The Detection of Infrared SiS Bands in Spectra of S Stars

We present Spitzer spectra of S stars, which are cool evolved stars with a C/O ratio near unity, some of which have enhanced s-process abundances. We present the detection of a strong and unusual band in the mid-infrared, at 13 is a subset of m, within the N-band window. Using quantum-chemically cal...

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Bibliographic Details
Published in:The Astrophysical journal 2009-01, Vol.690 (2), p.L122-L125
Main Authors: Cami, J, Sloan, G. C, Markwick-Kemper, A. J, Zijlstra, Albert A, Bauschlicher, C. W, Matsuura, M, Decin, L, Hony, S
Format: Article
Language:English
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Summary:We present Spitzer spectra of S stars, which are cool evolved stars with a C/O ratio near unity, some of which have enhanced s-process abundances. We present the detection of a strong and unusual band in the mid-infrared, at 13 is a subset of m, within the N-band window. Using quantum-chemically calculated line lists, and model spectra, we identify this band as the fundamental rovibrational band of SiS. Detection of the overtone band at 6.7 is a subset of m confirms the identification. Fitting the line profile shows that the molecule is located in relatively cool layers, at T ~ 1500 K. We discuss these results in the context of chemical equilibrium models. The observed strength of these bands in the cool S stars makes them a promising observational diagnostic tool for studying the atmospheres of brown dwarfs and exoplanets.
ISSN:1538-4357
0004-637X
1538-4357
DOI:10.1088/0004-637X/690/2/L122