NOAO >   Observing Info >   Approved Programs >   2009B-0284

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Proposal Information for 2009B-0284


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 those assumptions, 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 ~2500. Something is wrong by a factor of 10: the models, the assumptions, or the survey completeness. Usually, extinction is suspected, but in surveys of external galaxies like M31 where extinction is not a major problem, the numbers are also low (Merrett et al 2006), and unlikely to exceed 10,000 after correcting for their flux limited sample of ~2600. If there really are <10,000 PNe, 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) gives further arguments for the binary model. 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 now need to confirm through spectroscopy the classification of 61 of our 97 targets.


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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