Diamond sky

The Beatles might not have been too far off the mark when they sang about diamonds in the sky – scientists have discovered a planet made of diamond.

[caption id="" align="alignnone" width="200" caption="Artist's impression of the pulsar, with its twin beams of radiation, and orbiting planet. The pulsar-planet system could fit inside the Sun, whose size is shown as the orange sphere credit: Swinburne Centre for Astrophysics and Supercomputing"][/caption]

An international team of scientists – including researchers from the University of Manchester – believe the diamond planet is all that remains of a once-massive star, which has been stripped of its matter by a nearby pulsar.

The planet was found during a systematic search for pulsars – small spinning stars which emits a beam of radio waves. Scientists discovered PSR J1719-1438 4,000 light-years away in the constellation Serpens and noticed a pattern in the arrival time of pulses.

They concluded this was due to the gravitational pull of a small companion planet orbiting the pulsar in a binary system. The planet orbits the pulsar in 2 hours 10 minutes at a distance of 600,000km – the planet is so close to the pulsar that, if it were any bigger it would be ripped apart by the pulsar’s gravity.

Scientists – who published their work in Science – believe the planet is likely to be a stripped down white dwarf which has lost its outer layers and 99.9% of its original mass.

“This remnant is likely to be largely carbon and oxygen, because a star made of lighter elements like hydrogen and helium would be too big to fit the measured orbiting times,” said Dr Michael Keith of CSIRO, where the pulsar was first detected.

The density of the planet means that this material is certain to be crystalline, with a large part similar to diamond.

The pulsar was found among 200,000 gigabytes of data – some of which came from the Lovell Telescope – using supercomputers at Swinburne University of Technology in Australia and the INAF-Osservatorio Astronomico di Cagliari in Italy.

“This is the largest and most sensitive survey of this type ever conducted,” said professor Michael Kramer. “We expected to find exciting things, and it is great to see it happening. There is more to come!”

Transformation of a Star into a Planet in a Millisecond Pulsar Binary http://www.sciencemag.org/content/early/2011/08/19/science.1208890.abstract