A SEARCH FOR GIANT PLANET COMPANIONS TO T TAURI STARS

Abstract

We present results from an ongoing multiwavelength radial velocity (RV) survey of the Taurus–Auriga star-forming
 region as part of our effort to identify pre-main-sequence giant planet hosts. These 1–3 Myr old T Tauri stars present
 significant challenges to traditional RV surveys. The presence of strong magnetic fields gives rise to large, cool
 star spots. These spots introduce significant RV jitter which can mimic the velocity modulation from a planet-mass
 companion. To distinguish between spot-induced and planet-induced RV modulation, we conduct observations at
 ∼6700Åand∼2.3μmand measure thewavelength dependence (if any) in theRVamplitude. CSHELL observations
 of the known exoplanet host Gl 86 demonstrate our ability to detect not only hot Jupiters in the near-infrared but
 also secular trends from more distant companions. Observations of nine very young stars reveal a typical reduction
 in RV amplitude at the longer wavelengths by a factor of ∼2–3. While we cannot confirm the presence of planets
 in this sample, three targets show different periodicities in the two wavelength regions. This suggests different
 physical mechanisms underlying the optical and the K-band variability.