White dwarves with oxygen

<a title=”oxygen-rich stars” href=”http://www.sciencedaily.com/releases/2009/11/091112141309.htm”><strong>Two earth-sized bodies that have oxygen in their atmospheres</strong></a> have been detected in space but they are not planets. They are dwarf stars. They are far along in the development of their nuclear furnaces. The stars are SDSS 0922+2928, 400 light years away, and SDSS 1102+2054, 220 light years away.

Sloan Digital Sky Survey spectroscopy of this inconspicuous blue object -- SDSS1102+2054 -- reveals it to be an extremely rare stellar remnant: a white dwarf with an oxygen-rich atmosphere (Credit: The Sloan Digital Sky Survey)

Notice the new catalogue numbers, from the Sloan Digital Star Survey.
<blockquote>Theoretical models suggest that massive stars (around 7 — 10 times the mass of our own Sun) will consume all of their hydrogen, helium and carbon, and end their lives either as white dwarfs with very oxygen-rich cores, or undergo a supernova and collapse into neutron stars. Finding such oxygen-rich white dwarfs would be an important confirmation of the models.</blockquote>
Usually such oxygen would be hidden by an outer layer of lighter gases, especially hydrogen and helium. <blockquote>[The] Lead author on the paper, astrophysicist Dr. Boris Gänsicke from the University of Warwick, said: “These surface abundances of oxygen imply that these are white dwarfs displaying their bare oxygen-neon cores, and that they may have descended from the most massive progenitors stars in that class.”</blockquote>


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