The Extended IRTF Spectral Library: Expanded Coverage in Metallicity, Temperature, and Surface Gravity

Abstract

Abstract We present a 0.7–2.5 μ m spectral library of 284 stars observed with the medium-resolution infrared spectrograph, SpeX, at the 3.0 m NASA Infrared Telescope Facility (IRTF) on Maunakea, Hawaii. This library extends the metallicity range of the IRTF Cool Star library beyond solar metallicity to −1.7 < [Fe/H] < 0.6. All of the observed stars are also in the MILES optical stellar library, providing continuous spectral coverage for each star from 0.35 to 2.5 μ m. The spectra are absolute flux calibrated using Two Micron All Sky Survey photometry, and the continuum shape of the spectra is preserved during the data reduction process. Synthesized JHK S colors agree with observed colors at the 1%–2% level, on average. We also present a spectral interpolator that uses the library to create a data-driven model of spectra as a function of , , and [Fe/H]. We use the library and interpolator to compare empirical trends with theoretical predictions of spectral feature behavior as a function of stellar parameters. These comparisons extend to the previously difficult to access low-metallicity and cool dwarf regimes, as well as the previously poorly sampled super-solar metallicity regime. The library and interpolator are publicly available.