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: As indicated by the image below, the open cluster NGC 1245 in Perseus is well-detached from the background background sky. It is comprised of over 100 stars all of moderate brightness and with an apparent diameter of nine arc-minutes. NGC 1245 has been estimated to lie 9,380 light-years away and to be approximately 500 million years old. The cluster is best observed using midpower magnifications (100-200x) during late fall and winter. Careful inspection of the hyperlinked image below will reveal several faint galaxies (PGC 12019, mag 15.7; PGC 2293652, mag 16.4; PGC 2291955, mag 16.8 and PGC 2293562, mag 17.3). NGC 1245 was discovered by William Herschel in 1786.