Hubble Space Telescope Spies a Scintillating Globular Cluster

Hubble Space Telescope image showcasing the globular cluster NGC 6540 in the constellation Sagittarius. Credit: ESA/Hubble & NASA, R. Cohen

This scintillating image, which was captured by the globular cluster NGC 6540 in the constellation Sagittarius. These two instruments each have slightly different fields of view — which determines how large an area of sky each instrument captures at one time. This composite image shows the star-studded area of sky that was captured in both instruments’ field of view.

NGC 6540 is a globular cluster, which is a stable, tightly bound multitude of stars. The populations of these clusters can range from tens of thousands to millions of stars, all of which are trapped in a closely-packed group by their mutual gravitational attraction.

Prominent cross-shaped patterns of light known as diffraction spikes adorn the brightest stars in this image. These astronomical embellishments are a type of imaging artifact. This means that they are caused by the structure of Hubble rather than the stars themselves. The path taken by the starlight as it enters the telescope is slightly disturbed by its internal structure, which causes bright objects to be surrounded by spikes of light.

Hubble peered into the heart of NGC 6540 to assist astronomers in measuring the ages, shapes, and structures of globular clusters towards the center of the galaxy has evolved.