Volume 372, Number 1, June II 2001
|Page(s)||130 - 137|
|Section||Interstellar and circumstellar matter|
|Published online||15 June 2001|
Bulk viscosity in superfluid neutron star cores
II. Modified Urca processes in matter
N. Copernicus Astronomical Center, Bartycka 18, 00-716 Warszawa, Poland
2 Ioffe Physical Technical Institute, Politekhnicheskaya 26, 194021 St.-Petersburg, Russia
Corresponding author: P. Haensel, email@example.com
Accepted: 9 March 2001
We study the bulk viscosity in neutron star cores due to modified Urca processes involving nucleons, electrons and muons and analyze its reduction by singlet-state or triplet-state superfluidity of nucleons. In combination with the results of our previous paper on the bulk viscosity due to direct Urca processes, a realistic description of the bulk viscosity in superfluid neutron star cores is obtained. Switching off direct Urca processes with decreasing density in a nonsuperfluid matter lowers the bulk viscosity by 3-5 orders of magnitude. The presence of muons opens additional source of bulk viscosity due to muon Urca processes and lowers the threshold density of the electron direct Urca process. The superfluidity may strongly reduce the bulk viscosity and affect thus damping of neutron star vibrations.
Key words: stars: neutron / dense matter / bulk viscosity
© ESO, 2001
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