Spitzer Space Telescope - General Observer Proposal #50793


IR Excesses of Central Stars of Planetary Nebulae

Principal Investigator: Jana Bilikova
           Institution: University of Illinois, Urbana-Champaign

     Technical Contact: Robert Gruendl, University of Illinois at Urbana-Champaign

Co-Investigators: 
You-Hua Chu, University of Illinois, Urbana-Champaign                 
Robert Gruendl, University of Illinois, Urbana-Champaign              
Kate Su, University of Arizona                                        
Thomas Rauch, Universitat Tubingen                                    
Kevin Volk, Gemini Observatory                                        
Orsola De Marco, American Museum of Natural History                   

Science Category: circumstellar/debris disks 
 Observing Modes: IrsMap IrsStare MipsPhot 
  Hours Approved: 2.8 

Abstract:
Dust disks have been detected around binary post-AGB stars, central stars of
planetary nebulae (CSPNs), and white dwarfs (WDs). It is not clear whether some
of the dust disks have a common origin and persist through the stellar
evolution. To search for connections among these dust disks, we have used
archival Spitzer observations to survey 40 resolved planetary nebulae and their
central stars. IR excesses indicating the existence of dust disks are found in
four CSPNs - in NGC 2346, NGC 2438, NGC 6804, and NGC 7139. To accurately
measure the continuum fluxes and to search for spectral features of dust grains,
we request IRS and MIPS 24 um observations of these nebulae, while avoiding
duplication of the archival data. The IRS observations will allow us to
unambiguously separate line and continuum emission components and to search for
mineralogical features of dust grains, and the MIPS 24 um observations allow us
to extend the SEDs to longer wavelengths for better constraint of the dust
temperature and distance from the central star. The results will be used to
assess the nature of the IR excess and the origin of the dust, and possible link
these dust disks to those around post-AGB stars and WDs.