S. Gettel, D. Charbonneau, C. D. Dressing, L. A. Buchhave, X. Dumusque, A. Vanderburg, A. S. Bonomo, L. Malavolta, F. Pepe, A. C. Cameron, D. W. Latham, S. Udry, G. W. Marcy, H. Isaacson, A. W. Howard, G. R. Davies, V. Silva Aguirre, H. Kjeldsen, T. R. Bedding, E. Lopez, L. Affer, R. Cosentino, P. Figueira, A. F. Martinez Fiorenzano, A. Harutyunyan, J. A. Johnson, M. López-Morales, C. Lovis, M. Mayor, G. Micela, E. Molinari, F. Motalebi, D. F. Phillips, G. Piotto, D. Queloz, K. Rice, D. Sasselov, D. Ségransan, A. Sozzetti, C. A. Watson, S. Basu, T. L. Campante, J. Christensen-Dalsgaard, S. D. Kawaler, T. S. Metcalfe, R. Handberg, M. N. Lund, M. Lundkvist, D. Huber, W. J. Chaplin
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 1.028-0.03+0.04 M☉ , the radius to be 1.066 ± 0.012 R☉, and the age to be 5.25-1.39+1.41 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 <2.7 R⊕ and precise mass measurements appear to fall into two populations, with those <1.6 R⊕ 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.
Keywords
planetary systems, planets and satellites: composition, stars: individual (KOI-273 = KIC 3102384), asteroseismology, techniques: radial velocities
The Astrophysical Journal
Volume 816, Number 2
2016 January
