1. A binary star system is observed containing a blue and a red star with roughly equal magnitudes. The optical spectra of the two stars are well approximated by black body curves with maximum intensity at a wavelength of 3250 Angstroms and 7250 Angstroms respectively. What is the ratio of the radii of these two stars?
2. If the two stars in the previous question produce a combined total flux at the Earth of 2.6x10**-6 erg/s/cm**2, and they have a measured parallax of 0.02 arcsec, what are the radii of the two stars?
3. Why is the Rayleigh-Jeans law so useful in radio astronomy?
4. Roughly how hot must a plasma be for most of the H to be ionized? For most of the He to be singly ionized? Doubly ionized?
5. Explain how the H-alpha absorption strength changes as we raise the temperature of a star.