We present spectroscopic observations from the Spitzer Space Telescope of six carbon-rich AGB stars in the Sagittarius Dwarf Spheroidal Galaxy ( Sgr dSph ) and two foreground Galactic carbon stars .
The band strengths of the observed C _ { 2 } H _ { 2 } and SiC features are very similar to those observed in Galactic AGB stars .
The metallicities are estimated from an empirical relation between the acetylene optical depth and the strength of the SiC feature .
The metallicities are higher than those of the LMC , and close to Galactic values .
While the high metallicity could imply an age of around 1 Gyr , for the dusty AGB stars , the pulsation periods suggest ages in excess of 2 or 3 Gyr .
We fit the spectra of the observed stars using the DUSTY radiative transfer model and determine their dust mass-loss rates to be in the range 1.0–3.3 \times 10 ^ { -8 } M _ { \odot } yr ^ { -1 } .
The two Galactic foreground carbon-rich AGB stars are located at the far side of the solar circle , beyond the Galactic Centre .
One of these two stars show the strongest SiC feature in our present Local Group sample .