PI: Bruce Hrivnak, Valparaiso University, Bruce.Hrivnak@valpo.edu
Address: Department of Physics and Astronomy, 1610 Campus Drive East, Valparaiso, IN 46383, USA
CoI: Ken Hinkle, NOAO
Title: Testing the Binary Hypothesis for Bipolar Proto-Planetery Nebulae
Abstract: We propose to test the popular but observationally unsupported hypothesis that the bipolar shapes of planetary nebulae (PNe) arise from the interaction of a binary companion. The observing targets are three edge-on proto-PNe (PPNe) in which the central star is obscured in visible light by an optically-thick torus but in which the central star can be seen in the near-infrared. We would obtain high-precision radial velocity observations of the central stars to search for radial velocity variations. This radial velocity study will provide a stringent test of the popular binary hypothesis as the mechanism to produce this torus that then collimates the outflow to produce the bipolar nebulae. A positive result would support the binary hypothesis and open the way to determine the exact shaping mechanism. A null result would rule out the presence of a close binary and also specifically the idea of post-AGB binaries (~30% of all AGB stars) as predecessors of bipolar PPNe and the close binary central stars of PNe as their progeny. A null result due to common envelope binary merger will be investigated by line- width measurements.
National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360