Stargazers spot oldest supernova yet
'I remember when it was all hydrogen around here...'
Astronomers from the University of California have spied a supernova which lit up the early universe 10.7 billion years ago - 1.5 billion years before the previous record holder and just 3 billions years after the big bang.
A team led by Jeff Cooke spotted the event - a "type II"* supernova provoked by the core collapse of a star 50-100 times more massive than the Sun - in images from the Canada-France-Hawaii Telescope Legacy Survey, which snapped the same four patches of sky over five years using a 3.6-metre telescope.
The 'scope concentrated on small areas of sky - roughly four times the size of the Moon, the Times explains - on around 130 nights of observation between between 2003 and 2007.
By combining all the photos, the atronomers were able to peer back much further into the distant past than previously possible.
Cooke explained: “If you stack all those images in one big pile then you can reach deeper and see fainter objects. It’s a bit like photography when you open the shutter for a long time. You’ll collect more light with a longer exposure.”
The researchers hope the ongoing survey will find other ancient supernovae and "shed light on how the universe became seeded with heavier elements", as New Scientist puts it.
The big bang is thought to have churned out just a few light elements - hydrogen, helium, and lithium - while supernovae took on the job of creating all the other elements which now form the universe.
As New Scientist notes, there are further projects in the pipeline which could use the same multiple imaging technique to peer back to the early universe. The 8.2-metre Subaru telescope in Hawaii should in 2012 be equipped with the splendidly-named Hyper Suprime-Cam (HSC), while NASA is planning to launch the James Webb Space Telescope in 2014.
Cooke said: "Using this method, we should be able to see objects much farther away and therefore much farther back in time, and actually see some of the first stars that ever lived."
The team's full findings are published in the current issue of Nature (subscription required). ®
*Characterised by a line of hydrogen in the spectrum. Hydrogen is not present in other types of supernovae.
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