TWHydraBand7 For CASA 3.3
Overview
TW Hya is a pre-main sequence classical T Tauri star at a distance of about 52+/-1 pc (Mamajek 2005,2010). TW Hya is the most well known member of the TW Hydra association (TWA) of low mass stars. From a wide variety of previous observations from the infrared to submillimeter, TW Hya is known to have a small optically thin hot inner disk to radii < 4 AU, and a larger cold dust disk out to about 200 AU (see for example introduction by Vacca & Sandell 2011, and references therein).
Recent optical interferometry finds that TW Hya also contains a hot optically thick disk on even smaller sizescales of ~0.5 AU, and suggests that the optically thin disk could be due to gas clearing by a planet (Akeson et al. 2011). TW Hya is still accreting from its disk at a rate of about (4-20) x 10^-10 Msun/year and most recently its spectral type, mass, and age have been estimated at M2.5V, 0.4 Msun, and 3 Myr (Vacca & Sandell 2011).
