Interacting galaxies are commonplace throughout the universe, sometimes as dramatic collisions, other times as stealthy mergers that result in new galaxies.
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Chee Chee LeungApril 25, 2008
GALACTIC smash-ups from the nearby universe have been captured in a series of stunning snapshots from the Hubble Space Telescope.
Various stages of this galactic "dance" are revealed in the Hubble atlas — with some galaxies involved in dramatic collisions and others taking part in large-scale mergers.
Intricate shapes emerge as the galaxies meet, a process that Dr Andy Bunker from the Anglo-Australian Observatory explains is driven largely by gravity.
"They spiral around each other initially, and there's lots of interactions of the gas and dust, which can fuel black holes and turn on quasars."
The mergers are also thought to trigger bursts of star formation and can produce long "tidal tails" of gas and dust that stream around the galaxies.
But collisions between stars are rare because so much of a galaxy is empty space.
The galactic interactions, which occur over several hundred million years, were more common in the early universe when galaxies were closer together.
Astronomers now observe only about one in a million galaxies in the nearby universe during the act of colliding.
Our own galaxy, which contains the remnants of many smaller galaxies it gobbled up in the past, is devouring the Sagittarius dwarf galaxy. Even the Milky Way will eventually be swallowed up by its giant neighbour, Andromeda.
The two galaxies are speeding towards each other at about 500,000 kilometres an hour, and are expected to merge in about 2 billion years to form one giant elliptical galaxy dubbed the "Milkomeda". The new galaxy images were released overnight to mark the 18th anniversary of the launch of the Hubble Space Telescope. Most come from a study of luminous infrared galaxies
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