HST planetary camera images of core of peculiar galaxy Arp 220

An image of the central part of the ultra-luminuous infrared galaxy Arp 220 taken with the WFPC on the Hubble Space Telescope. HST reveals a new complex structure within one arc second of the nucleus. While part of the this structure was seen in radio interfero-metric maps, most of the structure is new.

HST reveals a new class of object at the core: gigantic young star clusters which are ten times larger than any clusters observed previously. They were probably produces by the collision of two spiral galaxies. Stars are produced at a furious rate from the dust and gas supplied by the collision.