Coronal mass ejection followed by a prominence eruption and a plasma blob as observed by Solar Orbiter^⋆

¹ INAF – Osservatorio Astrofisico di Torino, Turin, Italy
e-mail: alessandro.bemporad@inaf.it
² INAF – Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, 80131 Naples, Italy
³ INAF – Osservatorio Astrofisico di Catania, Catania, Italy
⁴ Solar-Terrestrial Centre of Excellence – SIDC, Royal Observatory of Belgium, Brussels, Belgium
⁵ Institute of Geodynamics of the Romanian Academy, Bucharest, Romania
⁶ Skobeltsyn Institute of Nuclear Physics, Moscow State University, 119992 Moscow, Russia
⁷ KU Leuven, Leuven, Belgium
⁸ Naval Research Laboratory, Washington, DC, USA
⁹ Astronomical Institute, Slovak Academy of Sciences, Tatranská Lomnica, Slovakia
¹⁰ Faculty of Education, University of Ljubljana, Ljubljana, Slovenia
¹¹ Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana, Slovenia
¹² Astronomical Institute of the Czech Academy of Sciences, Ondřejov, Czech Republic
¹³ CNR – Istituto di Fotonica e Nanotecnologie, Padua, Italy
¹⁴ INAF – Osservatorio Astronomico di Trieste, Trieste, Italy
¹⁵ Università di Padova – Dip. Fisica e Astronomia “Galileo Galilei”, Padua, Italy
¹⁶ Università di Firenze – Dip. Fisica e Astronomia, Florence, Italy
¹⁷ INAF – Associate Scientist, Italy
¹⁸ Agenzia Spaziale Italiana, Roma, Italy
¹⁹ Max-Planck-Institut für Sonnensystemforschung, Göttingen, Germany

Received: 20 January 2022
Accepted: 7 February 2022

Abstract

Context. On 2021 February 12, two subsequent eruptions occurred above the western limb of the Sun, as seen along the Sun-Earth line. The first event was a typical slow coronal mass ejection (CME), followed ∼7 h later by a smaller and collimated prominence eruption, originating south of the CME, followed by a plasma blob. These events were observed not only by the SOHO and STEREO-A missions, but also by the suite of remote-sensing instruments on board Solar Orbiter.

Aims. We show how data acquired by the Full Sun Imager (FSI), the Metis coronagraph, and the Heliospheric Imager (HI) from the Solar Orbiter perspective can be combined to study the eruptions and different source regions. Moreover, we show how Metis data can be analyzed to provide new information about solar eruptions.

Methods. Different 3D reconstruction methods were applied to the data acquired by different spacecraft, including remote-sensing instruments on board Solar Orbiter. Images acquired by the two Metis channels in the visible light (VL) and H I Ly-α line (UV) were combined to derive physical information about the expanding plasma. The polarization ratio technique was also applied for the first time to Metis images acquired in the VL channel.

Results. The two eruptions were followed in 3D from their source region to their expansion in the intermediate corona. By combining VL and UV Metis data, the formation of a post-CME current sheet (CS) was followed for the first time in the intermediate corona. The plasma temperature gradient across a post-CME blob propagating along the CS was also measured for the first time. Application of the polarization ratio technique to Metis data shows that by combining four different polarization measurements, the errors are reduced by ∼5 − 7%. This constrains the 3D plasma distribution better.