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Core collapse can refer to: The collapse of the stellar core of a massive star, such as the core collapse that produces a supernova; Core collapse (cluster), the dynamic process that leads to a concentration of stars at the core of a globular cluster
It is considered a metal-poor inner halo cluster, being the third most metal-poor globular cluster within 9.8 kly (3 kpc) of the center. [8] The cluster has 5.72 × 10 5 times the mass of the Sun. [5] It is estimated to be around 12.9 billion years old, [6] and is believed to have undergone core collapse. [8]
The cluster contains around 400,000 stars, [8] and can be seen with the naked eye under good observing conditions. [10] NGC 6397 is one of at least 20 globular clusters of the Milky Way Galaxy that have undergone a core collapse, [8] meaning that the core has contracted to a very dense stellar agglomeration.
The first known globular cluster, now called M 22, was discovered in 1665 by Abraham Ihle, a German amateur astronomer. [4] [5] [6] The cluster Omega Centauri, easily visible in the southern sky with the naked eye, was known to ancient astronomers like Ptolemy as a star, but was reclassified as a nebula by Edmond Halley in 1677, [7] then finally as a globular cluster in the early 19th century ...
Messier 68 (also known as M68 or NGC 4590) is a globular cluster found in the east south-east of Hydra, away from its precisely equatorial part. It was discovered by Charles Messier in 1780. William Herschel described it as "a beautiful cluster of stars, extremely rich, and so compressed that most of the stars are blended together".
Messier 70 or M70, also known as NGC 6681, is a globular cluster of stars to be found in the south of Sagittarius. [a] It was discovered by Charles Messier in 1780. [b] [6] The famous comet Hale–Bopp was discovered near this cluster in 1995. [10] [c] It is about 29,400 [4] light years away from Earth and around 6,500 light-years [11] from the ...
The cluster does not display the normal indications of core collapse, but evidence suggests it may have instead passed through a post core-collapse bounce state within the past two billion years. The central luminosity density is 2.22 L ☉ ·pc −3, which is low for a globular cluster. [8]
NGC 6355 is a globular cluster located in the constellation Ophiuchus. [5] It is at a distance of 28,000 light years away from Earth, and is currently part of the Galactic bulge. [3] NGC was discovered by the German-born British astronomer William Herschel on 24 May 1784. [6]