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A newly discovered star is unlike any ever found. With an outermost layer of 99.9 percent pure oxygen, its atmosphere is the most oxygen-rich in the known universe. Heck, it makes Earth's meager 21 percent look downright suffocating. The strange stellar oddity is a radically new type of white dwarf star, and was discovered by a team of Brazilian astronomers led by Kepler de Souza Oliveira at the Federal University of Rio Grande do Sul in Brazil. The star is unique in the known pool of 32,000 white dwarf stars, and is the only known star of any kind with an almost pure oxygen atmosphere. The new white dwarf has a mouthful of a name—SDSSJ124043.01+671034.68—but has been nicknamed 'Dox' (pronounced Dee-Awks) by Kepler's team.
How did that happen?
Perhaps most perplexing, when oxygen atoms are found, they're spied in far heavier white dwarfs. Smaller white dwarfs evolve from smaller stars, which don't fuse together atoms into oxygen as they collapse. By all calculations, Dox would have had to be roughly double its weight to have even forged oxygen atoms in its earlier life. "You have to wonder where this oxygen even came from," says Kepler.In short, by simply being so weird, Dox completely defies our general, scientific understanding of how stars evolve and eventually form into white dwarfs. But Kepler suggests that maybe this shouldn't be all that surprising. That's because, he argues, scientists have often ignored the wacky results that can come about when stars grow and evolve while locked in a binary dance with other stars—rather than alone. "I think the main problem is that we [astronomers] have dedicated the last 50 years to calculate the evolution of stars that are not interacting with each other, when at least 30 percent of stars interact with a binary companion," he says.Kepler believes Dox looks so strange because of an unlikely binary origin-story. His rough theory goes like this:At some point Dox may have been a larger white dwarf, locked in a twirling ballet with another star much like our own Sun. These two stars were about the same distance apart as the Sun and Venus are. As Dox's dance partner started to sputter out of Hydrogen fuel, it formed what's called a red giant. It expanded rapidly—becoming so big that it actually engulfed the white dwarf in its outermost layer of gas. Kepler believes Dox would have started siphoning off the red giant's gas onto itself. At some point during that siphoning process, "when it reached a few million degrees, it exploded. That explosion threw all types of matter out. That's when [Dox] might have lost all its hydrogen and helium. This type of situation is known to have happened with other stars, although it's never been seen to leave just oxygen," he says.
How have they established - scientifically - what's contained in its atmosphere?
In almost every case, whether it is an instrument actually on the planet, or a telescope looking up from the earth, scientists use some variation of an instrument called a spectrometer. Spectrometers take a signal from whatever they are looking at (whether it is a rock, or a cloud or a whole planet or a star or a galaxy or a nebula, etc.) and spread the signal out into its components. Most spectrometers work with light and are a lot like extremely good prisms; they take the light coming from some object and separate it out into its colors. This is useful because it turns out that every element on the periodic table only gives off light of a few certain colors. So if we spread out the light coming from some object and see only certain colors, then we can match those colors to the elements that produce them. It's as if everything in the universe has a hidden fingerprint that we just need to learn how to read.
I realize stars are nuclear and not chemical reactions. Still, how does the oxygen not 'add fuel to the fire' and burn off in all the heat of fusion?
Actually, we don't 'know' that stars are nuclear objects
We have performed neutrino detection experiments that confirm that the Sun is powered by fusion.https://en.wikipedia.org/wiki/Solar_neutrino
Solar neutrino puzzle is solved?"The headline underscores a cultural problem in reporting science that leads to bald statements of “fact” when a conclusion is in fact conjectural. The detection of neutrino oscillations cannot confirm the Standard Solar model. It merely offers a possible solution to one of a number of serious observational problems with the Standard Solar model. There can be no confirmation of oscillation of neutrino flavours between the Sun and the Earth without simultaneous neutrino measurements being made near the Sun. And that poses formidable experimental problems."
