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Source of dangerous high-energy particles located on the Sun.

Source of dangerous high-energy particles located on the Sun.

Coronal mass ejection or CME erupting into space on August 31

, 2012. Pictured here is a mixed version of the wavelengths 171 and 304 angstroms taken from the Solar Dynamics Observatory. Credit: NASA / GSFC / SDO

The source of potentially dangerous solar particles released by the Sun at high speed during storms in its outer atmosphere was first discovered by researchers from UCL and George Mason University, Virginia, USA

These particles are highly charged and, if they reach the Earth’s atmosphere, could potentially disrupt satellites and electronic infrastructure, as well as pose a radiation risk to astronauts and people on planes. In 1859, during the so-called Carrington event, a major solar storm led to the failure of telegraph systems in Europe and America. With such a modern world relying on e-infrastructure, the potential for harm is much greater.

To minimize 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 a new study published in Scientific progress, the researchers analyzed the composition of solar energy particles directed at the Earth and found that they have the same “fingerprint” as the plasma, located low in the corona of the Sun, near the middle region of the Sun’s atmosphere, the chromosphere.

Co-author Dr. Stephanie Yardley (UCL Mullard Space Science Laboratory, MSSL) said: “In our study, we are observing for the first time exactly where the Sun’s solar energy particles come from. Our evidence supports theories that these highly charged particles originate from plasma, which is was trapped low in the Sun’s atmosphere by strong magnetic fields, and these energy particles, once released, are then accelerated by eruptions that travel at speeds of several thousand kilometers per second.

“Energy particles can arrive on Earth very quickly, within minutes to hours, and these events last for days. At this time, we can only provide predictions for these events, as they occur because it is extremely difficult to predict these events before they occur. By better understanding the processes of the Sun, we can improve our forecasts so that when a major solar storm strikes, we have time to act to reduce the risks. “

Lead author Dr. David Brooks (George Mason University and Honorary Associate Professor at UCL MSSL) said: “Our observations provide a harrowing look at where the material that produces solar energy comes from in several events of the last solar cycle. We are now starting a new solar cycle, and once it starts, we will use the same techniques to see if our results are usually correct 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 evolve rapidly in the coming years, thanks to data from two spacecraft – ESA’s Solar Orbiter and NASA Parker’s Solar Probe – which are direct closer to the Sun than any spacecraft has ever been. “

In the study, researchers used measurements from NASA’s Wind satellite between the Sun and Earth to analyze a series of solar energy fluxes from particles, each lasting at least one day, in January 2014. They compared this with spectroscopy data. from JAXA led the Hinode spacecraft. (The EUV Imaging Spectrometer on board 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 – as the plasma enclosed near the top of the Sun’s chromosphere. These places were at the “feet” of hot coronal loops – that is, at the bottom of chains with a magnetic field and plasma extending into the outer atmosphere of the Sun and vice versa.

Using a new technique, the team measured the strength of the coronal magnetic field at these points and found that it was very high, in the range of 245 to 550 Gauss, confirming the theory that the plasma is trapped in the Sun’s atmosphere by strong magnetic fields before space.

Solar energy particles are released by the Sun and are accelerated by solar flares (large explosions) or coronal mass ejections – ejections of huge clouds of plasma and magnetic fields. About 100 solar energy particles occur every 11-year solar cycle, although that number varies from cycle to cycle.

Recent findings support the idea that some solar energy particles come from a different source from the slow solar wind (the origin of which is still under discussion), as they are confined to specific conditions in hot coronal loops in the core of the source region. A faster solar wind is radiated continuously by the Sun; its encounter with the Earth’s atmosphere can generate the Northern Lights.

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

A strong radiation storm signal was issued at the time during the NOAA / NWS Space Weather Forecasting Center, but it is not known that the solar energy event caused disturbances in the Earth’s atmosphere, although the computer systems of the Hinode spacecraft itself recorded several hits of particles.

Measurement of the strength of the magnetic field in the area 11944 in a separate study soon after this period of time and was one of the highest ever recorded on the Sun – 8.2kG.

Coronary holes during the solar maximum

More info:
“The source of the main events of solar energy particles from the super active region 11944” Scientific progress (2021). advances.sciencemag.org/lookup … .1126 / sciadv.abf0068

Provided by University College London

Quote: Source of dangerous high-energy particles located on the Sun (2021, March 3), extracted on March 3, 2021 from https://phys.org/news/2021-03-source-hazardous-high-energy-particles -sun.html

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