  In this paper the neutrino emission processes being supposed to be the main
sources of energy loss in the stellar core in the later stages of stellar
evolution are reviewed. All the calculations are carried out in the framework
of electro-weak theory based on the Standard Model. It is considered that the
neutrino has a little mass, which is very much consistent with the
phenomenological evidences and presupposes a minimal extension of the Standard
Model. All three neutrinos (i.e., electron neutrino, muon neutrino and tau
neutrino) are taken into account in the calculations. It is evident that the
strong magnetic field, present in the degenerate stellar objects such as
neutron stars, has remarkable influence on some neutrino emission processes.
The intensity of such magnetic field is very close to the critical value
($H_{c}=4.414\times 10^{13}$ G) and sometimes exceeds it. In this paper the
region of dominance of different neutrino emission processes in absence of
magnetic field is picturized. The region of importance of the neutrino emission
processes in presence of a strong magnetic field is indicated by a picture. The
study reveals the significant contributions of some neutrino emission
processes, both in absence and in presence of a strong magnetic field in the
later stages of stellar evolution.
