I have dug up a copy of the paper (which I mostly don’t understand). According to a press release from Jodrell Bank (University of Manchester) astronomers believe that they have found a solid diamond planet that formed from the collapse of a star orbiting a pulsar.
A pulsar is a type of star that spins and emits regular bursts of radio waves. This particular pulsar, J1719-1438, spins more than 10,000 times a minute. The planet was found because there were oscillations in the the frequency with which the star emitted radio wave bursts; these fluctuations in signal were the result of the gravitational pull of this new planet. The scientists have established the planet’s orbit – it’s very rapid – and also the distance from the pulsar. From this they have also determined the density of the planet – despite being half the mass of Jupiter, it is smaller than the Earth – and therefore incredibly dense. The astronomers believe that the planet is all that remains of a star, probably a white dwarf, that has all of its matter was sucked away by the pulsar.
The researchers, from The University of Manchester as well as institutions in Australia, Germany, Italy, and the USA, first detected the pulsar using the Parkes radio telescope of the Australian Commonwealth Scientific and Industrial Research Organisation (CSIRO) and followed up their discovery with the Lovell radio telescope, based at Jodrell Bank Observatory in Cheshire, and one of the Keck telescopes in Hawaii.
The project is part of a systematic search for pulsars in the whole sky also involved the 100-m Effelsberg radio telescope of the Max-Planck-Institute for Radioastronomy (MPIfR). “This is the largest and most sensitive survey of this type ever conducted. We expected to find exciting things, and it is great to see it happening. There is more to come!”, promises Prof. Michael Kramer, Director at the MPIfR in Bonn, Germany.
Most pulsars have companion stars. Because the companion object is so small and so close to Pulsar J1719-1438, that the remaining a matter is likely to be carbon and oxygen, probably in a crystalline formation.
Cribbed together from a couple of press releases: