Gas Evolution in Inner Disk Cavities from a Synergic Analysis of IR-CO and UV-H2 Spectra

Abstract

We are conducting a multi-wavelength analysis of high-resolution molecular spectra that probe the evolution of gas in the inner 10 au in protoplanetary disks. A sample of 15 disks has been combined to probe a range of inner disk structures including small and large dust cavities. Half of the sample has been observed in far-ultraviolet H₂ emission with a new HST-COS program (GO-14703), that we have combined to near-infrared spectra of CO emission as observed with VLT-CRIRES and IRTF-iSHELL. This synergic dataset traces the evolution and depletion of CO and H₂ in inner disk cavities and shows an evolving radial stratification of the molecular gas, where CO lines are narrower than H₂ lines in disks with cavities. CO rotation diagrams also show significant evolution, suggesting a change in gas excitation as CO emission recedes to larger disk radii.