M52

M52 is a fine open cluster located in a rich Milky Way field. Containing about 200 members in a region of 9' radius, M52 yields a density near the center is about 3 stars per cubic parsec. 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 makes the cluster relatively young. This cluster also contains one peculiar Of star, i.e. an extremely hot star with peculiar spectral lines of ionized helium and nitrogene.

The distance of this cluster is not very well known, being between 3000 and 7000 light-years, due to the high interstellar absorption its light has suffered on its way to us. At a distance of 5000 light-years, its angular diameter of 13 arcminutes would yield a diameter of 19 light-years.

Taken September 26, 2009, with the ST-8 and the 300mm Nikkor lens- 5 minutes exposure. To the lower right of the cluster, a small amount of nebulosity from NGC 7635, the Bubble Nebula, can be seen.

taken January, 2006, with the 402 camera