A gas giant planet orbiting two stars instead of one has been spotted by NASA’s Hubble Space Telescope. The Saturn-mass planet is located 8,000 light years away in the system OGLE-2007-BLG-349.
This is the first time a planet orbiting two stars have been found using the gravitational microlensing technique. The objects were initially detected in 2007 by an international team of scientists but they were only sure about a planet and a star but could not identify the third object.
However, thanks to Hubble, the scientists realized that the starlight from this system was too faint to be a single star. Instead, they found that the brightness they detected were the same brightness expected from two closely orbiting red dwarf stars. Red dwarf stars are smaller and fainter than the sun.
“The ground-based observations suggested two possible scenarios for the three-body system: a Saturn-mass planet orbiting a close binary star pair or a Saturn-mass and an Earth-mass planet orbiting a single star,” says the study’s first author, David Bennett of the NASA Goddard Space Flight Center in Greenbelt, Maryland. He also points out, “We were helped in the analysis by the almost perfect alignment of the foreground binary stars with the background star, which greatly magnified the light and allowed us to see the signal of the two stars.”
The gas giant orbits 300 million miles or more than 480 million kilometers from the two red dwarf stars, which are seven million miles or more than 11 million kilometers from each other. The team says that it completes its orbit every seven years.
Hubble has also found 10 more planets orbiting binary stars but unlike this one, they are within a smaller distance to their stars. The research team hopes that they could find more exoplanets using the microlensing technique. This study will be published in The Astronomical Journal.