Problem set due in class, Feb 19. Show your work.

1) Use the mass-luminosity relation to compute the luminosity range of stars from the observed mass range of 0.085 solar masses to 100 solar masses. What is the mass of a star with 1/10 the luminosity of the Sun? What is the mass of a star with 1000 times the luminosity of the Sun? (4 points)

2) The absorption spectra of four stars exhibit the following characteristics. What are their spectral types? (4 points)

1. The strongest features are titanium oxide bands
2. The strongest lines are ionized helium
3. Hydrogen Balmer lines are very strong and some ionized metal lines are present
4. Ca II lines are the strongest in the spectrum

3) Calculate how much energy is released from the proton-proton reaction knowing that 0.71% of the four protons mass is missing. Assume the Sun is 100% hydrogen, how long will it burn at its current luminosity? [26 billion years] (4 points)

4) Use hydrostatic equilibrium to compare the central pressure of the Sun to (6 points) [see appendix of textbook for stellar values]

• a B0 V star
• a G2 III star
• a G2 I star