Rare white dwarf discovered

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brian livesey
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Joined: Mon Jan 09, 2006 11:05 am
Location: Lancashire

Rare white dwarf discovered

Post by brian livesey »

A problem for astrophysicists studying white dwarves is that these stellar objects are shrouded in a dense atmosphere of hydrogen and helium. This prevents observation of the underlying layers of these "dead" stars.
But astronomers in Germany and Brazil have discovered a white dwarf that has no hydrogen or helium at all, thus allowing them to explore the exposed core of the star. This might provide greater insights into stellar evolution:
"We only found one, so it is a rare event. This star will provide a rare observational test of the evolutionary path towards white dwarfs," said Professor Kepler de Souza Oliveira Filho of the Federal University of Rio Grande do Sul in Brazil, who headed the study.
The white dwarf, named Dox, lies at a distance of 1,200 light years in Draco. Its atmosphere consists of 99.9 per cent oxygen.
As to why this particular white dwarf differs from others is the subject of two current theories. One theory is that Dox might have been stripped of its lighter atmospheric elements, including hydrogen and helium, by the gravity of a close star. The other possibility is that the dwarf had a final intense burning of carbon that sent out a pulse of hot gas and plasma into space, taking the lighter elements with it.
Dox was found with a 2.5 metre wide-angle optical telescope that is being used to map the universe. The research was published in the journal "Science".
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