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U.S. Department of Energy
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The 16-39 micrometer spectroscopy of oxygen-rich stars

Technical Report ·
OSTI ID:5637470
Airborne observations of the 16-39 micrometer spectra of ten oxygen-rich stars with excess emission in the infrared was obtained. The stars show excess emission attributed to circumstellar dust grains in the 16-39 micrometer region in the form of a broad hump peaking near 18 micrometers and falling smoothly to longer wavelengths. The emission is similar in character to the emission from the Trapezium region of the Orion nebula this similarity indicating that the grain materials are quite similar in these objects. The existence of a feature in the 20 micrometer region is consistent with the 0-Si-0 bending resonance expected for silicate material. The lack of any sharp structure in the spectra indicates the silicate is in an amorphous, disordered form. A simple model of small grains of carbonaceous chondrite silicate material in a diffuse circumstellar envelope is shown to give a good qualitative fit to the observed 8-39 micrometer circumstellar spectra. Comparison of the observed spectra with the model spectra indicates the grain emissivity falls as 1/lambda squared from 20 micrometers to 40 micrometers.
Research Organization:
Cornell Univ., Ithaca, NY (USA). Center for Radiophysics and Space Research
OSTI ID:
5637470
Report Number(s):
N-79-19963
Country of Publication:
United States
Language:
English