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Amateur method nets two farthest supernovae.

Amateur astronomers pioneered the technique of stacking astro-images to reduce noise, cut through poor atmospheric seeing, and see deeper. Professionals have picked up on these methods and recently used them to discover the two farthest-ever supernovae, using multiple images from the Canada-France-Hawaii Telescope atop Mauna Kea.

Spectra show that the two stars exploded 10.8 and 10.3 billion years ago (at redshifts 2.357 and 2.013), when the universe was just 21% and 24% of its present age. Both were Type IIn supernovae, which result from very massive stars (50 to 100 Suns) that throw off much of their mass into space before they explode. The expanding shock wave slams into the previously ejected matter and creates an unusually bright, ultraviolet-rich blaze.

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Above is a deep frame from the CFHT Legacy Survey of the sort in which the supernovae were detected.

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Title Annotation:News Notes
Publication:Sky & Telescope
Article Type:Brief article
Geographic Code:1USA
Date:Oct 1, 2009
Words:145
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