Ro-vibrational Spectroscopy of CI Tau - Evidence of a Multi-Component Eccentric Disk Induced by a Planet

CI Tau may be the only T Tauri star with a protoplanetary disk in the sub-AU region which hosts a planet that has been detected by radial velocity surveys. This provides the unique opportunity to study disk features that were imprinted by an embedded companion. We present multi-epoch spectroscopic data of the 12CO ro-vibrational spectra and the hydrogen Pf-β line which were taken with NASA IRTF in 2022 spanning 9 consecutive nights. This covers one of the planet’s proposed orbitals periods and we found that the star varied accordingly which may indicate companion driven accretion. Analysis of the 12CO emission line profiles reveals that the disk can be described with an inner and outer component spanning orbital radii 0.05-0.13 au and 0.15-1.5 au, respectively. This alludes to such a companion being located around an orbital distance of 0.14 au, which is in broad agreement with recent radial-velocity analysis of spectroscopic data from SPIRou and ESPaDOns as well as photometric data from K2 and Las Cumbres Observatory Global Network. We also determined that the protoplanetary disk’s inner and outer components have eccentricities of about 0.05 whose arguments of periapses are oppositely aligned. Our results are the first empirical evidence of disk eccentricities being potentially induced by an embedded planet.