Long-lived energetic particle source regions on the Sun

TL;DR

This paper investigates long-lived regions on the Sun that produce recurrent impulsive solar energetic particle events, focusing on the role of magnetic flux emergence in sustaining these sources over extended periods.

Contribution

It provides new insights into the evolution of source regions for recurrent 3He-rich SEPs, highlighting the significance of magnetic flux emergence for long-term particle emission.

Findings

Recurrent 3He-rich SEPs occur after magnetic flux emergence.

Long-lived source regions can produce repeated SEP events over extended periods.

The study utilizes data from the STEREO spacecraft to analyze source region evolution.

Abstract

Discovered more than 40 years ago, impulsive solar energetic particle (SEP) events are still poorly understood. The enormous abundance enhancement of the rare 3He isotope is the most striking feature of these events, though large enhancements in heavy and ultra-heavy nuclei are also observed. Recurrent 3He-rich SEPs in impulsive events have only been observed for limited time periods, up to a few days which is typically the time that a single stationary spacecraft is magnetically connected to the source active regions on the Sun. With the launch of the two STEREO spacecraft we now have the possibility of longer connection time to solar active regions. We examined the evolution of source regions showing repeated 3He-rich SEP emissions for relatively long time periods. We found that recurrent 3He-rich SEPs in these long-lived sources occur after the emergence of magnetic flux.