Letter to the Editor

Solar origins of a strong stealth CME detected by Solar Orbiter

¹ Mullard Space Science Laboratory, UCL, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK
e-mail: ucasjro@ucl.ac.uk
² Department of Physics, Imperial College London, London, UK
³ Space Research Institute, Austrian Academy of Sciences, Graz, Austria
⁴ Institute of Physics, University of Graz, Graz, Austria
⁵ Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, Kiel, Germany

Received: 21 February 2021
Accepted: 30 March 2021

Abstract

Aims. We aim to locate the origin of a stealth coronal mass ejection (CME) detected in situ by the MAG instrument on board Solar Orbiter and make connections between the CME observed at the Sun and the interplanetary CME (ICME) measured in situ.

Methods. Remote sensing data were analysed using advanced image processing techniques to identify the source region of the stealth CME, and the global magnetic field at the time of the eruption was examined using potential field source surface models. The observations of the stealth CME at the Sun were compared with the magnetic field measured by the Solar Orbiter spacecraft, and plasma properties were measured by the Wind spacecraft.

Results. The source of the CME is found to be a quiet Sun cavity in the northern hemisphere. We find that the stealth CME has a strong magnetic field in situ, despite originating from a quiet Sun region with an extremely weak magnetic field.

Conclusions. The interaction of the ICME with its surrounding environment is the likely cause of a higher magnetic field strength measured in situ. Stealth CMEs require multi-wavelength and multi-viewpoint observations in order to confidently locate the source region; however, their elusive signatures still pose many problems for space weather forecasting. The findings have implications for Solar Orbiter observing sequences with instruments such as EUI that are designed to capture stealth CMEs.