The chemical compositions of 30 Galactic carbon stars are determined from high-resolution infrared (1.5-2.5 ¡im) spectra and new model atmospheres. Elemental C, N, and O abundances (with respect to hydrogen) are obtained from lines of the C 2 Phillips system's Ay =-2 sequence, the CN red system's Ay =-2 sequence, and the CO X l '2 + vibration-rotation second-overtone bands. The 12 C/ 13 C ratios are extracted from the CN Ay =-2 sequence and, in two semi-independent ways, from the CO first-and second-overtone bands. Metal abundances are determined from a handful of atomic fines. Spectra at 3-4 jüim for a few stars provide additional fines which are used as checks. These include the HCN 3 fim bands, the CN red system's Af =-3 sequence, and the NH X 3 2and the CH X 2 U fundamental vibration-rotation bands. The H 2 1-0 S(0) fine near 2.22 ^m is also available as a check. Model atmospheres accounting for the fine blanketing by the poly atomics HCN and C 2 H 2 were computed for a grid of effective temperatures and surface gravities. Selected models for differing opacities and assumptions (e.g., surface heating) were computed. Effective temperatures are on the scale established by lunar occultation angular diameters. The surface gravity is based on a mean stellar mass and absolute luminosity. The principal results are as follows: 1. The dispersion in C, N, and O abundances for the 30 program stars is small. 2. The stars show only modest carbon enrichments; the most carbon-rich star has C/O-1.6, and about 50% of the stars in the sample have C/O <1.1. 3. The 13 C abundance is, in general, low, with 30< 12 C/ 13 C < 70 encompassing the larger part of our sample, and the very 13 C-rich (12 C/ 13 C-4) stars are the exceptions, not the rule. 4. The oxygen abundances are, in general, slightly subsolar and in good agreement with results for M and MS giants (progenitors) and carbon-rich planetary nebulae (descendants). 5. The nitrogen abundances are subsolar and below the values measured for M and MS giants and planetary nebulae. This difference may reflect an error in the CN dissociation energy or possibly in the effective temperature scale. 6. The metal abundances are approximately solar. 7. The weak H 2 fines are not evidence for hydrogen-deficient atmospheres. It is shown that the observed CH fine strengths are less than the predicted strengths. This discrepancy is discussed but not resolved. Possible explanations include non-LTE effects in the excitation and/or formation of CH, strengthened by thermal inhomogeneities, and a significant underestimate of the effective temperature scale. For the typical star with a low 13 C content, conversion to a carbon star was achieved by addition of pure 12 C, a product of helium burning, to the envelope of a typical G, K, or M giant. The 13 C-rich stars are not nitrogen-rich and, therefore, may not have undergone severe exposures to the hydrogen-burning CNO cycles. It is shown that the abundances may be used to calibrate published spectrophotometric indices of C 2 , CO, and CN bands. Suc...

ABSTRACT. A spectral atlas of the infrared spectrum of the bright K2 giant Arcturus has been completed using the 4-m Mayall telescope and FTS. The 0.9-5.3 ¡im spectrum of Arcturus was observed at high signal to noise with a resolution of 100,000. Telluric lines were removed by using telluric transmission spectra generated from McMath-Pierce solar spectra or 4-m lunar spectra. The spectrum of Arcturus was observed on two different dates selected to give large opposite heliocentric shifts. The spectra observed on the different dates have been independently corrected for telluric absorption with the result that the telluric spectrum has been effectively removed from all but the most obscured wavelengths of the Arcturus spectrum. We attempted to identify lines with central depths stronger than a few percent. Identifications seem well in hand with the unidentified lines apparently atomic in origin. The atlas is available either on an AAS CD-ROM or as an ASP monograph.

We present a catalog of H-band spectra for 85 stars of approximately solar abundance observed at a resolving power of 3000 with the KPNO Mayall 4 m Fourier Transform Spectrometer. The atlas covers spectral types O7ÈM5 and luminosity classes IÈV as deÐned in the MK system. We identify both atomic and molecular indices and line ratios that are temperature and luminosity sensitive, allowing spectral classiÐcation to be carried out in the H-band. The line ratios permit spectral classiÐcation in the presence of continuum excess emission, which is commonly found in preÈmain-sequence or evolved stars. We demonstrate that with spectra of R \ 1000 obtained at signal-to-noise ratio [50, it is possible to derive spectral types within^2 subclasses for late-type stars. These data are available electronically through the Astronomical Data Center in addition to being served on the World Wide Web.