Predicting radial-velocity jitter induced by stellar oscillations based on Kepler data

TL;DR

This paper develops a method to predict stellar oscillation-induced radial-velocity jitter using Kepler data, aiding exoplanet detection efforts by estimating stellar noise levels based on stellar parameters.

Contribution

The authors introduce a new predictive model for RV jitter caused by stellar oscillations, utilizing Kepler data and stellar parameters, with publicly available code for practical application.

Findings

Predictive accuracy of 17.9% for dwarfs and 27.1% for giants using luminosity, mass, and temperature.

Equivalent precision achieved with luminosity, temperature, and gravity parameters.

The method is useful for planning follow-up spectroscopic observations for TESS and PLATO exoplanet missions.

Abstract

Radial-velocity (RV) jitter due to intrinsic stellar variability introduces challenges when characterizing exoplanet systems, particularly when studying small (sub-Neptune-sized) planets orbiting solar-type stars. In this Letter we predicted for dwarfs and giants the jitter due to stellar oscillations, which in velocity have much larger amplitudes than noise introduced by granulation. We then fitted the jitter in terms of the following sets of stellar parameters: (1) Luminosity, mass, and effective temperature: the fit returns precisions (i.e., standard deviations of fractional residuals) of 17.9% and 27.1% for dwarfs and giants, respectively. (2) Luminosity, effective temperature, and surface gravity: The precisions are the same as using the previous parameter set. (3) Surface gravity and effective temperature: we obtain a precision of 22.6% for dwarfs and 27.1% for giants. (4): Luminosity and effective temperature: the precision is 47.8% for dwarfs and 27.5% for giants. Our method will be valuable for anticipating the radial-velocity stellar noise level of exoplanet host stars to be found by the TESS and PLATO space missions, and thus can be useful for their follow-up spectroscopic observations. We provide publicly available code (https://github.com/Jieyu126/Jitter) to set a prior for the jitter term as a component when modeling the Keplerian orbits of the exoplanets.