NOAO >   Observing Info >   Approved Programs >   2007B-0086

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Proposal Information for 2007B-0086


PI: Orsola De Marco, American Museum of Natural History, orsola@amnh.org
Address: Astrophysics, Central Park West at 79th street, New York, NY 10024, USA

CoI: Maxwell Moe, University of Colorado
CoI: George Jacoby, WIYN
CoI: Howard Bond, Space Telescope Science Institute
CoI: Todd Hillwig, Valparaiso University

Title: Do most planetary nebulae come from binaries?

Abstract: There is evidence suggesting that the vast majority of planetary nebulae (PNe) harbor close binary central stars. If so, PNe would be a binary interaction phenomenon. If this were the case, there would be repercussion in our understanding of galactic enrichment, nebular shaping mechanisms, and the relationship between central stars of PN and other post-common envelope and strong interaction binary classes. In this proposal we seek to test this hypothesis by determining the central star binary fraction. So far we know that at least 10-15% of central stars of PN are in binaries with periods <3 days, but the light- variability technique used for detection is insensitive at longer periods. We have more recently carried out a radial velocity survey which \it indicated a binary fraction higher than 50%, but no periods were determined. While periods are still being pursued by our team, it is now clear that the radial velocity technique, applied to the faint, broad-lined central stars of PN is not efficient. After the success of a pilot project, we are therefore proposing to determine the central star binary fraction by detecting near infrared excess indicative of companions as faint and cool as M6 main sequence stars, in the spectrum of selected hot, low luminosity and nearby central stars.


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