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Science. 2014 Jul 04;345(6192):46-9. doi: 10.1126/science.1251527.

Exoplanet detection. A terrestrial planet in a ~1-AU orbit around one member of a ~15-AU binary.

Science (New York, N.Y.)

A Gould, A Udalski, I-G Shin, I Porritt, J Skowron, C Han, J C Yee, S Kozłowski, J-Y Choi, R Poleski, Ł Wyrzykowski, K Ulaczyk, P Pietrukowicz, P Mróz, M K Szymański, M Kubiak, I Soszyński, G Pietrzyński, B S Gaudi, G W Christie, J Drummond, J McCormick, T Natusch, H Ngan, T-G Tan, M Albrow, D L DePoy, K-H Hwang, Y K Jung, C-U Lee, H Park, R W Pogge, F Abe, D P Bennett, I A Bond, C S Botzler, M Freeman, A Fukui, D Fukunaga, Y Itow, N Koshimoto, P Larsen, C H Ling, K Masuda, Y Matsubara, Y Muraki, S Namba, K Ohnishi, L Philpott, N J Rattenbury, To Saito, D J Sullivan, T Sumi, D Suzuki, P J Tristram, N Tsurumi, K Wada, N Yamai, P C M Yock, A Yonehara, Y Shvartzvald, D Maoz, S Kaspi, M Friedmann

Affiliations

  1. Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA.
  2. Warsaw University Observatory, Aleje Ujazdowskie 4, 00-478 Warszawa, Poland.
  3. Turitea Observatory, Palmerston North, New Zealand.
  4. Department of Physics, Chungbuk National University, Cheongju 371-763, Republic of Korea. [email protected].
  5. Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA.
  6. Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA. Warsaw University Observatory, Aleje Ujazdowskie 4, 00-478 Warszawa, Poland.
  7. Warsaw University Observatory, Aleje Ujazdowskie 4, 00-478 Warszawa, Poland. Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK.
  8. Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA. Universidad de Concepción, Departamento de Astronomia, Casilla 160-C, Concepción, Chile.
  9. Auckland Observatory, Auckland, New Zealand.
  10. Possum Observatory, Patutahi, New Zealand.
  11. Farm Cove Observatory, Centre for Backyard Astrophysics, Pakuranga, Auckland, New Zealand.
  12. Possum Observatory, Patutahi, New Zealand. Auckland University of Technology, Auckland, New Zealand.
  13. Perth Exoplanet Survey Telescope, Perth, Australia.
  14. Department of Physics and Astronomy, University of Canterbury, Private Bag 4800, Christchurch, New Zealand.
  15. Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843-4242, USA.
  16. Department of Physics, Chungbuk National University, Cheongju 371-763, Republic of Korea.
  17. Korea Astronomy and Space Science Institute, Daejeon 305-348, Republic of Korea.
  18. Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya 464-8601, Japan.
  19. University of Notre Dame, Department of Physics, 225 Nieuwland Science Hall, Notre Dame, IN 46556-5670, USA.
  20. Institute of Information and Mathematical Sciences, Massey University, Private Bag 102-904, North Shore Mail Centre, Auckland, New Zealand.
  21. Department of Physics, University of Auckland, Private Bag 92-019, Auckland 1001, New Zealand.
  22. Okayama Astrophysical Observatory, National Astronomical Observatory of Japan, Asakuchi, Okayama 719-0232, Japan.
  23. Department of Earth and Space Science, Osaka University, Osaka 560-0043, Japan.
  24. Department of Physics, University of Auckland, Private Bag 92-019, Auckland 1001, New Zealand. Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK.
  25. Nagano National College of Technology, Nagano 381-8550, Japan.
  26. Department of Earth, Ocean and Atmospheric Sciences, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
  27. Tokyo Metropolitan College of Aeronautics, Tokyo 116-8523, Japan.
  28. School of Chemical and Physical Sciences, Victoria University, Wellington, New Zealand.
  29. Mount John University Observatory, Post Office Box 56, Lake Tekapo 8770, New Zealand.
  30. Department of Physics, Faculty of Science, Kyoto Sangyo University, Kyoto 603-8555, Japan.
  31. School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978, Israel.

PMID: 24994642 DOI: 10.1126/science.1251527

Abstract

Using gravitational microlensing, we detected a cold terrestrial planet orbiting one member of a binary star system. The planet has low mass (twice Earth's) and lies projected at ~0.8 astronomical units (AU) from its host star, about the distance between Earth and the Sun. However, the planet's temperature is much lower, <60 Kelvin, because the host star is only 0.10 to 0.15 solar masses and therefore more than 400 times less luminous than the Sun. The host itself orbits a slightly more massive companion with projected separation of 10 to 15 AU. This detection is consistent with such systems being very common. Straightforward modification of current microlensing search strategies could increase sensitivity to planets in binary systems. With more detections, such binary-star planetary systems could constrain models of planet formation and evolution.

Copyright © 2014, American Association for the Advancement of Science.

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