# # Program information file # PROGRAM_ID 2021B070 PROGRAM_TITLE Characterization of Variable 4.7micron CO Emission from CI Tau: Investigation of Potential Spectroscopic Signposts of Planet Formation in the Classical T Tauri Star Exoplanet Host PROGRAM_INV1 Sean Brittain PROGRAM_INV2 Josh Kern PROGRAM_INV3 Stanley Jensen PROGRAM_INV4 Joan Najita PROGRAM_INV5 John Carr PROGRAM_SCICAT stellar PROGRAM_ABSTRACT_BEG CI Tau is one of two young stars with an accretion disk where an exoplanet has been unambiguously detected. A radial velocity study of this star points to the presence of a supra-Jovian mass planet on a 9day orbit. Models of disk-planet interactions predict various signposts of planet formation in disks. While many of these signposts have been observed, they have not yet been validated in disks where the identification of the planet has been independently verified. One of these signposts of ongoing planet formation is line emission from gas in the circumplanetary disk. The Doppler shift of this emission should vary on an orbital time scale relative to circumstellar emission. This signature has been observed from the transition disk object HD100546. Multi-epoch observations of CITau show variable CO emission, though the timing of these observations [three observations spaced ~10yrs and ~3months apart] are insufficient to demonstrate that the emission varies on an orbital time scale [~9days]. Here we propose a campaign to acquire short observations of ro-vibrational fundamental CO emission on 9 consecutive nights. The timing of the variability and Doppler shift of the emission will allow us to determine whether and how the emission is connected to the planet in this disk. We require SNR=50/resolution element spectra of CI Tau on each night. The iSHELL ETC indicates that 30m of integration will be required each night. Earth's atmosphere has deep low-J CO absorption lines, thus a significant Doppler shift is necessary to minimize the blending of CO emission from the disk and CO absorption from Earth's atmosphere. This star is on the ecliptic, thus Earth's orbital velocity contributes +/-30km/s. The radial velocity of the star is +17km/s, so the Doppler shift of this source is optimal from late December through January. PROGRAM_ABSTRACT_END