Andromeda galaxy was formed in 'recent' star crash: study

February 14, 2018
Calculating the birth date of the Andromeda galaxy has been a major challenge for astrophysicists

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 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 ' 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 below:

Explore further: Stream of stars in Andromeda satellite galaxy shows cosmic collision

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Benni
1.5 / 5 (8) Feb 14, 2018
....in addition to this our two visible matter galactic halos are already touching:

https://io9.gizmo...04945980

......betch'a DM Cosmic Fairy Dust Enthusiasts never knew this. I won't bother explaining what this portends for the presence of the most abundant substance in the Universe that has never been found except within the print of the printed pages of Astronomy magazine.
nrauhauser
not rated yet Feb 14, 2018
Oh, Benni, did your Above Top Secret account get suspended? What strange stories you have to share.
mackita
5 / 5 (1) Feb 14, 2018
Andromeda, was formed in a colossal crash between two smaller star systems no more than three billion years ago when Earth already existed
You can see at the above infrared photo, that Andromeda disk isn't fully homogeneous and flat like the Milky Way and another galaxies - it consists of multiple rings, which aren't perfectly collinear = i.e. it still "wobbles" from the time of collision.

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