It is shown that the beta decay of quarks in degenerate quark matter is kinematically allowed. The resulting neutrino emissivity is dramatically larger than that of neutron matter and comparable to that of matter with pion condensate. Thus a star with a quark-matter core would cool at a rate comparable to that for a star with a pion-condensed core, and much faster than an ordinary neutron star.

• Received 15 February 1980

DOI:https://doi.org/10.1103/PhysRevLett.44.1637