NOAO >   Observing Info >   Approved Programs >   2011A-0430

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Proposal Information for 2011A-0430


PI: Orsola De Marco, Macquarie University, orsola.demarco@mq.edu.au
Address: Physics Department, North Ryde, Sydney, NSW 2109, Australia

CoI: Dimitri Douchin, Macquarie University
CoI: George Jacoby, Carnagie Observatories and GMT
CoI: Maxwell Moe, Harvard University
CoI: Todd Hillwig, Valparaiso University
CoI: David Frew, Macquarie University
CoI: Jean-Claude Passy, University of Victoria

Title: The Binary Fraction of Central Stars of Planetary Nebulae

Abstract: There is growing evidence that a 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 repercussions 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 (e.g., novae, SN Ia). In this proposal we continue to test this hypothesis by determining the central star binary fraction. This is one of the suite of observational projects from a collaboration of 30 researchers, testing the PN binary hypothesis. So far we know that 15-20% of central stars of PN are in binaries with periods \laa few days, but the technique used to find them is insensitive at longer periods. We have recently carried out a pilot I-band excess survey at the NOAO 2.1 m telescope, from which we determined a binary fraction much larger than predicted. However, with a sample of only 26 objects, the statistical relevance of our result is limited. We therefore propose to extend the sample by a factor of two to improve the significance of the detected binary rate to the ~3\sigma level.


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