# # Program information file # PROGRAM_ID 2021A066 PROGRAM_TITLE Observing planet formation in the transition disk of AB Aurigae using iSHELL PROGRAM_INV1 Joshua Kern PROGRAM_INV2 Sean Brittain PROGRAM_INV3 Andrea Banzatti PROGRAM_INV4 Michael Henderson PROGRAM_INV5 Janus Kozdon PROGRAM_SCICAT extra-solar planets PROGRAM_ABSTRACT_BEG Long term monitoring of protoplanetary disks using high resolution spectroscopy has been shown to provide evidence of forming planets. Previous iSHELL observations of AB Aurigae and its transition disk present the case for asymmetric CO ro-vibrational emission lines originating from the inner tens of AU of the disk. With the recent discovery of a protoplanet candidate located at 30 AU, we propose to reobserve AB Aurigae with iSHELL and obtain a SNR per pixel ~300 in order to characterize the asymmetry in the CO ro-vibrational emission and detect any asymmetric source of emission. We will also observe the system along 3 PAs [semi-major and -minor axes, and along the direction of the forming planet] in order to make spectro-astrometric measurements to localize the asymmetric source. With a SNR per pixel ~300, our fidelity in the spectro-astrometric measurement will be ~1 mas. Including a dilution factor of 3%, a forming planet at 30 AU would manifest a spatial offset of ~5 mas which we will be measurable. This spectro-astrometric signal can be used to confirm whether this protoplanet candidate is the source of the asymmetry in the CO ro-vibrational emission lines or if the asymmetry is caused by a planet driven eccentricity in AB Aurigae's inner disk. PROGRAM_ABSTRACT_END