Published in "The Interstellar Medium in Galaxies", eds. Harley A. Thronson, Jr. and J. Michale Shull, 1990.

For a postscript version of the article, click here.


INTERSTELLAR GAS IN GALAXIES

Michael Rowan-Robinson

Astronomy Unit, Queen Mary College, Mile End Rd, London E1 4NS


Abstract. Current ideas about the nature of interstellar dust in galaxies are reviewed, with a strong emphasis on the nature of the very small grain component needed to explain the mid-infrared diffuse emission and unidentified infrared features. Models for the infrared spectra of galaxies are reviewed and the evidence that most of the radiation in star-forming regions is being absorbed by a high visible-uv optical depth of dust is summarized. The evidence for destruction of very small grains in regions of high radiation intensity is discussed.

A new model for interstellar grains in galaxies is presented, based on a revised version of the model of Rowan-Robinson (1986) and is compared to observed far infrared colour-colour diagrams and to far infrared spectra of galaxies which have been mapped at 800 µm by Hughes et al (1989). Work on far infrared and submillimeter mapping of galaxies is reviewed, as also is recent work on infrared emission from ellipticals and lenticulars. The determination of dust mass in galaxies is briefly discussed.


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