The Kepler-454 System: A Small, Not-rocky Inner Planet, a Jovian World, and a Distant Companion

• Published in: arXiv.org
• Main Authors: Gettel, Sara, Charbonneau, David, Dressing, Courtney D, Buchhave, Lars A, Dumusque, Xavier, Vanderburg, Andrew, Bonomo, Aldo S, Malavolta, Luca, Pepe, Francesco, Andrew Collier Cameron, Latham, David W, Udry, Stephane, Marcy, Geoffrey W, Isaacson, Howard, Howard, Andrew W, Davies, Guy R, Victor Silva Aguirre, Kjeldsen, Hans, Bedding, Timothy R, Lopez, Eric, Affer, Laura, Cosentino, Rosario, Figueira, Pedro, Fiorenzano, Aldo F M, Harutyunyan, Avet, John Asher Johnson, Lopez-Morales, Mercedes, Lovis, Christophe, Mayor, Michel, Micela, Giusi, Molinari, Emilio, Motalebi, Fatemeh, Phillips, David F, Piotto, Giampaolo, Queloz, Didier, Rice, Ken, Sasselov, Dimitar, Segransan, Damien, Sozzetti, Alessandro, Watson, Chris, Basu, Sarbani, Campante, Tiago L, Christensen-Dalsgaard, Jorgen, Kawaler, Steven D, Metcalfe, Travis S, Handberg, Rasmus, Lund, Mikkel N, Lundkvist, Mia S, Huber, Daniel, Chaplin, William J
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 29.11.2015
• Subjects: Earth; Extrasolar planets; Metallicity; Physics - Earth and Planetary Astrophysics; Physics - Solar and Stellar Astrophysics; Planetary composition; Populations; Radial velocity; Rotation; Spectrographs; Stellar temperature; Transit
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1511.09097

Kepler-454 (KOI-273) is a relatively bright (V = 11.69 mag), Sun-like starthat hosts a transiting planet candidate in a 10.6 d 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+0:04-0:03 M_Sun, the radius to be 1.066 +/- 0.012 R_Sun and the age to be 5.25+1:41-1:39 Gyr. We estimate the radius of the 10.6 d planet as 2.37 +/- 0.13 R_Earth. 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 Keck Observatory, we measure the mass of this planet to be 6.8 +/- 1.4M_Earth. We also detect two additional non-transiting companions, a planet with a minimum mass of 4.46 +/- 0.12 M_J in a nearly circular 524 d orbit and a massive companion with a period >10 years and mass >12.1M_J . The twelve exoplanets with radii <2.7 R_Earth and precise mass measurements appear to fall into two populations, with those <1.6 R_Earth 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.