present in the heliosphere at the time of the event onset on the propagation of energetic particles.
Methods. We analysed remote-sensing data, including flare, coronal mass ejection (CME), and radio emission to identify the parent solar source of the event. We investigated energetic particles, solar wind plasma, and magnetic field data from multiple spacecraft.
Results. Solar Orbiter was embedded in a MC erupting on 16 January from the same active region as that related to the SEP event on 20 January. The SEP event is related to a M5.5 flare and a fast CME-driven shock of similar to 1433 km s(-1), which accelerated and injected particles within and outside the MC. Taken together, the hard SEP spectra, the presence of a Type II radio burst, and the co-temporal Type III radio burst being observed from 80 MHz that appears to emanate from the Type II burst, suggest that the shock is likely the main accelerator of the particles.
Conclusions. Our detailed analysis of the SEP event strongly suggests that the energetic particles are mainly accelerated by a CME-driven shock and are injected into and outside of a previous MC present in the heliosphere at the time of the particle onset. The sunward-propagating SEPs measured by Solar Orbiter are produced by the injection of particles along the longer (western) leg of the MC still connected to the Sun at the time of the release of the particles. The determined electron propagation path length inside the MC is around 30% longer than the estimated length of the loop leg of the MC itself (based on the graduated cylindrical shell model), which is consistent with the low number of field line rotations.
Ladattava julkaisu This is an electronic reprint of the original article. |  |
Julkaisussa olevat rahoitustiedot:
LRG acknowledges support through the European Space Agency (ESA) research fellowship programme. The UAH team acknowledges the financial support by the Spanish Ministerio de Ciencia, Innovación y Universidades FEDER/MCIU/AEI Projects ESP2017-88436-R and PID2019-104863RB-I00/AEI/10.13039/501100011033 and by the European Union’s Horizon 2020 research and innovation program under grant agreement No. 101004159 (SERPENTINE). ND is grateful for support by the Research Council of Finland (SHOCKSEE, grant No. 346902). ND, CP, AW, and RV acknowledge funding by the European Union’s Horizon Europe research and innovation program under grant agreement No. 101134999 (SOLER). LAB acknowledges the support from the NASA program NNH17ZDA001N-LWS (Awards Nr. 80NSSC19K0069 and 80NSSC19K1235). EP acknowledges support from NASA’s LWS (grant no. 80NSSC19K0067) and LWS-SC (grant no. 80NSSC22K0893) programmes. AK acknowledges financial support from NASA NNN06AA01C (SO-SIS Phase-E) contract. ICJ acknowledges the support of Academy of Finland (SHOCKSEE, grant 346902). AW acknowledges support by the German Space Agency (DLR), grant numbers 50 OT 2304. JG thanks the support from National Natural Science Foundation of China (Grant Nos. 42188101, 42130204, 42474221. TL acknowledges support from the UK Science and Technology Facilities Council (STFC) through grants ST/V000934/1 and ST/Y002725/1. COL acknowledges support from the NASA LWS program (grant no. 80NSSC21K1325) and the MAVEN project funded through the NASA Mars Exploration Program. RV also acknowledges funding by the Research Council of Finland (FORESAIL, grant No. 352847). The authors acknowledge the different SOHO, STEREO instrument teams, and the STEREO and ACE science centers for providing the data used in this paper. Solar Orbiter is a space mission of international collaboration between ESA and NASA, operated by ESA. This research has used PyThea v0.7.3, an open-source and free Python package to reconstruct the 3D structure of CMEs and shock waves (GCS and ellipsoid model). ENLIL simulation results have been provided by the CCMC at NASA Goddard Space Flight Center (GSFC) through their public Runs on Request system (http://ccmc.gsfc.nasa.gov; run ID Laura_Rodriguez-Garcia_121523_SH_1). The WSA model was developed by N. Arge, currently at GSFC, and the ENLIL Model was developed by D. Odstrcil, currently at George Mason University.
