There are 12 red supergiants identified so far. These are massive young stars undergoing helium burning in their cores. There is also one yellow hypergiant, and one intermediate. The cluster is in the constellation Scutum at about 6.6 kpc from the Sun. It is at the intersection of the northern end of the Long Bar of the Milky Way and the inner portion of the Scutum–Centaurus Arm—one of its two major spiral arms.