Open star clusters are widely distributed in our galaxy and represent a loose collection of stars which number from a few dozen to a few hundred stars and are weakly-held gravitationally. Perhaps the three most famous such open clusters are the Pleiades (M45) in Taurus, the Beehive (M44) in Cancer and the double cluster in Perseus. They are all characterized with a handful of hot and white prominent stars and nebular material surrounding these stars.

Note: There is some ambiguity as to whether NGC 110 is an open cluster or simply a random collection of bright stars. NGC 110 is characterized with a central bright star (GSC 4303:1643, mag 9.92) surrounded by many mag 10 to mag 12 stars including an interesting chain emanating from the central star. Although the group does not stand out very well from the background, it is catalogued with an apparent diameter of approximately 20 arc-minutes. Neither a distance estimate nor a magnitude are available in the literature. NGC 110 was observed and catalogued by William Herschel in 1831.