Intermediate bandwidth spectrometry in the 10-micron region and its interpretation.

Infrared photometry from I 6 to 20 of several interesting sources is is presented, including intermediate bandwidth observations at five wavelengths within the 8- to I4- window. The general interpretation of spectral data in the 8- to I4-jL region is discussed, and the observed data is analysed according to these principles. It is shown that the grain opacity laws derived from several sources with apparent silicate emission peaks are consistent with the known wavelength dependence of opacity derived from IRS- only if the grain temperatures in these sources are close to 250 K. Three sources have excesses in the 8- to I4- region with spectral characteristics quite different from those of silicate' emission. It is inferred that these are probably due to carbon-rich material, which is of particular interest in the case of the WC9 star IRC - 20417 (Ve 2-45), and the peculiar early M star HR 3126.