First supernova seen repeatedly in an Einstein cross.

This is pretty neat. They might even be able to determine some dark matter information with it.



It is from

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a spiral galaxy roughly nine billion light-years from here. The light from this spiral has been bent and magnified both by the gravity of the intervening cluster, which is five billion light-years distant, and by one very massive galaxy in the cluster. As a result, ghost images of the spiral appear throughout the cluster and in particular in an Einstein Cross around that one galaxy.

Also related to this quasar. Someone could correct me if I'm wrong there.



http://ift.tt/1FfUtZh

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they have been watching the same star blow itself to smithereens in a supernova explosion over and over again, thanks to a trick of Einsteinian optics. The star exploded more than nine billion years ago on the other side of the universe, too far for even the Hubble to see without special help from the cosmos. In this case, however, light rays from the star have been bent and magnified by the gravity of an intervening cluster of galaxies so that multiple images of it appear. Four of them are arranged in a tight formation known as an Einstein Cross surrounding one of the galaxies in the cluster. Since each light ray follows a different path from the star to here, each image in the cross represents a slightly different moment in the supernova explosion. This is the first time astronomers have been able to see the same explosion over and over again, and its unique properties may help them better understand not only the nature of these spectacular phenomena but also cosmological mysteries like dark matter and how fast the universe is expanding.

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And the explosion is expected to appear again in another part of the sky in the next 10 years. Timing the delays between its appearances, he explained, will allow astronomers to refine measurements of how fast the universe is expanding and to map the mysterious dark matter that supplies the bulk of the mass and gravitational oomph of the universe.

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The exact timing of Supernova Refsdal’s reappearance depends on how the dark matter in the galaxy cluster is distributed, which will tell astronomers much about a part of the universe they cannot see any other way. The longer the path length or the stronger the gravitational field the light ray goes through, the longer the delay.

via International Skeptics Forum http://ift.tt/1w8q2UV