PHL?5038: a spatially resolved white dwarf $mathsf{+}$ brown dwarf binary

摘要

A near-infrared excess is detected at the white dwarf PHL5038 in UKIDSS photometry, consistent with the presence of a cool, substellar companion. We have obtained H- and K-grism spectra and images of PHL5038 using NIRI on Gemini North. The target is spatially and spectrally resolved into two components: an 8000K DAwhite dwarf, and a likely L8brown dwarf companion, separated by.The spectral type of the secondary was determined using standard spectral indices for lateL and Tdwarfs. The projected orbital separation of the binary is 55AU, so it becomes only the second known wide WD+dLbinary to be found after GD165AB. This object could potentially be used as a benchmark for testing substellar evolutionary models at intermediate to older ages.Key words: white dwarfs - stars: low-mass, brown dwarfs - binaries: general - binaries: visual