On the luminosity of AGB stars as observed in the infrared from space and from the ground

As a part of a reanalysis of galactic Asymptotic Giant Branch stars (hereafter AGB stars), we discuss here two samples for which photometry in the near- and mid-infrared and distance estimates exist. Whenever possible we searched also for mass loss rates. Spectral energy distributions were always up to 20 mu m and for the best observed sources up to 45 mu m. For the first sample (carbon-rich stars) we present rather complete results, while for the second sample (S stars) we give only the preliminary results. In particular, for carbon stars the wide wavelength coverage allows us to obtain reliable bolometric magnitudes. Moreover, we show that mid-IR fluxes are crucial to estimate the magnitudes of stars with dusty envelopes. The resulting brightness of C stars is relatively high (brighter than Mbol = -4.8), so that the long-claimed luminosity problem of C-rich stars does not appear to exist. We examine the different properties of the carbon rich stars according to their type of variability and find that the relevance of Miras and Semiregulars varies with evolution, with Miras dominating the final stages. We present here also the first results of a similar analysis that we are doing for a sample of galactic S stars. Finally, we show here a first comparison between mid-IR measurements made by space observatoriess (ISO, MSX) and ground observations performed by us with the IR camera TIRCAM2....