Is SiS2 the carrier of the unidentified 21 micron emission feature?
G.F. Kraus 1,
J.A. Nuth III 2 and
R.N. Nelson 3
Received 23 February 1997 / Accepted 4 March 1997
Spectra are presented of samples in a variety of crystal forms taken at both room temperature and at 600 K over the wavelength range from 5-25 microns. All spectra show strong features at 22.5 and 9.5 microns as well as less intense bands at 7.5, 8.5, and 12.5 microns. All room temperature spectra also show a feature at 10.7 microns that disappears on heating. One form of shows strong correlated absorption features at 20 and 17 microns that are rapidly quenched by exposure to humid air with no significant change to the 7-13 and 22 micron features also present in the sample. These spectra are consistent with previous spectra obtained by Nuth et al. (1985), are marginally consistent with the identification of as the source of the observed 21 micron peak in several carbon-rich stellar sources, and suggest additional observations of these stellar sources that might confirm or refute the presence of . Specifically, if no feature at 17 microns is detected in objects that display the strong 21 micron emission feature then should be ruled out as a candidate for this band.
Key words: line: identifications stars: circumstellar matter ISM: dust infrared: lines and bands methods: laboratory
Send offprint requests to: J.A. Nuth III
© European Southern Observatory (ESO) 1997
Online publication: March 24, 1998