PI: Richard A. Shaw, NOAO, email@example.com
Address: 950 N. Cherry Avenue, Tucson, AZ 85719, USA
CoI: Todd Hillwig, Valparaiso University
CoI: Armin Rest, Harvard University
Title: LMC Planetary Nebulae with Binary Progenitors
Abstract: Modern, high-resolution images of planetary nebulae (PNe) and pre- PNe, along with the most recent magneto-hydrodynamical models, have revealed a number of paradoxes in attempting to understand the mechanisms that govern the late stages of stellar evolution. New appeals to close binary interactions to shape axisymmetric PNe and govern their subsequent evolution must be reconciled with observations of volume-complete samples, and with predictions of chemical yields of such systems, which show that common-envelope evolution will suppress the observed nitrogen super-enhancement in bipolar PNe. This program is a step along the path to determining the fraction of PNe with binary nuclei by leveraging two extensive, wide-area time domain surveys of the Large Magellanic Cloud (LMC): SuperMACHO and OGLE-3, from which we have already identified photometric variability in two dozen targets-a number comparable to all Galactic PNe with binary central stars until recently. Combined with a recent, 25 deg^2 discovery survey in H(alpha) for LMC PNe, which is complete at least 8 mag below the brightest in the PN luminosity function, we have a unique opportunity make a direct measurement of the binary fraction of PN progenitors, and thus to address one of the most pressing scientific questions in stellar evolution research.
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