SETI: The Stability and Evolution of The Inner edge of protoplanetary disks

• Applicant: Dr. Mario Flock
• Subject Area: Astrophysics and Astronomy
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 517644750

Despite the great success of exoplanet astronomy in the past two decades, with more than three thousands of exoplanetary systems discovered, many question about their formation remain. One of the key result of the Kepler space telescope mission is that many planetary systems contain Earth-sized and super-Earth planets which orbit very close to their host star, well inside one astronomical unit. This fascinating result leads to the questions: how are those close in super-Earth systems formed? The question how and where these planets form can only be solved by understanding the early evolution of the inner disk regions in protoplanetary disks. Previous models of the inner disk regions highlight the trap for solid material of different sizes, located at the dead-zone inner edge, the transition between a highly viscously evolving inner disk and an less active outer disk. Until today, most of these theoretical models focused on radiation hydrostatic models. However especially for young disks, the dynamical interplay between accretion stress and heat transfer is crucial. In this case, the dead-zone inner edge can move outward due to its own generated accretion heating, leading to oscillations of the inner dead-zone edge location. With the project SETI we want to advance current state-of-the-art theoretical models of the inner edge of protoplanetary disks to answer the key crucial question: What is the time evolution and stability of the inner dead-zone edge? Which influence has the evolution of the inner dead-zone edge onto the drift and migration of the solid material? Can the variations of accretion rate explain accretion outburst, seen in a class of young protoplanetary disk systems? To solve these questions we propose to build, perform and analyse long-term 2D radiation hydrodynamical simulations of the inner dead-zone edge of protoplanetary disks, including irradiation heating, viscous heating and dust sublimation linked to the opacity. We will carefully trace for the change of the dead-zone inner edge and capture the variations in the mass accretion through the inner gas disk. By post-processing the simulation data we can learn key aspect of the planet formation process. Where are the dust pebbles get concentrated and what is the time evolution of the dust surface density? With a Lagrangian dust method we can learn about the radial drift and dust concentration region during the inner dead-zone edge evolution. Further we can calculate the planet migration rate from the dataset and determine where proto-planets would migrate or even get halted. The results of the project SETI will not only reveal the formation and evolution scenario of close-in multiplanetary systems but also build the bridge to the observations of EXors, young star disk systems which show variations in their accretion rate.

• DFG Programme: Research Grants