Scientists using the Hubble Space Telescope have identified an unusual planet that revolves around two stars at once, being very far from the latter.
The OGLE-2007-BLG-349 star system, located at a distance of 8 thousand light years from Earth, was discovered back in 2007. However, right now, scientists were able to unravel one of its main secrets. Initial observations indicated that the system could include one planet and two stars, or one star and two planets. As it turned out, the system contains two red dwarfs, as well as the planet OGLE-2007-BLG-349 (AB) b, which revolves around them. Note that the two luminaries are located at a distance of only 11 million km from each other.
The size of the planet can be compared to the size of Saturn: it orbits at a distance of 482 million km from a pair of stars: this is comparable to the distance separating the Sun and the asteroid belt. OGLE-2007-BLG-349 (AB) b takes seven years to complete one revolution around a stellar pair.
The planet was discovered by gravitational microlensing. The latter occurs when the gravitational field of a closer star magnifies light from a distant star, acting as a lens. In the event that a foreground star has a planet, the latter's own gravitational field can make a significant contribution to the lensing effect. This method has one drawback: it can only be used when both stars are precisely aligned along a straight line.
The new discovery is of great value for science: it is expected that it will help to better understand the mechanism of formation and evolution of planets in such systems as OGLE-2007-BLG-349.
Planets located in binary star systems are divided by scientists into two categories: exoplanets orbiting one of the components of the binary star, and planets orbiting both components (as in the case of OGLE-2007-BLG-349 (AB) b.
Ilya Vedmedenko