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OGLE-2003-BLG-235/MOA 2003-BLG-53 was a gravitational microlensing event which occurred in the constellation of Sagittarius during July 2003. The event was observed both as part of the Optical Gravitational Lensing Experiment (OGLE) and by the Microlensing Observations in Astrophysics group (MOA), hence the double designation.[1] The source star in the gravitational lens is a main sequence star of spectral type G located around 8.8 kiloparsecs (29,000 light years) away in the galactic bulge. The lens star is an orange dwarf star of spectral type K, which is accompanied by a giant planet.[2]

Lens system[edit]

Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Sagittarius
Right ascension 18h 05m 16.35s[3]
Declination –28° 53′ 42.0″[3]
Apparent magnitude (V) 19.7
Spectral type K5[3]
Distance ~19000 ly
(~5800 pc)
Mass 0.63 ±0.08 M
Other designations
EWS 2003-BUL-235, MOA 2003-BUL-53, MOA 2003-BLG-53
Database references
Extrasolar Planets

OGLE-2003-BLG-235L/MOA-2003-BLG-53L is the designation given to the star in the lens system.[4] In 2004, analysis of the light curve produced as it passed in front of the source star allowed detection of an exoplanet orbiting the star with a mass 0.0039 times that of the host star (this would put it in the jovian mass range). The star was originally assumed to be a red dwarf star, since they are the most common type of star in the galaxy.[1]

By 2006, the source and lens star had moved far enough apart (as viewed from Earth) that their light could be separated. Observations by the Hubble Space Telescope revealed that in fact the lens star was actually brighter and less red than expected, matching the expected spectra for a K dwarf of about 0.63 solar masses, more massive than the average star in the galaxy.[2] This enables an estimate of the distance to the lens star, which puts it at around 5.8 kiloparsecs (19,000 light years) away.

Planetary system[edit]

The OGLE-2003-BLG-235L/MOA-2003-BLG-53L system consists of one planet as determined by the discovery team and the follow-up confirmation observations.

The OGLE-2003-BLG-235L/MOA-2003-BLG-53L planetary system[2]
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
b 2.6+0.8

See also[edit]


  1. ^ a b Bond, I. A.; et al. (2004). "OGLE 2003-BLG-235/MOA 2003-BLG-53: A Planetary Microlensing Event". The Astrophysical Journal Letters. 606 (2): L155–L158. arXiv:astro-ph/0404309Freely accessible. Bibcode:2004ApJ...606L.155B. doi:10.1086/420928. 
  2. ^ a b c Bennett, David P.; et al. (2006). "Identification of the OGLE-2003-BLG-235/MOA-2003-BLG-53 Planetary Host Star". The Astrophysical Journal Letters. 647 (2): L171–L174. arXiv:astro-ph/0606038Freely accessible. Bibcode:2006ApJ...647L.171B. doi:10.1086/507585. 
  3. ^ a b c "SIMBAD query result: NAME OGLE 2003-BLG-235 -- Star". Centre de Données astronomiques de Strasbourg. Retrieved 2009-04-30. 
  4. ^ David Bennett. "The Microlensing Planet Finder (MPF)" (PDF). Navigator Program Forum-2007: Small- and Mid-Scale Exoplanet Space Missions. 

External links[edit]

Coordinates: Sky map 18h 05m 16.35s, −28° 53′ 42.0″