Homework Handout #4

4.01:  We wrote the mean molecular weight m for a fully ionized gas as 1/m  = 2 X + 3/4 Y + 1/2 Z.  Derive this relationship for m,indicating the assumptions and approximations used in each step.

4.02:  Use hydrostatic equilibrium and scaling arguments of example 10.1 of the text (see also example 8.5) to compare the central pressure of the Sun with

(a) a B0 V star
(b) a G2 III star
(c) a G2 I star
(Hint: use the stellar parameters from Appendix E.  Comparing with the Sun means expressing in units of the solar values.)