Globular Star Cluster NGC 6397 in Ara: An ancient stellar jewelry box | Hubble

Globular Star Cluster NGC 6397 in Ara: An ancient stellar jewelry box | Hubble

This glittering image captures a globular cluster called NGC 6397 (also known as Caldwell 86) that was discovered by French astronomer Nicolas-Louis de Lacaille in 1752. It 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.

This image is composed of a series of observations taken from July 2004 to June 2005 with Hubble’s Advanced Camera for Surveys. The research team used Hubble’s Wide Field Camera 3 to measure the distance to the cluster.

Learn more: "How White Dwarfs Get Their ‘Kicks’"
https://science.nasa.gov/missions/hubble/how-white-dwarfs-get-their-kicks/

Credit: NASA, ESA, and T. Brown and S. Casertano (STScI)

Acknowledgement: NASA, ESA, and J. Anderson (STScI)

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