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Uncovering the origins of super-Earths and giant planets

Yayaati Chachan (McGill University) // March 6, 2023

Abstract: Persistent efforts to characterize the properties of super-Earths and gas giants have discovered many remarkable features of these planet populations. Firstly, observations indicate that just like our solar system, giant planets are preferentially present at intermediate distances (1 – 10 au) from their host stars. I will show how dust dynamics and differences in grain properties across the water ice line create a region at intermediate distances where gas accretion is rapid, which facilitates the formation of giant planets. Secondly, long-term RV campaigns reveal that cold giant planets are almost always accompanied by close-in super-Earths. In defiance of early expectations and previous work, I will demonstrate that protoplanetary disks that are capable of forming cold giant planets are also capable of spawning close-in super-Earths, thereby naturally producing the observed correlation. Thirdly, close-in super-Earths are more common and giant planets are increasingly rare around lower mass stars. I will present some ongoing work that interprets these observations in light of the accretion efficiency of pebbles (mm-cm sized dust) that form the cores of these planets in different regions of protoplanetary disks.

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