Extreme Star Formation and Its Bright Future
Globular star clusters are the most ancient objects in the universe, almost as old as the universe itself. As such, these objects are fossil records of the primordial conditions at the time of galaxy assembly, and they are prevalent around all massive galaxies in the universe today. These objects are quite remarkable; each such cluster contains a million stars or more packed into a volume approximately equal to that of a sphere around our Sun that extends to the nearest star, Proxima Centauri. For many years the prevailing belief was that globular clusters were simply formed by gravitational collapse of inhomogeneities in the early universe. However, in the 1990s, observations using the Hubble Space Telescope found adolescent globular clusters in the local universe, but only in extreme environments such as those created by galaxy collisions. Despite the importance of finding young globular clusters in the present day, the optical studies using Hubble could not probe their actual birth conditions. Star formation throughout the universe takes place within giant and massive clouds of molecules and dust that optical light cannot penetrate. Radio and infrared observations gave rise to the recent discovery of natal globular clusters, still deeply embedded in their birth cocoons. I will discuss what we think we now know about the formation of globular clusters, as well as the major unresolved questions. With major new observing facilities in the infrared and radio on the horizon, the future for this research is extremely bright.