White Dwarf, Oxygen Atmosphere?

[Ray McCarthy]

Sounds mad:

The white dwarf – known as Dox – is situated about 1,200 light-years away in the constellation Draco and has an atmosphere that is 99.9 per cent oxygen.
The researchers are unsure why Dox differs from other dead stars, but they do have a couple of theories.
One possibility is that the gravitational pull of a nearby star may have stripped Dox of its lighter elements, such as hydrogen and helium.

Rare white dwarf will reveal secrets of star evolution

It ought to have a mixed Hydrogen and Helium atmosphere. Our own Yellow Dwarf is in its primary sequence, so has almost entirely Hydrogen atmosphere.

 

[Mirannan]

White dwarfs are the remnant cores of red giants, so one would expect them to have a fairly large amount of carbon and oxygen in their makeup. Which of the two predominates probably depends on the precise mass; although I'm no sort of expert, I'd expect the higher mass ones to have more oxygen because the helium fusion stage was more complete.

 

[Ray McCarthy]

White dwarfs are the remnant cores of red giants

Mostly, some are Primary sequence.

so one would expect them to have a fairly large amount of carbon and oxygen in their makeup.

Yes, usually below an outer layer of hydrogen and helium, what seems to be unusual here isn't the oxygen but that 98% of surface is oxygen, i.e. Hydrogen & Helium is less than 2%.

 

[feralreason]

Wow! Never heard of this. Hopefully Astro Physicists are actively trying to figure out why.