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Astronomers using the Chandra X-ray observatory have unexpectedly found an exotic star made entirely of quarks.

They came across the bizarre find while looking at the debris of recent supernovae - the titanic explosions that happen when stars run out of fuel. In a supernova, a star's core can collapse so rapidly that atomic nuclei are squashed into a "liquid soup" of neutrons. The process squeezes material weighing as much as our Sun into the volume of a large city.

Now Jeremy Drake and colleagues at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts say the nearby star RX J1856 is at just 11 kilometres across, far too small to be a neutron star.
[The star 3C58 discovered by Columbia University astronomers is also thought to contain quarks Photo: NASA/SAO/CXCP/P.Slane et al]

This only makes sense if the 1983 supernova thought to have created RX J1856 forced the neutrons together so strongly that they dissolved into their constituent quarks, creating a superdense quark star.

"This is an astonishing discovery with fundamental significance," says Norman Glendenning, a neutron star theorist at Lawrence Berkeley National Laboratory.


Very hot, very tiny

Drake and colleagues measured the star's size by imaging it in the optical part of the spectrum using the Hubble Space Telescope. "It's an extremely faint blue star," says Drake.

But the star's X-ray spectrum reveals a temperature of 700,000 degrees centigrade, 100 times hotter than our Sun. Something that hot can only be faint in visible light if it is very, very small, says Drake.

Not everyone is convinced by the team's claims. Mike Turner, an astrophysicist at the University of Chicago in Illinois says it is possible the team have merely imaged a hotspot on the surface of a larger neutron star. "Very few people will be convinced that this is an iron clad case," he says.

But Turner says he is encouraged by a similar discovery by David Helfand and colleagues at Columbia University in New York City. They claim to have found another star containing exotic matter using Chandra data, although their star is probably too large to be made entirely made of quarks.

Particle physicists have tried in vain for years to create quark-only matter by smashing particles together at high energies. Now Turner says they should be able to pin down the exact mass of strange quarks by studying quark stars. This is because theory says if strange quarks are very heavy, quark stars will be less likely to form. "Nature has carried out an experiment we cannot duplicate on Earth," says Turner.


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Интересно, а это не может быть черная дыра? ЧД как раз образуются при взрыве сверхновой и характеризуются мощным рентгеновским излучением и тем, что падающая на ЧД материя жутко разогревается. Они не пробовали посчитать радиус сферы Шварцшильда для этого образования?