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Proposal Information for 2010A-0205


PI: George Jacoby, NOAO, jacoby@noao.edu
Address: 950 N Cherry Ave, Tucson, AZ 85719, USA

CoI: Evan Kaplan, Vassar College

Title: Spectroscopic Confirmation of Very Old Planetary Nebula Candidates

Abstract: Planetary Nebulae (PNe) are considered a normal evolutionary phase of all 1-8 M_\sun stars as they evolve beyond the AGB. With that assumption, and a lifetime of ~25,000 years, population synthesis models predict a Galactic population of 25,000-50,000 PNe (Moe & De Marco 2006). After 85 years of searching, sometimes intensively in the IR, radio, and optical, we know of only ~3000. Something is wrong by a factor of 10: the models, the assumptions, or survey completeness. Often, extinction is implicated. But, the numbers are also low in surveys of external galaxies where extinction is not a big problem. In M31, for example, Merrett et al (2006) identified ~2600 PNe. After correcting their flux limited sample for incompleteness, the total is unlikely to exceed 10,000. If there really are <10,000 PNe in the Milky Way, then the assumptions and models must be challenged. In particular, there is growing evidence that a close binary is required to provide the energy to shape PNe via magnetic fields, and to accelerate the evolution of the central star so that it can ionize the nebula before it dissipates into the ISM (De Marco 2009). In this proposal, we wish to explore further the survey incompleteness question. We have been searching for PN candidates using digital sky survey data (POSS I, II, 2MASS) and we need to complete the spectroscopic confirmation for our classifications for the remaining 30 targets that were not observed in our September 2009 run due to weather.


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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