4-8 October 2015
Hans Harnack Haus
Europe/Berlin timezone
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Contribution Contributed Talk

Hans Harnack Haus -

Planet formation in evolving protoplanetary discs


  • Dr. Bertram BITSCH

Primary authors


In this talk, we will present a new model for time evolving accretion discs (Bitsch et al. 2015) and its influence on the formation of planetary cores via pebble accretion and on the formation of gas giants in these discs (Bitsch et al. 2015b, in review). We will also show the influence of the ice to silicate ratio on the structure of the protoplanetary disc and hence on planet formation (Bitsch et al. 2015c, in prep.).

The formation of dust, pebbles, planetesimals and planetary embryos is influenced by the structure of the underlying protoplanetary disc, in particular the profiles of temperature, gas scale height and density. The formation of gas giants is additionally tied to the lifetime of the protoplanetary disc, which is expected to be several Myr. During this time the disc looses mass and changes its structure. This evolution of the disc over several Myr is studied in 2D hydrodynamical simulations featuring viscous and stellar heating as well as radiative cooling. The cooling is influenced by the ice to silicate ratio (through the disc's opacity), which changes the disc structure and hence the formation path of planets. A larger ice fraction results in a larger aspect ratio $H/r$ of the disc at $r > r_{ice}$ and a smaller aspect ratio for $r < r_{ice}$. A smaller ice fraction has the opposite effect (smaller $H/r$ for $r > r_{ice}$ and larger $H/r$ for $r < r_{ice}$).

During the evolution of the disc planets can form via the accretion of pebbles quite quickly (a few 100kyr) until they reach pebble isolation mass where the accretion of pebbles terminates, allowing for the accretion of gas. During this whole process, planets migrate through the disc either in type-I migration (for planets of a few Earth masses) or in type-II migration, when planets are big enough to open a gap in the disc. We discuss the interplay of pebble and gas accretion in combination with disc evolution and planetary migration on the formation of giant planets as a function of their initial orbital distance where they form, their initial formation time during the disc evolution and the ice to silicate ratio in the protoplanetary disc. We will focus here particularly on the formation of the giant planets in our own solar system.