Optical and thermal properties of perturbed interstellar grains.
Abstract
Since interstellar grains are perturbed by defects, built-in impurities, and radiation damage, their infrared absorption and heat capacity is enhanced appreciably, compared with unperturbed material. As a consequence, spiking in the temperature history of small grains is no longer expected, the relaxation time for energy exchange with the ambient gas is increased, and the optical depth for the dominant grain radiation in cold dense clouds shows a quadratic dependence on temperature. Due to the enhancement of catalytic activity and bonding energy at surface defects, radical and atomic recombination takes place at all realistic grain temperatures. The recombination energy liberated afffects the formation of grain mantles.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- April 1977
- Bibcode:
- 1977A&A....56..353D
- Keywords:
-
- Absorption Spectra;
- Infrared Spectra;
- Interstellar Extinction;
- Interstellar Matter;
- Thermal Emission;
- Granular Materials;
- Impurities;
- Infrared Astronomy;
- Optical Properties;
- Radiative Recombination;
- Relaxation;
- Temperature Effects;
- Astrophysics