OGLE 2003-BLG-235/MOA 2003-BLG-53: A Planetary Microlensing Event

We present observations of the unusual microlensing event OGLE 2003-BLG-235/MOA 2003-BLG-53. In this event, a short-duration (~7 days) low-amplitude deviation in the light curve due to a single-lens profile was observed in both the MOA (Microlensing Observations in Astrophysics) and OGLE (Optical Gravitational Lensing Experiment) survey observations. We find that the observed features of the light curve can only be reproduced using a binary microlensing model with an extreme (planetary) mass ratio of 0.0039 for the lensing system. If the lens system comprises a main-sequence primary, we infer that the secondary is a planet of about 1.5 Jupiter masses with an orbital radius of ~3 AU.

[1]  S. Mao,et al.  Can lensed stars be regarded as pointlike for microlensing by MACHOs , 1994 .

[2]  The Luminosity Function and Initial Mass Function in the Galactic Bulge , 1998, astro-ph/9801321.

[3]  David P. Bennett,et al.  Simulation of a Space-based Microlensing Survey for Terrestrial Extrasolar Planets , 2002 .

[4]  Extinction map of the Galactic centre: OGLE‐II Galactic bulge fields , 2003, astro-ph/0309206.

[5]  Cheongho Han Heon-Young Chang.  Direct lens imaging of Galactic bulge microlensing events , 2003 .

[6]  Andrew Gould,et al.  Proper Motions of MACHOs , 1994 .

[7]  Gilles Chabrier,et al.  The Galactic Disk Mass Function: Reconciliation of the Hubble Space Telescope and Nearby Determinations , 2003, astro-ph/0302511.

[8]  O. Shemmer,et al.  Discovery of a planet orbiting a binary star system from gravitational microlensing , 1999, Nature.

[9]  A. J. Drake,et al.  Difference Image Analysis of Galactic Microlensing. I. Data Analysis , 1999, astro-ph/9903215.

[10]  Macho,et al.  Binary Microlensing Events from the MACHO Project , 1999, astro-ph/9907369.

[11]  M. Bessell,et al.  JHKLM PHOTOMETRY: STANDARD SYSTEMS, PASSBANDS, AND INTRINSIC COLORS , 1988 .

[12]  M. Dominik,et al.  Detection of Rotation in a Binary Microlens: PLANET Photometry of MACHO 97-BLG-41* , 2000 .

[13]  David P. Bennett,et al.  Detecting Earth-Mass Planets with Gravitational Microlensing , 1996, astro-ph/9603158.

[14]  A. Gould,et al.  Statistical Determination of the MACHO Mass Spectrum , 1995, astro-ph/9504078.

[15]  Philip Yock,et al.  On Planetary Companions to the MACHO 98-BLG-35 Microlens Star , 2000 .

[16]  Bohdan Paczynski,et al.  Gravitational microlensing by double stars and planetary systems , 1991 .

[17]  R. Nemiroff,et al.  Finite source sizes and the information content of macho-type lens search light curves , 1994, astro-ph/9401005.

[18]  Y. Watase,et al.  Real-time difference imaging analysis of moa galactic bulge observations during 2000 , 2001 .

[19]  R. Paul Butler,et al.  A Pair of Resonant Planets Orbiting GJ 876 , 2001 .

[20]  T. Nakamura,et al.  Study by MOA of extrasolar planets in gravitational microlensing events of high magnification , 2001, astro-ph/0102184.

[21]  Andrew Gould,et al.  Discovering Planetary Systems through Gravitational Microlenses , 1992 .

[22]  Predicting Stellar Angular Sizes , 1999, astro-ph/9904295.

[23]  Planetary microlensing at high magnification , 2002, astro-ph/0204478.

[24]  A. Loeb,et al.  Gravitational Microlensing of Gamma-Ray Burst Afterglows by Single and Binary Stars , 2000, astro-ph/0010029.

[25]  A. Drake,et al.  Binary Microlensing Events from the MACHO Project , 2000 .

[26]  A. J. Drake,et al.  Direct detection of a microlens in the Milky Way , 2001, Nature.