Problem set due in class, Feb 05. Show your work.

1) The V magnitudes of two stars are both observed to be 7.5, but their blue mags are 7.2 and 8.7. What is the color index of each star? Which star is bluer and by what factor is it brighter at blue wavelengths then the other star? (4 points)

2) A variable star is observed to change its B-V color from 0.5 to 0.7. Assuming the star radiates as a blackbody, what would be the temperatures corresponding to the two color indices? (4 points)

3) What is the absolute bolometric magnitude of a star with a luminosity of 10^33 W? (4 points)

4) What is the sum of stellar masses in a visual binary of period 40 years, maximum separation of 5.0 arcsecs and a parallax of 0.3 arcsecs? Assume the orbital inclination is zero and a circular apparent orbit. (6 points)

5) An eclipsing binary has an orbital period of 2 days and 22 hours, the duration of each eclipse is 18 hours and totality lasts 4 hours. Find the stellar radii in terms of the circular orbital radius, a. If spectroscopic data indicates a relative orbital speed of 200 km/sec, what are the actual stellar radii in kilometers (6 points)?