Formation of quark stars?

AbsoluteZer0

Hi,

In the case of the gravitational collapse of a star where neither electron or neutron degeneracy pressure is sufficient to prevent further collapse, is there a possibility that the star will become a quark star rather than a black hole?

From what I understand, quarks are perpetually bound to each other by color confinement, so would this prevent a quark star from being possible?

Thanks,

mathman

Whether or not a star ends up as a black hole depends only on its radius and mass. What its composition is doesn't matter. So if a neutron star collapsed to be a quark star (I am not sure what it means physically), it will be a black hole if the radius is small enough.

Chronos

A quark star is hypothetically the last stop on the road to becoming a black hole. Their existence is still conjecture, although some promising candidates exist - e.g., http://arxiv.org/abs/astro-ph/0204159 and http://arxiv.org/abs/astro-ph/0204151. Unfortunately our knowledge of the equation of state of quark matter is virtually nonexistent. Even our knowledge of neutron star EOS is extremely poor and we can only guess at the states of matter that exist beneath their surfaces. A quark star could be dense enough to exceed the schwarzschild limit making it a black hole without a singularity. Needless to say this is an active area of research. We still have much to learn about condensed matter.

twofish-quant

Not really in the sense of a "neutron star". The trouble is that quarks are less massive than neutrons, which means that if the neutrons are relativistic then the quarks are even more relativistic.

Now it's possible (even likely) that the interior of a "neutron star" is actually not made of neutrons but of "quark soup". This matters because if particles start behaving like quarks rather than neutrons, the mass at which black holes form decreases a lot.

The difference is that when you put enough matter into a white dwarf, it suddenly changes into a neutron star. With neutron stars, the current thinking is that as you pile on matter, the center gradually behaves more and more like free quarks, so there isn't a sharp transition between a neutron star and a quark star.