Messier 18

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Open star cluster
Messier 18
Image of the open star cluster Messier 18 using the VST.
Image of the open star cluster Messier 18 using the VST .
AladinLite
Constellation Sagittarius
Position
equinox : J2000.0
Right ascension 18 h 20.0 m
declination −17 ° 06 ′
Appearance

classification II 3 pn
Brightness  (visual) 7.1 likes
Angular expansion 10 '
Brightest star HD 168352, 8.65 mag
Physical data

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

swell

  1. a b SIMBAD
  2. HD 168352 at SIMBAD
  3. SuW 10.2016 p. 14
  4. Seligman