Milky Way to face a one-two punch of galaxy collisions

Image of a web of blue threads, representing dark matter, and orange galaxies that form along them.

Enlarge / A simulation of
galaxies forming in the early Universe. By chance, some of them
experience a history that’s similar to the Milky Way’s. (credit:

If our knowledge of galaxy structures was limited to the Milky
Way, we’d get a lot of things wrong. The Milky Way, it turns out,
is unusual. It’s got a smaller central black hole than other
galaxies its size; its halo is also smaller and contains less of
the heavier elements. Fortunately, we’ve now looked at enough other
galaxies to know that ours is a bit of an oddball. What’s been less
clear is why.

Luckily, a recent study provides a likely answer: compared to
most galaxies, the Milky Way’s had a very quiet 10 billion years or
so. But the new study suggests we’re only a few billion years from
that quiet period coming to an end. A collision with a nearby dwarf
galaxy should turn the Milky Way into something more typical
looking—just in time to have Andromeda smack into it.


The researchers behind the new work, from the UK’s Durham
University, weren’t looking to solve the mysteries of why the Milky
Way looks so unusual. Instead, they were intrigued by recent
estimates that suggest one of its satellite galaxies might be
significantly more massive than thought. A variety of analyses have
suggested that the Large
Magellanic Cloud
has more dark matter than the number of stars
it contains would suggest. (Its stellar mass is estimated to only
be five percent of the Milky Way’s.)

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Source: FS – All – Science – News
Milky Way to face a one-two punch of galaxy collisions