White dwarfs are the faint, vanishing cores of dead stars the size of Earth.They stay after
They consist of the "ashes" of thermonuclear reactions that took place in the star: oxygen, carbon, neon, and so on.Under the conditions existing in the interior of the white dwarf, these elements cannotTherefore, all that remains for such a luminary is to cool down slowly.
However, everything will change if the white dwarf significantly increases its mass.If this companion is an ordinary star, then the white dwarf will beIf it's another white dwarf, the two bodies will sooner or later collide and merge.
If the white dwarf gains weight in the first or second way and its mass exceedsa certain limit, a thermonuclear explosion awaits him.Astronomers call such events Type Ia supernova explosions.
Previous studies have suggested that all of this is only possible if the white dwarf has a nearby companion star.Otherwise, it is in danger of nothing but gradual cooling.
Now, scientists have proposed a new way for Type Ia supernovae to form.
According to astronomers' calculations, sometimes a single whitea dwarf can do without a companion to explode. Apparently, as the white dwarf cools, the substance in it from gas takes on a crystalline form. And, although the temperature is still measured in millions of degrees, it can no longer withstand the enormous pressure in the center of the former star. As a result, the heaviest elements such as uranium are the first to solidify first.
Computer simulations show a uranium crystal (orange) formed in a liquid from nuclei of carbon and oxygen (white). (Image credit: CJ Horowitz and ME Caplan)
In percentage terms, the content of such elements in the white dwarf is very small.But when all the uranium of the former star crystallizes and gathers in its center under the influence of gravity, the situation changes.The authors of the new study calculated that in some conditions, this can beA nuclear explosion similar to those found on Earth will then occur.
It is the crystallization of uranium that serves as the trigger for thermonuclear reactions.
Everything will happen like in man-made hydrogen bombs, where a small nuclear charge servesThe same process in a white dwarf is a Type Ia supernova.
The authors of the study note that so far their calculations remain hypothetical and require verification.
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