Model of grain properties based on IRAS observations. I. Evidence fornew particle populations.
Abstract
The properties of interstellar grains derived from IRAS observations are discussed. A model satisfying all available observational constraints is obtained by extending the multipopulation concept first applied to the interpretion of interstellar extinction by Hong and Greenberg (1980). Two new populations must be introduced to explain the measurements at 12, 25, 60 microns. Classical grains included in the extinction model give rise to nearly all the emission measured at 100 microns and about 50 percent of the observed 60 micron flux. The excess emission in the IRAS 60 micron band is attributed to a population of small particles of metallic iron emitting at equilibrium temperatures of about 50 K and containing a large, possibly dominant, fraction of cosmic iron.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- December 1988
- Bibcode:
- 1988A&A...207L..11C
- Keywords:
-
- Infrared Astronomy Satellite;
- Interstellar Chemistry;
- Interstellar Matter;
- Astronomical Spectroscopy;
- Interstellar Extinction;
- Iron;
- Metallicity;
- Astrophysics