Astronomy 100 Name: Homework 5 Due November 9, 2012 at 5 p.m., either electronically or on paper. 1. What is a stellar association, how big are they, how many stars do they contain, how long do they last? Finally, what is their fate? 2. In our part of the Milky Way galaxy, what “triggers” lead to star formation? Hint: there are three. What feature do all the “triggers” have in common? 3. Why are binary star systems so much easier to calculate the stars’ masses, then calculating the mass of a star in a single star system? Your answer must involve Kepler’s third law. 4. How is shell hydrogen-burning different than the proton-proton cycle? The same fusion reaction is occurring, so how are the two processes different?