Beehive Cluster, Praesepe
|Rektascenzija||08 : 40.1 (u:m)
|Deklinacija||+19 : 59 (sto:m)
|Razdalja||0.577 (*1000 sv.l.)
|Vizual. magnituda||3.7 (mag)
|Zorni kot||95.0 (loc min)
This famous cluster, M44, is also called Praesepe (Latin for "manger"), or the Beehive cluster. It is also one of the objects easily visible to the naked eye, and thus known since prehistoric times. Galileo has first resolved this "nebulous" object, and reported: "The nebula called Praesepe, which is not one star only, but a mass of more than 40 small stars."
With larger telescopes, more than 200 of the 350 stars in the cluster area have been confirmed as members. According to the new determination by ESA's astrometric satellite Hipparcos, the cluster is 577 light years distant (previous estimates have been at 522 light years), and its age was estimated at about 400 million years. Curiously, both this age and the direction of proper motion of M44 coincide with that of the Hyades, another famous naked-eye and longly known cluster, which however was neither included in Messier's list nor in the NGC and IC catalogs. Probably these two clusters, although now separated by hundreds of light years, have a common origin in some great diffuse gaseous nebula which existed 400 million years ago. Consequently, also the stellar populations are similar, both containing red giants (M44 at least 5 of them) and some white dwarfs.
M44 also contains one peculiar blue star. Among its members, there is the eclipsing binary TX Cancri, the metal line star Epsilon Cancri, and several Delta Scuti variables of magnitudes 7-8, in an early post-main-sequence state.
The Praesaepe cluster was classified by Trumpler as of class I,2,r (according to Kenneth Glyn Jones), as II,2,m by the Sky Catalog 2000, and as class II,2,r by Götz.
As mentioned in the description for the Orion Nebula M42,
it is a bit unusual that Messier added the Praesepe cluster (together with the
Orion Nebula M42/M43 and the
Pleiades M45) to his catalog, and will perhaps
stay subject to speculation.