| NGC 457 | |
|---|---|
 Open cluster NGC 457 in Cassiopeia | |
| Observation data (J2000.0epoch) | |
| Right ascension | 01h 19m 32.6s |
| Declination | +58° 17′ 27″ |
| Distance | 7.922kly (2.429[1]kpc) |
| Apparent magnitude (V) | 6.4 |
| Apparent dimensions (V) | 13.0′ |
| Physical characteristics | |
| Other designations | Owl Cluster, E.T. Cluster,Caldwell 13,Cr 12,Mel 7, OCL 321, Lund 43, H VII-42, h 97, GC 256, |
| Associations | |
| Constellation | Cassiopeia |
| See also:Open cluster,List of open clusters | |
NGC 457 (also designatedCaldwell 13, and known as theDragonfly Cluster,E.T. Cluster,Owl Cluster,Kachina Doll Cluster orPhi Cassiopeiae Cluster)[2] is anopen star cluster in theconstellationCassiopeia.
It was discovered byWilliam Herschel on August 18, 1780, with a 6.2 inch reflector telescope, and catalogued as VII 42.[3]
It is an easy target for amateur astronomers, and can be seen even with small telescopes in light-polluted skies.
It lies over 7,900light years away from theSun. It has an estimated age of 21 million years.[1] The cluster is sometimes referred byamateur astronomers as theOwl Cluster[4] or theE.T. Cluster (due to its resemblance to the movie character).Two bright starsPhi Cassiopeiae (magnitude 5 and spectral type F0) and HD 7902 (magnitude 7) can be imagined as eyes. It is not yet clear if Phi Cassiopeiae is a member of the cluster, and if it is, then it would be one of the brightest stars known, surpassingRigel in luminosity. For comparison, the Sun at the same distance as Phi Cassiopeiae would shine at just 17.3 magnitude. The next brightest star is thered supergiantvariable star V466 Cassiopeiae. The cluster features a rich field of about 150 stars of magnitude 9-13. About 60 stars have been identified as true members of the cluster.
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