Massive Diamond Found Orbiting Pulsar 204
HairyNevus writes "A recent survey of pulsars has revealed a fascinating discovery of a millisecond pulsar in system PSR J17191438 that has stripped a nearby white dwarf star down to its very core. Although no longer visible, is still has the mass of Jupiter. The remaining core rotates its neutron star companion with a period of just under 2 hours, indicating extremely close proximity. Given this distance, scientists have calculated that the substance of the core must be very compact, and, without building up the point, they conclude it is made of diamond. One thing I found misleading about the article is that it refers to the core as having 'the size of Jupiter' and 'the mass of Jupiter.' Given their different densities (diamond vs. mostly helium), it would seem clear that their size (i.e. volume) differs."
Better Press Release (Score:5, Informative)
One thing I found misleading about the article is that it refers to the core as having 'the size of Jupiter' and 'the mass of Jupiter.'
Here's the correct Science Journal link [sciencemag.org] and here is a better press release from the Max Planck Institute [mpifr-bonn.mpg.de] that clarifies:
For the newly discovered pulsar, known as PSR J1719-1438, the astronomers noticed that the arrival times of the pulses were systematically modulated and concluded that this is due to the gravitational pull of a small orbiting companion, a planet. These modulations can tell astronomers several more things about the companion. First, it orbits the pulsar in just two hours and ten minutes, and the distance between the two objects is 600,000 km - a little bit less than the radius of our Sun. Second, the companion is so close to the pulsar that if its diameter was any larger than 60,000 km (less than half the diameter of Jupiter) it would be ripped apart by the gravity of the pulsar.
So it appears that the article saying "size equivalent to Jupiter" (volume?) is wrong if the Max Planck Institute is correct in saying that its diameter has to be less than half the diameter of Jupiter.
This isn't diamond the way you're thinking (Score:4, Informative)
This isn't diamond in any sense that we usualy think of it. Yes, it's carbon atoms, and yes, they're "crystallized", but the core of a white dwarf is composed mostly of electron-degnerate matter where all of the electrons have been disassociated from their parent atoms and all the nuclei clump together, floating in a sea of electrons. This stuff has a density of roughly 1000 kilograms (2,200 lbs) per cubic centimeter. I imagine it would *catastrophically* decompress if you could teleport a chunk of it back to earth. It's not diamond.
Re:Is it really diamond? (Score:5, Informative)
The answer is no it is not diamond.
One issue is the one you point out, that the correct crystalline structure at high densities/pressures is not a diamond lattice. There is also the pesky fact that the inner portions of white dwarf stars are made of carbon and oxygen.
One could actually go on and on because diamond is a covalently bonded crystal, while this stuff will be a degenerate electron gas containing an ionic crystal, much more like a crystalline metal.
I study white dwarf stars for a living (yes really) and calling this stuff diamond is just idiotic.