Keeping up with the cool stars: one TESS year in the life of AB Doradus

Abstract

The long-term, high precision photometry delivered by the Transiting Exoplanet Survey Satellite (TESS) enables us to gain new insight into known and hitherto well-studied stars. In this paper, we present the result of our TESS study of the photospheric activity of the rapid rotator AB Doradus. Due to its favorable position near the southern ecliptic pole, the TESS satellite recorded almost 600 rotations of AB Doradus with high cadence, allowing us to study starspots and flares on this ultra-active star. The observed peak-to-peak variation of the rotational modulations reaches almost 11%, and we find that the starspots on AB Doradus show highly preferred longitudinal positions. Using spot modeling, we measured the positions of the active regions on AB Doradus and we find that preferred spot configurations should include large regions extending from low to high stellar latitudes. We interpret the apparent movement of spots as the result of both differential rotation and spot evolution and argue that the typical spot lifetimes should range between 10 and 20 days. We further find a connection between the flare occurrence on AB Doradus and the visibility of the active regions on its surface, and we finally recalculated the star’s rotation period using different methods and we compared it with previous determinations.