A 1.9 EARTH RADIUS ROCKY PLANET and the DISCOVERY of A NON-TRANSITING PLANET in the KEPLER-20 SYSTEM

Lars A. Buchhave, Courtney D. Dressing, Xavier Dumusque, Ken Rice, Andrew Vanderburg, Annelies Mortier, Mercedes Lopez-Morales, Eric Lopez, Mia S. Lundkvist, Hans Kjeldsen, Laura Affer, Aldo S. Bonomo, David Charbonneau, Andrew Collier Cameron, Rosario Cosentino, Pedro Figueira, Aldo F. M. Fiorenzano, Avet Harutyunyan, Raphaëlle D. Haywood, John Asher JohnsonDavid W. Latham, Christophe Lovis, Luca Malavolta, Michel Mayor, Giusi Micela, Emilio Molinari, Fatemeh Motalebi, Valerio Nascimbeni, Francesco Pepe, David F. Phillips, Giampaolo Piotto, Don Pollacco, Didier Queloz, Dimitar Sasselov, Damien Ségransan, Alessandro Sozzetti, Stéphane Udry, Chris Watson

Research output: Contribution to journalArticlepeer-review

41 Citations (Scopus)

Abstract

Kepler-20 is a solar-type star (V = 12.5) hosting a compact system of five transiting planets, all packed within the orbital distance of Mercury in our own solar system. A transition from rocky to gaseous planets with a planetary transition radius of ∼1.6 R has recently been proposed by several articles in the literature. Kepler-20b (∼ 1.9 R) has a size beyond this transition radius; however, previous mass measurements were not sufficiently precise to allow definite conclusions to be drawn regarding its composition. We present new mass measurements of three of the planets in the Kepler-20 system that are facilitated by 104 radial velocity measurements from the HARPS-N spectrograph and 30 archival Keck/HIRES observations, as well as an updated photometric analysis of the Kepler data and an asteroseismic analysis of the host star (M= 0.948 ± 0.051 Mand = R = 0.964 ± 0.018 R). Kepler-20b is a 1.868-0.034+0.006 planet in a 3.7 day period with a mass of 9.70-1.44+1.41M, resulting in a mean density of 8.2-1.3+1.5, indicating a rocky composition with an iron-to-silicate ratio consistent with that of the Earth. This makes Kepler-20b the most massive planet with a rocky composition found to date. Furthermore, we report the discovery of an additional non-transiting planet with a minimum mass of 19.96-3.61+3.08M and an orbital period of ∼34 days in the gap between Kepler-20f (P ∼ 11 days) and Kepler-20d (P ∼ 78 days).

Original languageEnglish
Article number160
JournalAstronomical Journal
Volume152
Issue number6
DOIs
Publication statusPublished - 11 Nov 2016

Keywords

  • planetary systems
  • planets and satellites: composition
  • stars: individual
  • techniques: radial velocities

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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