Chemical composition of exoplanetary atmospheres due to pebble and planetesimal accretion


Recent studies of extrasolar planets suggest high metallicities of planetary atmospheres compared to the atmospheres of their host stars. Previous research adopted either pebble- or planetesimal accretion for the growth of these planets to gain insights into this question. We investigate whether the combination of pebble- and planetesimal accretion will help to explain the enrichment of heavy elements in exoplanetary atmospheres. To achieve this goal, we perform semi analytical 1D models of protoplanetary disks including the treatment of viscous evolution and heating, pebble drift and simple chemistry to grow planets from embryos to Jupiters by accretion of pebbles, planetesimals and gas while they migrate through the disc. The treatment of pebble- and planetesimal accretion simultaneously unveils that indeed measured compositions of the atmosphere might be explainable depending on the amount of solids accreted on the envelope.

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