Italian astronomer Alessio Mucciarelli from the University of Bologna has received evidence of the absorption of neighboring dwarf galaxies by the Large Magellanic Cloud (BMO) in the distant past. This has become a significant brick in the theory of hierarchical assembly, according to which large galaxies are formed by absorbing small ones. In 5 billion years, the Andromeda galaxy will capture our Milky Way, but a billion years before that, it will have time to absorb both Magellanic clouds, which previously did this with ancient unnamed galaxies.

With its mass of 250 billion Suns, the BMO is large enough to have its own tiny satellite galaxies, but it’s not easy to find them. It is believed that there are 4-6 of them, but in 2018, Mucciarelli’s team found something else – the globular cluster NGC 2005. Such formations are a kind of “stubs” from former galaxies, dense spherical clusters consisting of 0.1-1 million very old stars.

There are up to 150 globular clusters in the Milky Way, and at least 60 in the BMO. But NGC 2005 differs from all others in its extremely low metallicity, which is a convincing proof of its venerable age. Mucciarelli was able to establish that by this indicator NGC 2005 is older than all other objects that exist in the BMO and the Milky Way. Most likely, these are the last “crumbs”, the remains of a very ancient galaxy that was absorbed by the BMO in immemorial times.
Source – Nature Astronomy