Letter to the Editor

Prominence eruption observed in He II 304 Å up to >6 R_⊙ by EUI/FSI aboard Solar Orbiter^⋆

¹ Solar–Terrestrial Centre of Excellence – SIDC, Royal Observatory of Belgium, 1180 Brussels, Belgium
e-mail: marilena.mierla@oma.be
² Institute of Geodynamics of the Romanian Academy, 020032 Bucharest-37, Romania
³ Skobeltsyn Institute of Nuclear Physics, Moscow State University, 119992 Moscow, Russia
⁴ Université Paris-Saclay, CNRS, Institut d’Astrophysique Spatiale, 91405 Orsay, France
⁵ Astronomical Institute of the Czech Academy of Sciences, 251 65 Ondřejov, Czech Republic
⁶ University of Wrocław, Center of Scientific Excellence – Solar and Stellar Activity, Kopernika 11, 51-622 Wrocław, Poland
⁷ Southwest Research Institute, Boulder, CO 80302, USA
⁸ Predictive Science Inc., San Diego, CA 92121, USA
⁹ Faculty of Education, University of Ljubljana, 1000 Ljubljana, Slovenia
¹⁰ Faculty of Mathematics and Physics, University of Ljubljana, 1000 Ljubljana, Slovenia
¹¹ Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK
¹² ESTEC, European Space Agency, 2201 AZ Noordwijk, The Netherlands
¹³ INAF – Osservatorio Astronomico di Capodimonte, 80131 Naples, Italy
¹⁴ Dipartimento di Fisica e Astronomia, Università di Firenze, 50019 Sesto Fiorentino FI, Italy

Received: 13 May 2022
Accepted: 20 May 2022

Abstract

Aims. We report observations of a unique, large prominence eruption that was observed in the He II 304 Å passband of the Extreme Ultraviolet Imager/Full Sun Imager telescope aboard Solar Orbiter on 15–16 February 2022.

Methods. Observations from several vantage points – Solar Orbiter, the Solar-Terrestrial Relations Observatory, the Solar and Heliospheric Observatory, and Earth-orbiting satellites – were used to measure the kinematics of the erupting prominence and the associated coronal mass ejection. Three-dimensional reconstruction was used to calculate the deprojected positions and speeds of different parts of the prominence. Observations in several passbands allowed us to analyse the radiative properties of the erupting prominence.

Results. The leading parts of the erupting prominence and the leading edge of the corresponding coronal mass ejection propagate at speeds of around 1700 km s⁻¹ and 2200 km s⁻¹, respectively, while the trailing parts of the prominence are significantly slower (around 500 km s⁻¹). Parts of the prominence are tracked up to heights of over 6 R_⊙. The He II emission is probably produced via collisional excitation rather than scattering. Surprisingly, the brightness of a trailing feature increases with height.

Conclusions. The reported prominence is the first observed in He II 304 Å emission at such a great height (above 6 R_⊙).