Merging and high star-formation rate galaxies are known to produce vast amounts of young, globular cluster like, objects. Quiescent galaxies, and areas like the solar neighborhood, also form clusters, however with much lower masses. This difference has been long thought to represent at least two different modes of star-formation, a "normal" and "starburst" mode. However, recent observations have shown that this is most likely a size-of-sample effect, where starburst galaxies are simply forming more stars/clusters, and hence are able to sample further up in the cluster mass function than low star-formation rate galaxies. Taking this intoaccount, the basic properties of clusters are independent of environment, and the fraction of star-formation which happens in clusters is remarkablyuniversal, contrary to basic theoretical predictions.
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