A giant planet beyond the snow line in microlensing event OGLE-2011-BLG-0251

¹ European Southern Observatory, Karl-Schwarzschild Straße 2, 85748 Garching bei München, Germany
² Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Goleta, CA 93117, USA
³ Department of Physics, Institute for Astrophysics, Chungbuk National University, 371-763 Cheongju, Korea
⁴ Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warszawa, Poland
⁵ Divisão de Astrofisica, Instituto Nacional de Pesquisas Espeaciais, Avenida dos Astronauntas, 1758 Sao José dos Campos, 12227-010 SP, Brazil
⁶ School of Chemical and Physical Sciences, Victoria University, Wellington, New Zealand
⁷ Niels Bohr Institute, University of Copenhagen, Juliane Maries vej 30, 2100 Copenhagen, Denmark
⁸ Centre for Star and Planet Formation, Geological Museum, Øster Voldgade 5, 1350 Copenhagen, Denmark
⁹ Qatar Foundation, PO Box 5825, Doha, Qatar
¹⁰ Dipartimento di Fisica “E.R Caianiello”, Università di Salerno, via Ponte Don Melillo, 84084 Fisciano, Italy
¹¹ Istituto Nazionale di Fisica Nucleare, Sezione di Napoli, Italy
¹² SUPA School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, KY16 9SS, UK
¹³ Deutsches SOFIA Institut, Universität Stuttgart, Pfaffenwaldring 31, 70569 Stuttgart, Germany
¹⁴ SOFIA Science Center, NASA Ames Research Center, Mail Stop N211-3, Moffett Field CA 94035, USA
¹⁵ Istituto Internazionale per gli Alti Studi Scientifici (IIASS), Vietri Sul Mare ( SA), Italy
¹⁶ Institut für Astrophysik, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
¹⁷ Korea Astronomy and Space Science Institute, 305-348 Daejeon, Korea
¹⁸ National Astronomical Observatories/Yunnan Observatory, Joint laboratory for Optical Astronomy, Chinese Academy of Sciences, 650011 Kunming, PR China
¹⁹ Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Århus C, Denmark
²⁰ Armagh Observatory, College Hill, Armagh, BT61 9DG, Northern Ireland, UK
²¹ Danmarks Tekniske Universitet, Institut for Rumforskning og -teknologi, Juliane Maries Vej 30, 2100 København, Denmark
²² Jodrell Bank Centre for Astrophysics, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
²³ Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
²⁴ Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA
²⁵ Department of Physics, Sharif University of Technology, PO Box 11155–9161, Tehran, Iran
²⁶ Perimeter Institute for Theoretical Physics, 31 Caroline St. N., Waterloo ON, N2L 2Y5, Canada
²⁷ Institut d’Astrophysique et de Géophysique, Allée du 6 Août 17, Sart Tilman, Bât. B5c, 4000 Liège, Belgium
²⁸ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
²⁹ INFN, Gruppo Collegato di Salerno, Sezione di Napoli, Italy
³⁰ European Southern Observatory (ESO), Alonso de Cordova 3107, Casilla 19001, Santiago 19, Chile
³¹ Max Planck Institute for Solar System Research, Max-Planck-Str. 2, 37191 Katlenburg-Lindau, Germany
³² Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
³³ Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg (ZAH), Mönchhofstr. 12-14, 69120 Heidelberg, Germany
³⁴ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
³⁵ Alsubais Establishment for Scientific Studies, Doha, Qatar
³⁶ Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead, Wirral., CH41 1LD, UK
³⁷ School of Mathematical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UK
³⁸ Vintage Lane Observatory, 83 Vintage Lane, RD3, Blenheim, New Zealand
³⁹ Auckland Observatory, 670 Manukau Rd, Royal Oak 1023, Auckland, New Zealand
⁴⁰ Dept. of Physics and Astronomy, Texas A&M University College Station, TX 77843-4242, USA
⁴¹ Possum Observatory, Patutahi, Gisbourne, New Zealand
⁴² Farm Cove Observatory, Centre for Backyard Astrophysics, Pakuranga, Auckland, New Zealand
⁴³ Institute for Radiophysics and SpaceResearch, AUT University, Auckland, New Zealand
⁴⁴ Dept. of Astronomy and Space Science, Chungnam University, Korea
⁴⁵ Departamento de Astronomiá y Astrofísica, Universidad de Valencia, 46100 Burjassot, Valencia, Spain
⁴⁶ UPMC-CNRS, UMR7095, Institut d’Astrophysique de Paris, 98bis boulevard Arago, 75014 Paris, France
⁴⁷ University of Canterbury, Dept. of Physics and Astronomy, Private Bag 4800, 8020 Christchurch, New Zealand
⁴⁸ McDonald Observatory, 16120 St Hwy Spur 78 #2, Fort Davis, Tx 79734, USA
⁴⁹ University of the Free State, Faculty of Natural and Agricultural Sciences, Dept. of Physics, PO Box 339, 9300 Bloemfontein, South Africa
⁵⁰ School of Math and Physics, University of Tasmania, Private Bag 37, GPO Hobart, 7001 Tasmania, Australia
⁵¹ Institute of Geophysics and Planetary Physics (IGPP), L-413, Lawrence Livermore National Laboratory, PO Box 808, Livermore, CA 94551, USA
⁵² Université de Toulouse, UPS-OMP, IRAP, 31400 Toulouse, France
⁵³ CNRS, IRAP, 14 avenue Edouard Belin, 31400 Toulouse, France
⁵⁴ Physics Department, Faculty of Arts and Sciences, University of Rijeka, Omladinska 14, 51000 Rijeka, Croatia
⁵⁵ Technical University of Vienna, Department of Computing, Wiedner Hauptstrasse 10, Vienna, Austria
⁵⁶ NASA Exoplanet Science Institute, Caltech, MS 100-22, 770 S. Wilson Ave., Pasadena, CA 91125, USA
⁵⁷ Perth Observatory, Walnut Road, Bickley, 6076 Perth, Australia
⁵⁸ South African Astronomical Observatory, PO Box 9, Observatory 7935, South Africa
⁵⁹ Solar-Terrestrial Environment Laboratory, Nagoya University, 464-8601 Nagoya, Japan
⁶⁰ Dept. of Physics, University of Notre Dame, Notre Dame, IN 46556, USA
⁶¹ Institute of Information and Mathematical Sciences, Massey University, Private Bag 102-904, North Shore Mail Centre, Auckland, New Zealand
⁶² Dept. of Physics, University of Auckland, Private Bag 92019, Auckland, New Zealand
⁶³ Okayama Astrophysical Observatory, National Astronomical Observatory of Japan, Asakuchi, 719-0232 Okayama, Japan
⁶⁴ Mt. John Observatory, PO Box 56, 8770 Lake Tekapo, New Zealand
⁶⁵ Dept. of Physics, Konan University, Nishiokamoto 8-9-1, 658-8501 Kobe, Japan
⁶⁶ Nagano National College of Technology, 381-8550 Nagano, Japan
⁶⁷ Tokyo Metropolitan College of Industrial Technology, 116-8523 Tokyo, Japan
⁶⁸ Dept. of Earth and Space Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, 560-0043 Osaka, Japan
⁶⁹ Universidad de Concepción, Departamento de Astronomia, Casilla 160–C, Concepción, Chile

Received: 24 October 2012
Accepted: 1 March 2013

Abstract

Aims. We present the analysis of the gravitational microlensing event OGLE-2011-BLG-0251. This anomalous event was observed by several survey and follow-up collaborations conducting microlensing observations towards the Galactic bulge.

Methods. Based on detailed modelling of the observed light curve, we find that the lens is composed of two masses with a mass ratio q = 1.9 × 10^-3. Thanks to our detection of higher-order effects on the light curve due to the Earth’s orbital motion and the finite size of source, we are able to measure the mass and distance to the lens unambiguously.

Results. We find that the lens is made up of a planet of mass 0.53 ± 0.21 M_J orbiting an M dwarf host star with a mass of 0.26 ± 0.11 M_⊙. The planetary system is located at a distance of 2.57 ± 0.61 kpc towards the Galactic centre. The projected separation of the planet from its host star is d = 1.408 ± 0.019, in units of the Einstein radius, which corresponds to 2.72 ± 0.75 AU in physical units. We also identified a competitive model with similar planet and host star masses, but with a smaller orbital radius of 1.50 ± 0.50 AU. The planet is therefore located beyond the snow line of its host star, which we estimate to be around  ~1−1.5 AU.