Abstract

With current and upcoming radial velocity (RV) spectrographs capable of extreme precision (30 cm/s and below), the next hurdle for measuring precise masses of Earth-mass exoplanets is intrinsic stellar variability, or “jitter”, which can imprint RV signals at the m/s level. It is therefore crucial that we better understand the effects of stellar RV jitter in order to select and prioritize targets best suited for RV observations. To that end, I will present the results of an in-depth analysis of stellar RV jitter for more than 600 California Planet search stars with as many as 20 years of observations, providing an astrophysical framework to describe the evolution of RV jitter and the resulting “jitter minimum” – the period during which a star is most amenable to RV observations. Using that framework, I will highlight various models to predict the RV jitter of stars from a priori based on their stellar properties. In particular, I will show the results of a hierarchical Bayesian model that fits individual astrophysical sources of RV jitter: activity, granulation, and oscillations, making it capable of estimating not only the overall amplitude of stellar RV jitter for a given star, but also each astrophysical component, which will allow for informed observing strategies for RV follow-up in order to mitigate individual sources of stellar RV variability.