In this proposal, more time is being requested for MRIEKE.M31_M32.
Almost any stellar population present in a galaxy should contain a number
of asymptotic giant branch (AGB) stars. This phase of stellar evolution is
very difficult to model, and hence the inverse issue of trying to model the
output of a composite stellar population as a function of time is extremely
uncertain. We propose a search for emission from the circumstellar shells
around the AGB stars present in the nuclues of NGC 3115, a nearby S0 galaxy
with an old stellar population. This will extend the ISO study of AGB stars
in M31 and M32 to the only other quiescent galaxy observable. The AGB star
emission will be characterized by the presence of a silicate feature at 10
microns.