From the Sun to solar-type stars: radial velocity, photometry, astrometry and logR′HK time series for late-F to early-K old stars

Solar simulations and observations showed that the detection of Earth twins around Sun-like stars is difficult in radial velocities with current methods techniques. The Sun has proved to be very useful to test processes, models, and analysis methods. The convective blueshift effect, dominating for the Sun, decreases towards lower mass stars, providing more suitable conditions to detect low mass planets. We describe the basic processes at work and how we extended a realistic solar model of radial velocity, photometry, astrometry and LogR′HK variability, using a coherent grid of stellar parameters covering a large range in mass and average activity levels. We present selected results concerning the impact of magnetic activity on Earth-mass planet detectability as a function of stellar type. We show how such realistic simulations can help characterizing the effect of stellar activity on RV and astrometric exoplanet detection.