Image: Hubble captures a cosmic fossil (NGC 2005)

This NASA/ESA Hubble Area Telescope picture options the globular cluster NGC 2005. It isn’t an uncommon globular cluster in and of itself, however it’s a peculiarity when in comparison with its environment.

NGC 2005 is situated about 750 light-years from the center of the Giant Magellanic Cloud (LMC), which is the Milky Way’s largest satellite galaxy some 162,000 light-years from Earth. Globular clusters are densely-packed teams of stars that may maintain tens of 1000’s or hundreds of thousands of stars. Their density means they’re tightly sure by gravity and subsequently very steady.

This stability contributes to their longevity: Globular clusters could be billions of years outdated and are sometimes comprised of very outdated stars. Learning globular clusters in space is usually a little like finding out fossils on Earth: The place fossils give insights into the traits of historical vegetation and animals, globular clusters illuminate the traits of historical stars.

Present theories of galaxy evolution predict that galaxies merge with each other. Astronomers suppose the comparatively giant galaxies we observe within the fashionable universe shaped when smaller galaxies merged. If that is appropriate, then we might count on to see proof that probably the most historical stars in close by galaxies originated in numerous galactic environments.

As a result of globular clusters maintain historical stars, and due to their stability, they’re a superb laboratory to check this speculation. NGC 2005 is such a globular cluster, and its very existence offers proof that helps the idea of galaxy evolution through mergers.

Certainly, what makes NGC 2005 a bit peculiar from its environment, is the truth that its stars have a chemical composition that’s distinct from the stars round it within the LMC. This implies that the LMC underwent a merger with one other galaxy someplace in its historical past. That different galaxy has long-since merged and in any other case dispersed, however NGC 2005 stays behind as an historical witness to the long-past merger.