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Paper: Unidentified Infrared Bands in the Diffuse Interstellar Medium
Volume: 309, Astrophysics of Dust
Page: 163
Authors: Onaka, T.
Abstract: Observations of the Unidentified Infrared (UIR) bands in the diffuse Galactic emission are reviewed. Spectroscopic observations by cooled telescopes in space have unambiguously demonstrated the presence of the UIR bands in the diffuse emission, indicating that the carriers of these bands are a ubiquitous and important component in the interstellar medium. The spatial distribution of the UIR bands in the Galactic scale is investigated in terms of the correlation with the far-infrared (FIR) intensity. The UIR band intensity is very well correlated with the FIR and the relative band strengths do not show systematic variations over a wide range of the incident radiation field in the inner Galaxy, suggesting that the band carriers are stable species in interstellar medium. The latest investigation, on the other hand, indicates possible variations in the UIR/FIR correlation as well as in the relative band strengths in the outer Galaxy. Implications of the variations are also discussed.
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