NOAO >   Observing Info >   Approved Programs >   2002B-0201

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Proposal Information for 2002B-0201


PI: Patrick Durrell, Penn State University, pdurrell@astro.psu.edu
Address: 525 Davey Lab, State College, PA 16803, USA

CoI: Robin Ciardullo, Penn State University
CoI: George Jacoby, WIYN Observatories
CoI: Mary Beth Laychak, Penn State University
CoI: John Feldmeier, Case Western Reserve University

Title: The Velocity Dispersion of the M33 Disk

Abstract: Although the mass-to-light profile of spiral disks is poorly known, this function is crucial for interpreting the information of spiral rotation curves. We propose to measure this quantity throughout the disk of the Local Group Sc galaxy M33 by obtaining precision radial velocities for 160 of the galaxy's planetary nebulae using WIYN+HYDRA. From these data, we will determine the vertical velocity dispersion of M33's old-disk stars, and thereby measure the galaxy's surface-mass density over ~ 5 disk scale lengths. This information will then be combined with measurements of the galaxy's rotation curve to derive the radial profile of M33's dark-matter halo. Our data will therefore provide a direct test of CDM cosmological models which predict cuspy profiles for these halos.


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