Space Telescope Science
Two is company, but three might not always be a crowd, at least in space. When astronomers found an extrasolar planet orbiting a neighboring star, a detailed analysis of the data uncovered a third body. But astronomers couldn't definitively identify whether the object was another planet or another star in the system.
Now, nine years later, astronomers have used ultra-sharp images from the Hubble Space Telescope to determine that the system consists of a Saturn-mass planet circling two diminutive, faint stars in a tight orbit around each other. The system, called OGLE-2007-BLG-349, resides 8,000 light-years away. Astronomers teased the signature of the three objects using an observational technique called gravitational microlensing. This occurs when the gravity of a foreground star bends and amplifies the light of a background star that momentarily aligns with it. The particular character of the light magnification can reveal clues to the nature of the foreground star and any associated planets.