PHL 5038 : A spatially resolved white dwarf + brown dwarf binary

A near-infrared excess is detected at the white dwarf PHL 5038 in UKIDSS photometry, consistent with the presence of a cool, substellar companion. We have obtained Hand K-grism spectra and images of PHL 5038 using NIRI on Gemini North. The target is spatially and spectrally resolved into two components; an 8000 K DA white dwarf, and a likely L8 brown dwarf companion, separated by 0.94 ′′. The spectral type of the secondary was determined using standard spectral indices for late L and T dwarfs. The projected orbital separation of the binary is 55 AU, and so it becomes only the second known wide WD+dL binary to be found after GD 165AB. This object could potentially be used as a benchmark for testing substellar evolutionary models at intermediate to older ages.