Just in time for Valentine's Day, astronomers have discovered a white dwarf star with a very special center. This star would truly be the gift for the person who has everything: a celestial diamond in the sky!
"You would need a jeweler's loupe the size of the Sun to grade this diamond!" says astronomer Travis Metcalfe (Harvard-Smithsonian Center for Astrophysics), who leads a team of researchers that discovered the giant gem. "Bill Gates and Donald Trump together couldn't begin to afford it."
The reason this star, with the obscure designation of BPM 37093 is so special to astronomers is that it has aided them in proving a theory held for decades: that white dwarf stars cool and crystallize into carbon, a giant diamond.
Astronomers say the star has a diameter of 2,500 miles and weighs in at an astonishing five million, trillion, trillion pounds. That would make the diamond core ten billion, trillion, trillion carats! The largest gem-quality diamond yet found on Earth was the 3,106-carat "Cullinan" discovered in 1905. The 530-carat "Star of Africa" in the British crown jewels was cut from it.
The star is located in the constellation Centaurus and is about fifty light years distant (A light-year is the distance light travels in a year, or about 6 trillion miles.)
There are many kinds of stars in the cosmos. The Sun is part of a group of stars called main sequence stars, and most of these end their lives as white dwarves.
The stars burn up all their hydrogen and then begin to expand into red giant stars. Red giants are extremely large. If our Sun was a red giant, it would extend well beyond the orbit of Mars, swallowing the Earth in it's atmosphere!
The stars continue fusing elements until it loses its shell of gases, leaving behind a hot core of about 180,000 degrees Fahrenheit. Then the star begins to cool. The star pulsates as it burns helium in fusion reactions creating heavier and heavier elements until at the very end there is carbon and a very small amount of oxygen. A star will spend billions of years in this phase.
The problem with proving the theory about the crystallization is that by the time the star has crystallized, it is no longer pulsating and is so cool that they are impossible to detect. But BPM 37093 is the most massive known dwarf star. Because it is so massive, the star is crystallizing on the inside while light and sound continue to pulsate from the surface.
"By measuring those pulsations, we were able to study the hidden interior of the white dwarf, just like seismograph measurements of earthquakes allow geologists to study the interior of the Earth. We figured out that the carbon interior of this white dwarf has solidified to form the galaxy's largest diamond," says Metcalfe.
The same fate awaits our own Sun. In about five billion years, our Sun will use up it's hydrogen, expand into a red giant and at last become a white dwarf star. A few billion years after that, our Sun will have cooled and the core crystallized into a diamond that is truly forever.
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