Star Spot Induced Radial Velocity Variability in LkCa 19

TL;DR

This study investigates radial velocity variations in the young star LkCa 19, attributing the observed signals to star spots, which impacts the detection of planets around active young stars.

Contribution

It introduces a new radial velocity survey of T Tauri stars and demonstrates that star spots can mimic planetary signals, affecting planet detection efforts.

Findings

Radial velocity variations in LkCa 19 are caused by star spots.

Star activity induces noise that limits planet detection around young stars.

Simulation confirms star spots can produce observed radial velocity signals.

Abstract

We describe a new radial velocity survey of T Tauri stars and present the first results. Our search is motivated by an interest in detecting massive young planets, as well as investigating the origin of the brown dwarf desert. As part of this survey, we discovered large-amplitude, periodic, radial velocity variations in the spectrum of the weak line T Tauri star LkCa 19. Using line bisector analysis and a new simulation of the effect of star spots on the photometric and radial velocity variability of T Tauri stars, we show that our measured radial velocities for LkCa19 are fully consistent with variations caused by the presence of large star spots on this rapidly rotating young star. These results illustrate the level of activity-induced radial velocity noise associated with at least some very young stars. This activity-induced noise will set lower limits on the mass of a companion detectable around LkCa 19, and similarly active young stars.