V1298 Tau: A window into planet formation and early evolution

Young planets (<100 Myr old) provide a unique opportunity to understand the imprint of planet formation and early evolutionary processes (such as atmospheric mass loss) and help us to connect planet formation theories to atmospheric observations of exoplanets. In this presentation, I will focus on the youngest known transiting four-planet system, V1298 Tau (23 Myr old). We observed one primary transit each of V1298 Tau b and V1298 Tau c using the Hubble Space Telescope to characterize their atmospheric properties. I will present the results from this observing program and discuss the challenges of transit observations around young stars and the techniques used to overcome these challenges. We derive constraints on the atmospheric abundances, planet mass and also find evidence of disequilibrium chemistry. The V1298 Tau system is a missing link between forming planets in disks and the mature planet population and promises to tackle the questions related to the early evolution of these systems. In this presentation I will discuss our findings in the context of planet formation, comparative exoplanetology with other young systems as well as within the same system.