Molecular Bands in the 1.1-1.4 μm Spectra of M-S-C stars

Extract

Spectra are presented in the J band (7400 to 9700 cm^-1) for four Miras ranging in spectral type from M through C. All the program stars have been observed near minimum light. The program stars cover a considerable range in C/0 and the spectral features exhibit a progression as a function of C/0. The S-type stars contain strong bands not previously reported. Especially striking are two sets of triple-headed bands in the J-band spectrum of the S-type Mira R And. The bandheads, which are degraded to longer wavelengths, are at 7877, 7957, 8030 cm^-1 and 8379, 8459, 8530 cm^-1. The former triplet, which is the stronger of the two, also is present in the mild S star × Cyg but not in the M star R Cas. Additional heads are found in R And at 7477 cm^-1, near the short wavelength edge of strong telluric absorption, and at 8968, 9031, 9063 cm^-1. The bands are identified as the Δv = -1, 0, 1, and 2 sequences of a predicted (³II-³Δ) transition of ZrS. Additional conspicuous features in the spectra of × Cyg and R Cas are identified with V0, TiO, and H₂0 bands. These observations provide additional evidence that ZrS is responsible for the majority of the Keenan-Wing bands in the near infrared (0.7-1.1 μ). With additional laboratory work, the ZrS bands will provide an opportunity to measure sulfur abundances in late-type stellar photospheres.