Astronomers from the University of Warwick recently participated in a study that shows that stars similar to our sun may become crystal white dwarfs with cores made up of carbon and oxygen. Our sun may become one of these crystal white dwarfs in about 10 billion years
White dwarfs are old stars that have stopped the fusion process that generates their light and heat and gradually shed their remaining energy. The cooling process of crystal white dwarfs is slower than the current modeling of white dwarfs predicts. That means some white dwarfs may actually be billions of years older than previously thought.
Diamond Star Found in 2014
The first hint of these carbon white dwarfs was found in 2014, when scientists discovered a white dwarf that appeared to be made entirely of diamond. This star is about 50 light-years away in the constellation Centaurus and is about 2/3 the size of Earth.
“You would need a jeweler’s loupe the size of the Sun to grade this diamond,” said research team leader Travis Metcalfe.
This crystal white dwarf is informally known as “Lucy” from the Beatles song “Lucy in the Sky With Diamonds.”
Don’t Expect to Mine Diamonds in Crystal White Dwarfs
Naturally formed diamonds on Earth typically originate in zones of immense heat and pressure. The areas where they form are typically referred to as “diamond stability zones” and are usually located about 100 miles under the surface of Earth. Temperatures in diamond stability zones reach 2200 degrees Fahrenheit and the pressure can reach 725,000 pounds per square inch. This intense heat and pressure causes carbon to gradually crystallize into diamonds.
Old stars often fuse atoms into progressively heavier elements, including carbon and oxygen, as part of their death process. In the case of crystal white dwarfs, the carbon and oxygen crystallization is unlikely to resemble the diamonds that you are familiar with. The term “crystallization” simply refers to the transition from a fluid state like liquid or gas, in which atoms can move freely, to a more rigid solid state in which atoms do not move much. Water goes through the crystallization process whenever it freezes.
The intense heat and pressure still contributes to the crystallization of oxygen and carbon in these white dwarfs. Conditions in a white dwarf’s core are so extreme that atoms are stripped of their electrons, and then the carbon and oxygen separate into layers and “freeze” into a metallic state as the white dwarf cools.
It is unlikely that a diamond mining expedition will visit these crystal white dwarfs anytime soon and such an expedition would have to put up with the same intense conditions that produced the crystallized carbon in any event. Lucy is actually one of the coolest crystal white dwarfs ever detected at 5,000 degrees Fahrenheit.