PI: Tammy Smecker-Hane INSTITUTION: University of California, Irvine
Dr. Smecker-Hane and her colleagues will undertake the first major campaign to determine the evolution of M33, a low-mass, late-type, spiral galaxy. Unlike the giant spirals in the Local Group (the Milky Way and M31), M33 has no galactic bulge, only a thin disk and either a thick disk or flattened halo. Hubble Space Telescope imaging has suggested the bulk of M33's globular clusters are significantly younger, by more than 6 Gyr, than globular clusters in the Milky Way and M31. Because hierarchical galaxy formation models, such as Cold Dark Matter, predict low mass galaxies form later than massive galaxies, studies of M33 will yield powerful constraints on galaxy evolution and structure formation theories.
These researchers will determine, with high precision, the spatial extent, kinematics, and chemical abundances of the distinct stellar populations of M33 by obtaining spectra of approximately 1000 stars. Smecker-Hane and her graduate students will use the Mosaic Camera on the Kitt Peak National Observatory 4-meter Telescope to complete an imaging survey of the outer disk/halo of M33 designed to separate bona fide M33 red giants from foreground Galactic dwarfs. They will use the Keck II 10-meter Telescope to obtain near-infrared spectra of M33 red giants from which they will derive chemical abundances and radial velocities. The relative masses of the thin disk and thick disk/halo of M33 will be determined and constraints will be place on theories of thick disk/halo formation, e.g., monolithic collapse verses satellite mergers. The metallicity distribution functions can be combined with color-magnitude diagrams to break the degeneracy of age and metallicity and uniquely, and accurately, derive M33's star-formation history.
During this project, two graduate students will learn sophisticated data reduction and analysis techniques that are critical to crowded-field photometry and multi-slit spectroscopy. Six undergraduate students will participate in this research: three UCI undergraduates and three NSF REU summer students. The graduate and undergraduate students will participate in numerous educational outreach projects organized by Smecker-Hane. including Visitor Nights at the UCI Observatory for the general public and tours for smaller groups of K-12 students. Each summer, Smecker-Hane and a graduate student will teach in the UCI COSMOS program, a summer program for high-school students who demonstrate excellence in math and science. COSMOS classes have equal numbers of male and female students, and approximately 30% are under represented minorities. ***
