The California-Kepler Survey. VII. Precise Planet Radii Leveraging Gaia DR2 Reveal the Stellar Mass Dependence of the Planet Radius Gap

By B. Fulton, E. Petigura. Astronomical Journal, 2018

438 citations recorded by the source corpus.

The distribution of planet sizes encodes details of planet formation and evolution. We present the most precise planet size distribution to date based on Gaia parallaxes, Kepler photometry, and spectroscopic temperatures from the California-Kepler Survey. Previously, we measured stellar radii to 11% precision using high-resolution spectroscopy; by adding Gaia astrometry, the errors are now 3%. Planet radius measurements are, in turn, improved to 5% precision. With a catalog of ∼1000 planets with precise properties, we probed in fine detail the gap in the planet size distribution that separates two classes of small planets, rocky super-Earths and gas-dominated sub-Neptunes. Our previous study and others suggested that the gap may be observationally under-resolved and inherently flat-bottomed, with a band of forbidden planet sizes. Analysis based on our new catalog refutes this; the gap is partially filled in. Two other important factors that sculpt the distribution are a planet’s orbital distance and its host-star mass, both of which are related to a planet’s X-ray/UV irradiation history. For lower-mass stars, the bimodal planet distribution shifts to smaller sizes, consistent with smaller stars producing smaller planet cores. Details of the size distribution including the extent of the “sub-Neptune desert” and the width and slope of the gap support the view that photoevaporation of low-density atmospheres is the dominant evolutionary determinant of the planet size distribution.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/8cdbbb11c20b0b3bc5ec1524fa82a3bb4d9492b7

How researchers see this paper

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In Astronomy and Astrophysics

1. N. Madhusudhan
2. Jon Fortney
3. D. Deming
4. J. D'esert
5. H. Knutson
6. A. Showman
7. Laura Kreidberg
8. M. Line

In Instrumentation

1. Jon Fortney
2. N. Madhusudhan
3. J. D'esert
4. H. Knutson
5. D. Deming
6. Laura Kreidberg
7. D. Huber
8. E. Gaidos

Citations in the corpus

• A sub-Neptune exoplanet with a low-metallicity methane-depleted atmosphere and Mie-scattering clouds (2019, background): “[1] Department of Physics and Institute for Research on Exoplanets, Université de Montréal, Montréal, QC, Canada [2] Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA [3] Lunar & Planetary Laboratory, University of Arizona, 1629 E.”
• Angular Momentum Transport in Stellar Interiors (2018, background): “Gaia DR2 already led to radii at ∼2% precision for a number of (exoplanet host) stars (e.g., Fulton & Petigura 2018) and even ∼ 1% for asteroseismic targets (Zinn et al. 2018).”
• The Gaia–Kepler Stellar Properties Catalog. I. Homogeneous Fundamental Properties for 186,301 Kepler Stars (2020, background): “The masses determined here will allow us to constrain the stellar mass dependence of the planet radius gap (Fulton & Petigura 2018; Gupta & Schlichting 2019; Wu 2019).”
• The CARMENES search for exoplanets around M dwarfs (2018, background): “The diagrams exhibit a bimodal distribution that resembles the one found in planetary radius using Kepler data mainly for solar-like stars (Fulton et al. 2017; Fulton & Petigura 2018), but also confirmed for validated and well-characterized transiting planets around M dwarfs (Hirano et al. 2018).”