NOAO >   Observing Info >   Approved Programs >   2002B-0284

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Proposal Information for 2002B-0284


PI: Denise Hurley-Keller, Case Western Reserve University, denise@smaug.astr.cwru.edu
Address: 10900 Euclid Ave., Cleveland, OH 44106, USA

CoI: Heather Morrison, Case Western Reserve University
CoI: Paul Harding, Case Western Reserve University
CoI: George Jacoby, WIYN

Title: Planetary Nebulae in the Halo of M31

Abstract: Opportunities to observe the stellar halos of disk galaxies are relatively rare, and so most of our ideas about the formation of halos derive from studies of the Milky Way. M31 is the next logical target; it has a much larger bulge-to-disk ratio than the Milky Way, suggesting that different processes have been important in its formation and evolution. Early results from a Burrell Schmidt survey of planetary nebulae (PN) with velocities from WIYN Hydra spectroscopy (Hurley-Keller et al. 2002) show that the outer PN (at distances commonly thought of as the halo's) actually show significant rotational support and belong instead to the bulge or thick disk. A few intriguing objects have velocities which are not compatible with any rapidly rotating population, and are likely true halo objects. But we cannot characterize the kinematic properties of the halo or untangle the kinematics of the bulge and thick disk without a deeper survey than is possible with the Burrell Schmidt. We are requesting 0.9m time, with follow-up Hydra spectroscopy, to push our survey deeper down the PN luminosity function and to extend the survey to the rest of the galaxy, increasing the number of halo PN in our sample from ~ 10 to ~ 60.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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