A Supergiant Star Goes Missing, and a Supernova Mystery Is Solved
By John Matson
Every so often in the vast cosmos something exciting happens in one of the relatively few places that humans happen to watch closely. Like a rare bird touching down for a bath in the Trevi Fountain, such serendipitously placed exotica produces a wealth of witnesses and plenty of photographic documentation.
So it was with a recent supernova in the spiral galaxy M51—better known to casual stargazers as the Whirlpool galaxy, a photogenic swirl some 25 million light-years away. Shortly after the light from an exploding star there reached Earth at the end of May 2011, amateur reports of the cataclysm began pouring in to the Central Bureau for Astronomical Telegrams, a clearinghouse for new telescope data. Soon the explosion was assigned the official designation supernova 2011dh.
The Whirlpool galaxy has plenty of admirers, so a brand-new bright spot on the edge of the spiral was sure to catch the attention of many observers. “It’s really one of the nearest galaxies, and it’s a galaxy that’s beautiful and very famous,” says astronomer Schuyler Van Dyk of the California Institute of Technology.
Even better, the well-documented supernova in the Whirlpool galaxy turned out to be a rare variety known as a type IIb supernova. Those explosions result from the collapse of a massive star that has been stripped of most of its outlying hydrogen shell, possibly by the pull of a binary stellar companion. Of all the stars that end their lives in a catastrophic collapse—just one of two ways to produce a supernova—only about one in 10 produces a type IIb.
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http://www.scientificamerican.com/article.cfm?id=sn2011dh-vanishing-star
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This happened back when these guys were the world's top land predators:
5.88trillion miles. Truly amazing, our universe. I watched the stars for years. Great place to go when I'm tired of the grief on this little, yet important ball of dirt. Why important? So far we are the only sentient creature found in all those trillions of miles and billions of light years we can view because of the Hubble, Chandra, Swift telescopes outside our atmosphere. Good watching. It's fun. Excellent post, thank you.
