A little over two years ago, like an episode out of the Hitchhiker’s Guide to the Galaxy, The Harvard-Smithsonian Center for Astrophysics announced the discovery of a mass of crystallized carbon formerly known as star BPM 37093, now known as the biggest diamond in the galaxy, fifty light years away from Earth in the constellation Centaurus.
The star, named “Lucy” after the Beatles song, “Lucy in the Sky with Diamonds,” is estimated to be 2,500 miles across and weighs approximately 10 billion-trillion-trillion-carats – a one, followed by 34 zeros.
Travis Metcalfe, an astronomer from the Harvard-Smithsonian Center for Astrophysics and leader of the team who discovered the gem, says "You would need a jeweler's loupe the size of the sun to grade this diamond. Bill Gates and Donald Trump together couldn't begin to afford it."
Now, scientist are explaining how it may be possible for the planets Neptune (image above) and Uranus to contain liquid diamond oceans.
The research was conducted by taking detailed measurements of the melting point of diamond. When diamond is melted it behaves like water during freezing and melting, with solid forms floating atop liquid forms. Diamond is a very hard material which makes it difficult to melt. Measuring the melting point of a diamond is very difficult because when it’s heated to very high temperatures the diamond changes to graphite.
Since it’s the graphite and not the diamond that turns to liquid, scientist are faced with the problem of melting the diamond without it turning to graphite. Scientists can get around this problem by exposing the diamond to extremely high pressures by blasting it with lasers. The diamond is liquefied at pressures 40 million times greater than that found at Earth’s sea level.
When the pressure is lowered to 11 million times greater than Earth’s sea level and the temperature drops to about 50,000 degrees, chunks of diamond start to appear.
Scientists discovered something they didn’t expect, after the pressure kept dropping the temperature of the diamond remained the same, with more chunks of diamond forming. The chunks of diamond did not sink but floated on top of the liquid diamond, creating diamond icebergs.
These ultrahigh temperatures and ultrahigh pressures are found in huge gas giant planets like Neptune and Uranus. Neptune and Uranus are estimated to be made up of 10% carbon. A large ocean of liquid diamond could deflect or tilt the magnetic field out of alignment with the rotation of the planet.
The only way scientists can know for sure if liquid diamond exists on these gas giant planets is either by sending a scientific spacecraft to one of them or by simulating the conditions on earth. Both methods would be very expensive and take years to prepare.
Meanwhile,back to the diamond as big as the Earth (image above): The diamond is actually the crystallized interior of a white dwarf – or the hot core of a star that is left over after the star uses up its nuclear fuel and dies. It is made mostly of carbon and is coated by a thin layer of hydrogen and helium gases. Five billion years from now, our sun will die and become a white dwarf. Approximately two billion years after that, its ember core will crystallize as well, leaving a giant diamond in the center of our solar system.
The paper is published in Nature Physics.
http://www.physorg.com/news183044315.html
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