Contributed Talk - Splinter Exoplanets

Thursday, 16 September 2021, 15:00   (virtual Exo)

Earth-sized Transiting Planets in the Stellar Habitable Zones - from Kepler to PLATO

René Heller (1,2), Michael Hippke (3,4), Jan-Vincent Harre (1,2), Réza Samadi (5), Natalie Batalha (6), Jantje Freudenthal (2), Steve Bryson (7)
(1) Max Planck Institute for Solar System Research, Göttingen (GER); (2) Institut für Astrophysik Göttingen, Georg-August-Universität Göttingen (GER); (3) Sonneberg Observatory, Sonneberg (GER); (4) Visiting Scholar, Breakthrough Listen Group, Berkeley SETI Research Center, UC Berkeley (USA); (5) LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université Paris Diderot (FRA); (6) Department of Astronomy & Astrophysics, UC Santa Cruz (USA); (7) NASA Ames Research Center, Moffett Field (USA)

In the search for life beyond the solar system, transiting extrasolar planets may be the most promising targets. When such a planet passes in front of its host star, a fraction of the star light passes through the upper atmosphere of the planet, thereby sampling its chemical composition that can be analyzed using transmission spectroscopy. For now though, even the detection of Earth-sized planets in Earth-like (one-year) orbits around sun-like stars, for example with the Kepler mission, is extremely challenging. Most solar type stars are photometrically more active than the sun. Moreover, the Kepler telescope suffered from the systematic rolling-band effect that caused many false positives mimicking Earth-like planet candidates. Our detection of the super-Earth KOI-456.04 in an Earth-like orbit around a solar twin illustrates how to overcome this challenge. The detection of Earth-sized transiting planets in the habitable zones around red dwarf stars is much easier, provided the star is sufficiently inactive. The Trappist-1 exoplanet system, for example, allows exquisite planet characterization (radius and mass measurements) through its mean motion resonance chain and ensuing transit timing variations in K2 data. Towards the end of this decade, the PLATO mission will detect and characterize dozens of transiting Earth-sized planets in the habitable zones around sun-like stars. Our new results for PLATO's yield of Earth-like planets in the habitable zones around sun-like star predict a major contribution to this yet poorly sampled part of the exoplanet parameter space.