A Possible Brown Dwarf Companion to the White Dwarf GD 1400

An unresolved, likely L dwarf companion to the DA white dwarf GD1400 is reported. This would be only the second such system known, discovered 17 years after the prototype L dwarf, GD165B, was determined to be a companion to a white dwarf. Photometric observations and model predicted stellar parameters of the well studied white dwarf primary indicate that GD1400B has J −K � 2.0 and MK = 12.13 mag. If correct, this would place GD1400B at spectral type L6, and it would be the lowest luminosity unevolved companion known to a white dwarf, and thus a definite brown dwarf. However, a low resolution Keck NIRSPEC 2.1−2.4µm spectrum may not be consistent with known L dwarfs. Uncertainties in classification remain until the binary is resolved or a trigonometric parallax is measured. Subject headings: binaries: general—stars: low mass, brown dwarfs—stars: individual(GD1400)—white dwarfs 1.