The radius distribution of M dwarf-hosted planets and its evolution

Autor(en): Eric Gaidos, Aleezah Ali, Adam L. Kraus, Jason F. Rowe
Abstrakt: M dwarf stars are the most promising hosts for detection and characterization of small and potentially habitable planets, and provide leverage relative to solar-type stars to test models of planet formation and evolution. Using Gaia astrometry, adaptive optics imaging, and calibrated gyrochronologic relations to estimate stellar properties and filter binaries, we refined the radii of 117 Kepler objects of interest (confirmed or candidate planets) transiting 74 single late K-type and early M-type stars, and assigned stellar rotation-based ages to 113 of these. We constructed the radius distribution of 115 small (<4 R) planets and assessed their evolution. As for solar-type stars, the inferred distribution contains distinct populations of ‘super-Earths’ (at ∼1.3 R) and ‘sub-Neptunes’ (at ∼2.2 R) separated by a gap or ‘valley’ at ≈1.7 R that has a period dependence that is significantly weaker (power-law index of −0.03⁺₋₀⁰₀₃⁰¹) than for solar-type stars. Sub-Neptunes are largely absent at short periods (<2 d) and high irradiance, a feature analogous to the ‘Neptune desert’ observed around solar-type stars. The relative number of sub-Neptunes to super-Earths declines between the younger and older halves of the sample (median age 3.86 Gyr), although the formal significance is low (p = 0.08) because of the small sample size. The decline in sub-Neptunes appears to be more pronounced on wider orbits and low stellar irradiance. This is not due to detection bias and suggests a role for H₂O as steam in inflating the radii of sub-Neptunes and/or regulating the escape of H/He from them.
Organisation(en): Institut für Astrophysik
Externe Organisation(en): University of Hawaii at Manoa, University of Hawaii, University of Texas, Austin, Bishop's University
Journal: Monthly Notices of the Royal Astronomical Society
Band: 534
Seiten: 3277-3290
Anzahl der Seiten: 14
ISSN: 0035-8711
DOI: https://doi.org/10.1093/mnras/stae2207
Publikationsdatum: 11-2024
Peer-reviewed: Ja
ÖFOS 2012: 103003 Astronomie, 103004 Astrophysik
Schlagwörter
ASJC Scopus Sachgebiete: Astronomy and Astrophysics, Space and Planetary Science
Link zum Portal: https://ucrisportal.univie.ac.at/de/publications/813e473e-789d-4c66-9654-476f7f097fb1

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