How Can a Star Become a Giant Crystal?

After our sun dies, it and many other stars will eventually crystallize. Learn how astrophysicists figured this out -- and how it works -- in today's episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:02):
Welcome to brain Stuff from How Stuff Works, Hey, brain Stuff,
Lauren Vogel bomb Here. Our Sun may look like an
eternal miasma of incandescent plasma, but one day it 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

(00:22):
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. It's massive gravity crushes hydrogen atoms together in

(00:45):
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 side
as in temperature around fifteen million kelvin, producing energy that
radiates throughout the Solar system, ultimately nurturing the evolution of

(01:07):
life on a certain habitable planet. This hydrogen burning phase
of a star's life will last 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

(01:28):
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.

(01:51):
It's predicted that this will start happening in about five
billion years, marked with a sudden outbrush of energy known
as a helium flash. As the helium fuses, carbon and
oxygen are formed and the temperature of the core rises
yet again. Soon after, even heavier elements also begin to fuse,
and the Sun on the whole will start looking a
bit worse for the wear. It will begin to swell,

(02:13):
blasting into planetary space with savage solar winds that will
begin to strip away its upper layers. Though our Sun
isn't massive enough to explode as a supernova, it will
turn into a red giant star, possibly expanding beyond the
orbit of Earth. Our planet will be toast. After the
death of our star, it will leave behind whispy remains

(02:34):
of solar plasma, creating a beautiful planetary nebula, enriched with
newly formed heavy elements that will go on to create
the next generation of stars and planets, And in its
core will be a hot stellar remnant known as a
white dwarf, a tiny dense star shimmering brightly, a testament
to the Sun that used to be in its place.
White dwarfs can sustain themselves for billions of years before

(02:56):
fizzing out in dimming forever. But this isn't the end
of the story. Using observations by the European GUIA mission,
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 secret that has remained hidden
until now. Soon after forming, white dwarfs are extremely hot,

(03:19):
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 dwarves 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

(03:42):
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 dwarves 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

(04:04):
itself will become a crystal white dwarf in about ten
billion years. Tremblay's team analyzed the Gaia observations to measure
the luminosities and colors of fifteen thousand white dwarves within
three d 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

(04:26):
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 researchers found that
some of these stars had extended their lifespan by up
to two billion years. Tremblay said in the statement, this
is the first direct evidence that white dwarfs crystallize or

(04:47):
transition from liquid to solid. It was predicted fifty years
ago that we should observe a pile up in the
number of white dwarves at certain luminosities and colors due
to crystallization, and only now has this been observed. Stalized
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

(05:10):
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 was written by

(05:37):
Ian O'Neil and produced by Tyler Claying for iHeart Media
and How Stuff Works. For more on this and lots
of other shining topics, visit our home planet, how stuff
Works dot com