Messier 18
Image of the open star cluster Messier 18 using the VST . | |
AladinLite | |
Constellation | Sagittarius |
Position equinox : J2000.0 |
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Right ascension | 18 h 20.0 m |
declination | −17 ° 06 ′ |
Appearance
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classification | II 3 pn |
Brightness (visual) | 7.1 likes |
Angular expansion | 10 ' |
Brightest star | HD 168352, 8.65 mag |
Physical data
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Affiliation | Sagittarius spiral arm, Milky Way |
Radial velocity | (−14 ± 4) km / s |
distance | approx. 4080 ly (approx. 1250 pc ) |
diameter | approx. 3.5 pc, approx. 11 ly |
Age | approx. 30 million years |
history | |
Discovered by | Charles Messier |
Discovery time | June 3, 1764 |
Catalog names | |
M 18 • NGC 6613 • C 1817-171 • OCl 40 • Cr 376 • Lund 826 • GC 4401 • h 2007 |
Messier 18 (also known as NGC 6613 ) is an approximately 7 mag bright open star cluster with an angular extent of 10 'in the constellation Sagittarius . There are numerous bright, blue giant stars in it . They are so hot that they glow predominantly in blue light and in the nearby ultraviolet . M 18 is around 4600 light years from the sun. Using the massive blue stars, the researchers estimate that the star cluster is around 30 million years old.
Charles Messier discovered the star cluster in 1764 and listed it in his catalog .
Web links
- astronews.com: Picture of the day October 14, 2016