Messier 9
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Globular cluster data from Messier 9 |
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| The center of the globular cluster Messier 9 as seen by the Hubble Space Telescope | |
| AladinLite | |
| Constellation | Snake bearer |
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Position equinox : J2000.0 , epoch : J2000.0 |
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| Right ascension | 17 h 19 m 11.8 s |
| declination | −18 ° 30 ′ 59 ″ |
| Appearance | |
| Concentration class | VIII |
| Brightness (visual) | 7.8 likes |
| Angular expansion | 12.0 ' |
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Color excess E (BV) (redness) |
0.36 |
| Physical data | |
| Affiliation | Milky Way |
| distance | 26 kLj (8.1 kpc ) |
| Concentration lg (r t / r c ) | 1.15 |
| Metallicity [Fe / H] | −1.78 |
| history | |
| discovery | Charles Messier |
| Discovery date | May 28, 1764 |
| Catalog names | |
| M 9 • NGC 6333 • C 1716-184 • GCl 60 • ESO 587-SC5 • GC 4287 • h 1979 • h 3677 | |
Messier 9 or M9 (also referred to as NGC 6333 ) is an 8.2 mag bright globular cluster with an angular extent of 11–12 'in the constellation of the Serpent Bearer (Ophiuchus). It was discovered on May 28, 1764 by the French astronomer Charles Messier and, at 26,000 light years, is one of the most distant globular clusters in the Messier catalog with a very dense center. Of the 5 bright globular clusters in the constellation (M9, 10, 12, 14 and 107), it is the southernmost.
Messier noted it as a small, round "nebula without a star". It was not until 20 years later that Wilhelm Herschel recognized it as a cluster with many stars but dense, and Lord Rosse saw a dark dividing line on the southern edge. To see the first single stars at the edge of the "nebula", a telescope with an opening of at least 20 cm is required. Curtis noticed in 1918 that M9 - unlike other globular clusters - retains the small 3 'diameter in photographs. However, the latest measuring methods determined a further extension to about 10 '.
In a 10x50 binoculars you can only see a small, shapeless disc, in a 10 cm telescope an elongated nebula. The brightest single stars (25 from 13.5 to 15.5 mag) can only be seen in a medium-sized amateur telescope ( eight-inch or larger, depending on the visibility conditions ).
The western edge is covered somewhat by an adjacent Barnard 64 (25 × 15 ') dark cloud . Two smaller globular clusters (NGC 6342 and 6356) lie 1 ° to the south and northeast.
Web links and literature
- M9 at SEDS
- Ronald Stoyan : Atlas of the Messier Objects - The Highlights of the Deep Sky . Oculum-Verlag, Erlangen 2006
- Bernd Koch, Stefan Korth: The Messier Objects - The 110 classic goals for sky observers . Pp. 26/27, Kosmos-Verlag, Stuttgart 2010.
- Spektrum .de: amateur recordings [1]
