The Exotic Stellar Population of Westerlund 1

Westerlund 1 is an impressive example of a super star cluster. It contains hundreds of very massive stars, some shining with the brilliance of almost one million Suns, and others up to two thousand times larger than the Sun. In fact, if the Solar System were located at the heart of this remarkable cluster, our sky would be filled with hundreds of stars as bright as the full Moon. Located roughly 12,000 light-years away in the southern constellation Ara (the Altar), Westerlund 1 boasts a large, dense, and diverse population of evolved, massive stars. It contains so many massive stars that, within a timespan of less than 40 million years, it will be the site of more than 1,500 supernovae. This cluster serves as a natural laboratory for studying extreme stellar physics, helping scientists understand how the most massive stars in our galaxy live and die, and how stellar winds, supernovae, and other ejected material influence star formation in their environment.