Luminous extranuclear star formation in the interacting galaxy Arp 118 - NGC 1143/44

The interacting system Arp 118 (NGC 1143/44) has been observed at infrared and radio wavelengths. The interaction has produced a pair of distorted loops and several luminous radio and infrared sources in NGC 1144 which emit a total power of 2.5 x 10 to the 11th lunar masses, 80 percent of which is reradiated in the thermal infrared. Remarkably, the present observations reveal that much of the midinfrared emission originates in an extra-nuclear star-forming region. Arp 118 has many of the same characteristics as the well-studied interacting system Arp 299 (NGC 3690), including luminous extranuclear activity; the main difference between the two systems is that the nuclei of NGC 1143/44 are much less luminous at 10 microns than their counterparts in NGC 3690.