Short objekt description:
NGC 6397 is an ancient
stellar jewel box and an often overlooked and relatively unknown globular
cluster in the constellation Ara (Altar). Yet, with an apparent diameter of
over 30 arcminutes and a magnitude 5.3 brightness, it is a very prominent
object in the southern night sky.
The brightest stars have a magnitude
10 brightness. It is classified as type IX. At a
distance of only 7,800 light years, it is the second closest globular cluster
to the Solar System - after Messier 4 in the constellation of Scorpio - and has
therefore been studied in many scientific publications. During one of these
investigations, an elliptical galaxy about 1 billion light years away was found
by chance between the stars of NGC 6397, which in turn is surrounded by a swarm
of about 200 globular clusters. This is the most distant known cluster of
globular clusters to date.
The central region of the cluster is
extremely dense (core collapse). It contains about 400,000 stars and the stars
are - according to a study with the Hubble Space Telescope - about 13.5 billion
years old. Recent studies with the Hubble telescope suggest that there may be
several stellar black holes at the centre of the globular cluster. NGC 6397 was
discovered in 1751 by the French astronomer Nicolas Louis de
Lacaille. |