2017ApJ...838...22G -
Astrophys. J., 838, 22-22 (2017/March-3)
K2 ultracool dwarfs survey. I. Photometry of an L dwarf superflare.
GIZIS J.E., PAUDEL R.R., SCHMIDT S.J., WILLIAMS P.K.G. and BURGASSER A.J.
Abstract (from CDS):
We report on K2 Campaign 8 measurements of a huge white light flare on the L1 dwarf SDSSp J005406.55-003101.8 (EPIC 220186653). The source is a typical L1 dwarf at a distance of ∼50 pc, probably an old hydrogen-burning star rather than a young brown dwarf. In the long (30-minute) cadence photometry, the flare peak is 21 times the flux of the stellar photosphere in the broad optical Kepler filter, which we estimate corresponds to ΔV ≃ -7.1. The total equivalent duration of the flare is 15.4 hr. We estimate that the total bolometric energy of the flare was 4 x 1033 erg, more powerful than the previously reported Kepler white light flares for the L1 dwarf WISEP J190648.47+401106.8, but weaker than the ΔV = -11 L0 dwarf superflare ASASSN-16ae. The initial (impulsive) cooling phase is too rapid to resolve with our 30-minute cadence data, but after 1 hour the gradual cooling phase has an exponential time constant of 1.8 hr. We use template fitting to estimate that the full time-width-at-half-amplitude of the light curve is <10 minutes and that the true flare maximum reached ∼70 times the stellar photosphere, or ΔV ≃ -8. This flare is comparable to the most powerful Kepler flares observed on the active M4 dwarf GJ 1243.
Abstract Copyright:
© 2017. The American Astronomical Society. All rights reserved.
Journal keyword(s):
stars: activity - stars: chromospheres - stars: flare - stars: individual: SDSSp J005406.55-003101.8 - stars: low-mass - stars: low-mass
Simbad objects:
4
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