Astrophysicists Listen to Loops Shivering on the Sun

You would imagine that a 500,000 kilometre long arch of super heated plasma releasing energy equal to the simultaneous explosion of 40 billion Hiroshima atomic bombs would be as easy to “hear” as it is to “see” – but it’s not. Astrophysicists have long thought about using the acoustic waves in these flares to understand more about these gigantic events, that can be dozens of times bigger than the Earth, but have been unable to use effectively up till now. Now researchers at the University of Warwick, and Lockheed Martin’s Solar and Astrophysics lab in Palo Alto, have found a way to “listen” to how these gigantic loops “shiver” – vastly increasing our ability to understand these huge events which are big enough to affect telecommunications, GPS satellites, and even energy supply lines.

Researchers at the University of Warwick and Lockheed Martin’s Solar and Astrophysics lab in Palo Alto have found a way to spot and use an intense “shivering” of flaring loops to get a clear look at their structure. The closest analogy is the attack of shivering we suffer having a severe cold or fever. But, a flaring coronal loop suffers from the temperature up to tens of million degrees Kelvin. The University of Warwick led team have found that they can use radio and X-ray observation to spot a shiver or oscillation in the really high temperature loops (around 20 million degrees Kelvin) that behaves like an acoustic (sound) wave.

Previously researchers had noted these acoustic oscillations but had paid little attention to them as they were convinced that they dissipated quickly and were therefore of little use. However University of Warwick researcher Dr Valery Nakariakov and his team have been able to prove that these oscillations do not dissipate quickly and can in fact be sustained over a period from 10 seconds to 5 minutes in length. This means the data from these oscillations is much more useful than previously thought and can now actually be used, in combination with other observations, to calculate both the temperature and the length of each of these individual great loops of plasma. These results are just one of the successes of a new method for remote diagnostic of astrophysical plasma by University Warwick physicists known as MHD seismology.