(ORDO NEWS) — Over billions of years, galaxies grow and evolve, creating new stars and merging with other galaxies as a result of galactic immigration.
Astronomers are trying to unravel the history of these events by studying the extended halo of galaxies and the movements of individual stars.
Until now, however, such space archeology has only been possible in the Milky Way.
An international team of researchers has found startling evidence of a major galactic immigration in the Andromeda galaxy.
The new results were obtained using the DESI dark energy spectroscopy instrument installed on the 4-meter Nicholas W. Mayall Telescope at Kitt Peak National Observatory as part of NSF’s NOIRLab program.
By measuring the movement of nearly 7,500 stars in the inner halo of the Andromeda galaxy, the team found characteristic patterns in their arrangement and movement.
They showed how these stars began their lives in another galaxy that merged with Andromeda about 2 billion years ago.
Although such patterns have long been predicted by theory, they have never been observed with such clarity in any galaxy.
This study sheds light not only on the history of our galactic neighbors, but also on the history of our galaxy.
Most of the stars in the Milky Way’s halo formed in another galaxy and later migrated to ours in a galactic merger 8 to 10 billion years ago.
To trace the history of migration to Andromeda, the team turned to DESI.
DESI was designed to map tens of millions of galaxies and quasars in the nearby universe to measure the effect of dark energy on the expansion of the universe.
“This study could not have been carried out at any other facility in the world.
The amazing efficiency, throughput and field of view of DESI make it the best system in the world for surveying stars in the Andromeda galaxy,” the researchers say.
“In just a few hours of observations, DESI was able to outperform more than a decade of spectroscopy made with much larger telescopes.”
The team now plans to use the unprecedented capabilities of DESI and the Mayall telescope to study more of Andromeda’s distant stars.
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