Spitzer Space Telescope - Guaranteed Time Observer Proposal #30285


Spitzer Observations of Planetary Nebulae - 2

Principal Investigator: Giovanni Fazio
           Institution: Harvard-Smithsonian Astrophysical Observatory

Co-Investigators: 
William Latter, NASA/Herschel Science Center                          
Massimo Marengo, Harvard-Smithsonian Center for Astrophysics          
Luciano Cerrigone, Harvard-Smithsonian Center for Astrophysics        

Science Category: evolved stars/pn/sne 
 Observing Modes: IracMap IrsStare 
  Hours Approved: 10.6 

Abstract:
Several interesting results have been obtained so far from our initial
programs of observations of Planetary Nebulae (PNe) with Spitzer.  The
emission from PNe in the IRAC bands is redder than expected, due
mainly to stronger than expected emission in the 8.0  ?m band due to
lines of molecular hydrogen (H2) and forbidden line emission from the
ionized gas.  The IRAC images have detected new structures in some
nebula (e.g., NGC 246) and has detected H2 emission far out in the
halos of several PNe (NGC 6543, NGC 6720, NGC 7293).  We are proposing
several new observations to follow-up on these results.  There are
three categories of new observations:  follow-up IRAC mapping related
to previously observed PNe, follow-up IRS spectra of PNe that have
been previously imaged with IRAC, and new IRAC imaging of an
additional sample of PNe.  These new observations will enable us to
map the full extent of the large PNe observed, to determine the
components of the emission detected in the IRAC images and ascertain
its temperature and excitation mechanisms, and search new PNe for
emission from H2 and dust in their halos.