Which dense cluster near the Galactic Center is named for five infrared sources?

The dense cluster near the Galactic Center named for five infrared sources is the Quintuplet Cluster.

It lies roughly 100 light-years from the Galactic Center and about 26,000 light-years from Earth. Heavy dust blocks its visible light, so astronomers study it mainly in infrared, radio, and X-ray wavelengths. The five especially prominent infrared sources inspired the name, although the cluster contains many more stars.

The Quintuplet was first recognized in 1983 as an infrared grouping. Later observations showed that its unusual bright sources were not protostars, as initially suspected, but evolved massive stars, including Wolf–Rayet stars and luminous blue variables. The cluster is about 4 million years old and has a mass of roughly 10,000 Suns.

A common mix-up is the nearby Arches Cluster, another massive young cluster near the Galactic Center. The Quintuplet is also associated with the Pistol Star and the Pistol Nebula, while its surrounding ionized gas is known as the Sickle Nebula.