Letter to the Editor

The long period of ³He-rich solar energetic particles measured by Solar Orbiter 2020 November 17–23

¹ Southwest Research Institute, San Antonio, TX 78238, USA
e-mail: radoslav.bucik@swri.org
² Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723, USA
³ Universidad de Alcalá, Space Research Group, 28805 Alcalá de Henares, Spain
⁴ Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD, USA
⁵ George Mason University, Fairfax, VA, USA
⁶ Lockheed Martin Advanced Technology Center, Palo Alto, CA 94304, USA
⁷ Goddard Planetary Heliophysics Institute, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
⁸ Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
⁹ Now at Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
¹⁰ Leibniz-Institut für Astrophysik Potsdam, 14482 Potsdam, Germany
¹¹ Now at Paradox Cat GmbH, 80333 München, Germany
¹² Now at German Aerospace Center (DLR), Dept. of Extrasolar Planets and Atmospheres, Berlin, Germany
¹³ Now at Univ. Colorado/LASP, Boulder, CO, USA
¹⁴ LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, Paris, France
¹⁵ Radboud Radio Lab, Department of Astrophysics, Radboud University Nijmegen, Nijmegen, The Netherlands

Received: 6 April 2021
Accepted: 19 May 2021

Abstract

We report observations of a relatively long period of ³He-rich solar energetic particles (SEPs) measured by Solar Orbiter. The period consists of several well-resolved ion injections. The high-resolution STEREO-A imaging observations reveal that the injections coincide with extreme ultraviolet jets and brightenings near the east limb, not far from the nominal magnetic connection of Solar Orbiter. The jets originated in two adjacent, large, and complex active regions, as observed by the Solar Dynamics Observatory when the regions rotated into the Earth’s view. It appears that the sustained ion injections were related to the complex configuration of the sunspot group and the long period of ³He-rich SEPs to the longitudinal extent covered by the group during the analyzed time period.