London, Sept 16 (ANI): Researchers, led by Chris W. Purcell of the University of Pittsburgh, have suggested that the signature spiral arms of the Milky Way galaxy were formed by a collision between the Milky Way and a dwarf galaxy not just once but twice in the last 2 billion years.
Now, an Iowa State University astronomer has said that the new hypothesis contradicts the notion that the Milky Way has somehow colonized a 'quiet galactic neighbourhood'.
Curtis Struck, who has studied galaxies for 30 years and focuses his research on galactic collisions, said in a News and Views commentary that the Purcell paper gives astronomers new ideas to study.
He said that the evolution of our Milky Way galaxy included collisions and wasn't as peaceful as astronomers had thought.
And, even though these dwarf galaxies are dim and difficult to detect, the effects of their collisions with bigger galaxies may be widespread across the universe.
Struck reported there are several clues to those widespread effects.
In recent years several dozen of the dwarf galaxies have been discovered around the Milky Way and Andromeda galaxies.
The effects of galaxy collisions with these dwarfs could be long lived. And models of galaxy formation indicate that these dwarf galaxies could be common and important parts of galaxy growth, said Struck.
Struck also says that the estimated range of the size of that the Sagittarius dwarf elliptical galaxy in its original form is likely to be the subject of study and contention.
He alos notes the estimates at the smaller end of the range indicate the dwarf galaxy would have smaller, but still significant, impacts on the Milky Way.
That means a galactic mouse could have once been a bear that has "been messing things up for some time," Struck wrote, warning "beware of the wildlife, even in apparently quiet galaxies."
The commentary appears in the journal Nature. (ANI)
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