Spitzer Space Telescope - Guaranteed Time Observer Proposal #50116


Investigating the Dust Chemistry in Pre-Planetary Nebulae

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

     Technical Contact: Luciano Cerrigone, Harvard-Smithsonian Center for Astrophysics

Co-Investigators: 
Luciano Cerrigone, CfA                                                
Joseph Hora, CfA                                                      
Grazia Umana, INAF, Italy                                             
Corrado Trigilio, INAF, Italy                                         
Massimo Marengo, CfA                                                  

Science Category: evolved stars/pn/sne 
 Observing Modes: IracMap IrsStare 
  Hours Approved: 10 

Abstract:
We propose to extend our study of young planetary nebulae/transition objects
with IRAC and IRS to 1) confirm the result of the previous observations of a
high (50%) incidence of dual-dust chemistry in these objects, and 2) examine a
sample of objects at an earlier evolutionary state to determine the point at
which the emission features arise in the shells around these objects. These
data, along with ground-based high spatial resolution imaging, will provide
information on the mechanisms that lead to their asymmetric shapes.