The California-Kepler Survey. III. A Gap in the Radius Distribution of Small Planets

By B. Fulton, E. Petigura, Andrew W. Howard, H. Isaacson, G. Marcy, Phillip Cargile, L. Hebb, L. Weiss, J. Johnson, Timothy Morton and 3 more. 2017

1,012 citations recorded by the source corpus.

The size of a planet is an observable property directly connected to the physics of its formation and evolution. We used precise radius measurements from the California-Kepler Survey to study the size distribution of 2025 Kepler planets in fine detail. We detect a factor of ≥2 deficit in the occurrence rate distribution at 1.5–2.0 . This gap splits the population of close-in (P < 100 days) small planets into two size regimes: and , with few planets in between. Planets in these two regimes have nearly the same intrinsic frequency based on occurrence measurements that account for planet detection efficiencies. The paucity of planets between 1.5 and 2.0 supports the emerging picture that close-in planets smaller than Neptune are composed of rocky cores measuring 1.5 or smaller with varying amounts of low-density gas that determine their total sizes.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/d5be079a7408699953229246bfe8034af66ce6e3

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In Astronomy and Astrophysics

1. Jon Fortney
2. N. Madhusudhan
3. J. Owen
4. D. Charbonneau
5. J. Johnson
6. J. Winn
7. C. Mordasini
8. Timothy Morton

Citations in the corpus

• The California-Kepler Survey. VII. Precise Planet Radii Leveraging Gaia DR2 Reveal the Stellar Mass Dependence of the Planet Radius Gap (2018, methodology): “The IDEM has been used in a number of previous works (e.g., Howard et al. 2010, 2012; Morton & Swift 2014; Fulton et al. 2017).”
• The California-Kepler Survey. II. Precise Physical Properties of 2025 Kepler Planets and Their Host Stars (2017, background): “The statistical significance of this structure in the planet radius distribution will be explored in detail in Paper III of this series (Fulton et al. 2017).”
• Characterization of the K2-18 multi-planetary system with HARPS: A habitable zone super-Earth and discovery of a second, warm super-Earth on a non-coplanar orbit (2017, background): “The measured radius of 2.38 R⊕ is suggestive of an extended H/He envelope (Valencia et al. 2013; Rogers 2015; Fulton et al. 2017) that may contain additional molecular species such as water and/or methane that could be detectable with the James Webb Space Telescope (JWST; Beichman et al. 2014).”
• Photoevaporation and high-eccentricity migration created the sub-Jovian desert (2018, background): “Such a maximum core-mass agrees well with the observed gap in the radius distribution of small close-in planets (Fulton et al. 2017), located at 1.8 R⊕, corresponding to a stripped solid core of roughly 10 M⊕.”
• The Gaia–Kepler Stellar Properties Catalog. I. Homogeneous Fundamental Properties for 186,301 Kepler Stars (2020, methodology): “Previous analyses have hinted at age-dependent effects on the radii of small exoplanets, particularly those at or near the gap, for subsamples of the Kepler exoplanets (Fulton et al. 2017; Mann et al. 2017; Berger et al. 2018a).”
• The nature of the TRAPPIST-1 exoplanets. (2018, background): “The upper mass limit is set to 4.5 M⊕ because this corresponds to 1.5 R⊕, an indicative limit for rocky worlds (Rogers 2015; Fulton et al. 2017).”
• Compositional Imprints in Density–Distance–Time: A Rocky Composition for Close-in Low-mass Exoplanets from the Location of the Valley of Evaporation (2017, background): “We note that the observations can currently not constrain the radial dependency of the transition because of a lack of completeness of small planets at larger distances (Fulton et al. 2017).”
• The California-Kepler Survey. IV. Metal-rich Stars Host a Greater Diversity of Planets (2017, methodology): “Similar filters clarified the bimodal planet radius distribution presented by Fulton et al. (2017), Paper III in the CKS series.”
• A New Window into Escaping Exoplanet Atmospheres: 10830 Å Line of Helium (2017, background): “This process has been proposed as an explanation for the observed paucity of short-period subJupiter planets and the bimodal distribution of planet radii (Owen & Wu 2013; Lundkvist et al. 2016; Fulton et al. 2017).”
• Core-powered mass-loss and the radius distribution of small exoplanets (2017, methodology): “E-mail: sivan.ginzburg@mail.huji.ac.il Recently, refined radius measurements by the California-Kepler Survey (Johnson et al. 2017; Petigura et al. 2017) allowed Fulton et al. (2017) to identify a distinct valley in the radius distribution of short-period planets.”
• The Disk Substructures at High Angular Resolution Project (DSHARP). II. Characteristics of Annular Substructures (2018, background): “Exoplanet surveys have uncovered remarkable diversity in the masses, radii, and composition of exoplanets, as well as in the overall architectures of exoplanetary systems (e.g., Howard et al. 2010; Borucki et al. 2011; Winn & Fabrycky 2015; Fulton et al. 2017).”
• About 30% of Sun-like Stars Have Kepler-like Planetary Systems: A Study of Their Intrinsic Architecture (2018, background): “The typical mass for Kepler planets is ∼ 3 M⊕ (Marcy et al. 2014; Fulton et al. 2017; Hadden & Lithwick 2017; Owen & Wu 2017).”
• Predictions of the WFIRST Microlensing Survey. I. Bound Planet Detection Rates (2018, background): “Additionally, a statistical accounting of planets on wider orbits more generally will be a valuable test of models of planet formation developed to explain the large occurrence rate of super-Earths closer than 1 AU.”