Contributed Talk - Splinter Exoplanets

Thursday, 24 September 2020, 14:50   (virtual room D)

Estimating the atmospheric mass loss of V1298 Tau's four young planets

Laura Ketzer, Katja Poppenhaeger, Matthias Mallonn
Leibniz Institute for Astrophysics Potsdam (AIP), University of Potsdam

Kepler observations revealed two striking features in the distribution of exoplanet radii: a dearth of short period sub-Neptune-sized planets, and a relatively clean gap around 2 Earth radii. Atmospheric escape of planetary H/He envelopes driven by the high-energy X-ray and UV irradiation from the host star can explain the presence of the desert at short periods as well as the radius valley. The very young (~ 25 Myr) V1298 Tau system with its four Neptune- to Jupiter-sized planets is an excellent system to test planet formation and evolution models. To investigate the fate of the four planets, we obtained X-ray measurements of V1298 Tau with Chandra. We then calculated the future photoevaporative mass loss rates using PLATYPOS, an open-source tool to model the (energy-limited) atmospheric escape of planetary systems over several Gigayears. We allowed for the host star to spin down at three different ages, which translates into a low, intermediate, and high activity stellar evolutionary track. Our findings show that in certain planetary mass and orbital distance regimes, the stellar high-energy evolution determines if a planet is stripped completely or can retain some fraction of its initial gaseous envelope.