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Space Diamonds Reveal Supernova Origins

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Collisions in space may be behind mysterious diamonds found in meteorites.
By Brian Jacobsmeyer, ISNS Contributor
Inside Science News Service

Space diamonds may now be an astrophysicist’s best friend.
For years, scientists have found DNA-sized diamonds in meteorites on Earth. New research suggests that these diamonds spring from violent cosmic collisions, which may help scientists unravel mysteries surrounding exploding stars — the birthplaces of ancient materials that predate our solar system.

Although diamonds are rare on Earth, scientists believe that minuscule “nanodiamonds” abound in space. Researchers have been trying to decipher the origin of these enigmatic minerals for decades.

On Earth, traditional diamonds are forged deep underground under intense heat and pressure over the course of billions of years. Space diamonds, however, can form in a millionth of a millionth of a second according to new research appearing in the journal Physical Review Letters.

“The transformation is quite astonishing,” said Nigel Marks, a materials scientist at Curtin University in Perth, Australia, and coauthor of the research paper. “I never would have imagined this was possible.”

Marks simulated space dust collisions on his computer and found that diamond formation didn’t require blistering temperatures or crushing pressures. Instead, in simulations, diamonds formed when carbon-containing dust grains smashed together at speeds exceeding 10,000 miles per hour.

Within the original grains, spherical fullerenes — soccer-ball-shaped carbon molecules — enclose one another like Russian nesting dolls. Together, these concentric molecules compose layered carbon “onions.”

When the carbon onions slammed into each other, the molecules flattened, squeezed and linked together. During this process, the onions rearranged themselves into hexagonal shapes indicative of diamond structure.

If they collided at high enough speeds, then the carbon onions were destroyed. And if the particles weren’t moving fast enough, then the carbon onions did not complete the transition to diamonds. The researchers found that the narrow speed range that facilitates nanodiamond formation is common in space.

“They found that there’s sort of a sweet spot,” said Andrew Davis, a geochemist at the University of Chicago, who was not affiliated with the research. “If you can do it just right, you can make nanodiamonds. That was interesting.”

With this new model for nanodiamond formation, scientists hope to unlock some of the secrets these diamonds contain. Until now, scientists have only extracted limited information from nanodiamonds partly because they didn’t have a suitable theory for their formation, said Marks.

“There’s a huge message embedded in the nanodiamond,” said Marks. “[Researchers] just couldn’t figure out what it was.”

Forms of elements such as gaseous xenon with different amounts of neutrons have been found inside meteorite nanodiamonds. Called isotopes, these variants of the same elements convey information about exploding stars from earlier in the universe’s history. Different ratios of isotopes are produced in different nuclear reactions, giving scientists clues as to what types of dying stars gave birth to these isotopes.

According to Marks and his team, xenon is likely incorporated into carbon onions before they collide and produce nanodiamonds. By better understanding where these embedded isotopes originate, scientists can glean new information about the death of stars and the origins of our solar system.

Several competing theories, however, suggest nanodiamonds were formed differently than Marks’ research indicates. For instance, some scientists think that shock waves from exploding stars may have created nanodiamonds. Intense pressure and heat from the shock wave could also have led to the implantation of noble gases like xenon.

But all theories put forth so far have been hampered by limited experimental evidence. Because nanodiamonds are so small, it’s been extremely difficult to look at them individually.

To help resolve this issue, Marks and his colleagues hope to translate their simulations into lab experiments in the coming months. By creating nanodiamonds on Earth, the research team could produce large enough samples to analyze.

The samples could also be used for biomedical and industrial applications.

Manufacturers already create similarly sized nanodiamonds to use as drug markers or dry lubricants. Current methods require extremely high temperatures, though, limiting the types of materials that can be coated. Using the method put forth by Marks and his team, manufacturers could create coatings for materials that melt relatively easily, such as steel.

High speeds on such a small scale can be tricky, however.

“I think it’s probably not trivial to accelerate these grains to 5 kilometers per second,” said Davis. “That’s a hard thing to do in a lab.”

Nonetheless, Marks hopes that his simulations will guide future experiments.

“Now that we know this possibility exists, we want to go on and figure out what you can do with it,” said Davis….

Read more: insidescience.org

Written by physicsgg

February 15, 2012 at 3:19 pm

Posted in ASTRONOMY, ASTROPHYSICS

Tagged with , ,

Candles shine new light on diamonds

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By Christine Lavelle
Candle flames contain millions of tiny diamond particles, a university professor has discovered.
Research by Wuzong Zhou, a professor of chemistry at the University of St Andrews in Fife, revealed that around 1.5 million diamond nanoparticles are created in a candle flame every second it is burning.

Discovery could have implications for diamond industry

Dr Zhou used a new sampling technique to remove particles from the centre of the flame, which is believed to have never been done before, and found that it contained all four known forms of carbon.
He said: “This was a surprise because each form is usually created under different conditions.”
Dr Zhou added that the diamond particles are burned away in the process, but the discovery could lead to future research into how diamonds could be created more cheaply, and in a more environmentally friendly way.
He said: “This will change the way we view a candle flame forever.”
The academic said he uncovered the secret after a challenge from a fellow scientist in combustion.
Dr Zhou said: “A colleague at another university said to me: ‘Of course no one knows what a candle flame is actually made of.
“I told him I believed science could explain everything eventually, so I decided to find out.”
The first candle is said to have been invented in China more than 2,000 years ago, and previous research has shown that hydro-carbon molecules at the bottom of the flame are converted into carbon dioxide by the top of the flame.
However, the process in between has remained a mystery until now, with the discovery of the diamond nanoparticles, as well as fullerenic particles and graphitic and amorphous carbon.
Rosey Barnet, artistic director of one of Scotland’s biggest candle manufacturers, Shearer Candles, said the discovery was “exciting”.
She said: “We were thrilled to hear about the discovery that diamond particles exist in a candle flame.
“Although currently there is no way of extracting these particles, it is still an exciting find and one that could change the way people view candles.
“The research at St Andrews University will be of interest to the entire candle making industry.
“We always knew candles added sparkle to a room but now scientific research has provided us with more insight into why.”
http://www.independent.co.uk

Written by physicsgg

August 18, 2011 at 8:22 am