2018ApJ...868...44F

We report on the characterization of a nearby (d=11.20_–0.08^+0.09 pc) ultracool L dwarf (WISE J192512.78+070038.8; hereafter W1925) identified as a faint (G = 20.038 ± 0.009) object with high proper motion (219.834 ± 1.843 mas yr^–1)in the Gaia Data Releases 1 and 2. A Palomar/TripleSpec near-infrared spectrum of W1925 confirms a photometric L7 spectral type previously estimated by Scholz & Bell, and its infrared colors and absolute magnitudes are consistent with a single object of this type. We constructed a spectral energy distribution using the Gaia parallax, literature photometry, and near-infrared spectrum and find a luminosity log(L_bol/L_☉) = -4.443 ± 0.008. Applying evolutionary models, we infer that W1925 is likely a 53 ± 18 M_Jup brown dwarf with T_eff = 1404 ± 71 K and log g = 5.1 ± 0.4 dex (cgs). While W1925 was detected in both the 2MASS and WISE infrared sky surveys, it was not detected in photographic plate sky surveys. Its combination of extreme optical-infrared colors, high proper motion, and location near the crowded Galactic plane (b = -4.°2) likely contributed to its having evaded detection in pre-Gaia surveys.