An IRTF-iSHELL survey of near-infrared CO spectra in Herbig disks: sample and excitation analysis

We are conducting a survey of high-resolution near-infrared CO rovibrational spectra in Herbig disks. We are using IRTF-iSHELL with the 0.375” and 0.75” slits, providing 4 km/s and 7.5 km/s resolution, high sensitivity, and covering 4.55-5.2 um in one shot. This includes part of the rovibrational R branch and the entire P branch of the CO fundamental band, one of the best tracers of warm gas in protoplanetary disks. The high quality of this survey will enable multiple investigations to study the structure, kinematics, composition, and evolution of the inner 10 au in Herbig disks. The sample is growing and currently includes ~20 Herbig disks within 200 pc, complementing extensive imaging campaigns that are observing these disks at optical, infrared, and millimeter wavelengths, and revealing structures and planets forming in their disks. Here we present an analysis of CO excitation as linked to structures and cavities in the inner disk regions, leveraging on the unprecedented spectral coverage, resolution, and sensitivity of these spectra. The reduced spectra will become available to the community through the web interface of SpExoDisks, a multi-observatory database that we are building for high-resolution infrared spectra of exoplanet-forming disks