2MASS 1315-2649: A High Proper Motion L Dwarf with Strong H-alpha Emission

Abstract

In Hall (2002) I reported that 2MASSI J1315309-264951 is an L dwarf with strong H-alpha emission. Two spectroscopic epochs appeared to show that the H-alpha was variable, decreasing from 121 Angstroms to 25 Angstroms EW, which I interpreted as a flare during the first observation. Gizis (2002) independently discovered this object, and his intermediate spectroscopic epoch shows H-alpha with 97 Angstroms EW. A new fourth epoch of spectroscopy again shows a very large H-alpha EW (124 Angstroms), confirming this object to be a persistent, strong H-alpha emitter. Whether the H-alpha is steady (like 2MASS 1237+6526) or from continuous strong flaring (like PC0025+0447) remains unclear. Imaging confirms that 2MASS 1315-2649 has a high proper motion (0.71"/year), corresponding to a transverse velocity of ~76 km/s at its distance of ~23 pc. Thus 2MASS 1315-2649 is consistent with being >~2 Gyr old and therefore relatively massive. If that is so, the correlation of H-alph activity with mass found by Gizis et al. (2000) would seem to support the continuous strong flaring scenario, though it does not rule out a brown dwarf binary accretion scenario.

arXiv comment2 pages, ApJL accepted

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