Old stellar populations. II. an analysis of K-giant spectra.

Eleven strong absorption features are studied in a sample of 110 K-giant stars, based on spectra taken at 9-A resolution, including such features as CN 4170 A, G-band, H-beta, Mg b, MgH, two Fe lines, NaD, and two TiO bands. The surface features sensitive to surface gravity are determined; it is noted that the most accurate gravity indicator appears to be the index Mg2. Previously identified super metal-rich stars generally show the strongest lines of iron, CN, Mg, and NaD; essentially all intermediate and strong blends are also markedly enhanced in these stars. Finally, iron-line residual Delta-Fe is shown to be a good measure of metallicity and at the same time independent of surface gravity.