Question

2. a) Show that energy transfer by radiative diffusion implies a non-zero gradient for the radiation pressure which is proportional to the radiant energy flow. b) Bearing in mind that the magnitude of the force per unit volume in a fluid due to the pressure is equal to the pressure gradient, find the radiant energy flux density which can, by itself, support the atmosphere of a star with surface gravity g. c) Show that a star of mass M has a maximum luminosity given by Lmax = 4nCGM/k, where k is the opacity near the surface. This is called the Eddington luminosity. d) Obtain a numerical estimate for this luminosity for a 15 solar mass star (in solar units, Lo) by assuming that the surface is hot enough for the opacity to be dominated by electron scattering.

Answer 1

Answer @ the energy transfer by radialie differsion non-zero fa radiation pressure For at der or (for a Reus) Brad = I ath - ff - ų at?d to man = hell GM The magnitude of force por unil vo luke flered equation se .; radiation flexe dky F = d Prad E d Prad af kp The Hydrostatic equalen i apare dr = 4lyf , f = 2

a Prad - Lk de LITICGH Since we know =P = PatP. (P. cap, ) man - pr pr. dPr = 1 © The star of mass m - Maximum huminosity man- ketle Gry -3.3410 Lour Conan & Assuming the radiative deffund doments energy transport stars and capacity due to Thomson scallrig - Scaking arguened bestimate the mass m at the luminosity of share order of magnitude estimate with respect Lams Sublulite eddiglion Suninsente , we find me M Flores como Scars ~ 180 - Msum