April 28, 2017: Challenges in computational planet formation; from disk instability to planetesimal formation.

Talk Title: Challenges in computational planet formation; from disk instability to planetesimal formation.

Abstract: I will discuss recent progress in modeling a number of important regimes in planet formation. First I will report on recent developments in the disk instability model for giant planet formation, which is attractive to explain extrasolar gas giants on wide orbits. I will show how new Lagrangian hydrodynamical techniques can solve the long standing issue of non-convergence of the critical cooling for disk fragmentation. The same hydro method allows to study the combination of self-gravity and MHD turbulence in disks, offering the intriguing possibility that angular momentum dissipation by MRI may promote gravitational instability. I will then discuss planetesimal formation scenarios, introducing a new drag-vorticity instability whereby vortices in disks can generate long-lived, large enhancements of dust density which could be the precursors of planetesimals. This scenario is alternative to the conventional streaming instability and can take place starting from a wider range of initial properties of the dust layer. Finally, with the help of a novel sub-grid model for the coagulation and fragmentation of dust grains implemented in our multi-fluid code, we show how the common practice of simulating only single grain sizes can lead to incorrect results for the transport of dust through the disk.

Lucio Mayer is Professor of Computational and Theoretical Astrophysics at the Center for Theoretical Astrophysics and Cosmology of the University of Zurich, Switzerland. He obtained his PhD in Astrophysics in 2001 from the University of Milan (Italy), while working also at the Max Planck Institut für Astrophysik in Garching, and at the Computational Cosmology Institute at Durham University in UK, was then a postdoc at the University of Washington in Seattle until 2003, subsequently was awarded the Zwicky Prize Fellowship at ETH Zurich, and then became faculty at the University of Zurich in 2006 (tenured since 2012). He and his team have made contributions in a range of areas where state-of-the-art supercomputer simulations are demanded, from galaxy formation and the structure of dark matter halos to the origin and merging of supermassive black holes, from self-gravitating protoplanetary disks to planet formation and migration. He is one of the group leaders of the National Center for Competence in Research “PlanetS” in Switzerland, the largest European network focused on exoplanet studies.

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