Homework 2

And 1 e 10 pt based on part d it appears that a star

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: cP show that: ad 1 + (4 + β )(1 − β )/β 2 = 5/2 + 4(4 + β )(1 − β )/β 2 Plot ∇ad as a function of β and determine the limits for β = 0 and 1. (e) [10 pt] Based on part (d), it appears that a star supported by radiation pressure might nevertheless transport heat through convection (because of the reduced adiabatic gradient). Using our previously derived expression for ∇rad and assuming the opacity is dominated by Thompson (free-free) scattering, κ ≈ 0.35 cm2/g, in what mass/luminosity regime would this be the case? Explain the relevance of this constraint to the maximum mass a star can have (the Eddington limit). (3) Adiabatic gradient for a partially ionized gas. We’ll now repeat the above analysis for a partially ionized ideal gas, to show how ionization can influence thermal transport. Consider a pure H gas, with pressure P= ρkT µmH and ionization fraction n− 1 − n0 n+ = = y≡ n n n where n+, n-, n0 and n are the number densities of free protons, free electrons, neutral H atoms and total particles, respectively; and n+ = n-. (a) [10 pt] First compute the mean molecular weight, and show that: 1 1 1 1 1...
View Full Document

This document was uploaded on 02/28/2014 for the course PHYS 223 at UCSD.

Ask a homework question - tutors are online