On the Nature of the Unique H$\alpha$-Emitting T Dwarf 2MASS J12373919+6526148

Abstract

We explore and discount the hypothesis that the strong, continual H$\alpha$-emitting T dwarf 2MASS J12373919+6526148 can be explained as a young, low gravity, very low mass brown dwarf. The source is already known to have a marginally-fainter absolute magnitude than similar T dwarfs with trigonometric parallax measurements, and has a tangential velocity consistent with old disk kinematics. Applying the technique of Burgasser, Burrows & Kirkpatrick on new near infrared spectroscopy for this source, estimates of its {\teff}, $\log g$ and metallicity ([M/H]) are obtained. 2M 1237+6526 has a {\teff} $\approx$ 800-850 K. If [M/H] is solar, $\log g$ is as high as $\sim$5.5 (cgs) and this source is older than 10 Gyr. We find a more plausible scenario to be a modestly subsolar metallicity ([M/H] = -0.2) and moderate $\log g$ $\sim$ 5.0, implying an age older than 2 Gyr and a mass greater than 0.035 M$_{\sun}$. The alternative explanation of the unique emission of this source, involving an interacting, close, double degenerate system, should be investigated further. Indeed, there is some evidence of a {\teff} $<$ 500 K companion to 2M 1237+6526 on the basis of a possible $SpitzerIRAC$ [3.6]--[4.5] color excess. This excess may, however, be caused by a subsolar metallicity.

Astrophysical Journal, in press 15 pages, 5 figures

References in corpus (2)

• Discovery of Two T Dwarf Companions with the Spitzer Space Telescope
• Spitzer/IRAC Photometry of M, L, and T Dwarfs

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