NOAO >   Observing Info >   Approved Programs >   2009A-0162

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Proposal Information for 2009A-0162


PI: Daniel Caputo, University of Missouri - Columbia, dpce5b@mizzou.edu
Address: Department of Physics and Astronomy, 223 Physics Building UMC,, Columbia MO 65211, United States

CoI: Angela Speck, University of Missouri -Columbia
CoI: Kevin Volk, Gemini Observatory - North

Title: NIRI/Altair imaging of PAH bands around carbon stars: determining the formation and processing mechanisms of organic molecules.

Abstract: The Unidentified Infrared Bands (UIBs), due to Polycyclic Aromatic Hydrocarbons (PAHs), are widely observed in the ISM of the Milky Way and other galaxies of similar metallicity, and often dominate Spitzer mid-IR images of galaxies. Carbon stars (C-stars) are frequently cited as the source of PAHs, although only a very small number of C-stars, all with hot companions, actually exhibit UIBs. We propose to obtain NIRI mid-IR imaging of six C-stars with hot companions, several of which are known to show UIB emission. We will determine whether UIBs are associated with all binary C-stars with hot companions, or whether a further criterion is needed. Using the N-band data still being obtained from program GN-2007B-Q-5 and these observations we will obtain the 3.3/11.3 micron ratio, which can diagnose the PAHs size and help discriminate between competing PAH formation hypotheses. This size information will allow us to constrain the species of the PAHs being formed. If there is a relationship between the geometry of the system and a distribution of the sizes of the PAHs then we will be able to provide a foundational observation for PAH processing.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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