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Transition between Ice and Gas giants explored with TESS and Radial Velocity follow-up

Presentation #104.04 in the session Transits 1.

Published onJun 20, 2022
Transition between Ice and Gas giants explored with TESS and Radial Velocity follow-up

Planets in the radii-range between Neptune and Saturn (R = 4–9.1 R) are important probes of the gas accretion phase of planet formation. During this short formation stage isolated cores are growing by accreting the surrounding gas in the proto-planetary disk (Pollack et al. 1996, Helled et al. 2014). The growth-rate will determine whether a planet ends up as a Saturn-like gas giant or a Neptune-like ice giant. Recent gravitational microlensing studies (Suzuki et al 2018) point towards a larger fraction of intermediate-mass planets than predicted by population synthesis (Alibert et al. 2005), challenging our current view on core accretion. Building up a large sample of planets with masses derived from radial velocities (RVs) will be necessary to corroborate this finding.

To date only a few tens of planets with radii between 9.1 and 4 R have well-characterized RV-masses, as illustrated in the attached figure. Mass and radius are the most fundamental properties that characterize planets, giving us insight into the planet’s internal structure. We will present our follow-up RV programme which targets TESS planet candidates with radii between 4 and 9.1 R, using the high resolution spectrographs CORALIE and HARPS. Besides an analysis of false positives, we will present our most recently confirmed planetary systems. These targets include the transition between volatile-rich and volatile-poor low-mass exoplanets, the Neptune desert, bloated Neptunes and evaporated hot Jupiters. All of them will be prime targets for atmospheric structure and composition characterization.

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