| |
 |
| Paper: |
Interstellar dust and extinction |
| Volume: |
12, The Evolution of the Interstellar Medium |
| Page: |
63 |
| Authors: |
Mathis, John S. |
| Abstract: |
Recent developments are reviewed regarding the interstellar extinction law in diffuse dust and outer-cloud dust so that observations can be corrected for the effects of the dust. The concept of extinction is defined and a comparison of data from related diagnostics is followed by an overview of grain theories. One key parameter is identified as a mean extinction law to describe the general UV extinction properties of interstellar dust: RV = A(V)/E(B-V). The value for diffuse ISM is RV = 3.2, and the values for the outer regions of dense clouds and other phenomena are different. Several theories are reviewed which offer differing explanations of optical extinction, but all of the theories consider the bump at the 2175 wavelength to be related to graphite. The theories mentioned include biological-grain, composite-grain, fractal-grain, and bare-silicate-graphite-grain interpretations. |
|
|
|
|
|
