Yahoo – AFP,
February 14, 2018
Calculating the birth date of the Andromeda galaxy has been a major challenge for astrophysicists (AFP Photo/HO) |
Paris (AFP)
- The Milky Way's neighbouring galaxy, Andromeda, was formed in a colossal
crash between two smaller star systems no more than three billion years ago
when Earth already existed, researchers said Wednesday.
Calculating
the birth date of the galaxy has been a major challenge for astrophysicists
given the vast age gap between the different stars it is made up of.
For the
latest study, French and Chinese researchers led by Paris Observatory
astronomer Francois Hammer used "the most powerful available computers in
France" to crunch about a terabyte of data -- the equivalent of two
million 500-kilobyte photos.
This allowed
them to zoom in on "the physical mechanisms of the Andromeda formation, so
lifting the veil on its origin," the observatory said in a statement.
The results
were published in the Monthly Notices of the Royal Astronomical Society.
Previous
research had noted one major difference between our own galaxy and Andromeda --
long considered twin clusters, the team pointed out.
In
Andromeda, certain stars orbit erratically while in the Milky Way, all stars
observe a simple rotation around the galaxy's centre.
Why?
The star
agitation was due to the galaxy's "recent" formation, the team said.
The data
showed that between seven and 10 billion years ago, two galaxies -- one four
times more massive than the other -- found themselves on a collision course.
The team
simulated both precursor galaxies' trajectories and calculated that they fused
between 1.8 billion and three billion years ago to forge Andromeda.
Two
reconstructions of the event can be seen here:
https://www.youtube.com/watch?v=zz86Dd_L7HY,
and
https://www.youtube.com/watch?v=exetDytuUYQ
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