View source for NGC 457

{{short description|Open star cluster in the constellation Cassiopeia}}
{{Infobox cluster
| image=[[File:NGC457WIKIcropped.jpg|300px|]]
| caption=Open cluster NGC 457 in Cassiopeia
| name = NGC 457| epoch = J2000.0
| ra = {{RA|01|19|32.6}}
| dec = {{DEC|+58|17|27}}
| constellation = [[Cassiopeia (constellation)|Cassiopeia]]
| dist_ly = 7.922 [[light year|kly]]
| dist_pc = 2.429<ref name="aj136">{{cite journal
 | first=Peter M. | last=Frinchaboy |display-authors=etal
  | title=Open Clusters as Galactic Disk Tracers. I. Project Motivation, Cluster Membership, and Bulk Three-Dimensional Kinematics
 | year=2008 | journal=The Astronomical Journal
 | volume=136 | issue=1 | pages=118&ndash;145
 | doi=10.1088/0004-6256/136/1/118
 | arxiv=0804.4630 | bibcode=2008AJ....136..118F
| s2cid=16641439 }} See table I, p. 12.</ref> [[Parsec|kpc]]
| appmag_v = 6.4
| size_v = 13.0′
| names = Owl Cluster, E.T. Cluster, [[Caldwell catalogue|Caldwell]] 13, [[Collinder catalogue|Cr]] 12, [[Philibert Jacques Melotte|Mel]] 7, OCL&nbsp;321, Lund&nbsp;43, H&nbsp;VII-42, h&nbsp;97, GC&nbsp;256, }}

'''NGC 457''' (also designated '''Caldwell 13''', and known as the '''Dragonfly Cluster''', '''E.T. Cluster''', '''Owl Cluster''', '''Kachina Doll Cluster''' or '''Phi Cassiopeiae Cluster''')<ref>{{cite web|url=https://in-the-sky.org/data/object.php?id=NGC457|title=The Dragonfly Cluster (Open Cluster)|access-date=2020-10-28}}</ref> is an [[open cluster|open star cluster]] in the [[constellation]] [[Cassiopeia (constellation)|Cassiopeia]]. 

== Discovery ==
It was discovered by [[William Herschel]] on August 18, 1780, with a 6.2 inch reflector telescope, and catalogued as VII 42.<ref>{{Cite web |title=NGC 457, Owl Cluster, E.T. {{!}} Deep⋆Sky Corner |url=https://www.deepskycorner.ch/ngc457/ngc457.en.php |access-date=2022-05-28 |website=www.deepskycorner.ch}}</ref>

== Visibility ==
It is an easy target for amateur astronomers, and can be seen even with small telescopes in light-polluted skies.

== Characteristics ==
It lies over 7,900 [[light year]]s away from the [[Sun]]. It has an estimated age of 21 million years.<ref name="aj136" /> The cluster is sometimes referred by [[amateur astronomy|amateur astronomers]] as the ''Owl Cluster''<ref>{{cite web|url=http://cs.astronomy.com/asy/m/starclusters/490709.aspx|title=NGC 457|publisher=Astronomy Magazine|access-date=2020-10-13}}</ref> or the ''[[E.T. the Extra-Terrestrial|E.T.]] Cluster'' (due to its resemblance to the movie character).
Two bright stars [[Phi 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, surpassing [[Rigel]] 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 the [[red supergiant]] [[variable 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.

== Gallery ==
[[File:NGC 457 map.png|thumb|Map showing the location of NGC 457 in the constellation of Cassiopeia.]]

[[File:NGC457-OwlCluster.jpg|thumb|alt=NGC 457 and NGC 436|NGC 457 (center) pictured alongside open cluster NGC 436 (bottom right).]]

==References==
{{Reflist}}

==External links==
* {{commonscat-inline}}
* {{cite web|title=NGC 457 on SEDS |url=http://spider.seds.org/ngc/ngc.cgi?ngc457}}
* {{WikiSky}}

{{Catalogs|NGC=457|C=13|Collinder=12|GC=256}}
{{Caldwell catalogue}}
{{Ngc5}}
{{Cassiopeia (constellation)}}

{{DEFAULTSORT:NGC 0457}}
[[Category:Open clusters|NGC 0457]]
[[Category:Cassiopeia (constellation)|NGC 0457]]
[[Category:NGC objects|0457]]
[[Category:Caldwell objects|013b]]
[[Category:Astronomical objects discovered in 1787|17871018]]