Spitzer Space Telescope - Guaranteed Time Observer Proposal #50740


Exploring Dwarf Carbon Stars: Do They Really Have Disks?

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

     Technical Contact: Patrick Lowrance, SSC/Caltech

Co-Investigators: 
Patrick Lowrance, Caltech                                             

Science Category: circumstellar/debris disks 
 Observing Modes: IracMap MipsPhot 
  Hours Approved: 11.5 

Abstract:
With the discovery of G77-61 (Dahn et al. 1977) at a mere 58 pc and therefore
relatively low luminosity, a category of dwarf carbon (dC) stars was finally
recognized.This, however, presented a puzzle because a low mass star is
incapable of the helium fusion needed to create carbon. A reolution was proposed
and generally accepted a second member of a system could 'dump' carbon on it
through an AGB stage. Current understanding of the formation and evolution of
dC's is, however, limited by the small number of objects and observations. We
propose observations of each carbon dwarf with IRAC, MIPS 24um, and MIPS 70um to
attempt to detect a redsidual debris disk from such an event. The proposed model
for creating carbon dwarfs is based on three objects and the mechanism for
dumping material on these low-mass stars and building debris systems are
currently unexplored. Thus the opportunity afforded by our program to add
observational proof is valuable, especially for the very ill-studied carbon
dwarfs. Only Spitzer can provide the spectral range and sensitivity to gain the
observations needed in understanding disk formation and dissipation timescales
around all evolved stars placing carbon in our ISM - a building block of life as
we know it.