H I 21 cm Emission as a Tracer of Gas During the Evolution from Protoplanetary to Debris Disks

摘要: We present radiative transfer models for the H I 21 cm emission from circumstellar disks and use them to convert observed upper limits on flux total disk gas mass. also fresh of around HD 135344, LkCa 15, 163296, obtained with Giant Meterwave Radio Telescope. Our observations span a range types, young protoplanetary old debris disks. The self-consistently calculate chemistry (H/H2 balance) thermal structure UV irradiated Atomic hydrogen production is dominated by irradiation in transition phase objects as well disks, but very stellar X-rays important. This produces at surface In massive produced constitutes less than 0.5% mass, while clearly dominate thus production. mainly molecular, since high dust-to-gas mass ratio leads warmer cannot be detected currently available radio telescopes such strongest fluxes are predicted distances 100 pc. expected close current detection limits. A telescope about ~10% area SKA will able detect full provide resolved images. Such probe kinematics effects evaporation their layer.