Far-infrared emission in single and binary galaxies

The properties of the far-IR emission from a sample of optically selected isolated galaxies is studied using data obtained by the Infrared Astronomical Satellite (IRAS). This set of galaxies is used as a standard of comparison representing galaxies whose far-IR properties have been little influenced by interaction with their surroundings. An optically selected sample of isolated binary galaxies is then considered. For the binary galaxies, no extreme highly luminous IR emitters are found, reaffirming the rarity of these objects. However, the occurrence of some low-level enhancement of infrared activity is substantiated by the comparison of far-IR emission in single galaxies and those found to have nearby companions. This effect may be influenced by the occurrence of a few instances of more luminous galaxies. Indeed, many galaxies that show evidence for interaction, i.e., distortion, tails, etc., do not show enhanced IR emission.