16--39 micron spectroscopy of oxygen-rich stars

Journal Article · Mon Oct 15 04:00:00 EDT 1979 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/157422· OSTI ID:5729266

Forrest, W J; McCarthy, J F; Houck, J R

Airborne observations of the 16--39 ..mu..m spectra of 10 oxygen-rich stars with excess emission in the infrared have been obtained. The stars show excess emission attributed to circumstellar dust grains in the 16--39 ..mu..m region in the form of a broad hump peaking near 18 ..mu..m and falling smoothly to longer wavelengths. The emission is similar in character to the emission from the Trapezium region of the Orion Nebula, indicating the grain materials are quite similar in these objects. The existence of a feature in the 20 ..mu..m region is consistent with the O--Si--O 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 chrondrite silicate material in a diffuse circumstellar envelope is shown to give a good qualitative fit to the observed 8--39 ..mu..m circumstellar spectra. Comparison of the observed spectra with the model spectra indicates the grain emissivity falls as 1/lambda/sup 2/ from 20 to 40 ..mu..m.

• Research Organization: Center for Radiophysics and Space Research, Cornell University
• OSTI ID: 5729266
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 233:2; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
BLACKBODY RADIATION
CARBONACEOUS MATERIALS
CRYOGENIC FLUIDS
ELECTROMAGNETIC RADIATION
ELEMENTS
FLUIDS
GIANT STARS
INFRARED SPECTRA
INTERSTELLAR GRAINS
NONMETALS
OXYGEN
OXYGEN COMPOUNDS
PARTICLES
RADIATIONS
RED GIANT STARS
SILICATES
SILICON COMPOUNDS
SPECTRA
STARS
STELLAR ATMOSPHERES
STELLAR RADIATION