Westerlund 2 is an obscured compact young star cluster in the Milky Way with an estimated age of about one or two million years. It contains some of the hottest, brightest, and most massive stars known. The cluster resides inside a stellar breeding ground known as Gum 29, located 20,000 light-years away in the constellation Carina. It is half a degree from the Cepheid variable V399 Carinae.Photograph: NASA/ESA/Hubble Heritage Team/et al.