Back to Search
Start Over
Ionized polycyclic aromatic hydrocarbons in space
- Source :
- NASA, Washington. Interrelationships among Circumstellar, Interstellar and Interplanetary Dust.
- Publication Year :
- 1986
- Publisher :
- United States: NASA Center for Aerospace Information (CASI), 1986.
-
Abstract
- The mid-infrared spectrum of a continuously increasing number of stellar objects, planetary and reflection nebulae, H-II regions and extragalactic sources show a distinctive set of broad emission features at 3.3, 3.4, 6.2, 7.7, 8.6, and 11.3 micron known collectively as the unidentified infrared emission bands. A model is summarized in which the bands arise from positively charged polycyclic hydrocarbons (PAH's) on the basis of their low ionization potential and the excellent agreement between the emission bands and laboratory spectra of auto exhaust which contains these types of molecules. The proposed presence of PAHs in such a variety of objects points to their presence in the interstellar medium. Out of a previously published collection of solid state PAH radical cation spectra five were selected on the basis of the unique thermodynamic stability of their carrier and compared directly to the wavelengths of the DIB's. Although the match seems quite favorable, strongly suggesting that PAH radicals are the long sought after carrier of the diffuse interstellar absorption bands, much laboratory work must be done to test this hypothesis.
- Subjects :
- Astrophysics
Subjects
Details
- Language :
- English
- Database :
- NASA Technical Reports
- Journal :
- NASA, Washington. Interrelationships among Circumstellar, Interstellar and Interplanetary Dust
- Publication Type :
- Report
- Accession number :
- edsnas.19860014035
- Document Type :
- Report