Characterizing the Disk around the TW Hydrae Association Brown Dwarf 2MASSW J1207334−393254

Abstract

We present detailed modeling of the disk around the TW Hydrae Association\n(TWA) brown dwarf 2MASSW J1207334-393254 (2M1207), using {\\it Spitzer}\nobservations from 3.6 to 24 $\\micron$. The spectral energy distribution (SED)\ndoes not show a high amount of flaring. We have obtained a good fit using a\nflat disk of mass between $10^{-4}$ and $10^{-6}$ $M_{\\sun}$, $\\dot{M}$\n$\\la10^{-11} M_{\\sun}$/yr and a large inclination angle between 60$\\degr$ and\n70$\\degr$. We have used three different grain models to fit the 10 $\\micron$ Si\nemission feature, and have found the results to be consistent with ISM-like\ndust. In comparison with other TWA members, this suggests lesser dust\nprocessing for 2M1207 which could be explained by mechanisms such as aggregate\nfragmentation and/or turbulent mixing. We have found a good fit using an inner\ndisk radius equal to the dust sublimation radius, which indicates the absence\nof an inner hole in the disk. This suggests the presence of a small\nK-$L^{\\prime}$ excess, similar to the observed K-[3.6] excess.\n