Messier 7

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Open star cluster
Messier 7
Photo of the MPG / ESO 2.2 m telescope
Photo of the MPG / ESO 2.2 m telescope
AladinLite
Constellation Scorpio
Position
equinox : J2000.0
Right ascension 17 h 53.8 m
declination −34 ° 47 ′
Appearance

classification I, 3, m (Trumpler),
e (Shapley)
Brightness  (visual) 3.3 mag
Brightness  (B-band) 3.45 likes
Angular expansion 80 '
Number of stars 80 that are lighter than 10mag
Brightest star 5.89 likes
Physical data

Redshift -47  ·  10 -6
Radial velocity −14.21 km / s
distance  800 ly
(250 pc )
diameter 18–20 years
Age 220 million years
history
Discovery time prehistoric
Catalog names
 M  7 •  NGC  6475 • C 1750-348 • OCl 1028 •  Mel  183 •  Cr  354 • Lund 791 •  ESO  394-SC9 •

Messier 7 (also known as NGC 6475 ) is a +3.3 mag bright open star cluster in the eastern part of Scorpio north of Lesath with an extension of 80 '.

The cluster is about 800 light years away towards the galactic center . It consists of around 100 stars and has a diameter of around 25 light years. Its age is estimated to be 200 million years.

In 130 the mathematician and astronomer Claudius Ptolemy was the first to mention this star cluster, which is why it is also called the Ptolemy star cluster . After the Pleiades ( Messier 45 ) and the Praesepe ( Messier 44 ), M 7 is the third brightest star cluster in our sky. It is difficult to see in Central Europe, but a noticeable object in southern latitudes. M7 is the southernmost object in the Messier catalog .

Individual evidence

  1. ^ NED data for the Messier Objects
  2. a b c d e f g Messier 7 at SEDS
  3. a b c SIMBAD Astronomical Database
  4. http://www.eso.org/public/germany/news/eso1406/
  5. SuW 08.2017 p. 60f

Web links

Commons : Messier 7  - album with pictures, videos and audio files