The collapse of the core of a massive star in a Type II supernova results in the
ID: 105204 • Letter: T
Question
The collapse of the core of a massive star in a Type II supernova results in the formation of a neutron star and the release of large numbers of neutrinos. Neutrinos have a very small cross-section for interaction with matter, but the high densities encountered during stellar collapse become temporarily trapped before they scatter and escape. a) Consider a static star of mass M, radius r, made up of particles with mass m_n. If the cross-section for interaction between neutrinos and matter is sigma, derive an expression for the radius of a star that is just optically thick to neutrino emission from the core. b) Evaluate this radius for a star of mass M = 1.4 M_, assuming a neutrino-matter cross-section sigma = 10^-44 cm^2 and the star is made up entirely of neutrons.Explanation / Answer
a)The neutrino is said to be of less amount of weight and they are said to get temporarily trapped.
When comparing to a star,the mass of the neutrino is very very small. The mass of the star is M,radius r and the interaction between neutrinos and matter is sigma.
The expression can be given as,
R=r(sigma)+M
Where R is the radius of star
r is the radius of neutrino
M is the mass of star
b)R=r(10^-44)+1.4(Mo)
let r=1 and Mo=1
R=(10^-44)+1.4=1.4cm