Revealing infrared populations of nearby galaxies using the Spitzer
  Space Telescope
  Due to their brightness in infrared, asymptotic giant branch (AGB) stars are
in important evolutionary stage to be understood at this wavelength. In
particular, in next decades, when the infrared optimised telescopes, such as
the JWST and the ELT are in operation, it will be essential to include the AGB
phase more precisely into the population synthesis models. However, the AGB
phase is still one of the remaining major problems in the stellar evolution.
This is because the AGB stellar evolution is strongly affected by the mass-loss
process from the stars. It is important to describe mass loss more accurately
so as to incorporate it into stellar evolutionary models. Recent observations
using the Spitzer Space Telescope (SST) enabled us to make a significant
progress in understanding the mass loss from AGB stars. Moreover, the SST large
surveys contributed to our understanding of the role of AGB stars in chemical
enrichment process in galaxies. Here we present the summary of our recent
progress.
