M44 (NGC 2632)


M44 goes under two different names: The Beehive Cluster and Praesepe. This is one of the more visible open clusters in all the heavens, with a visual magnitude of 3.7.

The Greeks were aware of this deep sky object, and one of them, Aratos, a third-century BC poet, named it 'the manger' (Fatne, phatne). The nearby stars gamma and delta were seen as donkeys nibbling at the manger, and they still carry the names the northern donkey and the southern donkey (Asellus Borealis, Asellus Australis) respectively.

Praesepe is a direct Latin translation of phatne. Just where 'the Beehive' came from isn't certain, although many observers have commented that the stars indeed resemble a swarm of bees.

Finding the cluster is a breeze. Having found alpha Cancri, place this star at the left edge of your glasses and move one field north. You should find omicron1 and omicron2 at the lower left and delta Cancri upper right: omicron.

Move northwest, and delta Cancri will be near the lower left of your view. M44 will be centred: binoculars.

Having now located M44, you should find that it is visible with the naked eye, under normal conditions. Best viewing is mid-winter to early spring, with the constellation high in the sky.

The cluster contains over a thousand stars, about fifteen or twenty of which are bright enough to enjoy with binoculars. Two planets have been found here orbiting Sun-like stars.

The brightest star in the cluster is epsilon, 6.3 visual magnitude, 550 light years away (as is the cluster).

The best of many binaries in the cluster is Struve 1254. This is a multiple star system easily found in binoculars, but best studied in medium sized telescopes.
      Struve 1254 is a yellow primary with blue companion There are four yellow stars in the centre of the cluster; Struve 1254 is the central yellow star: binoculars.
      AB: 6.4, 10.4; 54, 20.5"
      AC: 6.5, 7.6; 343, 63.4"
      AD: 6.5, 9.2; 44, 82.7"


Just west one binocular field from the cluster is one of Cancer's most outstanding double stars, zeta Cancri.

In fact zeta is a multiple star system, two binary pairs -- zeta1 and zeta2-- orbiting a common centre of mass every 1100 years.

Zeta1 has an extremely close companion (B): 5.3, 6.3, 26, separation 1.1". Zeta2 also has two companions, designated C and D. Companion C is quite accessible; AB-C: 4.9, 5.9; 69, 6.1". Companion D is a red dwarf, perhaps a pair of red dwarfs, viewable in larger binoculars: AB-D 4.9, 8.9; 107 and separation an extremely wide 275".

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1999-2014 by Richard Dibon-Smith.