Messier 103
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| The open star cluster Messier 103 2MASS catalog |
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| AladinLite | |
| Constellation | Cassiopeia |
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Position equinox : J2000.0 |
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| Right ascension | 01 h 33 m 21.8 s |
| declination | + 60 ° 39 ′ 29 ″ |
| Appearance
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| classification | III, 2, p (Trumpler) , d (Shapley) |
| Brightness (visual) | 7.4 mag |
| Brightness (B-band) | 7.72 likes |
| Angular expansion | 6 ' |
| Number of stars | 172 |
| Brightest star | 10.5 mag |
| Physical data
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| Redshift | (−135 ± 5) · 10 −6 |
| Radial velocity | (−40.4 ± 1.6) km / s |
| distance | 8500 ly (2600 pc ) |
| diameter | 15 years |
| Age | 25 million years |
| history | |
| Discovered by | Pierre Méchain |
| Discovery time | April 1781 |
| Catalog names | |
| M 103 • NGC 581 • C 0129 + 604 • OCl 326 • Mel 8 • Cr 14 • Lund 46 • GC 341 • Raab 4 • OCISM 75 | |
Messier 103 (also referred to as NGC 581 ) is a +7.4 mag bright open star cluster with an angular extent of 6 'in the constellation Cassiopeia . Since the cluster lies in the Milky Way band when viewed from the earth, the determination of its distance is subject to some uncertainty; the distance from M 103 is estimated to be around 8500 light years . Its expansion is thus about 15 light years. The radial relative speed of M 103 to our solar system is about −40 km / s. According to recent calculations, the age of M 103 is estimated to be around 25 million years. The star cluster was discovered by Pierre-François-André Méchain in 1781 .
The brightest and most conspicuous star in the area of M 103 is Struve 131 (HD 9311, SAO 11822), a multiple star with a +7.3 mag and a +10.5 mag bright component. However, this is a foreground star that does not belong to the star cluster M 103. The brightest stars actually belonging to M 103 reach an apparent magnitude of 10.5 mag.
Messier 103 was the last item in the Messier catalog originally published in three parts by Messier .
