Scientific American - May 21, 2008
Astronomers have observed for the first time the thunderclap of x-rays that announces a star has exploded into a supernova. Researchers monitoring spiral galaxy NGC 2770, approximately 88 million light-years away, observed a brief but intense flash of x-rays in early January, followed by a prolonged afterglow of visible and ultraviolet light—the hallmark of a supernova.
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To confirm that it was really a supernova, she and her co-workers followed up two days later with the eight-meter (26-foot) Gemini North Telescope in Mauna Kea, Hawaii. The supernova glowed visibly for about 20 days, and the pattern of light indicated that the supernova was a type called IIbc, born from a star rich in helium.
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