We present the discovery of a T dwarf, 2MASS 2151-4853, via differential imaging through methane filters. The filters are designed to highlight the strong absorption in the H band due to methane found in the atmospheres of T dwarfs and provide a very efficient means of searching for them. Subsequent J- and H-band spectroscopy confirms 2MASS 2151-4853 as a T dwarf of type T4.5. It has an estimated spectrophotometric distance of 18 ± 3 pc and an estimated tangential velocity of v t = 50 ± 10 km s -1.
- Stars: individual (2MASS J21513839-4853542)
- Stars: low-mass, brown dwarfs