High spatial resolution imaging of Arp 220 from 3 to 25 microns

Images of Arp 220 from 3.45 to 24.5 mu m with 0." 5 resolution are presente d that clearly separate the nucleus into at least two components. The weste rn component is about 3 times more luminous than the eastern component, but the silicate absorption in the fainter, eastern component is roughly 50% g reater than the absorption in the western component. Each component is marg inally resolved. The two components seen at 24.5 mu m are identified with t he two radio components. The western source most likely coincides with the high-extinction disk previously suggested to exist in Arp 220, while the ea stern nucleus is identified with a faint, highly reddened source seen in HS T 2.2 mu m NICMOS images. The two nuclei together account for essentially a ll of the measured 24.5 mu m flux density. Two models are presented, both o f which fit the observations. In one the majority of the total luminosity i s produced in an extended star formation region, and in the other most of t he luminosity is produced in the compact but extincted regions associated w ith the two nuclei seen at 24.5 mu m. In both pictures, substantial luminos ity at 100 mu m emerges from a component having a diameter of 2 "-3 " (simi lar to 1 kpc).