[P-EM14] Frontiers in solar physics

[PEM14-06] High-velocity and massive prominence eruption leading to a CME associated with a superflare on an active star

*Shun Inoue¹, Hiroyuki Maehara², Yuta Notsu³, Kosuke Namekata², Satoshi Honda⁴, Keiichi Namizaki¹, Daisaku Nogami¹, Kazunari Shibata⁵ (1.Kyoto University, 2.NAOJ, 3.University of Colorado Boulder, 4.University of Hyogo, 5.Doshisha University)

Keywords:stellar flares, superflares, stellar mass ejection

Stellar CMEs have recently received much attention for their impacts on exoplanets and stellar evolution. Detecting prominence eruptions, the initial phase of CMEs, as the blue-shifted excess component of Balmer lines is a technique to capture stellar CMEs. However, most of stellar prominence eruptions identified thus far have been slow and less than the surface escape velocity. Therefore, whether these eruptions were developing into stellar CMEs remained unknown. RS CVn-type stars are magnetically active binary systems composed of K-type and G-type stars. They are good targets for observing large superflares and prominence eruptions. In this study, we conducted simultaneous optical photometric observations with Transiting Exoplanet Survey Satellite and optical spectroscopic observations with the 3.8m Seimei Telescope for the RS CVn-type star V1355 Orionis (Inoue et al. 2023, ApJ). We detected a superflare releasing 7.0 × 10³⁵ erg. In the early stage of this flare, a blue-shifted excess component of Hα extending its velocity up to 760 − 1690 km s^-1 was observed and thought to originate from prominence eruptions. The velocity greatly exceeds the escape velocity of this star (i.e., ∼ 350 km s^-1), which provides important evidence that stellar prominence eruptions can develop into CMEs. Furthermore, we found that the prominence is very massive (9.5 × 10¹⁸ g < M < 1.4 × 10²¹ g). The mass of this prominence is the largest ever observed. We confirmed that the scaling laws between the mass and kinetic energy of prominence and the energy of flares (Takahashi et al. 2016, ApJL; Namekata et al. 2022a, Nature Astronomy) hold for this event. This suggests that this very large prominence eruption and solar prominence eruptions may have a common physical mechanism. The high-velocity and massive prominence eruption detected in this study is a good sample to know how large an eruption the physical mechanism of solar prominence eruptions can cause at most.