Watching the Birth of Super Star Clusters

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AST 0307950PI: Jean TurnerINSTITUTION: University of California, Los Angeles Globular clusters present one of the great mysteries of modern astronomy. Globular clusters are large, spherical clusters containing hundreds of thousands of stars. In the Milky Way, globular clusters are all older than 10 billion years. Yet our Galaxy continues to form individual stars and small star clusters to the present day; why not globular clusters? For years it was believed that special conditions in the early universe were required for the formation of large clusters. Recently young "super star clusters", believed to be the precursors to globular clusters, have been discovered in nearby galaxies. The presence of young super star clusters in the local universe tells us that large clusters CAN form in the "present" universe, that is, within the past few million years. It also means that it is now possible to actually watch globular clusters being born, and to attempt to solve the puzzle of why globular clusters in the Milky Way are all old.Dr. Turner will study super star clusters that are very young, so young that they are still buried in their natal gas clouds. She will use the Very Large Array to image gaseous nebulae associated with young super star clusters at centimeter wavelengths, and to obtain precise locations and sharp images of the hot gas clouds that surround the clusters. Observations on the Keck Telescope will yield subarcsecond-resolution images of the infrared emission from dust in the gas clouds, to determine the energy outputs of the young clusters, and infrared spectra will be used to determine Doppler-shifted velocities for the gas, from which the motions, dynamics, and evolution of the gas clouds can be determined. Do these clusters cause superwinds, which might affect the galaxy around them? What properties of these gas clouds -density, angular momentum?-might explain the differences between super star cluster formation and star formation in the Milky Way? Is there evidence for the dissolution of these young clusters, which might explain why there are no young super star clusters in the Milky Way?The results of this ongoing research project will be widely disseminated to astronomers and physicists through articles in scholarly journals, scientific talks, and postings on the World Wide Web. Dr. Turner and her colleagues will provide reduced data and images to astronomers who request them and maintain the most popular radio and infrared images on the web. She and her collaborators and students will also reach the public with the presentation of images and results through popular talks, popular articles, press conferences, press releases, and web materials. A major component of this research project is the training of young physicists and astrophysicists, both graduate and undergraduate students. ***