A Medium‐Resolution Near‐Infrared Spectral Library of Late‐Type Stars. I.

We present an empirical infrared spectral library of medium resolution(R~2000-3000) H (1.6 micron) and K (2.2 micron) band spectra of 218 red stars,spanning a range of [Fe/H] from ~-2.2 to ~+0.3. The sample includes Galacticdisk stars, bulge stars from Baade's window, and red giants from Galacticglobular clusters. We report the values of 19 indices covering 12 spectralfeatures measured from the spectra in the library. Finally, we derivecalibrations to estimate the effective temperature, and diagnosticrelationships to determine the luminosity classes of individual stars fromnear-infrared spectra. This paper is part of a larger effort aimed at building a near-IR spectrallibrary to be incorporated in population synthesis models, as well as, attesting synthetic stellar spectra.Comment: 34 pages, 12 figures; accepted for publication at ApJS; the spectra are available from the authors upon reques