Our Sun Will Become a Solid Crystal in About 10 Billion Years

Artist's impression of debris around a white dwarf star. NASA/ESA

The universe is made up of some serious bling.

Researchers at the University of Warwick have discovered the first direct evidence of whole stars solidifying into giant crystals, and it could forever change how we understand the lifecycles of stars like our sun, reports Phys.org.

The evidence, which is largely based on observations taken with the European Space Agency's Gaia satellite, focuses on observations of about 15,000 white dwarf stars. White dwarfs are what lower mass stars become once they have exhausted all their central nuclear fuel. Our sun is slated to become a white dwarf once its fuel runs dry.

Theorists predicted decades ago that as white dwarfs age, they may solidify. But finding evidence for these transitions has proven elusive, until now.

"This is the first direct evidence that white dwarfs crystallize, or transition from liquid to solid. It was predicted fifty years ago that we should observe a pile-up in the number of white dwarfs at certain luminosities and colors due to crystallization and only now this has been observed," said Dr. Pier-Emmanuel Tremblay, team leader on the study.

How the crystallization process works

The process of transforming a star into a solid crystal is similar to water turning into ice, but at much higher temperatures. For instance, white dwarfs don't start to solidify until they cool to about 10 million degrees, at which time a metallic core forms at its heart with a mantle enhanced in carbon. Our sun isn't set to undergo this process for another 10 billion years or so, but it will crystalize.

Perhaps the most profound consequence of this discovery is that it will force us to re-think the lifecycles of these stars, which is important for our larger understanding of the evolution of the cosmos because white dwarfs are often used as cosmic clocks of sorts. They can age incredibly slowly, which makes them precise gauges. For instance, researchers found that some of the stars observed in the study slowed down their aging by as much as 2 billion years, or 15 percent of the age of our galaxy.

"All white dwarfs will crystallize at some point in their evolution, although more massive white dwarfs go through the process sooner. This means that billions of white dwarfs in our galaxy have already completed the process and are essentially crystal spheres in the sky," said Tremblay.

He added: "We've made a large step forward in getting accurate ages for these cooler white dwarfs and therefore old stars of the Milky Way. Much of the credit for this discovery is down to the Gaia observations. This experiment on ultra-dense matter is something that simply cannot be performed in any laboratory on Earth."