Cited by 584Stellar, planetary, and galactic studiesAstro and Planetary ScienceAstronomy and Astrophysical Research

One or more bound planets per Milky Way star from microlensing observations

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Cassan, A., Kubas, D., Beaulieu, J.-P., Dominik, M., Horne, K., Greenhill, J., Wambsganss, J., Menzies, J. +34 more·2012·Nature

Abstract

Most known extrasolar planets (exoplanets) have been discovered using the radial velocity or transit methods. Both are biased towards planets that are relatively close to their parent stars, and studies find that around 17-30% (refs 4, 5) of solar-like stars host a planet. Gravitational microlensing, on the other hand, probes planets that are further away from their stars. Recently, a population of planets that are unbound or very far from their stars was discovered by microlensing. These planets are at least as numerous as the stars in the Milky Way. Here we report a statistical analysis of microlensing data (gathered in 2002-07) that reveals the fraction of bound planets 0.5-10 AU (Sun-Earth distance) from their stars. We find that 17(+6)(-9)% of stars host Jupiter-mass planets (0.3-10 M(J), where M(J) = 318 M(⊕) and M(⊕) is Earth's mass). Cool Neptunes (10-30 M(⊕)) and super-Earths (5-10 M(⊕)) are even more common: their respective abundances per star are 52(+22)(-29)% and 62(+35)(-37)%. We conclude that stars are orbited by planets as a rule, rather than the exception.

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Authors
Cassan, A., Kubas, D., Beaulieu, J.-P., Dominik, M., Horne, K., Greenhill, J., Wambsganss, J., Menzies, J., Williams, A., Jørgensen, U. G., Udalski, A., Bennett, D. P., Albrow, M. D., Batista, V., Brillant, S., Caldwell, J. A. R., Cole, A., Coutures, C., Cook, K. H., Dieters, S., Prester, D. D., Donatowicz, J., Fouqué, P., Hill, K., Kains, N., Kane, S., Marquette, J.-B., Martin, R., Pollard, K. R., Sahu, K. C., Vinter, C., Warren, D., Watson, B., Zub, M., Sumi, T., Szymański, M. K., Kubiak, M., Poleski, R., Soszynski, I., Ulaczyk, K., Pietrzyński, G., & Wyrzykowski, Ł.
Affiliations
  • Centre National de la Recherche Scientifique (FR)
  • University of Copenhagen (DK)
  • University of Warsaw (PL)
  • University of Notre Dame (US)
  • Lawrence Livermore National Laboratory (US)
  • California Institute of Technology (US)
  • The University of Osaka (JP)
  • University of Concepción (CL)
  • University of Cambridge (GB)
Corresponding author
  • Cassan, A.
  • Cole, A.
Venue
Nature
Published
2012-01
Volume
481
Issue
7380
Pages
167-169
ISSN
  • 0028-0836 (ISSN-L)
  • 1476-4687
OpenAlex
W2119087912
Cited by
584
References
33
Citations by year
2026: 20 · 2025: 22 · 2024: 19 · 2023: 31 · 2022: 35 · 2021: 35 · 2020: 41 · 2019: 45 · 2018: 61 · 2017: 39 · 2016: 59 · 2015: 49 · 2014: 39 · 2013: 43 · 2012: 42
FWCI
29.72
Type
journal article
Language
en
Open access
Locations
  • Nature (publishedVersion)
  • PubMed (publishedVersion)
  • arXiv (Cornell University) (submittedVersion)
  • CaltechAUTHORS (California Institute of Technology) (submittedVersion)
  • eCite Digital Repository (University of Tasmania) (submittedVersion)
  • HAL (submittedVersion)
  • RePEc: Research Papers in Economics (submittedVersion)
  • Figshare (submittedVersion, cc-by)
  • Research at the University of Copenhagen (University of Copenhagen) (submittedVersion)
  • arXiv (Cornell University)
Funders
  • Science and Technology Facilities Council (ST/G001987/1)
  • Japan Society for the Promotion of Science (23340044, 23103002)
Topics
  • Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Stellar, planetary, and galactic studies
  • Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Astro and Planetary Science
  • Physical Sciences › Physics and Astronomy › Instrumentation › Astronomy and Astrophysical Research
Keywords
gravitational microlensing, exoplanets, planet occurrence rate, super-Earths, Jupiter-mass planets, Milky Way stars

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