Study on the Violent History of Andromeda Galaxy

An international team of galactic investigators has put together the intense history of the Andromeda galaxy, which is now looking at the Milky Way as its next victim.

muratart / Shutterstock - Elements of this image furnished by NASA.

The study published in Nature is headed by a team from the Australian National University. Along with researchers from the University of Surrey, they investigated data from the Pan-Andromeda Archaeological Survey. It was discovered that, over the last few billion years, Andromeda has consumed many small galaxies, based on the proof found in huge streams of stars.

Extremely faint traces of tiny galaxies that were devoured by Andromeda almost 10 billion years ago were discovered by the team even earlier. The team now fears that the home galaxy could be the next in roughly 4 billion years.

Indications of this shocking history can be traced in stars that orbit Andromeda, with the team reviewing dense clusters of stars called globular clusters. This enabled them to recreate how smaller galaxies were drawn in by Andromeda.

The research collaboration involved institutions from New Zealand, Australia, the United Kingdom, Netherlands, Canada, Germany, and France.

Seeing two distinct meal times for Andromeda was quite surprising. The way the globular clusters move around Andromeda suggest that this galaxy had a large breakfast around 10 billion years ago, and a big lunch perhaps only a few billion years ago.

Dr Michelle Collins, Researcher, University of Surrey

Dr Collins continued, “The two accretion events have come from strikingly different directions, as the two globular cluster populations are orbiting at right angles to one another. This directionality may tell us something about the cosmic web within which Andromeda and the Milky Way are embedded, and gives us insight into the formation of our massive neighbour.”


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