2MASS J0249−0557
2MASS J0249-0557 is a binary of brown dwarfs
2MASS J0249−0557 (also known as 2MASS J02495639−0557352) is a young low-mass binary brown dwarf in the beta Pictoris moving group. It has one circumbinary planetary-mass companion, called 2MASS J0249−0557 (AB)c, or just 2MASS J0249−0557 c.
The binary
The host was discovered as a member of the 22 ±6 Myr old beta Pictoris moving group in 2017 and a spectrum shows a spectral type of M6 with very low gravity. Keck Observatory adaptive optics aperture-masking interferometry showed that the primary 2MASS J0249−0557 is a binary. The binary is separated by 2.17 ±0.22 AU. 2MASS J0249−0557A has a mass of 48+13−12 MJ and 2MASS J0249−0557B has a mass of 44+14−11 MJ, making the host a binary of two brown dwarfs.
The companion
The companion 2MASS J0249−0557 c (also known as 2MASS J02495436−0558015) was discovered in 2018 using astrometry from the Canada–France–Hawaii Telescope as a wide-separation companion, with a separation of 1950 ± 200 AU. Two near-infrared spectra were obtained. One from IRTF and the other from APO. A spectral type of L2 ±1 was assigned. Several spectral features show a low gravity, such as stronger VO and weaker FeH. The mass of the companion was estimated to be 11.6+1.3−1.0 MJ, below the deuterium burning limit. The mass ration between companion and host binary is relative high (Mcomp/Mhost≥0.1), suggesting the system formed like a stellar triple. Unusual is the large separation of 2MASS J0249−0557 c.
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