WD 2317+1830

WD 2317+1830 is a massive white dwarf with a detected lithium atmosphere, surrounded by a debris disk from which it accretes material. It is notable as one of the first white dwarfs found with lithium, whose abundance matches Big Bang nucleosynthesis and galactic nucleosynthesis. The object likely originated as a B-type star with sub-solar metallicity, and its old age and kinematics suggest thick disk or halo membership. The lithium enhancement is not consistent with accretion of terrestrial continental crust, and while accretion of an exotic exoplanet is not ruled out, accretion of a primitive planetesimal is considered more likely; an exomoon source is excluded.