A Practical Approach to the Classification of IRAS Sources Using Infrared Colors Alone
Abstract
We have defined zones of the IRAS color-color planes in which a variety of different types of known source occur, for the purpose of obtaining representative IRAS colors for them. There is considerable overlap between many of these zones, rendering a unique classification difficult on the basis of IRAS colors alone, although galactic latitude can resolve ambiguities between galactic and extragalactic populations. We have investigated the color dependence of these zones on the presence of spectral emission/absorption features and on the spatial extent of the sources. We find that silicate emission features do not significantly influence the IRAS colors. Planetary nebulae may show a dependence of color on the presence of atomic or molecular features in emission, although the dominant cause of this effect may be the underlying red continua of nebulae with strong atomic lines. Only small shifts are detected in the colors of individual spatially extended sources when total flux measurements are substituted for point-source measurements. We do not find any evidence of major new populations of object among those sources well detected by IRAS in at least three wavebands.
- Publication:
-
The Astronomical Journal
- Pub Date:
- December 1989
- DOI:
- 10.1086/115287
- Bibcode:
- 1989AJ.....98.2163W
- Keywords:
-
- Giant Stars;
- Infrared Sources (Astronomy);
- Planetary Nebulae;
- Starburst Galaxies;
- Absorption Spectra;
- Classifying;
- Color-Color Diagram;
- Cool Stars;
- Emission Spectra;
- Infrared Astronomy Satellite;
- Reflection Nebulae;
- Astrophysics;
- INFRARED: GENERAL