CANBERRA—A team of Australian researchers has discovered that the Milky Way galaxy has been eating its neighbours.
Dr Stefan Keller and researchers from the Australian National University have found that a large band of stars at the edge of the galaxy were ripped from the nearby smaller Sagittarius dwarf galaxy.
The finding is documented in the latest issue of the Astrophysical Journal.
"The Sagittarius dwarf is a cosmic lightweight weighing 10,000 times less than our Milky Way," Dr Keller told AAP.
"It has ventured too close to our galaxy and is now getting stretched out and slowly torn apart, a bit like spaghetti being wound round a fork."
Dr Keller and his team made the discovery by searching over 15,000 images of the sky looking for a very rare type of star known as an RR Lyrae.
Because RR Lyraes all have the same "intrinsic brightness", Dr Keller and his team were able to determine the distance of the debris to over 150,000 light years away, right at the edge of the galaxy.
"The great thing about RR Lyraes is that they all have the same intrinsic brightness so each time we found one we were able to derive an accurate distance to the star," Dr Keller said.
The discovery of our galaxies most un-neighbourly behaviour could help in the study of elusive dark matter.
The Milky Way is approximately ten times heavier than it should be if you count up all the stars we can see and scientists have suggested that this extra weight comes from invisible dark matter.
"We can't see the dark matter itself but our study can see the effects of its gravitational pull on the Sagittarius dwarf," Dr Keller said.
Dr Keller said it was not the first time the Milky Way had developed a taste for its own and in the early days of the galaxy mergers like that were much more common.
"The devouring of the Sagittarius dwarf is like the after-dinner mint on top of what has been an extensive banquet for the Milky Way," Dr Keller said.
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