Multi-wavelength Campaign Observations of a Young Solar-type Star, EK Draconis I. Discovery of Prominence Eruptions Associated with Superflares - Astrophysique Stellaire
Article Dans Une Revue The Astrophysical Journal Année : 2023

Multi-wavelength Campaign Observations of a Young Solar-type Star, EK Draconis I. Discovery of Prominence Eruptions Associated with Superflares

Kosuke Namekata
Vladimir Airapetian
Hiroyuki Maehara
Kai Ikuta
Shun Inoue
Yuta Notsu
Rishi Paudel
Zaven Arzoumanian
  • Fonction : Auteur
Antoaneta Avramova-Boncheva
Keith Gendreau
Sandra Jeffers
Stephen Marsden
Julien Morin
Aline Vidotto
Kazunari Shibata

Résumé

Young solar-type stars frequently produce superflares, serving as a unique window into the young Sun-Earth environments. Large solar flares are closely linked to coronal mass ejections (CMEs) associated with filament/prominence eruptions, but its observational evidence for stellar superflares remains scarce. Here, we present a 12-day multi-wavelength campaign observation of young solar-type star EK Draconis (G1.5V, 50-120 Myr age) utilizing TESS, NICER, and Seimei telescope. The star has previously exhibited blueshifted H$\alpha$ absorptions as evidence for a filament eruption associated with a superflare. Our simultaneous optical and X-ray observations identified three superflares of $1.5\times10^{33}$ -- $1.2\times10^{34}$ erg. We report the first discovery of two prominence eruptions on a solar-type star, observed as blueshifted H$\alpha$ emissions at speed of 690 and 430 km s$^{-1}$ and masses of $1.1\times10^{19}$ and $3.2\times10^{17}$ g, respectively. The faster, massive event shows a candidate of post-flare X-ray dimming with the amplitude of up to $\sim$10 \%. Several observational aspects consistently point to the occurrence of a fast CME associated with this event. The comparative analysis of the estimated length scales of flare loops, prominences, possible dimming region, and starspots provides the overall picture of the eruptive phenomena. Furthermore, the energy partition of the observed superflares in the optical and X-ray bands is consistent with flares from the Sun, M-dwarfs, and close binaries, yielding the unified empirical relations. These discoveries provide profound implications of impact of these eruptive events on the early Venus, Earth and Mars and young exoplanets.
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hal-04286428 , version 1 (04-04-2024)

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Kosuke Namekata, Vladimir Airapetian, Pascal Petit, Hiroyuki Maehara, Kai Ikuta, et al.. Multi-wavelength Campaign Observations of a Young Solar-type Star, EK Draconis I. Discovery of Prominence Eruptions Associated with Superflares. The Astrophysical Journal, 2023, 961 (1), pp.23. ⟨10.3847/1538-4357/ad0b7c⟩. ⟨hal-04286428⟩
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