The 3.4 micrometer interstellar absorption feature
Abstract
The presence of the 3.4 micrometer absorption feature in the source IRS 7 is shown. The ratio of the absorption coefficient of grains at 3.4 micrometers to the extinction coefficient at lambda V = 5500A is shown to be in the range 0.003 to 0.006. The wavelength of the peak absorption is 3.39 micrometers, + or - 0.03 micrometers; the equivalent width 330A, and the intrinsic full width at half maximum 0.13 micrometers. The 3.4 micrometer absorption is believed to arise in the general interstellar medium, and not in the dense molecular clouds where absorption due to other CH and CC bonds is known to occur. A circumstellar origin is also discounted. A substantial fraction of carbon in the interstellar medium is deduced to be in the form of organic molecules in grains. Visual extinction coefficient equals 5500A. This is consistent with observational data. The band center varies slightly from one polysaccharide to another but is again consistent with observational data.
- Publication:
-
In its The 3.4 Micron Interstellar Absorption Feature and the Organic Composition of Interstellar Grains 9 p (SEE N82-15002 05-90
- Pub Date:
- June 1980
- Bibcode:
- 1980miaf.reptQ....W
- Keywords:
-
- Absorption Spectra;
- Infrared Spectra;
- Interstellar Radiation;
- Chemical Bonds;
- Granular Materials;
- Interstellar Matter;
- Interstellar Space;
- Stellar Envelopes;
- Astrophysics