The Kepler-454 system: a small, not-rocky inner planet, a Jovian world, and a distant companion

Sara Gettel, David Charbonneau, Courtney D. Dressing, Lars A. Buchhave, Xavier Dumusque, Andrew Vanderburg, Aldo S. Bonomo, Luca Malavolta, Francesco Pepe, Andrew Collier Cameron, David W. Latham, Stéphane Udry, Geoffrey W. Marcy, Howard Isaacson, Andrew W. Howard, Guy R. Davies, Victor Silva Aguirre, Hans Kjeldsen, Timothy R. Bedding, Eric LopezLaura Affer, Rosario Cosentino, Pedro Figueira, Aldo F M Fiorenzano, Avet Harutyunyan, John Asher Johnson, Mercedes Lopez-Morales, Christophe Lovis, Michel Mayor, Giusi Micela, Emilio Molinari, Fatemeh Motalebi, David F. Phillips, Giampaolo Piotto, Didier Queloz, Ken Rice, Dimitar Sasselov, Damien Ségransan, Alessandro Sozzetti, Christopher Watson, Sarbani Basu, Tiago L. Campante, Jorgen Christensen-Dalsgaard, Steven D. Kawaler, Travis S. Metcalfe, Rasmus Handberg, Mikkel N. Lund, Mia S. Lundkvist, Daniel Huber, William J. Chaplin

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Abstract

Kepler-454 (KOI-273) is a relatively bright (V = 11.69 mag), Sun-like star that hosts a transiting planet candidate in a 10.6 day orbit. From spectroscopy, we estimate the stellar temperature to be 5687 ± 50 K, its metallicity to be [m/H] = 0.32 ± 0.08, and the projected rotational velocity to be v sin i <2.4 km s-1. We combine these values with a study of the asteroseismic frequencies from short cadence Kepler data to estimate the stellar mass to be , the radius to be 1.066 ± 0.012 Ro, and the age to be Gyr. We estimate the radius of the 10.6 day planet as 2.37 ± 0.13 R. Using 63 radial velocity observations obtained with the HARPS-N spectrograph on the Telescopio Nazionale Galileo and 36 observations made with the HIRES spectrograph at the Keck Observatory, we measure the mass of this planet to be 6.8 ± 1.4 M. We also detect two additional non-transiting companions, a planet with a minimum mass of 4.46 ± 0.12 MJ in a nearly circular 524 day orbit and a massive companion with a period >10 years and mass >12.1 MJ. The 12 exoplanets with radii ⊕ and precise mass measurements appear to fall into two populations, with those ⊕ following an Earth-like composition curve and larger planets requiring a significant fraction of volatiles. With a density of 2.76 ± 0.73 g cm-3, Kepler-454b lies near the mass transition between these two populations and requires the presence of volatiles and/or H/He gas.

Original languageEnglish
Article number95
Number of pages13
JournalAstrophysical Journal
Volume816
Issue number2
DOIs
Publication statusPublished - 14 Jan 2016

Keywords

  • asteroseismology
  • planetary systems
  • planets and satellites: composition
  • stars: individual (KOI-273 = KIC 3102384)
  • techniques: radial velocities

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

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    Gettel, S., Charbonneau, D., Dressing, C. D., Buchhave, L. A., Dumusque, X., Vanderburg, A., Bonomo, A. S., Malavolta, L., Pepe, F., Cameron, A. C., Latham, D. W., Udry, S., Marcy, G. W., Isaacson, H., Howard, A. W., Davies, G. R., Aguirre, V. S., Kjeldsen, H., Bedding, T. R., ... Chaplin, W. J. (2016). The Kepler-454 system: a small, not-rocky inner planet, a Jovian world, and a distant companion. Astrophysical Journal, 816(2), [95]. https://doi.org/10.3847/0004-637X/816/2/95