CHARACTERIZING A DRAMATIC ΔV ∼ –9 FLARE ON AN ULTRACOOL DWARF FOUND BY THE ASAS-SN SURVEY

Journal Article · Sat Feb 01 00:00:00 EST 2014 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/781/2/L24· OSTI ID:22364017

Schmidt, Sarah J.; Stanek, K. Z.; Shappee, Benjamin J.; Kochanek, C. S.; Jencson, J.; Basu, U.; Beacom, John F. ^[1]; Prieto, Jose L. ^[2]; Morrell, Nidia ^[3]; Bardalez Gagliuffi, Daniella C. ^[4]; Szczygieł, D. M.; Pojmanski, G. ^[5]; Brimacombe, J. ^[6]; Dubberley, M.; Elphick, M.; Foale, S.; Hawkins, E.; Mullins, D.; others, and

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1. Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States)
2. Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Peyton Hall, Princeton, NJ 08544 (United States)
3. Las Campanas Observatory, Carnegie Observatories, Casilla 601, La Serena (Chile)
4. Center for Astrophysics and Space Science, University of California San Diego, La Jolla, CA 92093 (United States)
5. Warsaw University Astronomical Observatory, Al. Ujazdowskie 4, 00-478 Warsaw (Poland)
6. Coral Towers Observatory, Cairns, Queensland 4870 (Australia)

We analyze a ΔV ∼ –9 magnitude flare on the newly identified M8 dwarf SDSS J022116.84+194020.4 (hereafter SDSSJ0221) detected as part of the All-Sky Automated Survey for Supernovae. Using infrared and optical spectra, we confirm that SDSSJ0221 is a relatively nearby (d ∼ 76 pc) M8 dwarf with strong quiescent Hα emission. Based on kinematics and the absence of features consistent with low-gravity (young) ultracool dwarfs, we place a lower limit of 200 Myr on the age of SDSSJ0221. When modeled with a simple, classical flare light curve, this flare is consistent with a total U-band flare energy E{sub U} ∼ 10{sup 34} erg, confirming that the most dramatic flares are not limited to warmer, more massive stars. Scaled to include a rough estimate of the emission line contribution to the V band, we estimate a blackbody filling factor of ∼10%-30% during the flare peak and ∼0.5%-1.6% during the flare decay phase. These filling factors correspond to flare areas that are an order of magnitude larger than those measured for most mid-M dwarf flares.

• OSTI ID: 22364017
• Journal Information: Astrophysical Journal Letters, Vol. 781, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
DIAGRAMS
DWARF STARS
EMISSION
EMISSION SPECTRA
GRAVITATION
HYDROGEN
MASS
STELLAR FLARES
SUPERNOVAE
VISIBLE RADIATION