Messier 4

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Globular cluster
Messier 4
Messier 4 recorded with the MPG / ESO 2.2 m telescope
Messier 4 recorded with the MPG / ESO 2.2 m telescope
AladinLite
Constellation Scorpio
Position
equinoxJ2000.0 , epoch : J2000.0
Right ascension 16 h 23 m 35.4 s
declination −26 ° 31 ′ 32 ″
Appearance
Concentration class IX
Brightness  (visual) 5.4 likes
Angular expansion 36.0 '
Physical data
Integrated spectral type F8
Redshift (2.35 ± 0.01)  ·  10 -4
Radial velocity 70.4 ± 0.4 km / s
distance 7.2  kLj
(2.2  kpc ) 
diameter 75 years
Age 12–13 billion years
history
discovery De Chéseaux
Discovery date 1746
Catalog names
 M  4 •  NGC  6121 • C 1620-264 •  GCl  41 •

The globular cluster Messier 4 (M 4 for short) is in the constellation Scorpio , not far from the bright star Antares . In the NGC catalog the celestial object has the number 6121. M 4 is the closest globular cluster at 7000 ly, so it is often used for special investigations.

The cluster has about 100,000 stars with a diameter of 75 light years and is rather weakly concentrated (class 9), so it does not show a very pronounced central brightness. A study of more than 600 white dwarfs found an age of approximately 12.7 billion years.

Appearance

Photo from the Hubble Space Telescope

Although it is quite small, M 4 has a considerable angular expansion and is therefore an impressive object for astronomical observation. Because of its southern position, however, the cluster is less attractive to amateur astronomers in Central Europe than the nearby M5 or M19 .

The central bar structure , already described by Wilhelm Herschel in 1783, is striking. It consists of a 2.5 'long row of stars about 11th size and runs through almost the entire dense cluster core.

discovery

M 4 was discovered in 1746 by the amateur astronomer Philippe Loys de Chéseaux and cataloged by Charles Messier on May 8, 1764 .

Web links

Commons : Messier 4  - album with pictures, videos and audio files

Individual evidence

  1. NASA / IPAC EXTRAGALACTIC DATABASE
  2. ^ NED data for the Messier Objects
  3. SEDS : NGC 6121
  4. a b Messier 4 at SEDS
  5. Stars and Space , June 2006, p. 56.
  6. Bernd Koch, Stefan Korth: The Messier objects. The 110 classic destinations for sky watchers. Kosmos-Verlag, Stuttgart 2010.
  7. Seligman