Simulating starspot activity jitter for spectral types F-M: Realistic estimates for a representative sample of known exoplanet hosts
Résumé
Dark spots on the surface of active stars produce changes in the shapes of the spectral lines that mimic spurious Doppler shifts, compromising the detection of small planets by means of the radial velocity (RV) technique. Modeling the spot-driven RV variability (known as "jitter") and how it affects the RV data sets is therefore crucial to design efficient activity-filtering techniques and inform observing strategies. Here, we characterize starspots and simulate the RV curves induced by them to determine typical jitter amplitudes for a representative sample of 15 known host stars spanning between F and M spectral types. We collect information on the logRHK' activity index from the literature for 205 stars and, due to a lack of data in the temperature range 4,000-4,500 K, we measure it for 10 stars using archival data. Additional stellar parameters required for the simulations are collected from the literature or constrained by observational data in order to derive realistic estimates. Our results can be used as reference to determine typical peak-to-peak spot-induced RV jitter in the visible domain that can be expected when targeting host stars with different properties.