Title: Near-Infrared Spectroscopy and Young Stellar Populations

Abstract: Over the past decade, tremendous progress has been made in applying the techniques of MK classification to spectra obtained from 1-5 microns. This spectral region is rich in atomic and molecular features which are temperature and luminosity sensitive providing a powerful technique to study intrinsically red and/or heavily dust embedded stellar populations. We will summarize recent work with particular emphasis on data obtained for a set of 88 fundamental MK standards in the J-, H-, K-, and L-bands with the KPNO 4m FTS. One area that has benefited enormously from these efforts has been the study of extremely young stellar populations still embedded in the molecular cloud cores from which they formed. Such objects present peculiar challenges in applying the MK process such as sub-giant surface gravities at late-types and enhanced stellar activity associated with accretion from circumstellar disks. We will provide an overview of these difficulties and present preliminary results on possible solutions.