NGC 457 (also known as the Owl Cluster, the ET Cluster, or Caldwell 13) is an open star cluster in the constellationCassiopeia. It was discovered by William Herschel in 1787,[2] and lies over 7,900 light years away from the Sun. It has an estimated age of 21 million years.[1] The cluster is sometimes referred by amateur astronomers as the Owl Cluster, Kachina Doll Cluster,[2] the ET Cluster (due to its resemblance to the movie character) or the "Skiing Cluster".
Two bright stars, magnitude 5 Phi-1 Cassiopeiae and magnitude 7 Phi-2 Cassiopeiae can be imagined as eyes. The cluster features a rich field of about 150 stars of magnitudes 12-15.[2]
References
^ abFrinchaboy, Peter M.; et al. (2008). "Open Clusters as Galactic Disk Tracers. I. Project Motivation, Cluster Membership, and Bulk Three-Dimensional Kinematics". The Astronomical Journal. 136: 118–145. arXiv:0804.4630. Bibcode:2008AJ....136..118F. doi:10.1088/0004-6256/136/1/118. See table I, p. 12.
^ abcdef"NGC 457". The NGC/IC Project Database. Retrieved 2012-05-09.
