Washington: The faintest white dwarf star, possibly the coldest ever detected, has been identified by a team of astronomers. The carbon of this ancient stellar remnant is so cold that it has crystallised and it forms an earth sized diamond in space.
The White dwarf’s age is approximately 11 billion years old, likely the same as of the Milky Way.
They are extremely dense end-states of stars that have collapsed. They are mostly composed of carbon and oxygen and slowly cool and fade over billions of years.
“It is a really remarkable object,” said David Kaplan, professor at University of Wisconsin-Milwaukee in the US.
“These things should be out there, but because they are so dim, they are very hard to find,” he said.
Kaplan and his colleagues found this stellar gem using the National Radio Astronomy Observatory’s (NRAO) Green Bank Telescope (GBT) and Very Long Baseline Array (VLBA), as well as other observatories.
“Our final image should show us a companion 100 times fainter than any other white dwarf orbiting a neutron star and about 10 times fainter than any known white dwarf, but we don’t see a thing,” said Bart Dunlap, a graduate student at the University of North Carolina at Chapel Hill and one of the team members.
“If there is a white dwarf there, and there almost certainly is, it must be extremely cold,” he added.
White dwarf would be no more than a comparatively cool 3,000 degrees Kelvin (2,700 degrees Celsius) as calculated by the researchers.
Astronomers believe that such a cool, collapsed star would be largely crystallised carbon, not unlike a diamond.