Contributed Talk - Splinter Exoplanets

Friday, 15 September 2023, 15:15   (H 3007)

An enhanced view on the properties of the TOI-178 system

J. Cabrera (1), L. Delrez (2,3), A. Leleu (4, 5), and the CHEOPS Science Team
1: Deutsches Zentrum für Luft- und Raumfahrt, Rutherfordstr. 2, 12489 Berlin, Germany; 2: Astrobiology Research Unit, Université de Liège, Liège, Belgium; 3: Space sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Liège, Belgium; 4: Observatoire Astronomique de l’Université de Genève, Versoix, Switzerland; 5: Physikalisches Institut, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland

The precise determination of the planetary radius - from planetary transits - combined with its mass measurement - from radial velocity or transit timing analysis - allows the determination of the mean bulk density of the planet, which is the most direct way to constrain the planetary structure and hence its bulk composition. These are observational constraints that we use to better understand the processes of planetary formation. Multi-planetary systems are cornerstones of these studies. And in particular systems displaying mean motion resonances are especially important, as the fragility of their orbital configuration allows us to separate primordial formation processes from possible orbital evolution in the form of scattering or collisional events. We will present in this contribution the latest results obtained by the CHEOPS team on the TOI-178 system. It consists of a nearby late K-dwarf transited by six planets in the super-Earth to mini-Neptune regime, with radii ranging from ∼1.1 to 2.9 REarth and orbital periods between 1.9 and 20.7 days. All planets, but the innermost one, form a chain of Laplace resonances. We will discuss the most recent measurements on their masses and discuss implications on our understanding of planet formation and evolution models.