We present an analysis and re-appraisal of the massive , carbon-enriched ( DQ ) white dwarf ( WD ) LP 93-21 .
Its high mass ( \approx 1 ~ { } M _ { \odot } ) and membership to the class of warm DQ WDs , combined with its peculiar halo kinematics suggest that this object is the product of an ancient stellar merger event , most likely that of two WDs .
Furthermore , the kinematics places this object on a highly retrograde orbit driven by the accretion of a dwarf galaxy onto the Milky Way that occurred at a red shift greater than 1.5 .
As the product of a stellar merger LP 93-21 is probably representative of the whole class of warm/hot DQ WDs .