Messier 23

from Wikipedia, the free encyclopedia
Open star cluster
Messier 23
Messier object 023.jpg
The open star cluster
Messier 23
Atlas Image courtesy of 2MASS / UMass / IPAC-Caltech / NASA / NSF
AladinLite
Constellation Sagittarius
Position
equinox : J2000.0
Right ascension 17 h 57 m
declination −18 ° 59 ′
Appearance

classification III, 1, m (Trumpler),
d (Shapley)
Brightness  (visual) 5.5 mag
Brightness  (B-band) 6.03 mag
Angular expansion 27 '
Number of stars 150
Brightest star 9.21 mag
Physical data

distance  2150 ly
(660 pc )
diameter 15 years
Age 220 million years
history
Discovered by Charles Messier
Discovery time June 20, 1764
Catalog names
 M  23 •  NGC  6494 • C 1753-190 • OCl 30 •  Mel  184 •  Cr  356 • Lund 793 •  ESO  589-SC22 •

Messier 23 (M23, also known as NGC 6494 ) is one of the six brightest open star clusters in the summer constellation Sagittarius (Sagittarius). It has a brightness of +5.5 mag and an angular extent of 27 '. The cluster is about 2000 light years away, halfway between the sun and the Sagittarius arm of our galaxy. The analysis of the color-brightness diagram of Messier 23 shows an age of around 300 million years.

A few degrees to the east - almost in the center of the Milky Way - lies the small Sagittarius cloud (M24) and the star cluster Messier 25, which is comparable to M23 .

Web links

Commons : Messier 23  - album with pictures, videos and audio files

Individual evidence

  1. a b c SIMBAD query
  2. a b c d e f g Messier 23 at SEDS
  3. https://cseligman.com/text/atlas/ngc64a.htm#6494
  4. SuW 06.2016 p. 60f