Letter to the Editor

³He-rich solar energetic particle events observed on the first perihelion pass of Solar Orbiter

¹ Johns Hopkins Univ. Applied Physics Laboratory, Laurel, MD, USA
e-mail: glenn.mason@jhuapl.edu
² Space Research Group, Universidad de Alcalá, Alcalá de Henares, Spain
³ Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
⁴ Southwest Research Institute, San Antonio, TX, USA
⁵ NASA Goddard Space Flight Center, Greenbelt, MD, USA
⁶ German Aerospace Center (DLR), Berlin, Germany
⁷ Univ. Colorado/LASP, Boulder, CO, USA

Received: 23 October 2020
Accepted: 14 November 2020

Abstract

We report observations of five impulsive solar energetic particle (SEP) events observed inside 1 au during the first perihelion pass of the Solar Orbiter mission, which was launched in February 2020. These small events were all reasonably associated with active regions observed from Earth but which had rotated out of view by the time of the Solar Orbiter observations. Even though most of the events were small, their spectral forms, ³He content, and association with type III bursts convincingly identifies them as ³He-rich impulsive SEP events with properties similar to those previously observed at 1 au. Three of the events showed fast ion rise times, and two of them had long-lasting anisotropies consistent with the Compton-Getting effect.