Praesepe (M44, NGC 2632)

A large, bright, relatively nearby open cluster in the constellation Cancer, easily visible to the naked eye; also known as the Beehive Cluster, its Latin name means "manger." Ptolemy includes it as one of seven "nebulae" in his Almagest and Galileo first resolved it into stars. Large telescopes have revealed that more than 200 of the 350 stars in the region of sky covered by the cluster (about 1.5° across) are actual members of Praesepe; they include the eclipsing binary TX Cancri, the metal line star Epsilon Cancri, several Delta Scuti stars of magnitudes 7 to 8 in an early post-main-sequence state, and one peculiar blue star.

Interestingly, the age and the direction of proper motion of M44 are very similar to those of the Hyades, another famous naked-eye cluster. Probably these two clusters, though now separated by hundreds of light-years, have a common origin in some great diffuse gaseous nebula which existed 400 million years ago. This would also explain the similarity of the stellar populations – both clusters containing red giants (Praesepe at least five of them) and some white dwarfs.

visual magnitude	3.7
angular diameter	95'
distance	577 light-years
position	R.A. 08h 40.1m, Dec. +19° 59'

Related categories

• NEBULAE AND STAR CLUSTERS
• MESSIER CATALOGUE

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