At the end of his life, our Sun may end up as a crystal – and physicists now have observational evidence to support that theory.
Scientists have predicted that as white dwarfs cool, they can crystallize in a phase transition, something like water freezing on ice. New research from scientists in the UK, the US and Canada provides evidence of this transition in a survey of nearby white dwarfs. This is especially interesting for us because, as we report, scientists predict that the fate of our own Sun is to become a white dwarf.
White dwarfs are small, faint and incredibly dense stars, the result of stars like the sun running out of fuel that feeds their nuclear fusion. They have masses around the Sun, but they are just the size of the Earth. They consist of a dense plasma of atoms and their electrons. Electrons are prohibited from sharing exact states by the rules of quantum mechanics, so they exert pressure that prevents stars from collapsing.
Although they are plasmas, scientists have long predicted that these crushed atoms would eventually crystallize, beginning at the center of the stars. There was an indirect observation of crystallization, but scientists now claim to have observed the process directly. They describe their findings in an article published in Nature.
Models suggest that when white dwarfs crystallize, they release heat to enter the lower energy phase, the way heat energy leaves water when it freezes on ice. That would slow down the cooling of the star, an effect scientists can observe directly.
The team analyzed a catalog of 15,109 white dwarf candidates within 100 parsecs (326 light years) of our Sun using Gaia satellite data. And, in fact, they found a "heap" of stars in certain locations along a color versus brightness chart. This is evidence of stars passing through the phase transition from plasma to crystal, according to the paper.
Obviously, this depends on modeling, and perhaps other explanations may better explain the data. But it's exciting – that would imply that many white dwarfs could be older than scientists thought, since crystallization slows down the aging process.
And one day our sun can also be a beautiful crystal ball. And we'll be dead.