Andromeda borrows stars...permanently.
In the tumultuous gravity-based wars raging in the universe, no battles show more violence than the slamming together of two entire galaxies. Andromeda, itself our largest and closest rival galaxy, has already shown evidence of colliding with another galaxy in its history - and it survived to grow even larger.
True to form, Andromeda has begun another meal on a much smaller galaxy that orbits it, called Triangulum. Taking up not even a quarter of the mass of Andromeda, the Triangulum is currently being stripped of its stars and mass by the larger galaxy, and astronomers believe it will be ripped apart completely over its next orbit.
The process works much like the game Osmos, as larger masses influence smaller ones with gravity that attracts the loosely attached outer stars and pulls them into the larger galaxy. In effect, Andromeda is 'eating' the smaller galaxy, something that we can only observe now that we've got access to clearer telescopes.
Of course in reality it has taken a long time for the light to actually reach us here, and odds are the smaller galaxy has swung out of reach of Andromeda (albeit in a much smaller form), but it's still an interesting phenomenon that could explain how the super-sized galaxies in the sky came to be.
This might be a warning sign for a theorised collision of our Milky Way with Andromeda, as many astronomers have proposed that eventually Andromeda will become large enough to pull us in - already being roughly twice the mass. In any case it is not of immediate concern, and any devouring of the Milky Way is still millions of years away.
Head to the article over at CBC news to check out some more on the two warring galaxies, and the University of Sydney's story on it. The two galaxies are pictured below; Andromeda is the larger, Triangulum is the smaller.
Issue: 107 | December, 2009