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Crystaline White Dwarfs

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Wade Hampton III

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Crystaline White Dwarfs

PostSun Jan 13, 2019 9:58 pm

January 9, 2019, University of Warwick...
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The first direct evidence of white dwarf stars solidifying into crystals has been
discovered by astronomers at the University of Warwick, and our skies are filled
with them. Observations have revealed that dead remnants of stars like our Sun,
called white dwarfs, have a core of solid oxygen and carbon due to a phase
transition during their lifecycle similar to water turning into ice but at
much higher temperatures. This could make them potentially billions of years
older than previously thought.

Read more at: https://phys.org/news/2019-01-astronome ... s.html#jCp
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Wade Hampton III

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Re: Crystaline White Dwarfs

PostSat Jan 19, 2019 4:08 pm

Michael Soiron, PHD Physics, RWTH Aachen University
(2016) wants to know.....

If a 1 cm diameter solid diamond ball hit the earth at
99.9999999999999999999999999999999999% light speed,
what would happen to the surrounding planets?

If I count all the 9s correctly, the ball would have
an energy of 2.2*10^25 joules. About 5 petatons of
TNT equivalent. That is about the estimated energy
of the Chicxulub asteroid impact. So it would likely
trigger a mass extinction event on the Earth but have
no effect at all on other planets.

:!:
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Wade Hampton III

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Re: Crystaline White Dwarfs

PostSun Feb 03, 2019 3:18 am

In a process not unlike human aging, most stars entering the final chapter
of their lives tend to shrink, shrivel and slowly turn white. Astronomers
call these cold, dense husks of once-mighty stars white dwarfs and, unlike
humans, their dotage can last for billions of years. In that time, stars
with masses between about a tenth and eight times the mass of our sun burn
up the last of their nuclear energy, shed their fiery outer layers and dwindle
into ultracompact cores that pack about a sun's-worth of mass into a planet -
size package. While this might sound like an unglamorous ending for a star,
a new study published today (Jan. 9) in the journal Nature posits that white
dwarf-hood may be just the start of a beautiful new metamorphosis.
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Shine On!
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In a study of more than 15,000 known white dwarfs around the Milky Way, a
team of astronomers from the University of Warwick in the U.K. concluded
that dying stars don't just fizzle out of existence — they first turn into
luminous crystal orbs. "All white dwarfs will crystallize at some point
in their evolution," lead study author Pier-Emmanuel Tremblay, an astro -
physicist at the University of Warwick, said in a statement. "This means
that billions of white dwarfs in our galaxy have already completed the
process and are essentially crystal spheres in the sky." If that's accurate,
then Earth's star (Sol) itself — as well as an estimated 97 percent of stars in
the Milky Way — are also destined to end their days as crystal orbs
shimmering through the cosmos.
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Lucy
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For their new study, Tremblay and his colleagues used observations from the
European Space Agency's Gaia satellite to analyze the luminosity and colors
of about 15,000 known white dwarfs located within 300 light-years of Earth.
They saw that an excess of stars seemed to share the same luminosities and
colors, regardless of the stars' sizes and ages. The uniform appearance of
these stars suggested that the dwarfs had reached some sort of set phase
in their development, and one that could span billions of years. Using models
of star evolution, the researchers determined that these dwarfs had all
reached a phase where latent heat was being released from their cores in
large amounts, significantly slowing their cooling. And when a white dwarf
cools enough, the authors wrote, the molten liquid at its core begins to
solidify — in other words, the star begins turning to crystal.

According to Tremblay, this study provides "the first direct evidence that
white dwarfs crystallize," finally supporting a hypothesis first raised by
scientists 50 years ago. If these findings are indeed accurate, they could
give scientists reason to rethink the way they've been dating celestial
objects. Because it can take a star many billions of years to reach white
dwarf status, astronomers often use these stellar elder statesmen to come
up with date ranges for galaxies and other celestial bodies in a given
dwarf's neighborhood. According to the new study, though, the heat released
during a white dwarf's crystallization phase could slow the star's cooling
by as many as 2 billion years. If that's the case, known white dwarfs may
be billions of years older than thought. This complicates an already
mysterious chronology; scientists aren’t sure exactly how long a dying
star can remain a white dwarf before it ceases emitting light and heat
altogether, thus becoming what some researchers call a "black dwarf."
This theoretical endpoint of stellar evolution has never been observed,
as scientists think it could take a star quadrillions of years to reach
this state. At a nubile 13.8 billion years old, our universe is far too
young to host such elderly suns.

Further research is required for scientists to better understand the life
and death of the stars, and to hone their cosmic dating methods. Luckily,
thanks to the Gaia satellite's extensive observations, there's an
unprecedented number of known white dwarfs just itching to share the
tales of their long, long lives. "Before Gaia, we had 100 to 200 white
dwarfs with precise distances and luminosities," Tremblay said. "Now, we
have 200,000."
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Imagine!
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