by Paul Ratner
Scientists use artificial intelligence to reconstruct
the globular clusters that merged to form our Milky Way
researchers ran simulations on a neural network to
discover the history and details about our galactic
found that a collision with a previous galaxy called
"Kraken" was so powerful it transformed the Milky Way.
A team of
used AI to
of stars merged
to become our
The Milky Way, the galaxy
that contains our Solar System, is estimated to be about 13.6
billion years old.
But what was there
A loaded question that
scientists are getting closer to answering. A team of
astrophysicists reconstructed the cosmic ancestry of our galaxy.
They figured out its family tree by using artificial intelligence to
analyze globular clusters that orbit the Milky Way.
Globular clusters are collections of up to a million stars, almost
as old as the Universe itself. Over 150 clusters of this kind are
present in the Milky Way. Scientists believe that many of them were
created in smaller galaxies that merged to form our galaxy.
Astronomers treat them as
"fossils" for reverse engineering the history of our home in space.
The latest study allowed the research team to do exactly that.
The group led by Dr.
Diederik Kruijssen from the University
of Heidelberg (ZAH) and Dr.
Joel Pfeffer from Liverpool John Moores University modeled the merger story of the Milky Way.
sophisticated computer simulations called
E-MOSAICS to represent a
complete model of the creation, evolution and demise of globular
The researchers linked ages, the chemistry, and orbital
motions of these clusters to the composition of the preceding
galaxies that formed them, over 10 billion years ago.
The analysis allowed the
scientists to pinpoint how many stars the progenitor galaxies had as
well as when their merger forming the Milky Way took place.
"The main challenge
of connecting the properties of globular clusters to the merger
history of their host galaxy has always been that galaxy
assembly is an extremely messy process, during which the orbits
of the globular clusters are completely reshuffled," Kruijssen
Check out how E-MOSAICS
simulations shows the formation of a galaxy like the Milky Way:
Once they trained their artificial neural network to investigate the
galactic merger history, they,
algorithm tens of thousands of times on the simulations and were
amazed at how accurately it was able to reconstruct the merger
histories of the simulated galaxies, using only their globular
according to Kruijssen.
To dive deep into the
prehistory of our galaxy, the researchers directed their AI (artificial
intelligence) to study
global clusters that they suspected were formed in the progenitor
The orbital motion of the
clusters informed their predictions.
The AI was able to pinpoint the
masses of the stars and the details of the mergers with great
It also discovered a
collision 11 billion years ago between the Milky Way and a
mysterious galaxy the scientists evocatively dubbed "Kraken."
Credit: D. Kruijssen
Galaxy merger tree of the Milky Way. The main
progenitor of the Milky Way is shown by the trunk of
the tree, with color representing its stellar mass.
Black lines show the five identified satellites.
Grey dotted lines demonstrate other mergers that the
Milky Way likely underwent, but could not be
connected to a particular progenitor.
From left to right, the six images at the top list
the identified progenitor galaxies:
the Milky Way's Main progenitor
the progenitor of the Helmi streams
Kruijssen called this collision with Kraken,
"the most significant
merger the Milky Way ever experienced."
This event would have
superseded the collision with the
Gaia-Enceladus-Sausage galaxy of 9
billion years ago and was likely much more transformative, since our
galaxy at that time was four times less massive.
Overall, the researchers think the Milky Way consumed about five
galaxies of over 100 million stars, as well as 15 galaxies with 10
million stars or more...
The scientists hope their
findings will be used to locate debris from all of our galactic
Check out their study "Kraken
reveals itself - The merger History of the Milky Way reconstructed
with the E-MOSAICS simulations" published in Monthly
Notices of the Royal Astronomical Society.