Naked White Dwarf

Robin Leadbeater

I don’t know how it relates to the progenitor but as I understand it, naked electron degenerate white dwarfs don’t show any spectral features and there are indeed some WD like that, designated spectral type DC.  The spectral features then come from a thin skin of accreted material, the heavier elements rapidly sinking into the interior to become part of the electron degenerate material so most show just H while others have He or a mix of H/He. You do also find some cool white dwarfs with Carbon in their spectrum, presumably also recently accreted.