Source of dangerous high-energy particles in the sun

The source of potentially dangerous solar particles released during the storm in its outer atmosphere at high speeds from the sun was first detected by researchers at the UCL and George Mason University, Virginia, USA

These particles are highly charged and could potentially disrupt satellites and electronic infrastructure if they reach Earth’s atmosphere, and also pose astronauts and aircraft for astronauts. In 1859, during the Carrington Event, a major solar storm caused telegraphic systems to fail in Europe and America. Because the modern world is so dependent on electronic infrastructure, the potential for damage is much greater.

To reduce the danger, scientists are trying to understand how these streams of particles are produced so that they can better predict when they may affect the earth.

In the new study, published in Scientific progress, researchers analyzed the composition of solar energy particles on their way to Earth and found that they have the same “fingerprint” as plasma that is low in the sun’s corona, near the center of the sun’s atmosphere, the chromosphere.

Co-author dr. Stephanie Yardley (UCL Mullard Space Science Laboratory, MSSL) said: “In our study, we first observed exactly where solar energy particles come from in the sun. Our evidence supports the theories that these highly charged particles are formed from plasma produced by the strong magnetic fields are kept low in the atmosphere of the sun, these energetic particles, as soon as they are released, are accelerated by eruptions that move at a speed of several thousand kilometers per second.

“Energy particles can reach the earth very quickly within a few minutes to a few hours, and these events will take days. At the moment, we can only make predictions about these events, as it is very difficult to predict these events. “Before it happens. By better understanding the sun’s processes, we can improve the forecasts so that we have time to act to reduce the risks, when a major solar storm arrives.”

Lead author Dr David Brooks (George Mason University and honorary associate professor at UCL MSSL) said: “Our observations provide a tantalizing look at where the materials that produce solar energy particles come from in some events from the last solar cycle. we now with a new solar cycle and once it is underway, we will use the same techniques to see if our results are generally true, or if these events are somehow unusual.

‘We are fortunate that our understanding of the mechanisms behind solar storms and solar energy particles is likely to progress rapidly in the coming years thanks to data obtained from two spacecraft – ESA’s Solar Orbiter and NASA’s Parker Solar Probe – which are moving closer to the sun than any spacecraft before. ‘

In the study, researchers used measurements from NASA’s Wind satellite, located between the sun and Earth, to analyze a series of solar energy particle currents, each lasting at least a day, in January 2014. They compared it with spectroscopy data from the JAXA Hinode spacecraft. (The EUV Imaging Spectrometer aboard the spacecraft was built by UCL MSSL and Dr. Brooks is a member of the mission’s operational team in Japan.)

They found that the solar energy particles measured by the Wind satellite had the same chemical signature – an abundance of silicon compared to sulfur – since plasma near the top of the sun’s chromosphere is limited. These places were at the “footprints” of warm coronal loops – that is, at the bottom of loops with magnetic field and plasma extending to the sun’s outer atmosphere and back again.

Using a new technique, the team measured the coronal magnetic field strength at these foothills and found that it was very high in the region of 245 to 550 Gauss, confirming the theory that the plasma passes through strong magnetic fields in the sun’s atmosphere. held. before its release into space.

Solar energy particles are released from the sun and are accelerated by solar flares (large explosions) or coronal mass ejections – ejections of large clouds of plasma and magnetic field. Approximately 100 solar energy particle events occur every 11-year solar cycle, although this number varies from cycle to cycle.

The latest findings support the idea that some solar energy particles come from a source other than the slow solar wind (the origin of which is still debated), as it is limited in specific conditions in hot coronal loops in the core of the source region. A faster solar wind is continuously radiated by the sun; the encounter with the earth’s atmosphere can evoke the Northern Lights.

The high-energy particles released in January 2014 come from a volatile region of the sun with frequent solar flares and CMEs, and an extremely strong magnetic field. The region, known as 11944, was at that time one of the largest active regions on the Sun and was visible to observers on earth as a sunspot – a dark spot on the solar surface.

The NOAA / NWS Space Weather Prediction Center at the time issued a strong warning for the radiation of the storm, but it is not known that the event of the solar energy particle caused any disruption in the Earth’s atmosphere, although computer systems on the Hinode spacecraft itself recorded several particle hits. .

A measurement was taken of the strength of the magnetic field in the region of 11944 in a separate study shortly after this period, and was one of the highest ever recorded in the sun – 8.2kG.