The system belongs to only a few brown dwarf binaries that can be easily resolved by ground-based telescopes. Another example is SDSS J1416+1348.[2]
Brown dwarf system
The system consists out of a L1 primary with a mass of 72±12MJ and a T8 secondary with a mass of 34±22MJ. The brown dwarfs are separated by 341 astronomical units. Other brown dwarfs show a similar wide binary configuration, like Oph 162225-240515, but most of them are young or have a higher total mass. W2150AB is unusual as it does not show signs of youth. The age of the system was estimated between 0.5 and 10 billion years. The combination of low total mass and large separation results in a low gravitational binding energy for the system. The researchers compared the binding energy and the mass ratio of the system with other brown dwarf binaries and found 2M1101AB as a younger sibling. W2150AB must have formed like other brown dwarf binaries in a more crowded region and left this natal region surviving any interactions with nearby stars or giant molecular clouds that could easily perturb this pair, leaving only two single brown dwarfs.[2][5]
Artist's impression of the WISE 2150–7520 (W2150AB) system. The colder secondary W2150B is seen in front of the image over the Milky Way. The primary W2150A is seen as a bright star to the right of W2150B. Credit: SpaceEngine PRO, Kvasyrr
^Reid, I. Neill; Cruz, Kelle L.; Kirkpatrick, J. Davy; Allen, Peter R.; Mungall, F.; Liebert, James; Lowrance, Patrick; Sweet, Anne (September 2008). "Meeting the Cool Neighbors. X. Ultracool Dwarfs from the 2MASS All-Sky Data Release". The Astronomical Journal. 136 (3): 1290–1311. arXiv:0806.3413. Bibcode:2008AJ....136.1290R. doi:10.1088/0004-6256/136/3/1290. ISSN0004-6256.