Astronomers observe white dwarf stars solidifying into crystals

Mindy Sparks
January 11, 2019

For the first time astronomers have directly observed evidence of white dwarf stars solidifying into giant crystals.

Dr Pier-Emmanuel Tremblay from the University of Warwick's Department of Physics, said: "This is the first direct evidence". Using data from the ESA's Gaia satellite, an global group of researchers claim to have found evidence that supports the theory that when massive white dwarf stars like our brilliant host (the Sun) burn out and die, they solidify into metallic crystals. If you were keeping track with a thermometer, you would find that the temperature of water stalls at zero degrees Celsius for a bit - the exact time that the H20 molecules are rearranging themselves into the crystal structure of ice.

Many scientists thought it was likely that white dwarf stars would form crystals as they cooled, but there was disagreement about whether the energy released from the process would be detectable, Tremblay said. The information found a "pile-up", or a somewhat bigger number of white dwarfs with "specific colors and luminosities that do not correspond to any single mass or age".

"With Gaia we now have the distance, brightness and colour of hundreds of thousands of white dwarfs for a sizeable sample in the outer disc of the Milky Way, spanning a range of initial masses and all kinds of ages". "It is assessed that now and again these stars have slowed down their aging by as much as 2 billion years, or 15 percent of the age of our cosmic system".

The Gaia space telescope was trained by scientists on 15,000 white dwarf candidates that are around 300 light years of Earth.

"All white dwarfs will crystallize at some point in their evolution, although more massive white dwarfs go through the process sooner".

White dwarf stars start off extremely hot, but they no longer generate their own energy.

The Sun still has about five billion years before it becomes a white dwarf, and the astronomers estimate that it will take another five billion years after that to eventually cool down to a crystal sphere. Before it begins to solidify and harden gradually, the sun will turn into a red giant, and from that moment it will begin to shrink down and turn into a white dwarf.

"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. "This will push the carbon upward, and that separation will release gravitational energy". Thanks to the precise measurements that it is capable of, we have understood the interior of white dwarfs in a way that we never expected. "This experiment on ultra-dense matter is something that simply can not be performed in any laboratory on Earth".

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