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| Paper: |
Absorption Spectroscopy of Interstellar Dust |
| Volume: |
309, Astrophysics of Dust |
| Page: |
93 |
| Authors: |
Snow, T.P. |
| Abstract: |
Interstellar dust grains have spectroscopic features throughout the electromagnetic spectrum which can be used as diagnostics of grain properties such as composition, size, and abundance. In this review we describe the known or expected spectral absorption features due to dust in each wavelength band from X-rays to infrared, with emphasis on observational results and potential future observations. In the X-ray spectral region, ionization absorption edges and (potentially observable) fine structure near the edges can provide detailed information on dust grain composition and size. In the ultraviolet, the 2175 Å extinction bump contains important information about the carbonaceous component of interstellar dust; in addition, we can expect as-yet undetected weak features to provide information on carbon-based species such as PAHs and diamonds. In the visible regime, where the extinction curve is essentially featureless, hints of broad structure have been reported in the past, and some proposed explanations of the unidentified diffuse interstellar bands invoke solid state spectral features. Finally, the infrared spectral region contains vast amounts of information on interstellar dust, including absorption features due to refractory materials on or in dust grains such as the well-known silicate bands near 10 and 18 μm and the hydrocarbon feature near 3.4 μm; and absorption features due to ices such as water and CO (and many others). In addition to reviewing the principal results of previous studies in all these wavelength bands, we also discuss present and future work such as: potential new studies of interstellar dust using the Chandra X-ray Observatory; the ongoing search for ultraviolet spectral features due to dust; the quest to identify the carriers of the diffuse interstellar bands; and new efforts to compare the spectra of interstellar dust with inclusions in interplanetary grains that might be primordial interstellar dust particles. |
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