The densest known planet outside our solar system has been discovered orbiting a pulsar, and appears to be composed mostly of diamond, according to new findings published online in the journal Science on Aug. 25.
Pulsars are rapidly spinning stars that are only around 20 kilometers (12 miles) wide and send out powerful radio wave beams.
An international team of astronomers discovered this pulsar, PSR J1719-1438, in the constellation of Serpens, about 4,000 light years away from Earth.
Rotating more than 10,000 times per minute, PSR J1719-1438 is a millisecond pulsar—a type of neutron star believed to have absorbed matter from a binary companion, although around 30 percent of them are solitary.
Its pulses allowed the researchers to deduce various information about the star and its crystalline satellite. The planet orbits the pulsar approximately every two hours and 10 minutes, and the two bodies are only 600,000 kilometers apart.
The scientists believe the enormous diamond could be the remains of a massive white dwarf star that was almost destroyed by the pulsar.
“This high density of the planet provides a clue to its origin,” says Matthew Bailes at Melbourne’s Swinburne University of Technology, Australia, in a press release.
Theoretically, when the white dwarf lost almost all of its mass to the pulsar, the neutron star was transformed into a millisecond pulsar while the companion star was stripped to a diamond core.
“PSR J1719-1438 demonstrates that special circumstances can conspire during binary pulsar evolution that allows neutron star stellar companions to be transformed into exotic planets unlike those likely to be found anywhere else in the universe,” the researchers conclude in the paper.
“The chemical composition, pressure and dimensions of the companion make it certain to be crystallized (i.e., diamond).”
