HST planetary camera images of core of peculiar galaxy Arp 220 (ground-based image vs. HST)

[right]
A ground-based telescopic photograph of the peculiar galaxy Arp 220 (image taken by K. Borne, H. Levison, and R. Lucas at USNO Flagstaff Station, Arizona) shows a curious double-lobed structure. This structure was first interpreted as two galaxies merging together, until subsequent observations with highly sensitive CCD detectors revealed a dust lane down the center which made the galaxy appear double lobed.

[left]
A "true-color" image of the central pan of the Arp 220 taken with the WFPC on the Hubble Space Telescope. HST reveals a new complex structure within one arc second of the nucleus. HST reveals a new class of object at the core: gigantic young star clusters which are ten times larger than clusters previously observed. They were probably produced by the collision of two spiral galaxies. Stars are produced at a furious rate from the raw dust and gas supplied by the collision.