A Late-type L Dwarf at 11 pc Hiding in the Galactic Plane Characterized Using Gaia DR2

November 2018 • 2018ApJ...868...44F

Authors • Faherty, Jacqueline K. • Gagné, Jonathan • Burgasser, Adam J. • Mamajek, Eric E. • Gonzales, Eileen C. • Bardalez Gagliuffi, Daniella C. • Marocco, Federico

Abstract • 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.

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Federico Marocco

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