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

journal contribution
posted on 2023-05-17, 12:30 authored by Cassan, A, Kubas, D, Jean-Philippe BeaulieuJean-Philippe Beaulieu, Dominik, M, Horne, K, Greenhill, JG, Wambsganss, J, Menzies, J, Williams, A, Jorgensen, UG, Udalski, A, Bennett, DP, Albrow, MD, Batista, V, Brillant, S, Caldwell, JAR, Andrew ColeAndrew Cole, Coutures, C, Cook, KH, Dieters, S, Prester, DD, Donatowicz, J, Fouque, P, Kym HillKym Hill, Kains, N, Kane, S, Marquette, JB, Martin, R, Pollard, KR, Sahu, KC, Vinter, C, David WarrenDavid Warren, Watson, RD, Zub, M, Sumi, T, Szymanski, MK, Kubiak, M, Poleski, R, Soszynski, I, Ulaczyk, K, Pietrzynski, G, Wyrzykowski, L
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% 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 MJ,where MJ = 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.

History

Publication title

Nature

Volume

481

Issue

7380

Pagination

167-169

ISSN

0028-0836

Department/School

School of Natural Sciences

Publisher

Nature Publishing Group

Place of publication

Macmillan Building, 4 Crinan St, London, England, N1 9Xw

Rights statement

Copyright 2012 Macmillan Publishers Limited

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the physical sciences

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