Messier 22
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Globular cluster Messier 22 |
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| Panoramic shot | |
| AladinLite | |
| Constellation | Sagittarius |
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Position equinox : J2000.0 , epoch : J2000.0 |
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| Right ascension | 18 h 36 m 24.21 s |
| declination | −23 ° 54 ′ 12.2 ″ |
| Appearance | |
| Concentration class | VII |
| Brightness (visual) | 5.1 and 6.17 mag |
| Brightness (B-band) | 7.16 likes |
| Angular expansion | 32.0 ' |
| Physical data | |
| Redshift | (−494 ± 17) · 10 −6 |
| Radial velocity | (−148 ± 5) km / s |
| distance | 10.4 kLj (3.2 kpc ) |
| diameter | 97 ly |
| history | |
| discovery | Johann Abraham Ihle |
| Discovery date | August 26, 1665 |
| Catalog names | |
| M 22 • NGC 6656 • C 1833-239 • GCl 99 • | |
Messier 22 (also known as NGC 6656 ) is a 5.5 mag bright globular cluster with an area of 32 'in the constellation Sagittarius . It stands in the direction of the center of the Milky Way , 2 ° northeast of the star Lambda Sagittarii .
M22 is the brightest globular cluster visible from Europe, but it is low in the southern sky . Already visible to the naked eye as a star-like object, it is an attractive deep sky object in the telescope and almost as magnificent as the well-known Hercules cluster M13 . It consists of around 80,000 stars, of which around 100 are cataloged as variable stars .
Due to its brightness, M22 was also the first globular cluster to be observed: the German amateur astronomer Johann Abraham Ihle saw it on August 26, 1665 as a round nebula in his 2-inch telescope . In the eight-inch , a few dozen of the brightest stars (11 mag) can be seen at the edge of the cluster. In 2001, outbursts of brightness were observed, which were explained by a dwarf nova or by microlens effects of narrow star orbits.
In September 2012, an international team of researchers, with the help of the Very Large Array of the US Radio Astronomy Observatory NRAO , discovered that M22 contains more than one black hole , which was previously considered impossible for reasons of celestial mechanics . The two objects each have 10 to 20 solar masses .
In 2019 the remains of a 48 BC. In China observed Nova discovered in M22. This confirmed one of the oldest recorded observations of an event outside the solar system. You can see a reddish nebula with an extension of 8000 AU. The observations were made with the MUSE instrument of the Very Large Telescope .
Web links
Individual evidence
- ↑ a b c d SIMBAD Astronomical Database
- ^ NED data for the Messier Objects
- ↑ Koch / Korth, The Messier Objects , Kosmos-Verlag 2009
- ↑ a b Messier 22 at SEDS
- ↑ klima-luft.de: Johann Abraham Ihle , queried on August 25, 2011
- ↑ Koch / Korth, The Messier Objects , Kosmos-Verlag 2009
- ↑ Black holes discovered in globular clusters for the first time. In: Zeit Online. Zeit Online GmbH, October 3, 2012, accessed on October 4, 2012 .
- ↑ Observation including Göttingen participation confirms one of the oldest Chinese measurements , University of Göttingen, April 29, 2019
