Billions of white dwarf stars are crystallising, say astronomers

The Sun Will Turn Into a Giant Crystal Ball After It Dies

"This is the first direct evidence that white dwarfs crystallize, or transition from liquid to solid", Dr. Pier-Emmanuel Tremblay from the University of Warwick's Department of Physics said in a statement.

One of Discover's favorite space artists and regular contributors, Mark Garlick, created this impression of a white dwarf star solidifying to accompany the announcement. The work verified earlier predictions that such a catalog of white dwarf stars would reveal a number in the slow process of turning from what is essentially a liquid form to a solid state.

These ultra-dense remnants still emit thermal radiation as they cool, and are visible to astronomers as rather faint objects.

However, this form of energy generation burns quickly and will only last for a few billion years. As the oxygen and carbon in the star crystallise, they release heat, causing the star to stall its cooling for roughly 2 billion years.

An artist's impression of some possible evolutionary pathways for stars of different initial masses. Sun-like stars swell into red giants before puffing away their outer shells into colorful nebula while their cores collapse into a white dwarf. What they found was a "pile-up", or a large group of stars at specific colors/luminosities that "do not correspond to any single mass or age".

"We saw a pile-up of white dwarfs of certain colors and luminosities that were otherwise not linked together in terms of their evolution", Dr. Tremblay explained.

Tremblay said their studies suggested that white dwarfs stop their cooling by turning from liquid to almost 99 per cent solid over about 1.5 billion years.

That, in turn, has an impact on our understanding of the stellar groupings these white dwarfs are a part of.

The team selected 15,000 white dwarf candidates that were located within 300 light-years of Earth, and analyzed their brightness and colors. The data, shown as black dots, are from the second release of ESA's Gaia satellite. But when the Sun dies, it will turn into an enormous crystal ball, according to a new study.

Just like any other fluid that solidifies in cold enough temperatures, so will those liquified nuclei will when temps in the core cool down enough and releases enough for them to crystallize. Image credit: Tremblay et al, doi: 10.1038/s41586-018-0791-x.

Have you got "space" for more out-of-this-world trivia?

Not all white dwarfs crystallise at the same pace. They are the rest of the centers of red goliaths after these colossal stars have passed on and shed their external layers and are always cooling as they discharge their accumulated warmth through the span of billions of years.

Our sun is going to turn into a crystal sphere - although we won't be around to see it, as it'll happen in ten billion years.

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