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A monastic mystery of 350 years could be due to a fusion
CV Vulpeculae, probably the first collision ever seen between a white dwarf star and a brown dwarf star
The astrophysicists finally solved a mystery that lasted nearly 350 years to discover the first documented fusion between a white dwarf star and a dwarf star.
Father Dom Anthelme, an astronomer and French monk, described a dazzling explosion in the heavens below the constellation Swan, which would have the shape of a swan, as early as 1670. Scientists have long believed that the The star of the constellation nicknamed CK Vulpeculae was a nova, a kind of star that suddenly lights up, shines for a moment before fading away.
Novas are created when two nearby stars begin to merge. The most common type, called classica novas, is between a white dwarf and a main sequence, a sub-giant or a giant red star. The white dwarf begins to suck his companion's material to create a hydrogen gas envelope around him. As it heats up, the gas reaches a temperature high enough to begin to fuse, temporarily reviving the remaining dead core.
The explosion of 1670, however, is not a classic nova, according to a group of researchers. In an article published in the Monthly Notices of the Royal Astronomical Society, the team says that the light source is actually between a white dwarf star and a brown dwarf star – the first of its kind.
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Brown dwarfs are a class of objects that are about 15 to 75 times the mass of Jupiter and are not massive enough to restart the process of fusion with hydrogen. They never reach the stage of the main sequence to become a normal star.
Exploring the observations of CK Vulpeculae with ALMA telescopes in Chile, the researchers found evidence that the star was not a typical nova. Charles Woodward, co-author of the article and professor of physics and astronomy at the University of Minnesota, compared the violent fusion with the "fusion of salsa in a blender." [without] a lid on ".
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"The white dwarf looked like the lower blades and the brown dwarf the food. He was shredded and his remains were split into two streams – like a javelin throwing from the top of your mixer as you frantically searched for the lid. "
The researchers also found traces of lithium and formaldehyde and methyl alcohol molecules produced by star collisions. A telltale sign was the amount of dust in the debris around the star.
It measured about 1% of the mass of the sun. "It's too high for a classic nova explosion and too low for more massive star fusion, as had previously been proposed," said Sumner Starrfield, co-author of the article. and professor at Arizona State University.
The remaining star always loses matter. "Such collisions could contribute to the chemical evolution of our galaxy and our universe," said Robert Gehrz, co-author of the article and professor of physics and astronomy at the University of Toronto. University of Minnesota. "The ejected material moves in space, where it is embedded in new generations of stars." ®
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