The Radial Velocity (RV) method, measuring the Doppler Shifts from stellar spectra, is widely used for the detection and characterization of exoplanets. For low-mass planets, RV detection typically requires cm/s precision, whereas the stellar jitter becomes an issue at the m/s level. Thus, it is essential to mitigate such stellar jitter in order to detect Earth-like planets using RVs.
Our project focuses on the asteroseismic signals of stellar jitter, including stellar oscillation and granulation. We study HD 5562 with fitting the model of stellar jitter to the observational data from the Transiting Exoplanet Survey Satellite (TESS) and RVs from the Carnegie Planet Finder Spectrograph on the Magellan II Telescope (Magellan/PFS). We perform a Gaussian Process (GP) regression on the star's photometric and RV data to describe its asteroseismic signals.
The simultaneous fit model suggests that the primary mode of its oscillation is around 15 minutes or around 1000 muHz. We have reduced the RV scatter from 2.01 m/s to 0.72 m/s by fitting a GP model, which was trained on the TESS light curves, to the RV time series. We also explore multiple ways to model the oscillation in the photometry and how it could be transferred effectively to the RV domain. Our project is part of the RVxTESS program (RVxTESS.com), which combines simultaneous TESS photometry with ground-based RV observations to study stellar jitter.