|Messier 4 recorded with the MPG / ESO 2.2 m telescope|
equinox : J2000.0 , epoch : J2000.0
|Right ascension||16 h 23 m 35.4 s|
|declination||−26 ° 31 ′ 32 ″|
|Brightness (visual)||5.4 likes|
|Angular expansion||36.0 '|
|Integrated spectral type||F8|
|Redshift||(2.35 ± 0.01) · 10 -4|
|Radial velocity||70.4 ± 0.4 km / s|
(2.2 kpc )
|Age||12–13 billion years|
|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.
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 .
- Detailed information on M 4 ( Memento from September 28, 2007 in the Internet Archive )
- ESO: This globular cluster holds a secret + photos, map & animation - September 5th, 2012
- NASA / IPAC EXTRAGALACTIC DATABASE
- NED data for the Messier Objects
- SEDS : NGC 6121
- Messier 4 at SEDS
- Stars and Space , June 2006, p. 56.
- Bernd Koch, Stefan Korth: The Messier objects. The 110 classic destinations for sky watchers. Kosmos-Verlag, Stuttgart 2010.