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R. Ciardullo, S. Sigurdsson (Penn State), J.J. Feldmeier (NOAO), G.H. Jacoby (WIYN)
We investigate the possible progenitors of the brightest planetary nebulae (PNe) in elliptical and lenticular galaxies. We show that the central star luminosities of PNe in the top ~0.5~mag of the [O~III] \lambda 5007 planetary nebula luminosity function must be ~10,000 L\odot, or ~40~times brighter than is possible from the evolution of 8 to 10~Gyr old single stars. We couple this fact to measurements of the bolometric-luminosity specific PN number density to show that in a typical elliptical galaxy, only ~10% of the stars turning off the main sequence evolve into [O~III]-bright planetaries. Taken together, the data imply that either all early-type systems contain a small, distributed component of young (1 to 2~Gyr old) stars, or another mechanism exists for creating these extremely luminous objects. We argue that binary-star evolution is this mechanism, and show that blue stragglers have the appropriate core properties and number density to explain all the objects populating the bright end of the luminosity function. We discuss the implications binary star evolution have for future PN-based studies of galactic stellar kinematics and chemical evolution.
This work was supported by NSF grant AST 00-71238.
The author(s) of this abstract have provided an email address for comments about the abstract: rbc@astro.psu.edu
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.