Formation and Evolution of Planets orbiting Low-mass Stars

With recent and upcoming European and international space missions, the number and quality of observations of exoplanets reached an unprecedented level. These observations revealed a rich diversity in exoplanets` sizes, compositions, and orbits. A few resemble the Solar System planets, but many more are completely different (such as planets with masses between Earth and Neptune orbiting their stars closer than Mercury`s orbit). This observational success demands a further development of fundamental theories and models. The population of exoplanets, as we know it today, was shaped by a combination of planetary formation processes within the disks consisting of gas and dust surrounding infant stars, and billions of years of subsequent evolution after these protoplanetary disks vanish. During the first stage, planets gain mass and accrete atmospheres, heating up due to gravitational contraction. Through the second, planets cool and contract, and their atmospheres are exposed to high-energy radiation from their stars, which can alter the composition of these atmospheres or destroy them completely. Both planetary formation and evolution strongly depend on the primordial parameters and evolution of the host stars and should, ideally, be addressed as a continuous process guided by the stellar input. However, the large number and complexity of physical processes involved in both stages have, so far, prevented the creation of such a self-consistent model. Our project aims to bridge the formation and evolution models of (exo)planets and strengthen their compliance with different stellar types. We will particularly focus on planetary systems around low- mass stars, which are the focus of today`s observational efforts, whereas most theoretical studies in recent decades were dedicated to Sun-like stars. We will begin our studies at the earliest stages of planetary systems` formation: by collecting, analyzing, and systematizing the past observational data on young stars and protoplanetary disks to define the possible ranges of their parameters and reveal the dependencies of these parameters on stellar type. We will use these results to improve the planetary formation models developed in the Physics Institute of the University of Bern and study the effect of the various properties of stars and disks on young planets. This will allow us to constrain, in particular, the range of possible compositions of primordial atmospheres for planets orbiting stars of different types. With this information we will feed the atmospheric models developed at the Space Research Institute of the Austrian Academy of Sciences to model long-term planetary evolution. Combining all these tools, we will advance on the current level of understanding planetary formation and evolution and apply our results to hack the unknown history behind the diversity of exoplanets.