Hubble reveals ancient witness to galaxy merger

This Hubble Space Telescope image shows the globular cluster NGC 2005. It is located about 750 light-years from the center of the Large Magellanic Cloud, and about 162,000 light-years from Earth. This cluster is an example of ancient cosmic structures, containing millions of ancient stars that provide insights similar to fossils on Earth, revealing the properties of ancient stars. Image source: ESA/Hubble and NASA, F. Niederhofer, L. Girardi

NGC 2005, a globular cluster in the Large Magellanic Cloud, is crucial evidence supporting the theory of galaxy evolution through mergers.

This wonderful photo from Hubble Space Telescope The globular cluster NGC 2005 is unique. Although it is not unusual in itself, it is peculiar in relation to its surroundings.

NGC 2005 is located about 750 light-years from the heart of the Large Magellanic Cloud (LMC), the Large Magellanic Cloud. milky wayIts largest satellite galaxy is located about 162,000 light-years from Earth. Globular clusters are densely packed clusters that can form tens of thousands or millions of stars. Its density means that it is strongly bound to gravity, and is therefore very stable. This stability contributes to their longevity: globular clusters can be billions of years old, and as such often include very old stars.

Therefore, studying globular clusters in space can be a bit like studying fossils on Earth: fossils give insight into the properties of ancient plants and animals, and globular clusters shed light on the properties of ancient stars.

Current theories of galaxy evolution predict that galaxies merge with each other. It is widely believed that the relatively large galaxies we observe in the modern universe were formed by the merger of smaller galaxies. If this is true, astronomers would expect to see evidence that the oldest stars in nearby galaxies originated in different galactic environments. Since globular clusters are known to contain ancient stars, and because of their stability, they constitute an excellent laboratory to test this hypothesis.

NGC 2005 is a globular cluster, and its presence has provided evidence supporting the theory of galaxy evolution through mergers. In fact, the stars in NGC 2005 have a different chemical composition than the stars in the surrounding LMC. This suggests that the LMC underwent a merger with another galaxy somewhere in its history. That other galaxy long ago merged and dispersed, but NGC 2005 lingers behind as an ancient witness to the merger that happened long ago.