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Proposal Information for 2003B-0161


PI: Howard E. Bond, Space Telescope Science Institute, bond@stsci.edu
Address: 3700 San Martin Dr., Baltimore, MD 21218, USA

CoI: Orsola De Marco, American Museum of Natural History
CoI: Diane Harmer, Kitt Peak National Observatory

Title: Searching for Spectroscopic Binaries in Planetary Nebulae

Abstract: There are increasing indications that binary-star processes are intimately related to the ejection of many, or possibly even most, planetary nebulae (PNe). The evidence includes: the fact that ~10% of PN nuclei are found to be very close binaries (periods of hours to a few days) through photometric monitoring; population- synthesis studies suggesting that these may be just the short-period tail of a much larger binary population extending up to orbital periods of several months; and the prevalence of highly non-spherical morphologies among PNe. The photometric search technique does not work for binaries in PNe with periods of more than a few days, since it relies on proximity effects. We therefore propose to carry out radial-velocity monitoring of a sample of relatively bright PN nuclei, in order to search for the anticipated population of binaries with periods up to a few months. If they do exist, there will be new implications for the evolution of binary populations, the origin of compact binaries (CVs, SN Ia progenitors), and even the question whether single stars can produce visible ionized PNe at all. This program was started in 2002B, but we had very bad weather and instrumental problems. Nevertheless, about 50% of the small number of targets we were able to observe had variable radial velocities, thus demonstrating the promise of our program. We have time coming up in 2003A to begin a survey of PNe in the spring sky, and the present proposal is to follow up on the objects in the autumn sky that looked so promising in 2002B.


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