Rektascenzija	23 : 24.2 (u:m)
Deklinacija	+61 : 35 (sto:m)
Razdalja	5.0 (*1000 sv.l.)
Vizual. magnituda	7.3 (mag)
Zorni kot	13.0 (loc min)

M52 is a fine open cluster located in a rich Milky Way field. It is one of the rich clusters for which amateur Jeff Bondono has proposed the name "salt and pepper" clusters. Ake Wallenquist (1959) found 193 probable members in a region of 9' radius, and the 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 Catalog 2000 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 nitrogene.

The distance of this cluster is not very well known; Kenneth Glyn Jones adopts 3,000, Mallas/Kreimer 7,000 light years, while the Sky Catalog 2000 gives 5,200 (i.e., 1,600 pc) and Götz 5,050 light years. This uncertainty is mainly due to the high interstellar absorption its light has suffered on its way to us, which is complicated to estimate reasonably. M52 is classified as of Trumpler type I,2,r (Sky Catalog 2000) or II,2,r (Glyn Jones, Götz).

Vec posnetkov M52

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Povzeto po:
Hartmut Frommert (spider@seds.org)
Christine Kronberg (smil@lrz.uni-muenchen.de)