The Role of Kinetic Energy Flux in the Convective Urca Process

The previous analysis of the convective Urca neutrino loss process indegenerate, convective, quasi-static, carbon-burning cores by Barkat andWheeler omitted specific consideration of the role of the kinetic energy flux.The arguments of Barkat and Wheeler that steady-state composition gradientsexist are correct, but chemical equilibrium does not result in net cooling.Barkat and Wheeler included a "work" term that effectively removed energy fromthe total energy budget that could only have come from the kinetic energy,which must remain positive. Consideration of the kinetic energy in thethermodynamics of the convective Urca process shows that the convective Urcaneutrinos reduce the rate of increase of entropy that would otherwise beassociated with the input of nuclear energy and slow down the convectivecurrent, but, unlike the "thermal" Urca process do not reduce the entropy ortemperature.Comment: 16 pages, AAS LaTex, in press, Astrophysical Journal, September 20, Vol 52