The California-Kepler Survey. IV. Metal-rich Stars Host a Greater Diversity of Planets

Erik A. Petigura, Geoffrey W. Marcy, Joshua N. Winn, Lauren M. Weiss, Benjamin J. Fulton, Andrew W. Howard, Evan Sinukoff, Howard Isaacson, Timothy D. Morton, John Asher Johnson

Research output: Contribution to journalArticlepeer-review

74 Scopus citations

Abstract

Probing the connection between a star's metallicity and the presence and properties of any associated planets offers an observational link between conditions during the epoch of planet formation and mature planetary systems. We explore this connection by analyzing the metallicities of Kepler target stars and the subset of stars found to host transiting planets. After correcting for survey incompleteness, we measure planet occurrence: the number of planets per 100 stars with a given metallicity M. Planet occurrence correlates with metallicity for some, but not all, planet sizes and orbital periods. For warm super-Earths having P = 10-100 days and RP = 1.0-1.7 R, planet occurrence is nearly constant over metallicities spanning -0.4 to + 0.4 dex. We find 20 warm super-Earths per 100 stars, regardless of metallicity. In contrast, the occurrence of warm sub-Neptunes (RP= 1.7-4.0 R) doubles over that same metallicity interval, from 20 to 40 planets per 100 stars. We model the distribution of planets as df ∝ 10βM DM, where β characterizes the strength of any metallicity correlation. This correlation steepens with decreasing orbital period and increasing planet size. For warm super-Earths β = -0.3-0.2+0.2, while for hot Jupiters β = +3.40.8+0.9. High metallicities in protoplanetary disks may increase the mass of the largest rocky cores or the speed at which they are assembled, enhancing the production of planets larger than 1.7 R. The association between high metallicity and short-period planets may reflect disk density profiles that facilitate the inward migration of solids or higher rates of planet-planet scattering.

Original languageEnglish (US)
Article number89
JournalAstronomical Journal
Volume155
Issue number2
DOIs
StatePublished - Feb 2018

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • methods: statistical
  • planets and satellites: formation
  • planets and satellites: general
  • stars: abundances
  • stars: fundamental parameters
  • techniques: spectroscopic

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