K2 reveals pulsed accretion driven by the 2 Myr old hot Jupiter CI Tau b

TL;DR

This study uses K2 photometry to reveal that a hot Jupiter around the young star CI Tau influences the star's accretion flow, causing a periodic brightness modulation matching the planet's orbital period.

Contribution

It provides evidence of planet-disk interactions in a young star system, linking the planet's orbit to accretion variability observed in the lightcurve.

Findings

Detected a ~9-day brightness modulation linked to the planet's orbit.

No transit evidence for CI Tau b was found.

Planet-disk interactions likely cause the observed accretion variability.

Abstract

CI Tau is a young (~2 Myr) classical T Tauri star located in the Taurus star forming region. Radial velocity observations indicate it hosts a Jupiter-sized planet with an orbital period of approximately 9 days. In this work, we analyze time series of CI Tau's photometric variability as seen by K2. The lightcurve reveals the stellar rotation period to be ~6.6 d. Although there is no evidence that CI Tau b transits the host star, a ~9 d signature is also present in the lightcurve. We believe this is most likely caused by planet-disk interactions which perturb the accretion flow onto the star, resulting in a periodic modulation of the brightness with the ~9 d period of the planet's orbit.