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miercuri, 4 septembrie 2013

Milky Way Gas Cloud Causes Multiple Images of Distant Quasar

For the first time, astronomers have seen the image of a distant quasar split into multiple images by the effects of a cloud of ionized gas in our own Milky Way Galaxy. Such events were predicted as early as 1970, but the first evidence for one now has come from the National Science Foundation's Very Long Baseline Array (VLBA) radio telescope system.

The scientists observed the quasar 2023+335, nearly 3 billion light-years from Earth, as part of a long-term study of ongoing changes in some 300 quasars. When they examined a series of images of 2023+335, they noted dramatic differences. The differences, they said, are caused by the radio waves from the quasar being bent as they pass through the Milky Way gas cloud, which moved through our line of sight to the quasar.

The Milky Way Supernova You've Never Heard Of

Every year astronomers see hundreds of supernovae erupt in other galaxies, but from such great distances these stellar explosions look only like bright dots. Researchers therefore prize the few supernovae that past observers witnessed in the Milky Way, where telescopes can scrutinize the wreckage. Since the year A.D. 1000, skywatchers have seen five of our galaxy's stars die in brilliant explosions. Now a new distance determination to the most mysterious of these is yielding new insight into its nature.