M22( NGC 6656 ) [1] Is the best observation in the sky Globular cluster One, only than Nantian Centaur ω clusters and 47 Tucanae It is also one of the brightest globular clusters visible in the Northern Hemisphere [2] and Galaxy One of many globular clusters, and also one of the closest globular clusters to the Earth. M22 in Sagittarius The region is a loosely structured globular cluster, which can be observed very well with an 8 inch (20 cm) telescope, and even can distinguish many single stars in its center.
- Chinese name
- M22
- Foreign name
- Messier 22
- Alias
- NGC6656
- Classification
- Globular cluster
- Discoverer
- Abraham Ihle
- Discovery time
- August 26, 1665
- Quality
- 2.9 × 10 ^ 5 solar mass
- Diameter
- About 100 light years
- Apparent magnitude
- +5.1
- Right ascension
- 18:36:23.94s
- Declination
- –23°54′17.1″
- Distance from ground
- 10.6 ± 1.0 thousand light years (3 ± 0.3 thousand second gap)
- Metal abundance
- [Fe/H]=-1.49
- Number of stars included
- More than 100000
Globular cluster M22 stars are formed at the same time and are gravitation Bound together. The stars move around the center of the cluster, and the cluster moves around the center of our galaxy. So far, about 140 are known Globular cluster It exists in a nearly spherical halo around the silver core. The fact that these globular clusters do not appear to be spherically symmetric from the Earth's point of view is the main point that decides to suggest that the sun is not at the center of the Milky Way. Globular clusters are very old. There is a method to directly measure the age of globular clusters, and the measured results are basically close to the age of the entire universe of 13.7 billion years. 32 have been recorded in M22 Variable star 。 adopt Infrared astronomical satellite (IRAS), astronomers have observed in M22 Planetary nebula , making it one of the few globular clusters where planetary nebulae have been observed. The planetary nebula, numbered IRAS 18333-2357, is estimated to be 6000 years old and has a blue star at its core. Through Mexico Very large telescope Astronomers found that M22 has a Medium mass black hole The estimated mass is 10 to 20 solar masses. In 2012, Chandra X-ray Observatory The existence is confirmed again. M22 is a Metal poor cluster , is moving away from the earth at a speed of 149km per second. 
