Optical Properties of Circumstellar Silicate Grains
Abstract
The optical properties of circumstellar silicate dust grains around oxygen-rich giant stars are investigated with close attention to infrared observations of OH/IR stars. The optical constants are deduced from available astronomical and laboratory data. The deduced opacities at longer wavelengths (λ≥12 μm) for OH/IR stars are higher than the one for M-type Miras possibly because of the change of optical constants depending on temperature of dust grains. Absorption and scattering efficiencies are evaluated for various grain size distributions and shapes. The results of detailed radiative transfer model calculations based on our dust parameters are compared with observational data. The Planck mean values incorporating substantial far-infrared absorption are also calculated.
- Publication:
-
Astrophysics and Space Science
- Pub Date:
- July 1991
- DOI:
- 10.1007/BF00639091
- Bibcode:
- 1991Ap&SS.181..237S
- Keywords:
-
- Cosmic Dust;
- Giant Stars;
- Infrared Astronomy;
- Optical Properties;
- Silicates;
- Stellar Envelopes;
- Astronomical Models;
- Grain Size;
- Infrared Absorption;
- Opacity;
- Radiative Transfer;
- Astrophysics