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Final fling

作者:聂蔚醣    发布时间:2019-03-07 01:01:01    

THE Hubble Space Telescope has solved the puzzle of how galaxies full of dim old stars can shine brightly with ultraviolet light. Star formation ceased long ago in elliptical galaxies, so they lack hot young stars that emit strongly in the ultraviolet spectrum. But despite this, satellite instruments have detected bright ultraviolet emissions from these galaxies. After scanning a galaxy three million light years away, Hubble has now pinpointed the source of these emissions as stars that have switched to burning helium instead of hydrogen in their cores. “This has proved once and for all that these are the stars responsible,” says Thomas Brown of the NASA Goddard Space Flight Center in Greenbelt,

 

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