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NGC 457 (also designated Caldwell 13, and known as the Dragonfly Cluster, E.T. Cluster, Owl Cluster, Kachina Doll Cluster or Phi Cassiopeiae Cluster)[2] is an open star cluster in the constellation Cassiopeia.

NGC 457
Open cluster NGC 457 in Cassiopeia
Observation data (J2000.0 epoch)
ConstellationCassiopeia
Right ascension01h 19m 32.6s
Declination+58° 17′ 27″
Distance7.922 kly (2.429[1] kpc)
Apparent magnitude (V)6.4
Apparent dimensions (V)13.0′
Physical characteristics
Other designationsOwl Cluster, E.T. Cluster, Caldwell 13, Cr 12, Mel 7, OCL 321, Lund 43, H VII-42, h 97, GC 256,
See also: Open cluster, List of open clusters

Discovery


It was discovered by William Herschel on August 18, 1780, with a 6.2 inch reflector telescope, and catalogued as VII 42.[3]


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 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[4] or the 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 magnitudes. The next brightest star is the red supergiant variable star V466 Cassiopeiae. The cluster features a rich field of about 150 stars of magnitudes 9-13. About 60 stars have been identified as true members of the cluster.



Map showing the location of NGC 457 in the constellation of Cassiopeia.
Map showing the location of NGC 457 in the constellation of Cassiopeia.

References


  1. Frinchaboy, 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 (1): 118–145. arXiv:0804.4630. Bibcode:2008AJ....136..118F. doi:10.1088/0004-6256/136/1/118. See table I, p. 12.
  2. "The Dragonfly Cluster (Open Cluster)". Retrieved 2020-10-28.
  3. "NGC 457, Owl Cluster, E.T. | Deep⋆Sky Corner". www.deepskycorner.ch. Retrieved 2022-05-28.
  4. "NGC 457". Astronomy Magazine. Retrieved 2020-10-13.



На других языках

[de] NGC 457

NGC 457 ist ein offener Sternhaufen im Sternbild Kassiopeia am Nordsternhimmel. Er hat einen Durchmesser von 13' und eine scheinbare Helligkeit von +6,4 mag. Damit zählt der Haufen zu den hellsten Sternhaufen im Sternbild Cassiopeia und zu den hellsten offenen Sternhaufen, die nicht im Messier-Katalog aufgeführt sind. Aufgrund seines Aussehens wird der Sternhaufen auch mit den Spitznamen Eulenhaufen oder ET-Haufen betitelt.
- [en] NGC 457

[es] NGC 457

NGC 457 es un cúmulo abierto en la constelación de Casiopea. Se estima que se halla a unos 9.000 años luz de la Tierra. Su magnitud aparente es +6,4, siendo uno de los cúmulos abiertos más brillantes que no están incluidos en el Catálogo Messier. En astronomía amateur es conocido como el Cúmulo del Búho o el Cúmulo de ET, este último por su parecido con la película homónima.

[ru] NGC 457

NGC 457 (другое обозначение — OCL 321, также известно как Скопление Стрекоза, Скопление Сова) — рассеянное звёздное скопление в созвездии Кассиопея.


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