Saturday, February 11, 2023

3870 - MILKY WAY GALAXY - new discoveries?

 

-  3870  -    MILKY WAY  GALAXY    -   new discoveries?     The migration of stars to Andromeda and the galaxy's growth history is  similar to that of the Milky Way. That means the findings have implications for our understanding of both galaxies.


--------  3870  -  MILKY WAY  GALAXY    -   new discoveries?

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-    The influx of stars into the galaxy next door to the Milky Way was revealed by intricate patterns in their motion today and reflects a violent event in our galaxy’s past.

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-    Astronomers have discovered new evidence that Andromeda, the galaxy next door to our own, grew by merging with another galaxy. The event triggered a mass migration of stars into that galaxy.

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-    The evidence came in the form of observations of the individual motions of almost 7,500 stars in the inner halo of Andromeda. This showed these stars had begun their lives as part of another galaxy that merged with Andromeda around 2 billion years ago.

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-   Scientists have long predicted that large galaxies like the Milky Way and Andromeda have grown to their current sizes via collisions and mergers throughout their history, but the patterns in the motions of stars that could confirm this have been elusive.

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-    Although the night sky may seem unchanging, the universe is a dynamic place. Galaxies like M31 and our Milky Way are constructed from the building blocks of many smaller galaxies over cosmic history.

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-    The majority of the stars in the Milky Way's halo are also believed to have originated in another galaxy finding a new galactic home during a massive merger event thought to have occurred between 8 to 10 billion years ago.

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-    We have never before seen this so clearly in the motions of stars, nor had we seen some of the structures that result from this merger.  Our emerging picture is that the history of the Andromeda Galaxy is similar to that of our own galaxy, the Milky Way. The inner halos of both galaxies are dominated by a single immigration event.

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-    To trace stellar migration in the galaxy used “DESI” due to the fact that it is the most powerful multi-object survey spectrograph in the world, capable of measuring the spectra of more than 100,000 galaxies in a single night.

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-     DESI's amazing efficiency, throughput, and field of view make it the best system in the world to carry out a survey of the stars in the Andromeda Galaxy.  In only a few hours of observing time, DESI was able to surpass more than a decade of spectroscopy with much larger telescopes.

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-   Between DESI and the Mayall Telescope new investigations of stars are geing made closer to the edge of Andromeda. Astronomers hope this will further reveal the galaxy's structure and the immigration history of its stars.

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-    It's amazing that we can look out at the sky and read billions of years of another galaxy's history as written in the motions of its stars , each star tells part of the story.   Astronomers are now hoping to conduct a survey of the entire M31 halo with DESI. Who knows what new discoveries await!

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            February 11, 2023       MILKY WAY  GALAXY    -   new discoveries?      3870                                                                                                                          

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--------------------- ---  Saturday, February 11, 2023  ---------------------------

 

 

 

 

         

 

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