Giant branch planetary systems: Dynamical and radiative evolution

Abstract

In seven billion years, the Sun will be dead. As stars like the Sun pass from their present state to that of a dead white dwarf star, they undergo two phases of extremely high luminosity and radius -- the red giant branch and the asymptotic giant branch -- during which they will lose half or more of their mass. These changes to the star have a significant impact on orbiting planets, asteroids and comets. The large stellar radius (beyond the current orbit of the Earth) leads to the engulfment of bodies entering the stellar envelope, a process enhanced by strong tidal interactions. The high luminosity affects bodies' orbits and physical properties, while mass loss can later trigger the destabilisation of bodies around white dwarfs. It is necessary to understand these processes to understand both the future of our Solar System, and to interpret growing observations of planetary systems around evolved stars.