A Concentration of Black Holes Found in Globular Star Cluster NGC 6397 | Hubble

A Concentration of Black Holes Found in Globular Star Cluster NGC 6397 | Hubble

This European Space Agency (ESA) Space Sparks episode summarizes an exciting discovery from the NASA/ESA Hubble Space Telescope. Scientists were expecting to find an intermediate-mass black hole at the heart of the globular cluster NGC 6397, but instead they found evidence of a concentration of smaller black holes lurking there. Recent Hubble data have led to the first measurement of the extent of a collection of black holes in a core-collapsed globular cluster.

NGC 6397 sits 7,800 light-years away within the Milky Way galaxy, making it one of the closest globular clusters to Earth in the constellation Ara. This ancient stellar jewelry box glitters with the light from hundreds of thousands of stars.

The cluster’s blue stars are near the end of their lives. These stars have used up their hydrogen fuel that makes them shine. Now they are converting helium to energy in their cores, which fuses at a higher temperature and appears blue.

The reddish glow is from red giant stars that have consumed their hydrogen fuel and have expanded in size. The myriad small white objects include stars like our Sun.

Credits:
Directed by: Bethany Downer and Nico Bartmann   
Editing: Nico Bartmann   
Web and technical support: Enciso Systems   
Written by: Bethany Downer    
Footage and photos: ESA/Hubble, N. Bartmann

Duration: 1 minute, 39 seconds
Release Date: Feb. 11, 2021

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