|Rektascenzija||02 : 42.0 (u:m)
|Deklinacija||+42 : 47 (sto:m)
|Razdalja||1.4 (*1000 sv.l.)
|Vizual. magnituda||5.5 (mag)
|Zorni kot||35.0 (loc min)
This intermediate aged (190 million years according to the Sky Catalog 2000, 180 million according to the new calculations of G. Meynet's Geneva Team) open cluster of about 100 stars (according to H.S. Hogg) lies about 1,400 light years and is scattered over 35 arc minutes, more than the diameter of the full Moon. This angular diameter corresponds to a linear 14 light years; Wallenquist has estimated a little more (42' corresponding to 18.5 light years).
This cluster was classified as of Trumpler type I,3,m (Sky Catalog 2000) or II,3,r (Götz). It appearance is influenced by a nearby non-member of mag 7.3, while the brightest member star is of magnitude 7.9.
The age of M34 was estimated at 110 million years by Van Hoerner in 1957, while the Sky Catalog 2000 gives a more modern value of 190 million years.
M34 was probably first found by Hodierna before 1654, and independently rediscovered by Messier in 1764.
Open cluster M34 can quite easily be found (even with the naked eye under
good conditions) as it lies just north of the line from Algol (Beta Persei)
to Gamma Andromedae.