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Published 1990 | public
Book Section - Chapter

IRAS Observations of Galaxies


The basic properties of galaxies at 12μm, 25μm, 60μm and 100μm have been determined from IRAS observations. The far infrared luminosity of galaxies is a substantial, but not dominant, component of the luminosity output of the local universe. From a careful analysis of the spatial distribution of the infrared emission in the nearby spiral galaxy M33 it is found that approximately 3/4 of the total infrared luminosity from this galaxy originates in stars with ages less than a few hundred million years. To the extent that M33 is a typical spiral galaxy, this supports the prejudice that the infrared emission in galaxies is measuring the luminosity of newly formed stars. Interactions are found to be a major trigger of the high activity phase (L_(ir) > 10¹¹ L_⊙) in galaxies. A substantial fraction of all massive spiral galaxies probably undergo such a phase over the course of their evolution.

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© Kluwer Academic Publishers 1990. I have benefited from collaborations with many of my colleagues at Caltech. I particularly wish to thank W. Rice for allowing me to summarize his recent work on M33. Research at Caltech using the IRAS data is funded through the NASA Astrophysics Data Program.

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August 22, 2023
March 5, 2024