Using microlensing technology, researchers were able to find a giant planet orbiting a brown dwarf in the bulge of the Milky Way. The planet was designated as OGLE-2017-BLG-1522Lb, and it is 25% less massive than Jupiter.
The method of microlensing is based on the effect of a gravitational lens and is used to search for objects of planetary and stellar masses independently of the light they emit. Therefore, this method is attractive for finding low-mass planets rotating on a “snow line” near M-dwarfs and brown dwarfs.
The event of microlensing OGLE-2017-BLG-1522 was recorded on August 7, 2017 using the 1.3-meter telescope of the Las Campanas Observatory (Chile). An attentive review was able to notice a giant planet spinning around a brown dwarf.
Light curve OGLE-2017-BLG-1522
OGLE-2017-BLG-1522Lb is a giant with a mass of 0.75 Jupiter, circulating at a distance of 0.59 a. e. from the star. The researchers are 75% sure that the star is a brown dwarf, surpassing Jupiter in massiveness by 46 times.
The analysis also shows that the planet moves beyond the snow line — the distance where molecular species freeze and planets begin to form. It is also believed that the system is located in a galactic bulge. It is also interesting that the OGLE-2017-BLG-1522Lb may be the first planet orbiting around a brown dwarf with planetary proportions.