Spectra of late-type standard stars in the region 2.0-2.5 microns

The present atlas of K-band spectra for 26 near-solar abundance stars in the F8 to M7 spectral type range and dwarf to supergiant luminosity range is the basis of a comparison of the integrated absorption strengths of selected features with narrowband filter photometry. The comparison indicates that the filter photometric CO index of Frogel et al. (1978) in dwarfs is significantly diminished by H2O absorption in the reference band used to estimate the continuum. Temperature and luminosity dependencies of the strong atomic and molecular features reveal significant differences which are partly due to the higher excitation of the atomic features and partly to the differences in sensitivities of the atomic lines and molecular bands to microturbulence.