Poster Presentation
Linking observed exoplanet populations to pebble accretion
Presenter: Yi Duann (Graduate Institute of Astronomy, National Central University, Taiwan)
Close-in exoplanet populations offer an observational test of how disk conditions shape planetary growth. We present our recently published analysis of 529 transiting planets in single-star systems using a two-stage Gaussian mixture model in nine physical and orbital parameters, including derived dynamical quantities. The analysis identifies four primary groups and resolves the dominant group into two partially overlapping subgroups, yielding five categories. These include hot giants, warm-Jupiter-dominated systems, lower-mass giants, and very-massive gas giants. A sparsely represented fifth group is excluded from the formation comparison.
For these four populations, kernel density estimation links the observed groups to pebble-accretion simulations in the logarithmic space of planetary radius, planet–star mass ratio, and Hill radius. Restricting the comparison to overlapping observed and synthetic parameter space, we find systematic differences in formation timing, gas fraction, and ice–rock mass ratio. In the mapped synthetic population, very-massive gas giants are associated with earlier formation in more gas-rich disks than hot giants and warm-Jupiter-dominated systems. Hot giants exhibit more heterogeneous accretion histories, while lower-mass giants span a broader range of growth conditions. These associations connect present-day planetary demographics to disk evolution and accretion histories. Future work will seek independent observational tests of these population-level trends and assess how well they distinguish formation history from subsequent evolution.
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