Praesepe is not a star at all but a cluster of hundreds of stars, the open cluster known as the Beehive or Messier 44, lying at about 600 light years in the constellation Cancer. To the naked eye it is a faint hazy patch, the ancients called it the Manger, and the two stars flanking it, Asellus Borealis and Asellus Australis, the two Donkeys feeding at it. It is one of the nearest star clusters to the Sun and among the first objects Galileo turned his telescope on, resolving the little cloud into a swarm of separate stars. Its inclusion among the fixed stars of the astrological tradition reflects the old habit of treating any named point of light, cluster or nebula alike, as a star.
Praesepe's status as a genuine open cluster, several hundred stars gravitationally bound together and formed from the same collapsing cloud, was established well before its distance could be measured precisely; modern parallax work places it at almost exactly the same distance and age as the Hyades in Taurus, and the two clusters are now thought to share a common origin, having formed from related material at roughly the same time some six to seven hundred million years ago. Praesepe's designation as Messier 44 places it among Charles Messier's eighteenth-century catalogue of nebulous objects, compiled originally so that comet hunters would not mistake such fixed, non-moving fuzzy patches for a new discovery.
Sources AstronomyAndrew Fraknoi, David Morrison, and Sidney C. Wolff (OpenStax) with Almagest (Mathematike Syntaxis)Claudius Ptolemy