Movatterモバイル変換

[0]ホーム
URL:

Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Advertisement

Nature
  • Letter
  • Published:

Discovery of a cool planet of 5.5 Earth masses through gravitational microlensing

Naturevolume 439, pages437–440 (2006)Cite this article

Abstract

In the favoured core-accretion model of formation of planetary systems, solid planetesimals accumulate to build up planetary cores, which then accrete nebular gas if they are sufficiently massive. Around M-dwarf stars (the most common stars in our Galaxy), this model favours the formation of Earth-mass (M⊕) to Neptune-mass planets with orbital radii of 1 to 10 astronomical units (au), which is consistent with the small number of gas giant planets known to orbit M-dwarf host stars1,2,3,4. More than 170 extrasolar planets have been discovered with a wide range of masses and orbital periods, but planets of Neptune's mass or less have not hitherto been detected at separations of more than 0.15 au from normal stars. Here we report the discovery of aM⊕ planetary companion at a separation ofau from aM⊙ M-dwarf star, whereM⊙ refers to a solar mass. (We propose to name it OGLE-2005-BLG-390Lb, indicating a planetary mass companion to the lens star of the microlensing event.) The mass is lower than that of GJ876d (ref.5), although the error bars overlap. Our detection suggests that such cool, sub-Neptune-mass planets may be more common than gas giant planets, as predicted by the core accretion theory.

This is a preview of subscription content,access via your institution

Access options

Access through your institution

Subscription info for Japanese customers

We have a dedicated website for our Japanese customers. Please go tonatureasia.com to subscribe to this journal.

Buy this article

  • Purchase on SpringerLink
  • Instant access to the full article PDF.

￥ 4,980

Prices may be subject to local taxes which are calculated during checkout

Figure 1:The observed light curve of the OGLE-2005-BLG-390 microlensing event and best-fit model plotted as a function of time.
Figure 2:Bayesian probability densities for the properties of the planet and its host star.

Similar content being viewed by others

References

  1. Safronov, V.Evolution of the Protoplanetary Cloud and Formation of the Earth and Planets (Nauka, Moscow, 1969)

    Google Scholar 

  2. Wetherill, G. W. Formation of the terrestrial planets.Annu. Rev. Astron. Astrophys18, 77–113 (1980)

    Article ADS CAS  Google Scholar 

  3. Laughlin, G., Bodenheimer, P. & Adams, F. C. The core accretion model predicts few jovian-mass planets orbiting red dwarfs.Astrophys. J.612, L73–L76 (2004)

    Article ADS  Google Scholar 

  4. Ida, S. & Lin, D. N. C. Toward a deterministic model of planetary formation. II. The formation and retention of gas giant planets around stars with a range of metallicities.Astrophys. J.616, 567–572 (2004)

    Article ADS  Google Scholar 

  5. Rivera, E. et al. A∼7.5 Earth-mass planet orbiting the nearby star, GJ 876.Astrophys. J. (in the press)

  6. Mao, S. & Paczynski, B. Gravitational microlensing by double stars and planetary systems.Astrophys. J.374, L37–L40 (1991)

    Article ADS  Google Scholar 

  7. Gould, A. & Loeb, A. Discovering planetary systems through gravitational Microlenses.Astrophys. J.396, 104–114 (1992)

    Article ADS  Google Scholar 

  8. Wambsganss, J. Discovering Galactic planets by gravitational microlensing: magnification patterns and light curves.Mon. Not. R. Astron. Soc.284, 172–188 (1997)

    Article ADS  Google Scholar 

  9. Griest, K. & Safizadeh, N. The use of high-magnification microlensing events in discovering extrasolar planets.Astrophys. J.500, 37–50 (1998)

    Article ADS  Google Scholar 

  10. Bennett, D. P. & Rhie, S. H. Detecting Earth-mass planets with gravitational microlensing.Astrophys. J.472, 660–664 (1996)

    Article ADS  Google Scholar 

  11. Bennett, D. P. & Rhie, S. H. Simulation of a space-based microlensing survey for terrestrial extrasolar planets.Astrophys. J.574, 985–1003 (2002)

    Article ADS  Google Scholar 

  12. Albrow, M. et al. The 1995 pilot campaign of PLANET: searching for microlensing anomalies through precise, rapid, round-the-clock monitoring.Astrophys. J.509, 687–702 (1998)

    Article ADS  Google Scholar 

  13. Bond, I. A. et al. OGLE 2003-BLG-235/MOA 2003-BLG-53: A planetary microlensing event.Astrophys. J.606, L155–L158 (2004)

    Article ADS  Google Scholar 

  14. Udalski, A. et al. A jovian-mass planet in microlensing event OGLE-2005-BLG-071.Astrophys. J.628, L109–L112 (2005)

    Article ADS  Google Scholar 

  15. Gaudi, B. S. et al. Microlensing constraints on the frequency of Jupiter-mass companions: analysis of 5 years of PLANET photometry.Astrophys. J.566, 463–499 (2002)

    Article ADS  Google Scholar 

  16. Abe, F. et al. Search for low-mass exoplanets by gravitational microlensing at high magnification.Science305, 1264–1267 (2004)

    Article ADS CAS  Google Scholar 

  17. Dong, S. et al. Planetary detection efficiency of the magnification 3000 microlensing event OGLE-2004-BLG-343.Astrophys. J. (submitted); preprint athttp://arXiv.org/astro-ph/0507079 (2005)

  18. Udalski, A. The optical gravitational lensing experiment. real time data analysis systems in the OGLE-III survey.Acta Astron.53, 291–305 (2003)

    ADS  Google Scholar 

  19. Alard, C. Image subtraction using a space-varying kernel.Astron. Astrophys. Suppl.144, 363–370 (2000)

    Article ADS  Google Scholar 

  20. Kervella, P. et al. Cepheid distances from infrared long-baseline interferometry. III. Calibration of the surface brightness-color relations.Astron. Astrophys.428, 587–593 (2004)

    Article ADS CAS  Google Scholar 

  21. Claret, A., Diaz-Cordoves, J. & Gimenez, A. Linear and non-linear limb-darkening coefficients for the photometric bands R I J H K.Astron. Astrophys. Suppl.114, 247–252 (1995)

    ADS  Google Scholar 

  22. Gaudi, B. S. Distinguishing between binary-source and planetary microlensing perturbations.Astrophys. J.506, 533–539 (1998)

    Article ADS  Google Scholar 

  23. Dominik, M. Stochastical distributions of lens and source properties for observed galactic microlensing events.Mon. Not. R. Astron. Soc. (submitted); preprint athttp://arXiv.org/astro-ph/0507540 (2005)

  24. Vogt, S. S. et al. Five new multicomponent planetary systems.Astrophys. J.632, 638–658 (2005)

    Article ADS CAS  Google Scholar 

  25. Mayor, M. et al. The CORALIE survey for southern extrasolar planets. XII. Orbital solutions for 16 extrasolar planets discovered with CORALIE.Astron. Astrophys.415, 391–402 (2004)

    Article ADS CAS  Google Scholar 

  26. Borucki, W. et al. inSecond Eddington Workshop: Stellar Structure and Habitable Planet Finding (eds Favata, F., Aigrain, S. & Wilson, A.) 177–182 (ESA SP-538, ESA Publications Division, Noordwijk, 2004)

    Google Scholar 

  27. Moutou, C. et al. Comparative blind test of five planetary transit detection algorithms on realistic synthetic light curves.Astron. Astrophys.437, 355–368 (2005)

    Article ADS  Google Scholar 

  28. Sozzeti, A. et al. Narrow-angle astrometry with the space interferometry mission: the search for extrasolar planets. I. Detection and characterization of single planets.Pub. Astron. Soc. Pacif.114, 1173–1196 (2002)

    Article ADS  Google Scholar 

  29. Bennett, D. P. inASP Conf. Ser. on Extrasolar Planets: Today and Tomorrow (eds Beaulieu, J.-P., Lecavelier des Etangs, A. & Terquem, C.)Vol. 321, 59–68 (ASP, 2004)

    Google Scholar 

  30. Beaulieu, J. P. et al. PLANET III: searching for Earth-mass planets via microlensing from Dome C?ESA Publ. Ser.14, 297–302 (2005)

    Article  Google Scholar 

Download references

Acknowledgements

PLANET is grateful to the observatories that support our science (the European Southern Observatory, Canopus, Perth; and the South African Astronomical Observatory, Boyden, Faulkes North) and to the ESO team in La Silla for their help in maintaining and operating the Danish telescope. Support for the PLANET project was provided by CNRS, NASA, the NSF, the LLNL/NNSA/DOE, PNP, PICS France-Australia, D. Warren, the DFG, IDA and the SNF. RoboNet is funded by the UK PPARC and the FTN was supported by the Dill Faulkes Educational Trust. Support for the OGLE project, conducted at Las Campanas Observatory (operated by the Carnegie Institution of Washington), was provided by the Polish Ministry of Science, the Foundation for Polish Science, the NSF and NASA. The MOA collaboration is supported by MEXT and JSPS of Japan, and the Marsden Fund of New Zealand.

Author information

Authors and Affiliations

  1. PLANET/RoboNet Collaboration,

    J.-P. Beaulieu, D. P. Bennett, P. Fouqué, A. Williams, M. Dominik, U. G. Jørgensen, D. Kubas, A. Cassan, C. Coutures, J. Greenhill, K. Hill, J. Menzies, P. D. Sackett, M. Albrow, S. Brillant, J. A. R. Caldwell, J. J. Calitz, K. H. Cook, E. Corrales, M. Desort, S. Dieters, D. Dominis, J. Donatowicz, M. Hoffman, S. Kane, J.-B. Marquette, R. Martin, P. Meintjes, K. Pollard, K. Sahu, C. Vinter, J. Wambsganss, K. Woller, K. Horne, I. Steele, D. M. Bramich, M. Burgdorf, C. Snodgrass & M. Bode

  2. OGLE Collaboration,

    A. Udalski, M. K. Szymański, M. Kubiak, T. Wiȩckowski, G. Pietrzyński, I. Soszyński, O. Szewczyk, Ł. Wyrzykowski & B. Paczyński

  3. MOA Collaboration,

    D. P. Bennett, F. Abe, I. A. Bond, T. R. Britton, A. C. Gilmore, J. B. Hearnshaw, Y. Itow, K. Kamiya, P. M. Kilmartin, A. V. Korpela, K. Masuda, Y. Matsubara, M. Motomura, Y. Muraki, S. Nakamura, C. Okada, K. Ohnishi, N. J. Rattenbury, T. Sako, S. Sato, M. Sasaki, T. Sekiguchi, D. J. Sullivan, P. J. Tristram, P. C. M. Yock & T. Yoshioka

  4. Institut d'Astrophysique de Paris, CNRS, Université Pierre et Marie Curie UMR7095, 98bis Boulevard Arago, 75014, Paris, France

    J.-P. Beaulieu, A. Cassan, E. Corrales, M. Desort & J.-B. Marquette

  5. Department of Physics, University of Notre Dame, Indiana, 46556-5670, Notre Dame, USA

    D. P. Bennett

  6. Observatoire Midi-Pyrénées, Laboratoire d'Astrophysique, UMR 5572, Université Paul Sabatier—Toulouse 3, 14 avenue Edouard Belin, 31400, Toulouse, France

    P. Fouqué

  7. Perth Observatory, Walnut Road, Bickley, WA 6076, Perth, Australia

    A. Williams & R. Martin

  8. Scottish Universities Physics Alliance, University of St Andrews, School of Physics and Astronomy, North Haugh, KY16 9SS, St Andrews, UK

    M. Dominik, K. Horne & D. M. Bramich

  9. Niels Bohr Institutet, Astronomisk Observatorium, Juliane Maries Vej 30, 2100, København Ø, Denmark

    U. G. Jørgensen, C. Vinter & K. Woller

  10. European Southern Observatory, Casilla 19001, 19, Santiago, Chile

    D. Kubas & S. Brillant

  11. CEA DAPNIA/SPP Saclay, 91191, Gif-sur-Yvette cedex, France

    C. Coutures

  12. University of Tasmania, School of Mathematics and Physics, Private Bag 37, TAS 7001, Hobart, Australia

    J. Greenhill, K. Hill & S. Dieters

  13. South African Astronomical Observatory, PO Box 9, Observatory, 7935, South Africa

    J. Menzies

  14. Research School of Astronomy and Astrophysics, Australian National University, Mt Stromlo Observatory, Weston Creek, ACT 2611, Australia

    P. D. Sackett

  15. Department of Physics and Astronomy, University of Canterbury, Private Bag 4800, 8020, Christchurch, New Zealand

    M. Albrow, K. Pollard, T. R. Britton, A. C. Gilmore, J. B. Hearnshaw & P. M. Kilmartin

  16. McDonald Observatory, 16120 St Hwy Spur 78 #2, Texas, 79734, Fort Davis, USA

    J. A. R. Caldwell

  17. Department of Physics, Boyden Observatory, University of the Free State, PO Box 339, 9300, Bloemfontein, South Africa

    J. J. Calitz & P. Meintjes

  18. Lawrence Livermore National Laboratory, IGPP, PO Box 808, California, 94551, Livermore, USA

    K. H. Cook

  19. Institut für Physik, Universität Potsdam, Am Neuen Palais 10, 14469, Potsdam

    D. Dominis & M. Hoffman

  20. Astrophysikalisches Institut Potsdam, An der Sternwarte 16, D-14482, Potsdam, Germany

    D. Dominis & M. Hoffman

  21. Technische Universität Wien, Wiedner Hauptstrasse 8 / 020 B.A., 1040, Wien, Austria

    J. Donatowicz

  22. Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Florida, 32611-2055, Gainesville, USA

    S. Kane

  23. Space Telescope Science Institute, 3700 San Martin Drive, Maryland, 21218, Baltimore, USA

    K. Sahu

  24. Astronomisches Rechen-Institut (ARI), Zentrum für Astronomie, Universität Heidelberg, Mönchhofstrasse 12–14, 69120, Heidelberg, Germany

    J. Wambsganss

  25. Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, CH41 1LD, Birkenhead, UK

    I. Steele, D. M. Bramich, M. Burgdorf & M. Bode

  26. Astronomy and Planetary Science Division, Department of Physics, Queen's University Belfast, Belfast, UK

    C. Snodgrass

  27. Obserwatorium Astronomiczne Uniwersytetu Warszawskiego, Aleje Ujazdowskie 4, 00-478, Warszawa, Poland

    A. Udalski, M. K. Szymański, M. Kubiak, T. Wiȩckowski, G. Pietrzyński, I. Soszyński, O. Szewczyk & Ł. Wyrzykowski

  28. Departamento de Fisica, Universidad de Concepcion, Casilla 160–C, Concepcion, Chile

    G. Pietrzyński & I. Soszyński

  29. Jodrell Bank Observatory, The University of Manchester, Cheshire, SK11 9DL, Macclesfield, UK

    Ł. Wyrzykowski & N. J. Rattenbury

  30. Princeton University Observatory, Peyton Hall, New Jersey, 08544, Princeton, USA

    B. Paczyński

  31. Solar-Terrestrial Environment Laboratory, Nagoya University, 464-860, Nagoya, Japan

    F. Abe, Y. Itow, K. Kamiya, K. Masuda, Y. Matsubara, M. Motomura, Y. Muraki, S. Nakamura, C. Okada, T. Sako, M. Sasaki, T. Sekiguchi & T. Yoshioka

  32. Institute for Information and Mathematical Sciences, Massey University, Private Bag 102-904, Auckland, New Zealand

    I. A. Bond

  33. Department of Physics, University of Auckland, Private Bag 92019, Auckland, New Zealand

    T. R. Britton, P. J. Tristram & P. C. M. Yock

  34. School of Chemical and Physical Sciences, Victoria University, PO Box 600, Wellington, New Zealand

    A. V. Korpela & D. J. Sullivan

  35. Nagano National College of Technology, 381-8550, Nagano, Japan

    K. Ohnishi

  36. Department of Astrophysics, Faculty of Science, Nagoya University, 464-860, Nagoya, Japan

    S. Sato

Authors
  1. J.-P. Beaulieu
  2. D. P. Bennett
  3. P. Fouqué
  4. A. Williams
  5. M. Dominik
  6. U. G. Jørgensen
  7. D. Kubas
  8. A. Cassan
  9. C. Coutures
  10. J. Greenhill
  11. K. Hill
  12. J. Menzies
  13. P. D. Sackett
  14. M. Albrow
  15. S. Brillant
  16. J. A. R. Caldwell
  17. J. J. Calitz
  18. K. H. Cook
  19. E. Corrales
  20. M. Desort
  21. S. Dieters
  22. D. Dominis
  23. J. Donatowicz
  24. M. Hoffman
  25. S. Kane
  26. J.-B. Marquette
  27. R. Martin
  28. P. Meintjes
  29. K. Pollard
  30. K. Sahu
  31. C. Vinter
  32. J. Wambsganss
  33. K. Woller
  34. K. Horne
  35. I. Steele
  36. D. M. Bramich
  37. M. Burgdorf
  38. C. Snodgrass
  39. M. Bode
  40. A. Udalski
  41. M. K. Szymański
  42. M. Kubiak
  43. T. Wiȩckowski
  44. G. Pietrzyński
  45. I. Soszyński
  46. O. Szewczyk
  47. Ł. Wyrzykowski
  48. B. Paczyński
  49. F. Abe
  50. I. A. Bond
  51. T. R. Britton
  52. A. C. Gilmore
  53. J. B. Hearnshaw
  54. Y. Itow
  55. K. Kamiya
  56. P. M. Kilmartin
  57. A. V. Korpela
  58. K. Masuda
  59. Y. Matsubara
  60. M. Motomura
  61. Y. Muraki
  62. S. Nakamura
  63. C. Okada
  64. K. Ohnishi
  65. N. J. Rattenbury
  66. T. Sako
  67. S. Sato
  68. M. Sasaki
  69. T. Sekiguchi
  70. D. J. Sullivan
  71. P. J. Tristram
  72. P. C. M. Yock
  73. T. Yoshioka

Corresponding author

Correspondence toJ.-P. Beaulieu.

Ethics declarations

Competing interests

The photometric data set is available atplanet.iap.fr andogle.astrouw.edu.pl Reprints and permissions information is available atnpg.nature.com/reprintsandpermissions. The authors declare no competing financial interests.

Rights and permissions

About this article

Cite this article

Beaulieu, JP., Bennett, D., Fouqué, P.et al. Discovery of a cool planet of 5.5 Earth masses through gravitational microlensing.Nature439, 437–440 (2006). https://doi.org/10.1038/nature04441

Download citation

Access through your institution
Buy or subscribe

Editorial Summary

Found worlds

Over 170 extrasolar planets have so far been discovered, with a wide range of masses and orbital periods, but until last July no planet of Neptune's mass or less had been detected any more than 0.15 astronomical units (AU) from a normal star. (That's close — Earth is oneAU from the Sun). On 11 July 2005 the OGLE Early Warning System recorded a notable event: gravitational lensing of light from a distant object by a foreground star revealed a small planet of about 5.5 Earth masses, orbiting at about 2.6AU from the foreground star. This is the lowest known mass for an extrasolar planet orbiting a main sequence star, and its detection suggests that cool, sub-Neptune mass planets are more common than gas giants, as predicted by the favoured core accretion theory of planet formation.

Associated content

Light through a gravitational lens

  • Didier Queloz
NatureNews & Views

Advertisement

Search

Advanced search

Quick links

Nature Briefing

Sign up for theNature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox.Sign up for Nature Briefing
[8]ページ先頭
©2009-2026 Movatter.jp