IRTF/VLT M-band spectroscopic survey

We present an overview and first results from a M-band spectroscopic survey of planet-forming disks performed with iSHELL on the Infrared Telescope Facility, using two slits that provide resolving power R~60000-92000 (5-3.3km/s). iSHELL provides a nearly complete coverage at 4.52-5.24{mu}m in one shot, covering >50 lines from the R and P branches of 12CO and 13CO for each of multiple vibrational levels, and providing unprecedented information on the excitation of multiple emission and absorption components.

Some of the most notable new findings of this survey are: (1) the detection of two CO Keplerian rings at <2au (in HD259431), (2) the detection of H2O rovibrational lines at 5{mu}m (in AS205N), and (3) the common kinematic variability of CO lines over timescales of 1-14yr. By homogeneously analyzing this survey together with a previous survey of cooler stars, we discuss a unified view of CO spectra where emission and absorption components scan the disk surface across radii from a dust-free region within dust sublimation out to ~10au.