A library of 0.5 to 2.5 μm spectra of luminous cool stars

We present a library of 0.5 - 2.5 mum digital spectra of cool, mostly variable, giant and supergiant stars which should be useful for spectral synthesis applications, as well as for comparison with theoretical model atmosphere calculations. The library includes carbon stars. Galactic Bulge and Magellanic Cloud stars, and OH/IR stars. The stars observed cover a range of metallicities and masses. Most variable objects were observed several times, at different phases of their pulsation cycle. We discuss the effects of various fundamental parameters and of variability on the spectra. Based on period-luminosity relations and stellar evolutionary tracks, we tentatively assign initial masses to each object.