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Galactic collisions

发布时间:2019-03-08 07:02:02来源:未知点击:

THE Universe used to be far more violent than it is today. At last week’s meeting of the American Astronomical Society in Austin, Texas, researchers from Iowa State University in Ames showed that early galaxies smashed into each other more often than astronomers realised. If a small galaxy plunges through the centre of a spiral galaxy, the shock transforms the spiral into a ring—similar to the ripple that forms when a rock falls into a pond. These ring galaxies were thought to be relatively rare. But Russ Lavery found 10 times as many ring galaxies as expected when he used the Hubble Space Telescope to look at objects up to eight billion light years away. “Galaxies were probably colliding with each other more frequently than in the present day,