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The detection of the first hot Jupiter around a main sequence star 30 years ago has opened the question about the origin of these planets. Considering that these planets accrete their gaseous envelope in the protoplanetary disc they are born in, it makes sense to relate the formation location of these planets to the chemical composition of the disc. In particular, the idea to related the atmospheric C/O composition of giant planets to their birth location in the disc by comparing directly to the C/O ratio in the different disc regions where different carbon- and oxygen-bearing volatiles evaporate seemed promising, it suffers from the complexity of planet formation models. In the core-accretion scenarion, the planetary core forms first before gas accretion can commence, but it is also migrating through the disc at the same time. The composition that the planet accretes is thus a function of its accretion rate and how efficient the planet migrates through the disc, as the disc composition changes with orbital distance due to the evaporation of different volatile species (e.g. H2O, CO2, CH4, CO). We thus already have two unknowns (initial planetary location and migration speed) and only one know, the atmospheric C/O ratio. Clearly the formation location of planets can thus not be constrained via the C/O ratio alone. While planet formation simulations required different initial assumptions (e.g. disc mass, disc radius, level of turbulence) that complicate the picture, it is unclear how these assumptions influence the chemical composition of growing giant planets. In this talk, I will discuss the influence of the initial assumptions of the disc's properties on the growth and composition of giant planets in order to derive a slightly more complicated picture about the origin of giant planets by invoking more constraints derived from observations.

BIO

Prof. Bertram Bitsch obtained his PhD in 2011 from Tübingen University and has since then worked as a postdoctoral researcher in Nice (France) and Lund (Sweden) before joining the Max-Planck-Institute for Astronomy in Germany as a group leader funded by his ERC Starting grant. Since 2023, Bertram is a professor at the University College Cork in Ireland. His science focuses on models related to protoplanetary discs, planet-disc interactions, and planet formation in general.

Host: Wei Zhu