Andromeda catastrophe provokes a large-scale galactic migration

Astronomers have found new evidence that the nearest neighbor of the Milky Way – the Andromeda galaxy (M31) – grew by merging with another galaxy. This large-scale event provoked a mass migration of stars into the galaxy. The evidence was found as a result of observations of the movement of almost 7,500 stars in the inner halo of Andromeda. It turned out that almost all of them were part of another galaxy before the catastrophic collision about 2 billion years ago.

Andromeda Galaxy (M31)

The migration of stars to Andromeda, the history of the formation and growth of the galaxy is very similar to our Milky Way. Such a discovery is of great importance for our understanding of the evolution of both galaxies. Scientists have long predicted that large galaxies such as the Milky Way and the Andromeda nebula have grown to their current size as a result of collisions and mergers with smaller galaxies. But scientists have not been able to obtain evidence for a long time that can confirm this hypothesis.

Each of the dots in this image represents a separate star in the Andromeda Galaxy, and the movement of stars relative to the galaxy is indicated by the color from blue (moving towards us) to red (moving away from us). Authorship of the image: KPNO/NOIRLab/AURA/NSF

An international team of astronomers managed to find evidence using the Dark Energy Spectroscopic Instrument (DESI) on the Nicholas Ulrich Mayall 4-meter telescope at the Kitt Peak National Observatory under the leadership of NOIRLab. DESI has helped to track the migration of stars in the galaxy, as it is the most powerful multi-object spectrograph in the world, capable of measuring the spectra of more than 100 thousand galaxies in one night.

“DESI’s amazing efficiency, performance and field of view make it the best system in the world for conducting a survey of the stars of the Andromeda galaxy. In just a few hours of observations, DESI could overcome more than a decade of spectroscopy with much larger telescopes,” said NOIRLab lead researcher and astronomer Arjun Day.

The team will continue to collaborate between DESI and the Mayall Telescope to study stars closer to the edge of Andromeda. They hope that this will help reveal the structure of the galaxy and the history of star migration.

Earlier we reported on how a giant oxygen nebula was detected near the Andromeda galaxy.

According to The Astrophysical Journal

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