# # Program information file # PROGRAM_ID 2024A042 PROGRAM_TITLE Spectro-astrometric observations of the inner regions of protoplanetary disks PROGRAM_INV1 Jonathan Williams PROGRAM_INV2 Pietro Curone PROGRAM_INV3 Alexa Anderson PROGRAM_INV4 Adwin Boogert PROGRAM_INV5 PROGRAM_SCICAT stellar PROGRAM_ABSTRACT_BEG We propose to use iSHELL to study six protoplanetary disks at radii down to a few tenths of an au in the region where most exoplanets have been discovered through transit and radial velocity techniques. We will observe CO ro-vibrational lines in the M-band and measure how their spatial position on the slit varies with source velocity. We have demonstrated this technique for observations of HL Tau and now wish to add additional slit position angles to remove ambiguities on the inner disk geometry. We will also look for spectroastrometric signals that can diagnose rotation and winds from the inner disk regions in five other sources with bright CO lines. PROGRAM_ABSTRACT_END