A destroyed star becomes a planet made of diamonds

An international research team has found an exoplanet made entirely of diamonds. Although this may seem glamorous, researchers think it is only the desolate remains of a star, robbed of its mass by its companion.

Some time ago, a radio telescope picked up the repeated signal of a pulsar. A pulsar is a rapidly-spinning star with a rotation that emits radio waves in strong pulses outwards. This pulsar lay in the plane of the Milky Way, not particularly distinguishing itself from any other pulsar out there. That is, until the astronomers analyzed the spin of the pulsar and found that it was modulated in a certain way. It was almost as if the star was being tugged one way or another via gravity. The only thing that could be making that particular spin was an orbiting planet.

This planet was orbiting fast and close. It was circling the pulsar once every two hours and ten minutes, at a distance just about the radius of Earth's sun. It was about five times the size of earth, a relatively small planet, but it had the mass of Jupiter. This planet should not have gathered so much mass and packed it so tightly when it was so close to a high-gravity star.

Scientists think that it didn't. Actually, the planet is the remains of a star. The pulsar and the newly-discovered planet were once a binary system. As they burnt through their fuel and came closer to one another, one star starting siphoning off the matter of the other. When it was done, it left only a cold, fusion-less planet.

But a pretty one. Judging from the size and mass of the star, scientists think that a very large part of it will be crystalline carbon - the same stuff that diamonds are made of. The theft of most of its fuel left this celestial body a glittering jewel.

Via National Geographic and to be published in Science.