Astrophys. J., 876, 115-115 (2019/May-2)
The largest M dwarf flares from ASAS-SN.
SCHMIDT S.J., SHAPPEE B.J., VAN SADERS J.L., STANEK K.Z., BROWN J.S., KOCHANEK C.S., DONG S., DROUT M.R., FRANK S., HOLOIEN T.W.-S., JOHNSON S., MADORE B.F., PRIETO J.L., SEIBERT M., SEIDEL M.K. and SIMONIAN G.V.A.
Abstract (from CDS):
The All-sky Automated Survey for Supernovae (ASAS-SN) is the only project in existence to scan the entire sky in optical light approximately every day, reaching a depth of g ∼ 18 mag. Over the course of its first 4 yr of transient alerts (2013-2016), ASAS-SN observed 53 events classified as likely M dwarf flares. We present follow-up photometry and spectroscopy of all 53 candidates, confirming flare events on 47 M dwarfs, one K dwarf, and one L dwarf. The remaining four objects include a previously identified T Tauri star, a young star with outbursts, and two objects too faint to confirm. A detailed examination of the 49 flare star light curves revealed an additional six flares on five stars, resulting in a total of 55 flares on 49 objects ranging in V-band contrast from ΔV = -1 to -10.2 mag. Using an empirical flare model to estimate the unobserved portions of the flare light curve, we obtain lower limits on the V-band energy emitted during each flare, spanning log(EV/erg)=32-35, which are among the most energetic flares detected on M dwarfs. The ASAS-SN M dwarf flare stars show a higher fraction of Hα emission, as well as stronger Hα emission, compared to M dwarfs selected without reference to activity, consistent with belonging to a population of more magnetically active stars. We also examined the distribution of tangential velocities, finding that the ASAS-SN flaring M dwarfs are likely to be members of the thin disk and are neither particularly young nor old.
© 2019. The American Astronomical Society. All rights reserved.
stars: chromospheres - stars: late-type - stars: low-mass
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<Available at CDS (J/ApJ/876/115): table1.dat table2.dat table3.dat table5.dat table6.dat>
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