Case studies of multi-day ³He-rich solar energetic particle periods

¹ Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
e-mail: chenm@mps.mpg.de
² Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 27023, USA

Received: 6 January 2015
Accepted: 13 May 2015

Abstract

Context. Impulsive solar energetic particle events in the inner heliosphere show the long-lasting enrichment of ³He.

Aims. We study the source regions of long-lasting ³He-rich solar energetic particle (SEP) events

Methods. We located the responsible open magnetic field regions, we combined potential field source surface extrapolations with the Parker spiral, and compared the magnetic field of the identified source regions with in situ magnetic fields. The candidate open field regions are active region plages. The activity was examined by using extreme ultraviolet images from the Solar Dynamics Observatory (SDO) and STEREO together with radio observations from STEREO and WIND.

Results. Multi-day periods of ³He-rich SEP events are associated with ion production in single active region. Small flares or coronal jets are their responsible solar sources. We also find that the ³He enrichment may depend on the occurrence rate of coronal jets.