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We report high spectral resolution observations of the CO vibrationalovertone emission from the young stellar object 1548C27; our observationsinclude both the CO(2-0) and CO(5-3) bandhead regions. These data and similarobservations of the young stellar object WL16, reported in a previouscontribution to this journal, provide some of the most compelling evidence todate for the existence of inner disks around young stars. We describe thesimple procedure that we use to synthesize bandhead emission from disksincluding the effect of thermal dissociation of CO and non-LTE excitation ofthe vibrational levels. Using this spectral synthesis procedure to extract thekinematics and physical properties of the emitting gas from the overtone data,we show how these high signal-to-noise data are also powerful probes of thestellar and inner disk properties of these systems. Our modeling is consistentwith the identification of WL16 and 1548C27 as Herbig AeBe stars with stellarmasses of approximately 2 and 4 solar masses, respectively. Thus, the kinematicsignature of rotating disks in the overtone spectra of these sources providesstrong support for the role of accretion disks in the formation of intermediatemass stars. For both WL16 and 1548C27, we interpret our modeling results asindicating that the overtone emission arises from a temperature inversionregion in the inner disk atmosphere. We also find evidence for suprathermallybroadened lines and are able to place useful constraints on the radialtemperature and column density distributions of the CO line-formation region ofthe disk atmosphere.Comment: 38 pages (including figures) in gzip-ed uuencoded compressed  postscript format. Accepted for publication in Ap

Kinematic Diagnostics of Disks around Young Stars: CO Overtone Emission from WL 16 and 1548C27