Introduction to Astrophysics I, 29:119
Fall, 2008
Eighth Homework Set...November 4, 2008.
Due November 11, 2008

Show calculations and give reasons for your answers. Don't go around confused and despondent; if you do not know how to get started, ask me for help.

(1) Problem 9.13 from textbook

(2) Problem 9.22 from textbook

(3) Problem 9.23 from textbook

(4) Problem 10.1 from textbook

(5) Problem 10.3 from textbook

(6) Assume that the solar photosphere is isothermal, i.e. that its temperature is constant. Calculate the pressure scale height in the photosphere, i.e. the vertical scale length over which the pressure falls by a factor of $e$. Hint: You have to search in the textbook for some important numbers.

(7) Compare the pressure gradient in the photosphere with the maximum pressure gradient in the interior of the Sun. Hint: Information on conditions in the interior of the Sun are available in your textbook, and elsewhere.

(8) Use the chemical abundances of the Sun in Table 9.2. Demonstrate the truth of the statement in the textbook (p293) that

$$\left< \frac{1+z}{A}\right>_i \simeq \frac{1}{2}$$ (1)

(9) Given the result from problem # 8 and the data in Table 9.2, calculate the mean molecular weight for fully-ionized solar material.