Radial velocity jitter in cool stars

Stellar rotation-induced RV jitter dominates for stars with equatorial rotation velocities greater than 1km/s. A jitter floor of 2m/s dominates in stars with equatorial rotation velocities below 1km/s. This jitter floor likely contains contributions from stellar jitter, instrumental jitter and undetected companions.

We study the impact of the average magnetic field and the distributions of magnetic filling factors on the RV jitter. We find a series of stars with excess RV jitter and distinctive distributions of magnetic filling factors, characterized by a dominant magnetic field component between 2 to 4kG. A radial velocity jitter floor can be distinguished from activity-rotation- induced RV jitter based on the stellar equatorial rotation velocity.

Activity-rotation-induced RV jitter depends primarily on the equatorial rotation velocity. Activity-rotation-induced RV jitter is also related to the distribution of magnetic filling factors, emphasizing the role of the magnetic field in the generation of RV jitter.