This week’s online-only Astrophysics Seminar at 3pm on Wednesday is the last scheduled for the 2021-22 season.
Vincent van Eylen (UCL) will tell us about “The architecture of planets and their host stars”
Abstract: Thousands of exoplanets have now been detected and they exhibit a striking diversity in properties, with system architectures sometimes similar but often starkly different from that of our solar system. In this talk, I show how observable properties of exoplanets can be used to constrain models of planet formation and evolution. In particular, I focus on a gold sample of well-characterized planets for which the host stars are characterized through asteroseismology. I show how such a sample can be used to determine the presence and location of the radius gap, which separates super-Earths and sub-Neptunes. This has provided several key insights: 1) the slope of the radius gap is inconsistent with late gas-poor formation, but matches photo-evaporation models; 2) the complete lack of secure planet detections inside the gap is a result of homogeneous planet core compositions; and 3) these cores have a terrestrial composition, implying in situ formation rather than planet migration from beyond the ice line. Furthermore, I show how we measured differences in orbital eccentricities for systems with one or more transiting planets, and how various models of planet formation and evolution can explain these findings. I conclude with some recent results from the TESS mission and a forward look to PLATO.
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