Stellar activity and exoplanet observations

This lecture presents a general overview of the main challenges that stellar variability poses to exoplanet observations, some of the techniques that have been developed to mitigate them, and the way such observations can help characterise host stars. The main part focuses on starspots and faculae, some of their general properties and how they can help interpret measurements in radial velocity, transit photometry and low-resolution spectroscopy. The final part is dedicated to stellar granulation and its impact on the observations of small-size planets. Real-world applications are presented to support the discussion.