Messier 52 (also known as M 52 or NGC 7654) is an open cluster in the Cassiopeia constellation. It was discovered by Charles Messier in 1774. M52 can be seen from Earth with binoculars.
The brightest main sequence star of this cluster is of mag 11.0 and spectral type B7. Two yellow giants are brighter: The brightest is of spectral type F9 and mag 7.77, the other of type G8 and mag 8.22. The Sky Catalogue 2000.0 gives an age of only 35 million years, which coincides with the value given by Woldemar Götz, who mentions that this cluster contains one peculiar Of star, i.e. an extremely hot star with peculiar spectral lines of ionized helium and nitrogen.
