Spitzer Spectroscopy of the Transition Object TW Hya

摘要

We report sensitive Spitzer IRS spectroscopy in the region of TW Hya, a nearby T Tauri star. The unusual spectral energy distribution of the source, that of a 'transition object', indicates that the circumstellar disk in the system has experienced significant evolution, possibly as a result of planet formation. The spectrum we measure is strikingly different from that of other classical T Tauri stars reported in the literature, displaying no strong emission features of H2O, C2H2, or HCN. The difference indicates that the inner planet formation region of the gaseous disk has evolved physically and/or chemically away from the classical T Tauri norm. Nevertheless, TW Hya does show a rich spectrum of emission features of atoms and molecules, some of which are also detected in classical T Tauri spectra. The properties of the neon emission are consistent with an origin for the emission in a disk irradiated by X-rays.