Extreme superstarclusters
  The presence of superstarclusters is a characteristic feature of starburst galaxies. We examine the properties of star forming regions and young star clusters in various environments, ranging from common to extreme. We then discuss new high spatial resolution mid-infrared imaging and spectroscopy of extreme superstarclusters in the obscured region of the Antennae (NGC4038-4039). We find that the PAH emission in this region is not dominated by the superstarclusters but is mostly diffuse. Emission line ratios found in our high spatial resolution data differ significantly from those in larger apertures, strongly affecting the derived results. 
Paul P. van der Werf and Leonie Snijders