NGC 457

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Open star cluster
NGC 457
NGC457.jpg
NGC 457 , the owl cluster or ET cluster
AladinLite
Constellation Cassiopeia
Position
equinox : J2000.0
Right ascension 01 h 19 m 32.6 s
declination + 58 ° 17 ′ 27 ″
Appearance

classification I3r
Brightness  (visual) 6.4 mag
Brightness  (B-band) 6.97 likes
Angular expansion 20 '
Number of stars about 80
Brightest star 8.6 likes
Redness ( excess color  E (BV)) 0.472 mag
Physical data

Affiliation Arm of Perseus , Milky Way
Redshift (-105 ± 10)  ·  10 −6
Radial velocity (-31.61 ± 3.12) km / s
distance  approx. 9000 ly
diameter approx. 30 ly
Age about 20 million years
history
Discovered by Wilhelm Herschel
Discovery time October 18, 1787
Catalog names
 NGC  457 • C 0115 + 580 • OCl 321 •  Mel  7 •  Cr  12 • Lund 43 •  GC  256 • Raab 3 • H VII 42 • h 97

NGC 457 is an open star cluster in the constellation Cassiopeia in the northern sky . It is 13 'in diameter and has an apparent magnitude of +6.4 mag. This makes the cluster one of the brightest star clusters in the constellation Cassiopeia and one of the brightest open star clusters not listed in the Messier catalog . Because of its appearance, the star cluster is also nicknamed the Owl Cluster or ET Cluster .

The brightest and dominant star is Phi Cassiopeiae , which is why the cluster is sometimes referred to as the Phi Cassiopeiae cluster . Together with Phi Cassiopeiae, HD 7902 stands out clearly and the two stars together form the "eyes" of the cluster. However, both Phi Cassiopeiae and HD 790 2 are likely to be foreground stars and not actual members of the star cluster. NGC 457 lies in the Perseus arm of the Milky Way , about 9,000 light years from the solar system; the extent of the star cluster is estimated to be around 30 light years and its age around 20 million years.

The object was discovered by Wilhelm Herschel on October 18, 1787 .

Web links

Commons : NGC 457  - collection of images, videos, and audio files

Individual evidence

  1. ↑ NASA / IPAC EXTRAGALACTIC DATABASE
  2. ↑ a b SEDS: NGC 457
  3. ↑ a b c SIMBAD database
  4. ↑ Seligman