PoS - Proceedings of Science
Volume 358 - 36th International Cosmic Ray Conference (ICRC2019) - SH - Solar & Heliospheric
Occurrence of $^3$He-rich Solar Energetic Particles near Earth and Closer to the Sun
M.E. Wiedenbeck*, G.M. Mason, C.M.S. Cohen, D.J. McComas, E.R. Christian and  for the Advanced Composition Explorer SIS and ULEIS Teams and the Parker SolarProbe ISIS Team
Full text: pdf
Pre-published on: August 29, 2019
Published on: July 02, 2021
$^3$He-rich solar energetic particle (SEP) events, which result from the acceleration of energetic particles in association with reconnection events on the Sun, are identified on the basis of 3He/4He enhancements of at least several orders of magnitude over the solar coronal value of ~0.04%. The ULEIS and SIS instruments on the Advanced Composition Explorer (ACE) have been measuring the occurrence of SEP $^3$He in the interplanetary medium near Earth over nearly two full solar cycles. The $^3$He isotope has been observed nearly 90% of the time at solar maximum, but no more than a few % of the time at solar minimum. NASA’s Parker Solar Probe (PSP) spacecraft was launched in August 2018 on a mission designed to include 24 close flybys of the Sun over seven years. PSP’s scientific objectives include the study of the acceleration and transport of $^3$He-rich SEPs, and the spacecraft carries a two-instrument suite, ISOIS, that has the capability to perform these studies. The first two orbits of PSP occurred under extremely quiet solar-minimum conditions, which will provide an opportunity to search for small $^3$He-rich SEP events in the previously unexplored region <0.2 AU from the Sun under conditions with extremely low energetic-particle backgrounds. We present an update of the long-term record of SEP $^3$He occurrence near 1 AU and, with this context, discuss some advances that can be expected from PSP.
DOI: https://doi.org/10.22323/1.358.1171
How to cite

Metadata are provided both in "article" format (very similar to INSPIRE) as this helps creating very compact bibliographies which can be beneficial to authors and readers, and in "proceeding" format which is more detailed and complete.

Open Access
Creative Commons LicenseCopyright owned by the author(s) under the term of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.