PI: Tammy Smecker-Hane, University of California, Irvine, email@example.com
Address: Dept. of Physics & Astronomy, 4129 Frederick Reines Hall, Irvine, CA 92697-4575, USA
CoI: Michael Hood, University of California, Irvine
CoI: Matthew Teig, University of California, Irvine
CoI: Andrew Cole, Kapteyn Astronomical Inst., Groningen, NL
Title: Chemical Evolution of the Outer Disk/Halo of M33: Subtracting the Galactic Foreground
Abstract: We propose to conclude our imaging survey of M33, making up for time lost due to bad weather in our initial observing run. We are imaging fields in the outer disk/halo of M33 using the KPNO 4-meter telescope, MOSAIC camera, and V, I and DDO51 filters. The DDO51 filter measures the absorption strength of a Mg \small I triplet and MgH bandhead, which are highly sensitive to surface gravity in late-type stars. Thus we can reliable distinguish between bona fide M33 red giants stars and foreground Galactic dwarfs using the (V-I, 51-V) plane. Contamination by foreground Galactic dwarfs is significant because the surface density of M33 stars is low in the outer regions and the velocity separation between M33 and Galactic stars is not large enough to reliably discriminate between them using radial velocities. Subsequent to the photometry, we will obtain spectra of approximately 1000 M33 red giants with the Keck II 10-meter telescope to derive metallicities with random errors of ~ 0.15 dex and radial velocities with random errors of ~ 15 km/s per star. These data will allow us to accurately define the kinematic and chemical structure of M33's stellar populations (thin disk, thick disk and/or halo) and test models of galaxy formation and evolution. Our program adds value to the M33 photometry obtained by Massey et al. in an NOAO Survey program by extending it to larger radii and providing dwarf/giant discrimination. In addition, our data have defined photometric zeropoints for scheduled ACS/HST imaging of M33 halo fields.
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