25 august 2011

Nearest supernova of its type in 40 years, say scientists

Spot the difference: a new supernova appears in the right-hand image.
Spot the difference: a new supernova appears in the right-hand image.Image credit: Peter Nugent and the PTF collaboration

Astronomers last night discovered a bright supernova, otherwise known as an exploding star, and say it is the nearest of its type observed for 40 years.

The supernova was spotted in the Pinwheel Galaxy, M101, a spiral galaxy a mere 21 million light years away, lying in the famous constellation of the Great Bear (Ursa Major).

Scientists from the University of Oxford made the discovery with their colleagues from the Palomar Transient Factory (PTF) collaboration, using a robotic telescope in California in the United States.

Oxford team leader, Dr Mark Sullivan, said: 'The most exciting thing is that this is what's known as a type 1a supernova - the kind we use to measure the expansion of the Universe. Seeing one explode so close by allows us to study these events in unprecedented detail.'

The supernova, dubbed PTF11kly, is still getting brighter, and the team's best guess is that it might even be visible with good binoculars in ten days' time, appearing brighter than any other supernova of its type in the last 40 years.

Dr Sullivan said; 'The best time to see this exploding star will be just after evening twilight in the Northern hemisphere in a week or so's time. You'll need dark skies and a good pair of binoculars, although a small telescope would be even better.'

Following the discovery, which was made at 8pm UK time last night, astronomers around the world were scrambled to get follow up images and data. Among the first to respond, within 90 minutes, was the robotic 2m Liverpool Telescope, located in the Canary Islands.

The team will be watching carefully over the next few weeks, and hope to use NASA's Hubble Space Telescope to study the supernova's chemistry and physics.The scientists in PTF have discovered more than 1,000 supernovae since it started operating in 2008, but they believe this could be their most significant discovery yet. The last time a supernova of this sort occurred so close was in 1972.

'Before that, you'd have to go back to 1937, 1898, and 1572 to find more nearby Type 1a supernovae,' said Professor Peter Nugent, from the Lawrence Berkeley National Laboratory in the USA. 'Observing PTF 11kly unfold should be a wild ride. It is an instant cosmic classic.'

The Palomar Transient Factory is a wide-field survey operated at the Palomar Observatory by the California Institute of Technology on behalf of a worldwide consortium of partner institutions. Collaborating institutions are Caltech, Columbia University, Las Cumbres Observatory Global Telescope, Lawrence Berkeley National Laboratory, UC Berkeley, University of Oxford, and the Weizmann Institute of Science (Israel).