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C. J. Grillmair (Spitzer Science Center), K. C. Freeman (Australian National University), K. Gebhardt (University of Texas), G. Gilmore (Cambridge University), E. Grebel (University of Basil), J. Kormendy (University of Texas), D. Lin (University of California, Santa Cruz), M. Mateo (University of Michigan), J. Mould (National Optical Astronomy Observatories), C. Pryor (Rutgers University), M. Shetrone (University of Texas), S. Sigurdsson (Pennsylvania State University), R. Wyse (Johns Hopkins University)
We describe a proposed SIM PlanetQuest project to examine the nature of the dark matter which dominates several dwarf spherioidal galaxies in the Local Group. By measuring a total of five phase space coordinates for ∼ 100 stars per galaxy we can unambiguously isolate the effects of triaxiality and orbital anisotropy in these relatively simple systems and thereby characterize the underlying distribution (and thus temperature) of the dark matter. The project relies on the measurement of highly accurate proper motions (2-5 microarcseconds per year) for relatively faint stars ( V ≈ 19), a requirement which is uniquely satisfied by SIM PlanetQuest and which cannot be met by any other mission currently on the horizon.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.