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

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

The Kepler-454 System: A Small, Not-rocky Inner Planet, a Jovian World, and a Distant Companion,
The Astrophysical Journal, Vol. 816, Issue 2


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 Min 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.

Key words: planetary systems / planets and satellites: composition / stars: individual: KOI-273 & KIC 3102384 / asteroseismology / techniques: radial velocities

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