Space weather is dangerous. Solar winds, solar flares and ambient space radiation pose serious risks to astronauts and, somewhat more commonly, to the space equipment that astronauts and (increasingly) terrestrial humans rely on. Much of this weather remains poorly understood – a problem that a team of researchers led by University College London is helping to resolve. Using supercomputing resources from the DiRAC High Performance Computing facility, the researchers examined why gaseous outbursts from the Sun cool more slowly than expected.
These hot solar gases, carried on the solar winds, are disruptive to satellites and, if strong enough, disruptive to systems like transportation and mobile phones. Forecasting the strength of the bursts could help us insulate our infrastructure against those events. But there’s a problem: as it stands, the solar winds that hit Earth are an order of magnitude hotter than researchers would expect.
To solve that mystery, the researchers turned to DiRAC’s Data Intensive at Leicester (DIaL) service, with funding from the Science and Technology Facilities Council. DIaL, which is targeted at “data intensive science problems in theoretical astrophysics and particle physics,” has 400 dual-socket nodes equipped with Intel Skylake CPUs and 192 GB of memory per node, alongside three large-memory nodes (1.5 TB memory per node) and an even larger-memory node with 6 TB of memory.
Using DIaL, the research team simulated how those solar winds stretch from the Sun to Earth. They found that the winds were staying hot due to small magnetic reconnections, whereby opposing magnetic field lines break, then reconnect, releasing energy in the process. These reconnections arose in the turbulence of the solar winds, maintaining a large portion of their heat along the way.
Lead author of UCL said: “Magnetic reconnection occurs almost spontaneously and all the time in the turbulent solar wind,” added Jeffersson Agudelo, a PhD student in the space plasma physics group at University College London and lead author of the research. “This type of reconnection typically occurs across an area of several hundred kilometres – which is really tiny compared to the vast dimensions of space.”
“Using the power of supercomputers, we have been able to approach this problem like never before,” he continued. “The magnetic reconnection events we observe in the simulation are so complicated and asymmetric, we are continuing our analysis of these events.”
Now, the team is comparing their data to data from the European Space Agency’s Solar Orbiter, which itself is observing and studying the oddities of solar winds and other solar phenomena. The results of the comparison will, hopefully, validate the simulated results.