Research Interests

I am an observational astronomer whose principal area of research is the formation and evolution of galaxies studying the structure and star populations of distant galaxies. I use large telescopes to study the structure and star populations of distant galaxies. In early research I demonstrated, by studying galaxies in dense associations called "clusters," that both birth conditions and the later environment play a role in determining a galaxy's destiny. Currently, I am using a relatively new technique of investigating galaxy evolution directly by using the Hubble Space Telescope to take pictures of clusters of galaxies at distances of 4 to 5 billion light years to study the evolution of galaxy structure and morphology over this stretch of cosmic time. I was a principal contributor to a study of how uniform the expansion of the Universe is in our galactic neighborhood. This research led to the identification of the "great attractor," an enormous concentration of galaxies and invisible matter whose gravity appears to be pulling our Milky Way galaxy and its neighbors. Observations like these are relevant to understanding how galaxies and clusters formed from the once-smooth early Universe. I recently led a study that investigated the possible directions for space science in the coming decades, leading to a new effort to build a next-generation space telescope.

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Section 12: Astronomy