Observing and modeling young transiting planets

We study young transiting planets to measure their radii and masses, to understand their formation, and to model their interior. Most extrasolar planets known so far, including the transiting planets, are Gyr old, so that it is hard to understand planet formation from these observations. Hence, we search for young transiting planets, namely by photometric monitoring of young star clusters from about 1 to 100 Myr age. For stars exhibiting transit-like signals, we perform follow-up observations to measure the mass of the secondary object, i.e. to determine whether it is a planet. So far, we found one such young transit planet, namely in the cluster 25 Ori. This star is not only the youngest transit planet (few Myr) observed so far, but also the only star where both a close-in transit planet as well as a wide-orbit planet detected by direct imaging in known. We are currently performing follow-up observations for several more candidates in different cluster and plan to do so also for other young planet transit candidates.
Simultaneously to the observational campaigns, we are modeling the atmosphere and interior of young planets. In particular, atmosphere models which include the influence of clouds of different optical thickness and location in the atmosphere are implemented. We calculate the P-T profile and combine the atmosphere model with an adiabatic interior model assuming a layered structure as known from the Solar System giant planets. The resulting metallicity of the planet, in particular the size of the core, gives valuable information with respect to the possible formation scenarios. In a third step, an evolution model is applied in order to deliver insight into its cooling behavior (e.g. hot or cold start). This enables estimating the age of the planet.
The combined atmosphere-interior-evolution model of the Rostock group will be applied to known young transiting planets, in particular to those confirmed by the Jena group. The results with respect to the age of the planets and their early evolution will be compared with planet formation scenarios as developed in the SPP 1992.