Prevalence of Earth-size planets orbiting Sun-like stars
Abstract
Determining whether Earth-like planets are common or rare looms as a touchstone in the question of life in the universe. We searched for Earth-size planets that cross in front of their host stars by examining the brightness measurements of 42,000 stars from National Aeronautics and Space Administration's Kepler mission. We found 603 planets, including 10 that are Earth size (1-2 R⊕) and receive comparable levels of stellar energy to that of Earth (0.25 – 4 F⊕). We account for Kepler's imperfect detectability of such planets by injecting synthetic planet–caused dimmings into the Kepler brightness measurements and recording the fraction detected. We find that 11 ± 4% of Sun-like stars harbor an Earth-size planet receiving between one and four times the stellar intensity as Earth. We also find that the occurrence of Earth-size planets is constant with increasing orbital period (P), within equal intervals of logP up to ∼200 d. Extrapolating, one finds 5.7^(+1.7)_(2.2)% of Sun-like stars harbor an Earth-size planet with orbital periods of 200–400 d.
Additional Information
© 2013 National Academy of Sciences. Contributed by Geoffrey W. Marcy, October 22, 2013 (sent for review October 18, 2013). Published ahead of print November 4, 2013. We acknowledge extraordinary help from Howard Isaacson, John Johnson, David Ciardi, Steve Howell, Natalie Batalha, Jon Jenkins, William Borucki, Francois Fressin, David Charbonneau, and G. Willie Torres. We extend special thanks to those of Hawaiian ancestry on whose sacred mountain of Mauna Kea we are privileged to be guests. We thank NASA Exoplanet Science Institute (NExScI) and the University of California Observatories at University of California–Santa Cruz for their administration of the Keck Observatory. Kepler was competitively selected as the 10th Discovery mission, with funding provided by National Aeronautics and Space Administration's (NASA's) Science Mission Directorate. E.A.P. gratefully acknowledges support from a National Science Foundation graduate fellowship. A.W.H. and G.W.M. gratefully acknowledge funding from NASA Grants NNX12AJ23G and NNX13AJ59G, respectively. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. The Keck Observatory was made possible by the generous financial support of the W. M. Keck Foundation. This research used resources of the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the US Department of Energy under Contract DE-AC02-05CH11231. Author contributions: E.A.P., A.W.H., and G.W.M. designed research, performed research, analyzed data, and wrote the paper. The authors declare no conflict of interest. Data deposition: The Kepler photometry is available at the Milkulski Archive for Space Telescopes (archive.stsci.edu). All spectra are available to the public on the Community Follow-up Program website (cfop.ipac.caltech.edu). This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1319909110/-/DCSupplemental. Freely available online through the PNAS open access option.Errata
The authors note that the following statement should be added as a Note Added in Proof: "Estimates of the occurrence of Earth analog planets appear in several previous works including Catanzarite and Shao (25), Traub (26), and Dong and Zhu (27). These estimates, which range from 1% to 34%, were built upon early catalogs of Kepler planet candidates (based on less than 1.3 years of photometry). These estimates did not address survey completeness with injection and recovery or uncertain stellar radii with spectroscopy." The online version has been updated to include the following three references.Attached Files
Published - pnas.201319909.pdf
Erratum - PNAS-2013--19652.pdf
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Additional details
- PMCID
- PMC3845182
- Eprint ID
- 78415
- Resolver ID
- CaltechAUTHORS:20170621-111531758
- NSF Graduate Research Fellowship
- NNX12AJ23G
- NASA
- NNX13AJ59G
- NASA
- W. M. Keck Foundation
- DE-AC02-05CH11231
- Department of Energy (DOE)
- Created
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2017-06-21Created from EPrint's datestamp field
- Updated
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2023-06-01Created from EPrint's last_modified field