Probable detection of an eruptive filament from a superflare on a solar-type star

TL;DR

This study presents evidence of a filament eruption and potential CME from a superflare on a young solar-type star, revealing similarities to solar eruptions and implications for stellar and planetary environments.

Contribution

First direct spectroscopic evidence of a stellar filament eruption associated with a superflare on a solar-type star, expanding understanding of stellar activity and CME occurrence.

Findings

Detected a large filament eruption with high velocity (-510 km/s)

Erupted filament mass is ten times larger than solar CMEs

Spectral changes resemble solar filament eruptions

Abstract

Solar flares are often accompanied by filament/prominence eruptions ($\sim10^{4}$ K and $\sim 10^{10-11}$ cm$^{-3}$), sometimes leading to coronal mass ejections (CMEs) that directly affect the Earth's environment. `Superflares' are found on some active solar-type (G-type main-sequence) stars, but the association of filament eruptions/CMEs has not been established. Here we show that our optical spectroscopic observation of the young solar-type star EK Draconis reveals the evidence for a stellar filament eruption associated with a superflare. This superflare emitted a radiated energy of $2.0\times10^{33}$ erg, and blue-shifted hydrogen absorption component with a large velocity of $-510$ km s$^{-1}$ was observed shortly after. The temporal changes in the spectra greatly resemble those of solar filament eruptions. Comparing this eruption with solar filament eruptions in terms of the length scale and velocity strongly suggests that a stellar CME occurred. The erupted filament mass of $1.1\times10^{18}$ g is 10 times larger than those of the largest solar CMEs. The massive filament eruption and an associated CME provide the opportunity to evaluate how they affect the environment of young exoplanets/young Earth and stellar mass/angular-momentum evolution.