10.5281/zenodo.4564688
https://zenodo.org/records/4564688
oai:zenodo.org:4564688
Namekata, Kosuke
Kosuke
Namekata
0000-0002-1297-9485
Kyoto University
Maehara, Hiroyuki
Hiroyuki
Maehara
0000-0003-0332-0811
NAOJ
Honda, Satoshi
Satoshi
Honda
University of Hyogo
Notsu, Yuta
Yuta
Notsu
0000-0002-0412-0849
Colorado University
Okamoto, Soshi
Soshi
Okamoto
Kyoto University
Takahashi, Jun
Jun
Takahashi
University of Hyogo
Takayama, Masaki
Masaki
Takayama
University of Hyogo
Ohshima, Tomohito
Tomohito
Ohshima
University of Hyogo
Saito, Tomoki
Tomoki
Saito
University of Hyogo
Katoh, Noriyuki
Noriyuki
Katoh
University of Hyogo
Tozuka, Miyako
Miyako
Tozuka
University of Hyogo
Murata, Katsuhiro
Katsuhiro
Murata
Tokyo Institute of Technology
Ogawa, Futa
Futa
Ogawa
Tokyo Institute of Technology
Niwano, Masafumi
Masafumi
Niwano
Tokyo Institute of Technology
Adachi, Ryo
Ryo
Adachi
Tokyo Institute of Technology
Oeda, Motoki
Motoki
Oeda
Tokyo Institute of Technology
Shiraishi, Kazuki
Kazuki
Shiraishi
Tokyo Institute of Technology
Isogai, Keisuke
Keisuke
Isogai
Kyoto University
Ishii, Takako
Takako
Ishii
Kyoto University
Ichimoto, Kiyoshi
Kiyoshi
Ichimoto
Kyoto University
Nogami, Daisaku
Daisaku
Nogami
Kyoto University
Shibata, Kazunari
Kazunari
Shibata
Kyoto University
Detection of mass ejection from a superflare on a solar-type star
Zenodo
2021
Cool Stars on the main sequence
superflares on solar-type stars
stellar mass ejection
2021-02-26
Poster
10.5281/zenodo.4564687
https://zenodo.org/communities/coolstars20half
Creative Commons Attribution 4.0 International
Solar and stellar flares are caused by the sudden release of magnetic energy on the surfaces. In the case of the Sun, mass ejections often accompany solar flares and affect the Earth’s environment. Active solar-type stars (G-type main-sequence stars) sometimes show larger `superflares' (Maehara et al. 2012) that may cause more huge mass ejections than those of solar flares. The stellar mass ejections can greatly affect the exoplanet habitability and the stellar mass evolution (e.g. Airapetian et al. 2020). However, no observational indication of mass ejection has been reported especially for solar-type stars.
We conducted spectroscopic monitoring observations of the active young solar analog EK Dra (a famous zero-age main-sequence G-dwarf) by our new 3.8-m Seimei telescope, simultaneously with TESS photometry. Our time-resolved optical spectroscopic observation shows clear evidence for a stellar mass ejection associated with a superflare on the solar-type star (Namekata et al. submitted). After the superflare brightening with the radiated energy of 2.0×1033 erg observed by TESS, a blue-shifted H-alpha absorption component with a velocity of -510 km s-1 appeared. The velocity gradually decayed in 2 hours and the deceleration 0.34 km s-2 was consistent with the surface gravity on EK Dra (0.30 ± 0.05 km s-2). The temporal changes in the spectra greatly resemble that of a solar mass ejection observed by the SMART telescope at Hida observatory. Moreover, the ejected mass of 1.1×1018 g roughly corresponds to those predicted from solar flare-energy/ejected-mass relation. These discoveries imply that a huge stellar mass ejection occurs possibly in the same way as solar ones. Our high-quality dataset can be helpful for future studies to estimate its impacts on the young-planet atmosphere around young solar-type stars as well as stellar mass/angular momentum evolution.