SIMBAD references

2017ApJ...845...33G - Astrophys. J., 845, 33-33 (2017/August-2)

K2 ultracool dwarfs survey. II. The white light flare rate of young brown dwarfs.

GIZIS J.E., PAUDEL R.R., MULLAN D., SCHMIDT S.J., BURGASSER A.J. and WILLIAMS P.K.G.

Abstract (from CDS):

We use Kepler K2 Campaign 4 short-cadence (one-minute) photometry to measure white light flares in the young, moving group brown dwarfs 2MASS J03350208+2342356 (2M0335+23) and 2MASS J03552337+1133437 (2M0355+11), and report on long-cadence (thirty-minute) photometry of a superflare in the Pleiades M8 brown dwarf CFHT-PL-17. The rotation period (5.24 hr) and projected rotational velocity (45 km s–1) confirm 2M0335+23 is inflated (R 0.20 R) as predicted for a 0.06 M, 24 Myr old brown dwarf βPic moving group member. We detect 22 white light flares on 2M0335+23. The flare frequency distribution follows a power-law distribution with slope -α=-1.8±0.2 over the range 1031 to 1033 erg. This slope is similar to that observed in the Sun and warmer flare stars, and is consistent with lower-energy flares in previous work on M6-M8 very-low-mass stars; taking the two data sets together, the flare frequency distribution for ultracool dwarfs is a power law over 4.3 orders of magnitude. The superflare (2.6×1034 erg) on CFHT-PL-17 shows higher-energy flares are possible. We detect no flares down to a limit of 2×1030 erg in the nearby L5γ AB Dor moving group brown dwarf 2M0355+11, consistent with the view that fast magnetic reconnection is suppressed in cool atmospheres. We discuss two multi-peaked flares observed in 2M0335+23, and argue that these complex flares can be understood as sympathetic flares, in which fast-mode magnetohydrodynamic waves similar to extreme-ultraviolet waves in the Sun trigger magnetic reconnection in different active regions.

Abstract Copyright: © 2017. The American Astronomical Society. All rights reserved.

Journal keyword(s): brown dwarfs - stars: activity - stars: flare - stars: individual: (2MASS J03350208+2342356, 2MASS J03552337+1133437) - starspots - starspots

Simbad objects: 20

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