2018MNRAS.480L..48Y

Radial-velocity 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 per cent 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 per cent for dwarfs and 27.1 per cent for giants. (4) Luminosity and effective temperature: the precision is 47.8 per cent for dwarfs and 27.5 per cent 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 modelling the Keplerian orbits of the exoplanets.