Circumstellar Dust Emission Models
Abstract
We present the wavelength-dependent absorption coefficient Klambda the scattering coefficient olambda, the albedo wlambda, and the average cosine of the scattering phase function glambda between 0.0912 micrometers and 1000 micrometers for four interstellar medium grain models. These grain models are used in a radiation transfer code to calculate the properties of dust shells surrounding a newly formed O star. For each shell model a distribution of 25 grain sizes and two compositions were used in our calculations. The spectral type of the central star (O6 ZAMS), the geometry (shell), and circumstellar density distribution (constant) are the same in all models, so that different model predictions result entirely from differences in grain properties. For each grain type the models predict the emergent spectral energy distribution with wavelength, the optical depth with wavelength, and the mean dust temperature with distance from the central star. In addition, we find the emitted envelope flux (total flux minus the direct stellar contribution) included within an angular radius theta for several wavelengths between 2.2 micrometers and 100 micrometers. It is found that large differences in the emitted spectrum can occur when grains with different optical constants and size distributions are used.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 1994
- DOI:
- 10.1086/174194
- Bibcode:
- 1994ApJ...427..889W
- Keywords:
-
- Absorptivity;
- Albedo;
- Cosmic Dust;
- Emission Spectra;
- Scattering Coefficients;
- Stellar Envelopes;
- Stellar Models;
- Early Stars;
- Interstellar Matter;
- O Stars;
- Optical Thickness;
- Radiative Transfer;
- Spectral Energy Distribution;
- Stellar Evolution;
- Astrophysics;
- ISM: DUST;
- EXTINCTION;
- RADIATIVE TRANSFER;
- STARS: CIRCUMSTELLAR MATTER;
- STARS: EARLY-TYPE