AS102 Study Guide - Quiz Guide: Instability Strip, Cosmic Distance Ladder, Harlow Shapley
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Because all the stars were found in the same nebula she knew that the variation in brightness did not depend greatly on distance and she knew that the relationship she had discovered was a valid finding. Such stars lie on the h-r diagram in a region known as the instability strip. As long as they live in this region of the h-r diagram they pulsate. When they move off the strip, as they grow older, they no longer pulsate. Here is a 6. 5-minute video about leavitt"s work describing how important her finding is. http://www. youtube. com/watch?v=e9gvk_okrpw. In the last module we learned about two types of star clusters, open clusters and globular clusters. Around 1920 a young american astronomer, harlow shapley, noticed that these two types of clusters appear in different parts of the galaxy. Open clusters seemed to be concentrated along the milky way whereas globular clusters were more widely scattered.
