99.99% white dwarf atmosphere is pure oxygen

Astronomers first discovered a white dwarf with an outer layer containing 99.99% oxygen.

According to Science Alert, the team led by Souza Oliveira Kepler of the Federal University of Rio Grande do Sul, Brazil, observed white dwarf SDSS J124043.01 + 671034.68 (Dox ) with an external atmosphere containing more than 99, 99% oxygen. This special star contains traces of neon elements (Ne), magnesium (Mg), silicon (Si), but no hydrogen and helium at the surface. The results of the study are published in the March 31 issue of Science.

"This white dwarf surprised us. We have never seen a star like it before , " Kepler said.

Illustration a white star.(Photo: Sciencepics).

When stars are relatively small with about 10 times less mass than the Sun, they consume all the nuclear reactive fuel, they will gradually lose the outermost material and turn into white dwarfs. The heaviest elements usually fall into a dense core under the influence of gravity, while lighter components like hydrogen and helium move up to the star surface.

Dox is the only star in a total of 32,000 known white dwarfs whose atmosphere contains almost all oxygen. The team has not found the cause of lighter components such as hydrogen and helium disappearing. But according to Kepler and colleagues' hypothesis, Dox is part of the binary star system. The interaction between Dox and another star in the system causes it to lose its atmospheric composition, revealing the " oxygen " cover beneath it.

Another hypothesis involves what happens inside the star, such as a large impulse caused by the burning of carbon at the Dox's core, to the outside, causing the light particles to disappear on the surface.

The discovery of Dox helps scientists better understand stellar evolution , as well as the impact of binary star systems on the development of component stars.

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