In:
The Astrophysical Journal Letters, American Astronomical Society, Vol. 934, No. 1 ( 2022-07-01), p. L15-
Abstract:
Solar energetic particles (SEPs) associated with flares and/or coronal mass ejection (CME)-driven shocks can impose acute radiation hazards on space explorations. To measure energetic particles in near-Mars space, the Mars Energetic Particle Analyzer (MEPA) instrument on board China's Tianwen-1 (TW-1) mission was designed. Here, we report the first MEPA measurements of the widespread SEP event occurring on 2020 November 29 when TW-1 was in transit to Mars. This event occurred when TW-1 and Earth were magnetically well connected, known as the Hohmann–Parker effect, thus offering us a rare opportunity to understand the underlying particle acceleration and transport process. Measurements from TW-1 and near-Earth spacecraft show similar double-power-law spectra and a radial dependence of the SEP peak intensities. Moreover, the decay phases of the time–intensity profiles at different locations clearly show the reservoir effect. We conclude that the double-power-law spectrum is likely generated at the acceleration site and that a small but finite cross-field diffusion is crucial to understanding the formation of the SEP reservoir phenomenon. These results provide insight into particle acceleration and transport associated with CME-driven shocks, which may contribute to the improvement of relevant physical models.
Type of Medium:
Online Resource
ISSN:
2041-8205
,
2041-8213
DOI:
10.3847/2041-8213/ac80f5
Language:
Unknown
Publisher:
American Astronomical Society
Publication Date:
2022
detail.hit.zdb_id:
2207648-7
detail.hit.zdb_id:
2006858-X
