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One or more bound planets per Milky Way star from microlensing observations
Open accessAbstract
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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“Gravitational microlensing results have shown that, on average, every star in the Milky Way is accompanied by at least one bound planet (Cassan et al. 2012)”
From Implications for Planetary System Formation from Interstellar Object 1I/2017 U1 (‘Oumuamua) (2017) · cites this paper as Cassan et al. 2012
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Metadata
- 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.
- ORCID
- Cassan, A.
- Beaulieu, J.-P.
- Dominik, M.
- Horne, K.
- 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.
- Cook, K. H.
- Prester, D. Dominis
- Fouqué, P.
- Kains, N.
- Kane, S.
- Marquette, J.-B.
- Pollard, K. R.
- Sahu, K. C.
- Sumi, T.
- Szymański, M. K.
- Kubiak, M.
- Poleski, R.
- Ulaczyk, K.
- Pietrzyński, G.
- Wyrzykowski, Ł.
- 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
- green
- arxiv.org
- Licence
- www.springer.com/tdm (tdm)
- 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 › Earth and Planetary Sciences › Space and Planetary Science › 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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