Observations of a Solar Energetic Particle Event From Inside and Outside the Coma of Comet 67P

Wellbrock, A., Jones, G. H., Dresing, N., Coates, A. J., Simon Wedlund, C., Nilsson, H., Sanchez‐Cano, B., Palmerio, E., Turc, L., Myllys, M., Henri, P., Goetz, Charlotte, Witasse, O., Nordheim, T. A. and Mandt, K. (2022) Observations of a Solar Energetic Particle Event From Inside and Outside the Coma of Comet 67P. Journal of Geophysical Research: Space Physics, 127 (12). e2022JA030398. ISSN 2169-9380

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Official URL: https://doi.org/10.1029/2022JA030398


We analyze observations of a solar energetic particle (SEP) event at Rosetta's target comet 67P/Churyumov-Gerasimenko during 6–10 March 2015. The comet was 2.15 AU from the Sun, with the Rosetta spacecraft approximately 70 km from the nucleus placing it deep inside the comet's coma and allowing us to study its response. The Eastern flank of an interplanetary coronal mass ejection (ICME) also encountered Rosetta on 6 and 7 March. Rosetta Plasma Consortium data indicate increases in ionization rates, and cometary water group pickup ions exceeding 1 keV. Increased charge exchange reactions between solar wind ions and cometary neutrals also indicate increased upstream neutral populations consistent with enhanced SEP induced surface activity. In addition, the most intense parts of the event coincide with observations interpreted as an infant cometary bow shock, indicating that the SEPs may have enhanced the formation and/or intensified the observations. These solar transient events may also have pushed the cometopause closer to the nucleus. We track and discuss characteristics of the SEP event using remote observations by SOHO, WIND, and GOES at the Sun, in situ measurements at Solar Terrestrial Relations Observatory Ahead, Mars and Rosetta, and ENLIL modeling. Based on its relatively prolonged duration, gradual and anisotropic nature, and broad angular spread in the heliosphere, we determine the main particle acceleration source to be a distant ICME which emerged from the Sun on 6 March 2015 and was detected locally in the Martian ionosphere but was never encountered by 67P directly. The ICME's shock produced SEPs for several days which traveled to the in situ observation sites via magnetic field line connections.

Item Type: Article
Additional Information: Funding Information: The authors thank the Space Weather Forecast Office for the use of the ENLIL model ( http://helioweather.net/ ). The SOHO LASCO CME catalog (Gopalswamy et al., 2009 ) consulted here was accessed https://cdaw.gsfc.nasa.gov/CME_list/UNIVERSAL/2015_03/univ2015_03.html and 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. The authors acknowledge the use of level 5 SREM data from the PDS: H. Evans, P. Nieminen, I. Sandberg, I. Daglis, and M. Taylor, ROSETTA‐ORBITER X SREM 5 RVM1 V1.0, RO‐X‐SREM‐5‐RVM1‐V1.0, ESA Planetary Science Archive (PSA) and NASA Planetary Data System (PDS), 2020. The authors thank M. Rubin and A. Klassen for useful discussions. AW, GHJ and AJC acknowledge support from the STFC consolidated Grants to UCL‐MSSL ST/N000722/1, ST/S000240/1, and ST/W001004/1. ND is grateful for support by the Turku Collegium for Science, Medicine and Technology of the University of Turku, Finland. CSW thanks the Austrian Science Fund (FWF) Project P32035‐N36. BS‐C is funded through UK‐STFC Ernest Rutherford Fellowship ST/V004115/1 and STFC Grant ST/W00089X/1. EP acknowledges NASA O2R Grant 80NSSC20K0285. The work of LT is supported by the Academy of Finland (Grant 322544). Work at LPC2E/CNRS was supported by CNES and by ANR under financial Agreement ANR‐15‐CE31‐0009‐01. CG acknowledges support from the ESA as an ESA Research Fellow.
Subjects: F500 Astronomy
Department: Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User: John Coen
Date Deposited: 22 Feb 2023 15:38
Last Modified: 22 Feb 2023 15:45
URI: https://nrl.northumbria.ac.uk/id/eprint/51478

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