Precise Radial Velocities

Precise measurements of a star's radial velocity (RV) made using extremely stable, high-resolution, optical or near-infrared spectrographs can be used to determine the masses and orbital parameters of gravitationally bound extrasolar planets (exoplanets). Indeed, RV surveys and follow-up efforts have provided the vast majority of published exoplanet mass measurements and, in doing so, have enabled studies of exoplanet interior and atmospheric compositions. We review the current state of the RV field, with particular attention to: ▪ The evolution of precise RV methodologies over the past 2 decades. ▪ Modern RV spectrograph designs that can be calibrated to a stability level of ≤50 cms −1 over timescales of years. ▪ RV data reduction and postprocessing techniques that minimize the impact of instrument systematics and stellar variability. ▪ Techniques for detecting exoplanets in RV data and disentangling planetary signals from stellar variability.