Astronomers have long looked at brown dwarfs for hints of planets. After all, if brown dwarfs are formed in a similar way to stars, shouldn't they at some stage possess protoplanetary disks and eventually create planets?
Recently, astronomers have spotted young brown dwarfs sporting candidate protoplanetary disks, suggesting some planet-building potential. Also, other brown dwarfs have been discovered with a large planetary mass in tow. But after analysis of the mass and orbital distance, the consensus is that these masses could actually be other, smaller brown dwarfs creating a binary system. One brown dwarf, MOA-2007-BLG-192L, is known to host a small world of approximately 3.3 times the mass of Earth, but other examples have been hard to come by.
ANALYSIS: Rogue Brown Dwarf Lurks in Our Cosmic Neighborhood
But now an international collaboration of astronomers appear to have found another likely brown dwarf exoplanet.
The Optical Gravitational Lensing Experiment (OGLE) project - a 1.3 meter telescope operated by the University of Warsaw at the Las Campanas Observatory in Chile - was monitoring a microlensing event as a brown dwarf drifted in front of a distant star. Through a quirk of Einstein's general relativity, the mass of the brown dwarf warps the spacetime around it. As the light travels from the distant star, it gets bent around the brown dwarf. If Earth is positioned just right, the geometry of this cosmic alignment has a magnifying effect, lensing the starlight for a short time. These microlensing events are very powerful for measuring the lensing object's mass and it can be used as an effective expolanet detection tool. MOA-2007-BLG-192Lb was also discovered through microlensing.