The Mouse that Roared: A Superflare from the dMe Flare Star EV Lac detected by Swift and Konus-Wind

Understand

We report on a large stellar flare from the nearby dMe flare star EV Lac observed by the Swift and Konus-Wind satellites and the Liverpool Telescope.

• It is the first large stellar flare from a dMe flare star to result in a Swift trigger based on its hard X-ray intensity.
• Its peak f_X from 0.3--100 keV of 5.3x10^-8 erg/cm2/s is nearly 7000 times larger than the star's quiescent coronal flux, and the change in magnitude in the white filter is >4.7.
• This flare also caused a transient increase in EV Lac's bolometric luminosity (L_bol) during the early stages of the flare, with a peak estimated L_X/L_bol ~3.1.