NGC 4038, The Antennae Galaxy
PTF g and R-band view of the central region of NGC 4038, more commonly known as "The Antennae Galaxy". A nearby advanced merger of two spiral galaxies, the resulting tidal streams (not shown here) appear similar to insect antennae. In this image we see the merger core, which is dominated by super star-clusters, e.g. compact regions rapidly forming stars, causing this galaxy to be referred to as a "starburst".