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All the Diamonds one could fill your house with - and more - so near...yet so far.....
  
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Peter Lemkin




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PostPosted: Jul 17, 2018 05:50    Post subject: All the Diamonds one could fill your house with - and more - so near...yet so far.....  

There may be more than a quadrillion tons of diamond hidden in the Earth's interior, according to a new study from MIT and other universities. But the new results are unlikely to set off a diamond rush. The scientists estimate the precious minerals are buried more than 100 miles below the surface, far deeper than any drilling expedition has ever reached.

The ultradeep cache may be scattered within cratonic roots -- the oldest and most immovable sections of rock that lie beneath the center of most continental tectonic plates. Shaped like inverted mountains, cratons can stretch as deep as 200 miles through the Earth's crust and into its mantle; geologists refer to their deepest sections as "roots."

In the new study, scientists estimate that cratonic roots may contain 1 to 2 percent diamond. Considering the total volume of cratonic roots in the Earth, the team figures that about a quadrillion (1016) tons of diamond are scattered within these ancient rocks, 90 to 150 miles below the surface.

"This shows that diamond is not perhaps this exotic mineral, but on the [geological] scale of things, it's relatively common," says Ulrich Faul, a research scientist in MIT's Department of Earth, Atmospheric, and Planetary Sciences. "We can't get at them, but still, there is much more diamond there than we have ever thought before."

Faul's co-authors include scientists from the University of California at Santa Barbara, the Institut de Physique du Globe de Paris, the University of California at Berkeley, Ecole Polytechnique, the Carnegie Institution of Washington, Harvard University, the University of Science and Technology of China, the University of Bayreuth, the University of Melbourne, and University College London.

A sound glitch

Faul and his colleagues came to their conclusion after puzzling over an anomaly in seismic data. For the past few decades, agencies such as the United States Geological Survey have kept global records of seismic activity -- essentially, sound waves traveling through the Earth that are triggered by earthquakes, tsunamis, explosions, and other ground-shaking sources. Seismic receivers around the world pick up sound waves from such sources, at various speeds and intensities, which seismologists can use to determine where, for example, an earthquake originated.

Scientists can also use this seismic data to construct an image of what the Earth's interior might look like. Sound waves move at various speeds through the Earth, depending on the temperature, density, and composition of the rocks through which they travel. Scientists have used this relationship between seismic velocity and rock composition to estimate the types of rocks that make up the Earth's crust and parts of the upper mantle, also known as the lithosphere.

However, in using seismic data to map the Earth's interior, scientists have been unable to explain a curious anomaly: Sound waves tend to speed up significantly when passing through the roots of ancient cratons. Cratons are known to be colder and less dense than the surrounding mantle, which would in turn yield slightly faster sound waves, but not quite as fast as what has been measured.

"The velocities that are measured are faster than what we think we can reproduce with reasonable assumptions about what is there," Faul says. "Then we have to say, 'There is a problem.' That's how this project started."

Diamonds in the deep

The team aimed to identify the composition of cratonic roots that might explain the spikes in seismic speeds. To do this, seismologists on the team first used seismic data from the USGS and other sources to generate a three-dimensional model of the velocities of seismic waves traveling through the Earth's major cratons.

Next, Faul and others, who in the past have measured sound speeds through many different types of minerals in the laboratory, used this knowledge to assemble virtual rocks, made from various combinations of minerals. Then the team calculated how fast sound waves would travel through each virtual rock, and found only one type of rock that produced the same velocities as what the seismologists measured: one that contains 1 to 2 percent diamond, in addition to peridotite (the predominant rock type of the Earth's upper mantle) and minor amounts of eclogite (representing subducted oceanic crust). This scenario represents at least 1,000 times more diamond than people had previously expected.

"Diamond in many ways is special," Faul says. "One of its special properties is, the sound velocity in diamond is more than twice as fast as in the dominant mineral in upper mantle rocks, olivine."

The researchers found that a rock composition of 1 to 2 percent diamond would be just enough to produce the higher sound velocities that the seismologists measured. This small fraction of diamond would also not change the overall density of a craton, which is naturally less dense than the surrounding mantle.

"They are like pieces of wood, floating on water," Faul says. "Cratons are a tiny bit less dense than their surroundings, so they don't get subducted back into the Earth but stay floating on the surface. This is how they preserve the oldest rocks. So we found that you just need 1 to 2 percent diamond for cratons to be stable and not sink."

In a way, Faul says cratonic roots made partly of diamond makes sense. Diamonds are forged in the high-pressure, high-temperature environment of the deep Earth and only make it close to the surface through volcanic eruptions that occur every few tens of millions of years. These eruptions carve out geologic "pipes" made of a type of rock called kimberlite (named after the town of Kimberley, South Africa, where the first diamonds in this type of rock were found). Diamond, along with magma from deep in the Earth, can spew out through kimberlite pipes, onto the surface of the Earth.

For the most part, kimberlite pipes have been found at the edges of cratonic roots, such as in certain parts of Canada, Siberia, Australia, and South Africa. It would make sense, then, that cratonic roots should contain some diamond in their makeup.

"It's circumstantial evidence, but we've pieced it all together," Faul says. "We went through all the different possibilities, from every angle, and this is the only one that's left as a reasonable explanation."
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Peter Lemkin




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PostPosted: Jul 17, 2018 13:38    Post subject: Re: All the Diamonds one could fill your house with - and more - so near...yet so far.....  

I know this site is non-commercial...but I just had to do a calculation based on average price of natural diamonds....it comes to the mind blowing approximate sum of 2 x 10 to the 24th power Euros....but, of course if accessible, they would be worth not much more than beach sand - as they'd be equally plentiful, if a bit harder and more interesting to look at...... I have made a label in my collection and claim all of these diamonds for my collection - sorry everyone else ;-) LOL

The Universe really is a magical place and the mineral world is IMHO one of the windows into that......

And in the same vein.....what about the giant crystal of iron that might exist in the center of the Earth...only about 1,500 miles [2400 Km] in diameter......and a bit too big for the average collection.....not too mention hard to find a decent stand and display case for....

--------------------------------------

A Seismic Adventure
There's a giant crystal buried deep within the Earth, at the very center, more than 3,000 miles down. It may sound like the latest fantasy adventure game or a new Indiana Jones movie, but it happens to be what scientists discovered in 1995 with a sophisticated computer model of Earth's inner core. This remarkable finding, which offers plausible solutions to some perplexing geophysical puzzles, is transforming what Earth scientists think about the most remote part of our planet.

"To understand what's deep in the Earth is a great challenge," says geophysicist Lars Stixrude. "Drill holes go down only 12 kilometers, about 0.2 percent of the Earth's radius. Most of the planet is totally inaccessible to direct observation." What scientists have pieced together comes primarily from seismic data. When shock waves from earthquakes ripple through the planet, they are detected by sensitive instruments at many locations on the surface. The record of these vibrations reveals variations in their path and speed to scientists who can then draw inferences about the planet's inner structure. This work has added much knowledge over the last ten years, including a puzzling observation: Seismic waves travel faster north-south than east-west, about four seconds faster pole-to-pole than through the equator.

This finding, confirmed only within the past two years, quickly led to the conclusion that Earth's solid-iron inner core is "anisotropic" -- it has a directional quality, a texture similar to the grain in wood, that allows sound waves to go faster when they travel in a certain direction. What, exactly, is the nature of this inner-core texture? To this question, the seismic data responds with sphinx-like silence. "The problem," says Ronald Cohen of the Carnegie Institution of Washington, "is then we're stymied. We know there's some kind of structure, the data tells us that, but we don't know what it is. If we knew the sound velocities in iron at the pressure and temperature of the inner core, we could get somewhere." To remedy this lack of information, Stixrude and Cohen turned to the CRAY C90 at Pittsburgh Supercomputing Center.

Earth's layered structure -- a relatively thin crust of mobile plates, a solid mantle with gradual overturning movement, and the outer and inner core of molten and solid iron.
Getting to the Core
Don't believe Jules Verne. The center of the Earth is not a nice place to visit, unless you like hanging out in a blast furnace. The outer core of the Earth, about two-thirds of the way to the center, is molten iron. Deeper yet, at the inner core, the pressure is so great -- 3.5 million times surface pressure -- that iron solidifies, even though the temperature is believed to exceed 11,000 degrees Fahrenheit, hotter than the surface of the sun.

Despite rapid advances in high-pressure laboratory techniques, it's not yet possible to duplicate these conditions experimentally, and until Stixrude and Cohen's work, scientists could at best make educated guesses about iron's atom-to-atom architecture -- its crystal structure -- at the extremes that prevail in the inner core. Using a quantum-based approach called density-functional theory, Stixrude and Cohen set out to do better than an educated guess. With recent improvements in numerical techniques, density-functional theory had predicted iron's properties at low pressure with high accuracy, leading the researchers to believe that with supercomputing they could, in effect, reach 3,000 miles down into the inner core and pull out what they needed.

Three crystal structures of iron. Yellow lines show bonds between iron atoms.
Rethinking Inner Earth
On Earth's surface, iron comes in three flavors, standard crystalline forms known to scientists as body-centered cubic (bcc), face-centered cubic (fcc) and hexagonal close-packed (hcp). Working with these three structures as their only input, Stixrude and Cohen carried out an extensive study -- more than 200 separate calculations over two years -- to determine iron's quantum-mechanical properties over a range of high pressures. "Without access to the C90," says Stixrude, "this work would have taken so long it wouldn't have been done."


Prevalent opinion before these calculations held that iron's crystal structure in the inner core was bcc. To the contrary, the calculations showed, bcc iron is unstable at high pressure and not likely to exist in the inner core. For the other two candidates, fcc and hcp, Stixrude and Cohen found that both can exist at high pressure and both would be directional (anisotropic) in how they transmit sound. Hcp iron, however, gives a better fit with the seismic data. All this was new information, but even more surprising was this: To fit the observed anisotropy, the grain-like texture of the inner core had to be much more pronounced than previously thought.

"Hexagonal crystals have a unique directionality," says Stixrude, "which must be aligned and oriented with Earth's spin axis for every crystal in the inner core." This led Stixrude and Cohen to try a computational experiment. If all the crystals must point in the same direction, why not one big crystal? The results, published in Science, offer the simplest, most convincing explanation yet put forward for the observed seismic data and have stirred new thinking about the inner core.

Could an iron ball 1,500 miles across be a single crystal? Unheard of until this work, the idea has prompted realization that the temperature-pressure extremes of the inner core offer ideal conditions for crystal growth. Several high-pressure laboratories have experiments planned to test these results. A strongly oriented inner core could also explain anomalies of Earth's magnetic field, such as tilted field lines near the equator. "To do these esoteric quantum calculations," says Stixrude, "solutions which you can get only with a supercomputer, and get results you can compare directly with messy observations of nature and help explain them -- this has been very exciting."

Researchers: Ronald Cohen and Lars Stixrude, Carnegie Institution of Washington.
Hardware: CRAY C90
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Justin Hickok




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PostPosted: Jul 20, 2018 11:08    Post subject: Re: All the Diamonds one could fill your house with - and more - so near...yet so far.....  

Could be a 1,500 mile wide chunk of magnetite.
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PostPosted: Jul 20, 2018 11:09    Post subject: Re: All the Diamonds one could fill your house with - and more - so near...yet so far.....  

Could be a 1,500 mile wide chunk of magnetite.
Am I the winner winner of today's chicken dinner?
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PostPosted: Jul 20, 2018 13:25    Post subject: Re: All the Diamonds one could fill your house with - and more - so near...yet so far.....  

Justin Hickok wrote:
Could be a 1,500 mile wide chunk of magnetite.
Am I the winner winner of today's chicken dinner?


I trust you are joking or uninformed about deep Earth physics and chemistry. No - it can not be magnetite as there is almost or no Oxygen at that depth. What there is is only iron and perhaps some Ni and perhaps minor traces of Co under very very very high temperatures and pressures....
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PostPosted: Jul 21, 2018 00:23    Post subject: Re: All the Diamonds one could fill your house with - and more - so near...yet so far.....  

Thanks for the info and explanation. Interesting.
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PostPosted: Dec 20, 2018 10:00    Post subject: Re: All the Diamonds one could fill your house with - and more - so near...yet so far.....  

Lucy in the sky with sapphires...... the Universe is full of interesting minerals and xx!!

Sapphires and rubies in the universe!!!...but not likely to be in your collection anytime soon!

Researchers have discovered a new, exotic class of planets outside our solar system. These so-called super-Earths were formed at high temperatures close to their host star and contain high quantities of calcium, aluminium and their oxides -- including sapphire and ruby.

Illustration of one of the exotic super-Earth candidates, 55 Cnc e, which are rich in sapphires and rubies and might shimmer in blue and red colors.
Credit: Illustration Thibaut Roger
Researchers have discovered a new, exotic class of planets outside our solar system. These so-called super-Earths were formed at high temperatures close to their host star and contain high quantities of calcium, aluminium and their oxides -- including sapphire and ruby.

21 light years away from us in the constellation Cassiopeia, a planet orbits its star with a year that is just three days long. Its name is HD219134 b. With a mass almost five times that of Earth it is a so-called "super-Earth." Unlike the Earth however, it most likely does not have a massive core of iron, but is rich in calcium and aluminium. "Perhaps it shimmers red to blue like rubies and sapphires, because these gemstones are aluminium oxides which are common on the exoplanet," says Caroline Dorn, astrophysicist at the Institute for Computational Science of the University of Zurich. HD219134 b is one of three candidates likely to belong to a new, exotic class of exoplanets, as Caroline Dorn and her colleagues at the Universities of Zurich and Cambridge now report in the British journal MNRAS.

The researchers study the formation of planets using theoretical models and compare their results with data from observations. It is known that during their formation, stars such as the Sun were surrounded by a disc of gas and dust in which planets were born. Rocky planets like the Earth were formed out of the solid bodies leftover when the proto-planetary gas disc dispersed. These building blocks condensed out of the nebula gas as the disc cooled. "Normally, these building blocks are formed in regions where rock-forming elements such as iron, magnesium and silicon have condensed," explains Dorn who is associated to the NCCR PlanetS. The resulting planets have an Earth-like composition with an iron core. Most of the super-Earths known so far have been formed in such regions.

The composition of super-Earths is more diverse than expected

But there are also regions close to the star where it is much hotter. "There, many elements are still in the gas phase and the planetary building blocks have a completely different com-position," says the astrophysicist. With their models, the research team calculated what a planet being formed in such a hot region should look like. Their result: calcium and aluminium are the main constituents alongside magnesium and silicon, and there is hardly any iron. "This is why such planets cannot, for example, have a magnetic field like the Earth," says Dorn. And because the inner structure is so different, their cooling behavior and atmospheres will also differ from those of normal super-Earths. The team therefore speak of a new, exotic class of super-Earths formed from high-temperature condensates.

"What is exciting is that these objects are completely different from the majority of Earth-like planets," says Dorn -- "if they actually exist." The probability is high, as the astrophysicists explain in their paper. "In our calculations we found that these planets have 10 to 20 percent lower densities than the Earth," explains the first author. Other exoplanets with similarly low-densities were also analyzed by the team. "We looked at different scenarios to explain the observed densities," says Dorn. For example, a thick atmosphere could lead to a lower overall density. But two of the exoplanets studied, 55 Cancri e and WASP-47 e, orbit their star so closely that their surface temperature is almost 3000 degrees and they would have lost this gas envelope long ago. "On HD219134 b it's less hot and the situation is more complicated," explains Dorn. At first glance, the lower density could also be explained by deep oceans. But a second planet orbiting the star a little further out makes this scenario unlikely. A comparison of the two objects showed that the inner planet cannot contain more water or gas than the outer one. It is still unclear whether magma oceans can contribute to the lower density.

"So, we have found three candidates that belong to a new class of super-Earths with this exotic composition" the astrophysicist summarizes. The researchers are also correcting an earlier image of super-Earth 55 Cancri e, which had made headlines in 2012 as the "diamond in the sky." Researchers had previously assumed that the planet consisted largely of carbon, but had to abandon this theory on the basis of subsequent observations. "We are turning the supposed diamond planet into a sapphire planet," laughs Dorn.

Journal Reference:

C Dorn, J H D Harrison, A Bonsor, T O Hands. A new class of Super-Earths formed from high-temperature condensates: HD219134 b, 55 Cnc e, WASP-47 e. Monthly Notices of the Royal Astronomical Society, 2018; DOI: 10.1093/mnras/sty3435
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PostPosted: Jan 07, 2019 13:45    Post subject: Re: All the Diamonds one could fill your house with - and more - so near...yet so far.....  

Here is another likely mineral in the Earth I'll bet no one has in their collection....and not likely to have anytime soon.

Home for Helium inside Earth
December 21, 2018• Physics 11, 133
Computations predict the existence of a compound that could store the primordial helium that is known to be present somewhere inside the Earth.

Hot helium mystery. Ancient helium can emerge from the ground along with lava (here from Kilauea Crater in Hawaii). Computational studies now show that the helium source could be the compound FeO2He in rocks close to the Earth’s core.
Primordial helium—a remnant of the early Solar System—emanates from the ground at sites of lava plumes like those found in Hawaii, Iceland, and the Galapagos. But the source of this helium deep inside the Earth remains unknown. Now researchers predict the existence of a helium-bearing compound, FeO2He, that could serve to store this enigmatic element. Their calculations indicate that the compound is stable at temperatures and pressures consistent with those found at the bottom of the Earth’s mantle—the mostly-solid layer between the crust and the molten outer core. If verified, the results would support the science behind using helium to trace the age and history of cosmological bodies, since other similar planets should contain the same material.

After hydrogen, helium is the most abundant element in the Universe, and on Earth, there are two places to find it. Helium is continuously produced through radioactive decays in the crust, and it is also found in lava and gas plumes originating from the mantle [1]. This mantle helium bears signatures showing that it was present when the Earth formed. Researchers assume that it must exist somewhere in the Earth in solid form; otherwise it would have escaped long ago, thanks to helium’s low density. However, helium-bearing rocks are rare—the inert element has limited capabilities to form compounds with other elements. And so far, such compounds are absent from measurements and predictions of rocks, leaving the hypothesis unconfirmed.

Yanming Ma of Jilin University in China and his colleagues set out to solve this conundrum by computationally searching for minerals containing iron and magnesium that might react with helium. Iron and magnesium are good starting points for such an investigation, as the elements are both abundant inside the Earth, says team member Changfeng Chen of the University of Nevada, Las Vegas.

The team used a crystal structure search algorithm called CALYPSO—developed by Ma’s group—that finds compound candidates by calculating their energies [2]. When the presence of helium in a candidate compound lowers the energy compared with the helium-free version, the helium-containing compound is considered “favorable,” and the algorithm spits out a proposed crystal. The algorithm’s search turned up empty-handed for magnesium-based compounds. But the team found one potential iron-based compound that fit their criteria— FeO2He.

The team’s calculations show that FeO2He forms a stable structure at temperatures between 3000 and 5000 K and at pressures ranging from 135 to 300 gigapascals (GPa), conditions that correspond to those found at the core-mantle boundary. The team also carried out simulations of FeO2He at a temperature of 3000 K and a pressure of 135 GPa to find the material’s acoustic properties. They found that sound waves move through the compound at speeds equivalent to those obtained in seismic-wave measurements of the core-mantle boundary, indicating that the material’s properties are consistent with observations of this region.

Recent synthesis experiments also point to FeO2He being a strong contender for housing primordial helium. Both FeO2 and the hydrogen-containing compounds FeO2Hx have been formed in laboratory settings at the temperatures and pressures found in the lower regions of the mantle [3, 4]. Chen says that the successful creation of those materials indicates that researchers could—relatively quickly and easily—confirm in the lab that FeO2He is stable in deep Earth conditions.

Helium-bearing compounds have, until very recently, been considered unlikely to exist under the physical conditions on or inside the Earth, Chen says, but in his opinion, his team’s new predictions change that view. Chen suggests that primordial helium reacted with FeO2 back when the Earth was new, forming a solid material. The compound is sufficiently heavy that it would only rise to the surface through so-called mantle plumes, which are columns of hot, solid rock that move up to the crust. When FeO2He nears the surface and experiences a drop in temperature and pressure, it should destabilize and release helium gas.

If this result is correct, it could solve the problem of where and how primordial helium is stored, says Matt Jackson, a geochemist at the University of California, Santa Barbara. Jackson studies the chemical compositions of lava plumes and has found signatures of primordial helium. “This is an exciting result,” he says, but he cautions that the predictions need to be tested with laboratory experiments. Ronald Cohen, a geophysicist at the Carnegie Institution for Science in Washington, DC, agrees. He and others thought that primordial helium was most likely stored as impurities in mantle minerals, so the prediction of a helium-containing compound is a surprise, he says.

This research is published in Physical Review Letters.
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PostPosted: Jan 11, 2019 05:12    Post subject: Re: All the Diamonds one could fill your house with - and more - so near...yet so far.....  

And now white dwarf stars when they cool form crystals too....a bit large for the average collection....but you never know.

Thousands of stars turning into crystals
Date January 9, 2019

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.

The discovery, led by Dr Pier-Emmanuel Tremblay from the University of Warwick's Department of Physics, has been published in Nature and is largely based on observations taken with the European Space Agency's Gaia satellite.

White dwarf stars are some of the oldest stellar objects in the universe. They are incredibly useful to astronomers as their predictable lifecycle allows them to be used as cosmic clocks to estimate the age of groups of neighboring stars to a high degree of accuracy. They are the remaining cores of red giants after these huge stars have died and shed their outer layers and are constantly cooling as they release their stored up heat over the course of billions of years.

The astronomers selected 15,000 white dwarf candidates within around 300 light years of Earth from observations made by the Gaia satellite and analysed data on the stars' luminosities and colours.

They identified a pile-up, an excess in the number of stars at specific colours and luminosities that do not correspond to any single mass or age. When compared to evolutionary models of stars, the pile-up strongly coincides to the phase in their development in which latent heat is predicted to be released in large amounts, resulting in a slowing down of their cooling process. It is estimated that in some cases these stars have slowed down their aging by as much as 2 billion years, or 15 percent of the age of our galaxy.

Dr Tremblay said "This is the first direct evidence that white dwarfs crystallise, 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 colours due to crystallisation and only now this has been observed.

"All white dwarfs will crystallise 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 Sun itself will become a crystal white dwarf in about 10 billion years."

Crystallisation is the process of a material becoming a solid state, in which its atoms form an ordered structure. Under the extreme pressures in white dwarf cores, atoms are packed so densely that their electrons become unbound, leaving a conducting electron gas governed by quantum physics, and positively charged nuclei in a fluid form. When the core cools down to about 10 million degrees, enough energy has been released that the fluid begins to solidify, forming a metallic core at its heart with a mantle enhanced in carbon.

Dr Tremblay adds "Not only do we have evidence of heat release upon solidification, but considerably more energy release is needed to explain the observations. We believe this is due to the oxygen crystallising first and then sinking to the core, a process similar to sedimentation on a river bed on Earth. This will push the carbon upwards, and that separation will release gravitational energy.

"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. 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. Before Gaia we had 100-200 white dwarfs with precise distances and luminosities -- and now we have 200,000. This experiment on ultra-dense matter is something that simply cannot be performed in any laboratory on Earth."

Pier-Emmanuel Tremblay, Gilles Fontaine, Nicola Pietro Gentile Fusillo, Bart H. Dunlap, Boris T. Gänsicke, Mark A. Hollands, J. J. Hermes, Thomas R. Marsh, Elena Cukanovaite, Tim Cunningham. Core crystallization and pile-up in the cooling sequence of evolving white dwarfs. Nature, 2019-565-202
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