Infrared Spectra of Red Giants: Molecular and Atomic Lines

Abstract

We discuss some of the most severe problems concerning the calculation of synthetic high resolution spectra of cool oxygen rich giants by studying the small frequency interval between 4412 and 4419 cm^–1 which covers a part of the famous Ca I feature visible in the K band. The combination of uncertain opacity data with line blending and quasi-continuous molecular absorption, the importance of a selfconsistent and complete treatment of molecular opacities, the effects of sphericity as well as dynamical phenomena including velocity fields are investigated.