BrainStuff Classics: How Can a Star Become a Giant Crystal?

will die. This may sound like a bummer, especially for anything that's living on Earth in a few billion years, but there is a bright side to the solar doom. According to research published in the journal Nature, this very month, our dead star will leave behind a shimmering legacy. It'll turn into a massive crystal. Before we start talking about supersized stellar crystals, we first need to understand how stars like our Sun live and die. The Sun is fueled

by nuclear fusion. Its massive gravity crushes hydrogen atoms together in its core to create helium, and the vast quantities of energy released by these fusion processes push outward, maintaining a happy equilibrium so long as there's plenty of hydrogen fuel feeding this process, the core remains about the same size and temperature around fifteen million kelvin, producing energy that radiates throughout the Solar system, ultimately nurturing the evolution of

life on a certain habitable planet. This hydrogen burning phase of a star's life will last for ninety percent of the lifetime of our Sun. The period of stellar life is known as the main sequence. We're currently about four point five billion years into our Sun's main sequence days, or approximately halfway through its life. So what happens when that hydrogen is all used up? Things start to get

a little wild, to put it mildly. Without the outward pressure of the energy created by fusing hydrogen, the Sun's gravity overwhelms the core, crushing it into a smaller space and boosting its temperature tenfold. That's okay, though, the heavier helium nuclei will begin to fuse together, creating the outward pressure once again to maintain equilibrium. It's predicted that this will start happening in about five billion years, marked with a sudden outrush of energy known as a helium flash.

Our planet will be toast. After the death of our star, it will leave behind wispy remains of solar plasma, creating a beautiful planetary nebula enriched with newly formed heavy elements.

Using observations by the European Gay Emission, which is currently making precision measurements of stars throughout our galaxy, Researchers at the University of Warwick in the UK have stumbled on a white dwarf's secret that has remained hidden until now. Soon after forming, white dwarfs are extremely hot, radiating the intense energy that was once held in the core of the main sequence star that came before them. Over billions

of years. After forming, white dwarfs slowly cool and at a certain point, the oxygen and carbon they contain will go through a phase transition akin to liquid water freezing and turning into solid ice, only at much more extreme temperatures and pressures, and they'll solidify to form a huge crystal. Pierre Emmanuel Tremblay, from the University of Warwick's Department of Physics and leader of the study, said in a press release.

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. The sum itself will become a crystal

white dwarf in about ten billion years. Tremblay's team analyzed the Gaya observations to measure the luminosities and colors of fifteen thousand white dwarfs within three hundred light years of Earth. What they found was an excess in the population of

stars of specific colors and brightness. They realized that this group of stars represented a similar phase instellar evolution, where the conditions are right for this phase transition to occur, causing a delay in cooling, thus slowing down the aging process. The researcherch found that some of these stars had extended their lifespan by up to two billion year. Trembly said in the statement, 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 in certain luminosities and colors due to crystallization, and only now has this been observed. Crystallized white dwarfs aren't just a stellar curiosity. Their quantum makeup is unlike anything we can recreate in

the laboratory. As the white star material crystallizes, its material becomes ordered on a quantum level, nuclei aligning themselves in a complex lattice with a metallic oxygen core and an outer layer enriched with carbon. So it turns out that after stars like our sun die, their stories aren't over All. White dwarfs will go through this crystallization process, littering the

galaxy with massive diamond like stellar remnants. Today's episode is based on the article After the Sun does, It'll become a stellar crystal on HowStuffWorks.