- 3939 - ANDROMEDA GALAXY - grew from galaxy mergers? 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 the galaxy.
-------- 3939 - ANDROMEDA GALAXY - grew from galaxy mergers?
- These
galactic collisions suggests that the migration of stars to Andromeda and the
galaxy's growth history is very similar to that of the Milky Way. That means the
findings have implications for our understanding of both galaxies.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- To trace
stellar migration in the galaxy, the team turned to “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.
-
- This
science could not have been done at any other facility in the world. 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.
-
- Despite
first opening its eye to the universe in 1973, the Mayall Telescope is still
able to play a role in cutting-edge research like this thanks to five decades
of upgrades and improvements.
-
- 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. Our initial observations
exceeded our wildest expectations and we are now hoping to conduct a survey of
the entire M31 halo with DESI. Who knows what new discoveries await!
-
March 31, 2023 ANDROMEDA GALAXY
- grew from galaxy mergers? 3939
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--- Sunday, April 2, 2023
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