Speaker
Description
First Name: Samuel
Last Name: Hart
Affiliation: Southwest Research Institute
All Authors: George C. Ho, Michael Terres, Gabriel C. Muro, Maher A. Dayeh, Radoslav Bučík, Robert C. Allen, Glenn M. Mason, Christina M. S. Cohen, Prachi S. Pathare
Abstract: We investigate two 3He-rich SEP events originating from AR 13615 between April 1 – 4, 2024 observed by SO/SIS and PSP/LET at a radial distance of 0.3 AU and 0.16 AU. After performing Compton-Getting corrections, we find the two SEP events exhibit negative anisotropies, indicating these SEPs are streaming toward the Sun. Because all 3He-rich SEPs are accelerated at the Sun, large magnetic structures in the heliosphere likely caused the SEPs to reverse direction, evidenced by the anomalously large path lengths greater than three times expected values along the nominal Parker spiral field. We identify a slow ICME originating from AR 13615 on March 30, 2024 at 21:04 UT, and we propagate it through the heliosphere based on its near-Sun speed and width to obtain an estimate of its size and location at the time of the first 3He-rich SEP event. Assuming the SEPs travel around the ICME front, we infer a total path length of 0.76 – 0.95 AU when the SEPs first arrive at SO and a total path length of 0.94 – 1.1 AU at PSP, in reasonable agreement with the measured path lengths. This work provides results from the first multi-spacecraft observation of sunward streaming 3He-rich SEP events, and we discuss the implications on 3He-rich seed material for subsequent gradual SEP events as well as the previously-observed widespread 3He-rich SEP events.