Woosley: Astr220C – Advanced Stages of Stellar Evolution

If the neutron star formed in the core collapse of a massive star can be thought of as a sphere of constant density, and if the neutrino path length is, on average, 10cm, estimate:

a) the total energy in ergs that comes out in all forms of neutrinos (6 species) as the protoneutron star (1.4M\odot ) contracts to its final radius (10km)

b) the time scale of the neutrino burst

c) the average luminosity in each flavor (assuming each carries 1/6 of flux), and

d) assuming blackbody emission, the temperature of each neutrino species in either MeV or K

Don’t worry about the time dependence of the structure – treat the neutron star as a sphere of constant size and density. Of course, in reality it must contract, and its density is higher in the center.


a) binding energy

b) different t for each species