AGB stars

Stars on the Asymptotic Giant Branch (AGB) are in their final stage of evolution. During this phase they contribute to the chemical evolution of galaxies, and in some cases they are the main, or even the only, sources of interstellar matter. Also, due to their high luminosities and low effective temperatures, they dominate the infrared radiation and can be used as probes of the galactic structures.

RESPIRE will provide a spectroscopic stellar survey in the near and mid IR, complete down to magnitude K = 14. This will constitute a unique investigation tool for all types of stars, and especially AGB stars. It will allow to extend the stellar classification to the most advanced types. It will take over the objective-prism techniques which have been useful in the visible range. A very limited number of stellar spectra had been taken in this wavelength range and practically no information is available in the regions of strong absorption by the terrestrial atmosphere; as often in stellar physics, the statistical dimension brought by RESPIRE will be essential to accurately classify sources.

The RESPIRE data will allow us to specify:

• the nature and the chemical composition of the photospheres,
• the effective temperatures,
• the spectral types,
• the luminosities and
• the mass loss rates.

RESPIRE will be an essential complement to the GAIA mission for the study of stars of late spectral type.