NOAO >   Observing Info >   Approved Programs >   2003B-0397

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Proposal Information for 2003B-0397


PI: Denise Hurley-Keller, Case Western Reserve University, denise@smaug.astr.cwru.edu
Address: Astronomy Department, 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 as a result, 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 show that the PN at ``halo'' distances actually show significant rotational support (with v_rot=130 km/s) and likely belong instead to the outer bulge. So far, a few intriguing objects have velocities which are not compatible with either the bulge or disk, and may be true hot halo objects. But more velocities are needed before we can characterize the kinematics of this halo population. With the 0.9 m in September 2002, we extended the imaging survey out to nearly 30 kpc around M31 with great success, identifying nearly 100 new PN candidates in the outer disk, bulge and halo. We are requesting four nights for the follow-up Hydra spectroscopy (which was lost last year due to weather) and two additional nights of 0.9 m time to pursue regions of interest discovered in last year's imaging survey.


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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