by Louis Allen Rose
Under the supervision of Professor Edward Ney
- Laboratory infrared emission and absorption spectra have been taken of terrestrial silicates, meteorites and lunar soils in the form of micrometer and sun-micrometer grains. The emission spectra were taken in a way that imitates telescope observations. The purpose was to see which materials best simulate the 10 micron astrophysical feature.
- The emission spectra of frosterite, fayalite and Allende give a good fit to the 10 micron broadband emission feature of Comets Bennett and Kohoutek. Quartz can be ruled our as a major component of cometary grains since its silicate feature occurs near 9 micron and does not match the astrophysical emission feature. A study of the effect of grain size on the presence of the 10 micron emission feature of frosterite shows that for particles larger than 37 micron no feature is seen, but the feature is seen for particles smaller than this.
- Intermediate resolution emission spectroscopy was used to study a group of 9 terrestrial silicates, 1 synthetic silicate, 6 meteorites and 2 lunar soils; comparisons were made with the intermediate resolution spectra of Comet Kohoutek. Infrared absorption spectra were taken of selected materials from this group.
- This study has found three mixtures of silicates which would yield spectra that match the spectrum of Comet Kohoutek in the 10 micron region:
- 1) A hydrous layer silicate in combination with a high temperature condensate such as olivine or anorthite to broaden the feature; 2) an amorphous magnetism silicate in combination with a high temperature condensate and 3) glassy olivine and glassy anorthite in approximately equal proportions. Mixture 1 would be fairly close in composition to a C2 meteorite. Mixtures 1 and 2 would both form partly in a low temperature environment. Mixture 3 is made high temperature condensates which condense and cool in such a way so as to produce amorphous grains.