Discovery of a Uniquely Cool and Compact Source at 28 pc from the Sun

Abstract

We present the discovery of what appears to be both a uniquely cool and old white dwarf (WD) within 30 pc of the Sun. DES J214756.46-403529.3 is detected in four separate surveys, 50° away from the Galactic Plane. The combination of its very low luminosity and spectral energy distribution suggests an object unlike any other astrophysical body currently known. Among 8000 of the nearest single objects in the immediate solar neighborhood, it appears completely isolated in multiple color–magnitude diagrams. The data seem compatible with an extremely old and cool WD with a helium dominated atmosphere and a mass around 0.7–0.8 M⊙ but spectroscopic follow-up is required to confirm its nature.