June 6, 2020

04.02.11: A Gravitational Lensing Exoplanet.

Amid the sexier transiting exoplanet discoveries released earlier this week by the NASA Kepler team came an exoplanet discovered by a lesser known technique; that of gravitational lensing. MOA, or Microlensing Observations for Astrophysics, is a joint Japan/New Zealand venture looking for dark matter objects passing in front of stars and bending their light via gravitational lensing. First predicted by Einstein and famously observed during the total solar eclipse of 1919, several gravitational lenses are now known and documented in nature, from stellar type objects to massive galaxy clusters.

MOA uses a series of telescopes based on all six continents to conduct observations, and very occasionally they do turn up a transiting exoplanet. The release of the latest find is MOA-2009-BLG-387lb, a 2.6 Jupiter mass world orbiting an M type dwarf star about 3.5-79 kilo-parsecs distant. This exoplanet orbits its host star in 3.8-7.6 years at a distance of 1.1-2.7 astronomical units. The discovery is unique because of the micro-lens deviations observed over a 12-day interval, one of the longest observed for a planet discovered by this method. The star-to-planet mass ratio is about 100-1, relatively large for an exo-pair. Gravitational lensing is unique method in the search for exoplanets in that unlike radial velocity and the transit method, it can work over extremely long distances, and sometimes nab worlds in more leisurely orbits. Kudos to the International MOA team, and remember that not all discoveries come from multi-million dollar space platforms!


  1. [...] This post was mentioned on Twitter by David Dickinson, enrique servin. enrique servin said: RT @Astroguyz http://bit.ly/f7G67d Update-Gravitational Lensing Exoplanet post w/pics courtesy of Microlensing Observatory for Astrophysics [...]

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