Astronomers say they’ve discovered a planet with a pressure so high that its carbon has crystallized, turning it into an actual diamond.
The diamond planet is the companion to a neutron star that was discovered in 2009. The system is over 4,000 light-years away, part of the Serpens constellation. Its brightly-flashing star is what’s known as a millisecond pulsar, formed by a supernova.
Because 70% of millisecond pulsars have companions, scientists knew they could expect to find one orbiting this star. They didn’t know it would be a planet, though. The companion is usually another star, a white dwarf, and this is only the second system known with a planet instead.
Astronomers believe the planet may have been a white dwarf at one time, but it crashed into the pulsar, and now only its dead core remains. The 30% of pulsars without companions may have lost their white dwarfs in similar crashes.