Alicante 8

The age of Alicante 8 is estimated to be around 16–20 million years. The observed red supergiants are type II supernova progenitors. The cluster is heavily obscured and have not been detected in the visible light. It lies close to other groupings of red supergiants known as RSGC1, Stephenson 2, RSGC3, Alicante 7, and Alicante 10. The mass of the open cluster is estimated at 10–20 thousand solar masses, which makes it one of the most massive open clusters in the Galaxy.

A 2023 study of the radial velocities of the stars of Alicante 8 showed that they vary widely, instead of being similar as would be expected for a gravitationally bound star cluster. This study also found that some of the stars may not be red supergiants, but asymptotic giant branch stars.