New emission features in the 11-13 micron region and their relationship to polycyclic aromatic hydrocarbons
- NASA, Ames Research Center, Moffett Field, CA (USA)
Moderate-resolution spectra of NGC 7027, HD 44179, IRAS 2182+5050, and BD +30 deg 3639 are presented, showing that the 11.3-micron feature actually peaks at 11.22 microns. Evidence is found for new emission features near 11.9 and 12.7 microns, supporting an origin from PAHs. Also, the observed asymmetry of the 11.3-micron band is consistent with the anharmonicity expected in the C-H out-of-plane bending mode in PAHs. The analysis of the 11-13-micron emission suggests that the molecular structures of the most intensely emitting free PAHs vary between the high-excitation environment in NGC 7027 and the low-excitation but high-flux environment close to HD 44179. In addition, a series of regularly spaced features between 10 and 11 microns is detected in the spectrum of HD 44179, suggesting that a simple polyatomic hydride is present in the object's gas phase. 37 refs.
- OSTI ID:
- 5508586
- Journal Information:
- Astrophysical Journal; (USA), Journal Name: Astrophysical Journal; (USA) Vol. 341; ISSN ASJOA; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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Radio & X-Ray Sources
640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AROMATICS
CHEMICAL COMPOSITION
COSMIC RADIO SOURCES
EMISSION SPECTRA
H2 REGIONS
HYDROCARBONS
INFRARED SPECTRA
INTERSTELLAR SPACE
MOLECULES
NEBULAE
ORGANIC COMPOUNDS
ORIGIN
PLANETARY NEBULAE
SATELLITES
SIGNAL-TO-NOISE RATIO
SPACE
SPECTRA