Dr. Andrew Layden studies the formation of our Galaxy, the Milky Way. The motions, positions, and chemical composition of the stars in our Galaxy have "locked in" the memory of the properties of the gas clouds which formed them, thus providing us with a window into the past through which to view the formation and early evolution of the Milky Way. Layden's observations support the notion that the Galaxy formed from the slow accumulation of small, gas-rich dwarf galaxies, rather than through the coherent collapse of a single, large proto-Galactic cloud. This idea is further supported by the discovery of the Sagittarius dwarf galaxy (Sgr), caught "in the act" of merging with the Milky Way. Layden is studying the ages and compositions of the stars in Sgr, along with Sgr's huge globular cluster M54 (link to m54.gif), and comparing them with the properties of the old stars in the Galaxy. So far, it appears that Sgr is typical of the "building block" dwarf galaxies that merged to form the early halo, the exception being that Sgr's wider orbit kept it free of the tidal grasp of Galaxy unitl recently. Layden is also using the Hubble Space Telescope to study the stars in several globular clusters, and is using the BGSU 0.5-meter telescope with BGSU undergraduates to study the brightness and color changes in a sample of nearby variable stars. You can learn more about Dr. Layden's research here.