Cancer is a nebula in that galaxy.

Praesepe is a member of the open cluster, located in Cancer. Named for its location in a haunted house. Also known as hive clusters, it accumulates corpse gas. China called it corpse gas in ancient times. It is numbered M44 in the messier catalogue. The size of the ghost cluster is less than 10 parsec, and there are more than 200 member stars. The total mass is more than 200 times that of the sun, and its center is about 160 parsec from the sun, which is much farther than the Bi cluster. Ghost cluster is a moving cluster, which is moving away from the earth, and its speed and direction are almost the same as that of Bixing cluster. Galileros confirmed this "hazy" celestial body for the first time. He recorded: "The nebula called Praesepe is not just a star, but a collection of more than 40 small stars." Later, it was added to his catalogue on March 4 1764. M44 also contains a unique blue star. Among its member stars, there are eclipsing binary star-Cancer TX, a star with metal absorption line-Cancer ε, and several 7-8 shield Delta variables, all of which are in the early post-main sequence. Check out our list of brightest stars in M44.

Ghost clusters are classified by trumpler as I, 2, R (according to Kenneth Green Jones), and the classification of Sky Catalogue 2000 is II, 2, M, G? Tz divides it into type ii, type 2 and type R.

As mentioned in the description of Orion nebula M42, it is unusual for messier to add ghost clusters (together with Orion nebula M42/M43 and Pleiades cluster M45) to his catalog, and the reason may still be worth considering.