KOI-3158: The oldest known system of terrestrial-size planets

The first discoveries of exoplanets around Sun-like stars have fueled efforts to find ever smaller worlds evocative of Earth and other terrestrial planets in the Solar System. While gas-giant planets appear to form preferentially around metal-rich stars, small planets (with radii less than four Eart...

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Published in:arXiv.org 2015-01
Main Authors: Campante, T L, Barclay, T, Swift, J J, Huber, D, Adibekyan, V Zh, Cochran, W, Burke, C J, Isaacson, H, Quintana, E V, Davies, G R, V Silva Aguirre, Ragozzine, D, Riddle, R, Baranec, C, Basu, S, Chaplin, W J, Christensen-Dalsgaard, J, Metcalfe, T S, Bedding, T R, Handberg, R, Stello, D, Brewer, J M, Hekker, S, Karoff, C, Kolbl, R, Law, N M, Lundkvist, M, Miglio, A, Rowe, J F, Santos, N C, C Van Laerhoven, Arentoft, T, Elsworth, Y P, Fischer, D A, Kawaler, S D, Kjeldsen, H, Lund, M N, Marcy, G W, Sousa, S G, Sozzetti, A, White, T R
Format: Article
Language:English
Subjects:
Earth
Extrasolar planets
Galaxies
Mercury (planet)
Metallicity
Planet detection
Planet formation
Solar system
Stellar age
Stellar seismology
Terrestrial planets
Universe
Venus
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Summary:The first discoveries of exoplanets around Sun-like stars have fueled efforts to find ever smaller worlds evocative of Earth and other terrestrial planets in the Solar System. While gas-giant planets appear to form preferentially around metal-rich stars, small planets (with radii less than four Earth radii) can form under a wide range of metallicities. This implies that small, including Earth-size, planets may have readily formed at earlier epochs in the Universe's history when metals were far less abundant. We report Kepler spacecraft observations of KOI-3158, a metal-poor Sun-like star from the old population of the Galactic thick disk, which hosts five planets with sizes between Mercury and Venus. We used asteroseismology to directly measure a precise age of 11.2+/-1.0 Gyr for the host star, indicating that KOI-3158 formed when the Universe was less than 20% of its current age and making it the oldest known system of terrestrial-size planets. We thus show that Earth-size planets have formed throughout most of the Universe's 13.8-billion-year history, providing scope for the existence of ancient life in the Galaxy.
ISSN:2331-8422
DOI:10.48550/arxiv.1501.07869