science & techESA/Hubble

A star cluster in the Large Magellanic Cloud is a fossil of an ancient galaxy merger

the gist

NGC 2005 is a globular cluster, a dense ball of stars, located about 750 light-years from the heart of the Large Magellanic Cloud. The Large Magellanic Cloud is the largest satellite galaxy of the Milky Way, about 162,000 light-years away. Globular clusters can be billions of years old, so they preserve the earliest stars of their host galaxies, much as fossils preserve ancient life. The stars in NGC 2005 have a chemical makeup that differs from the stars around them. This suggests the Large Magellanic Cloud once merged with another galaxy, which has since dispersed, leaving this cluster behind as evidence.

so what

Galaxies are thought to grow by swallowing smaller ones, and this cluster provides a direct chemical clue to such a merger in our own neighbourhood. It shows that ancient star clusters can reveal the history of galaxies.

fun fact

The Large Magellanic Cloud is the largest satellite galaxy of the Milky Way.

ESA/Hubble · CC BY 4.0

Image: ESA/Hubble & NASA, F. Niederhofer, L. Girardi