Cowley 9417013 The two nearest galaxies to the Milky Way are the small, irregular galaxies known as the Large and Small Magellanic clouds. Unlike our own Galaxy, they contain little interstellar dust to dim the stars within them. By contrast much of the Milky Way is hidden from observation by thick bands of interstellar dust which lie along the plane of the Galaxy preventing observation of stars behind it. Thus, the Magellanic Clouds are ideal laboratories in which to study the overall properties of various classes of stars. Both of them contain numerous X-ray sources which are associated with highly evolved binary systems. Study of these objects allows us to learn about the properties of stars which are nearing the end of their evolution. These are unusual objects such as white dwarfs, neutron stars, and black holes. The goal of this project is to study the X-ray sources in the Magellanic clouds to learn more about these end-stages of stellar evolution. This project will combine the accurate positions for these stars obtained with the ROSAT X-ray satellite with optical photometry and spectroscopy of these same stars to measure their masses, sizes, temperatures, and other physical properties. It is only in these rare binary systems that we have the opportunity to investigate directly the properties of degenerate stars and learn how they interact with their mutually orbiting companion stars. ***
