Globular clusters are densely packed spherical collections of hundreds of thousands or even millions of stars. They are among the oldest known objects in the universe and are preferentially associated with the oldest components of galaxies. Our own galaxy, the Milky Way, is home to at least 150 such objects, and there are likely a few more hidden behind the thick disk of the galaxy.
This globular cluster specifically, named NGC 6717, is approximately 7,100 parsecs (or 23,157 light years) away from Earth in the constellation Sagittarius. Also known as ESO 523-14 and GCl 105, the cluster was discovered by British astronomer William Herschel.
“Globular clusters contain more stars at their centers than at their outer margins, as this image rightly demonstrates. The sparsely populated edges of NGC 6717 are in stark contrast to the bright collection of stars at its center, “ explain the Hubble astronomers.
“The center of the image also contains some intruders from closer to home. Bright foreground stars near Earth are surrounded by crisscrossing diffraction peaks formed by starlight that interact with structures supporting Hubble’s secondary mirror. The area of the night sky that contains the constellation Sagittarius also contains the center of the Milky Way, which is filled with light-absorbing gas and dust. This absorption of light, which we refer to as extinction, makes studying globular clusters near the galactic center a challenging endeavor, “say the researchers.
