Posted on 2 June 2014
Supernova explosions, triggered when the fuel in a star reignites or its core collapses, launch a detonation shock wave that sweeps through a few light years of space from the exploding star in just a few hundred years. But not all such explosions are alike and some, such as Cassiopeia A, show puzzling irregular shapes made of knots and twists.
To investigate what may cause these peculiar shapes an international team of scientists, including researchers from the University of York, has devised a method of studying supernovae explosions in the laboratory instead of observing them in space. A report by the team is published in Nature Physics.
Dr Nigel Woolsey, from York’s Department of Physics, said: ““The results of our experiments are significant because they help to piece together a story for the creation and development of magnetic fields in our Universe. We have provided the first experimental proof that turbulence amplifies magnetic fields in the tenuous interstellar plasma.”
Professor Gianluca Gregori, of Oxford University’s Department of Physics, who led the study, said: ‘It may sound surprising that a table-top laboratory experiment that fits inside an average room can be used to study astrophysical objects that are light years across. In reality, the laws of physics are the same everywhere, and physical processes can be scaled from one to the other in the same way that waves in a bucket are comparable to waves in the ocean. So our experiments can complement observations of events such as the Cassiopeia A supernova explosion.”
The Cassiopeia A supernova explosion was spotted about 300 years ago in the Cassiopeia constellation 11,000 light years away. Optical images of the explosion reveal irregular ‘knotty’ features and associated with these are intense radio and X-ray emissions. While no one is sure what creates these phenomena, one possibility is that the blast passes through a region of space that is filled with dense clumps or clouds of gas.
To recreate a supernova explosion in the laboratory the team used the Vulcan laser facility at the UK’s Rutherford Appleton Laboratory.
University of York Physics PhD student Rob Crowston spent five weeks working on the experiment as part of a multi-national team including researchers from Japan, USA and France.
Rob Crowston said: “While you cannot completely replicate an exploding star, you can capture some of the processes around it, allowing theories around magnetic fields to be tested.
“Being part of the experimental team at the Rutherford Appleton Laboratory as a first year PhD student was a hugely valuable experience. Not only did I see how large-scale experiments are conducted, but it was very useful meeting people with whom I subsequently formed very profitable partnerships. For example, it led to me working in Japan at the Institute of Laser Engineering at Osaka University.”
Dr Woolsey said: “It was wonderful to introduce Rob to such an international team, which he has been able to use as a launch pad for his research career.”
As well as scientists from York, the Oxford-led team also included researchers from the University of Chicago, ETH Zurich, the Queen’s University Belfast, the Science and Technology Facilities Council, the University of Michigan, Ecole Polytechnique, Osaka University, the University of Edinburgh, the University of Strathclyde, and the Lawrence Livermore National Laboratory.