How often can a star go supernova? Group of answer choices   Many times, depending on the size of its companion star.   Twice, the first time when it runs out hydrogen, and the second time when it runs out of iron.   Once, early in its evolution.   Once, late in its evolution.   At various times, depending on the composition of the star.

Match each statement with the appropriate item (If the first corresponds to B and the next 4 to C, enter BCCCC) 1) stars that have evolved off the main sequence and are growing in luminosity due to a hydrogen burning shell 2) young, spread out star cluster 3) cooler stars in a cluster that have not yet evolved off the main sequence 4) stars that are burning helium in their core 5) old, dense star cluster  A. red-giant branch B. open cluster C. lower main sequence D. horizontal branch stars E. globular cluster

List the following 5 terms in order through a stars life cycle (starting with the sun), through the remainder of its lifetime: a. Black dwarf b. Planetary nebula c. Red giant d. Star (Sun) e. White dwarf

Why are Cepheid variables important? O Cepheids variables are pulsating stars whose pulsation periods are directly related to their true luminosities. Therefore they can be used as distance indicators. O Cepheids variables are supermassive stars that are on the verge of becoming supernovae. Therefore they allow us to choose candidates to watch if we hope to observe a supernova. O Cepheid variables are stars that vary in brightness because they harbor a black hole. Therefore, they provide direct evidence for black holes. O Cepheids variables are a type of irregular galaxy, much more common in the early universe. Therefore they help to understand how galaxies formed.