Contributed Talk - Splinter Exoplanets

Wednesday, 23 September 2020, 15:20   (virtual room D)

GJ 367 b: an Ultra Short Period Super-Mars found by TESS

Kristine Lam, Szilard Csizmadia, Nicola Astudillo-Defru, Xavier Bonfils, Sebastiano Padovan, et al.
Technische Universit├Ąt Berlin

Ultra short period (USP) planets are planets with orbital periods of less than one day. These planets are almost as abundant as hot Jupiters and they are easier to detect via transits and radial velocities compared to planets with longer orbits. As such, the planetary radii, masses and bulk densities of USP planets are easier to measure, providing fundamental parameters that are important to understand planet formation under extreme conditions. The Transiting Exoplanet Survey Satellite (TESS) mission is delivering high precision photometric data of previously inaccessible portions of the sky, allowing for the discovery of the smallest planets transiting bright stars. We present the TESS discovery of GJ 367 b, an ultra short period super-Mars size planet orbiting an M dwarf every 7.7 hours, which is only at a distance of 9.4 parsecs. The planet has a radius of 0.72+-0.08 R_earth, a mass of 0.53+-0.10 M_earth, and a bulk density of 7.59+-3.92 g/cm^3, corresponding to a bulk composition of predominantly iron. Close proximity to the host star exposed to strong stellar irradiation which could drive planet mass loss due to photoevaporation. The atmosphere of the planet could be stripped as a result, leaving behind a bare core of a formerly gas-rich planet.