The 2MASS Wide-Field T Dwarf Search. V. Discovery of a T Dwarf via Methane Imaging

Abstract

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. © 2005. The American Astronomical Society. All rights reserved.