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Source of hazardous high energy particles in the sun

Source of hazardous high energy particles in the sun

A coronal mass ejection, or CME, erupting into space on August 31

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

The source of potentially dangerous solar particles, released from the sun at high speed during storms in its outer atmosphere, has been found for the first time by researchers at UCL and George Mason University, Virginia, USA

These particles are highly charged, and if they reach the Earth’s atmosphere, they could potentially disrupt satellites and electronic infrastructure as well as pose a radiation risk to astronauts and humans in aircraft. In 1859, during a so-called Carrington event, a major solar storm caused telegraphic systems throughout Europe and America to fail. With the modern world so dependent on electronic 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 they can better predict when they may affect the Earth.

In the new study, published in Scientific progress, scientists analyzed the composition of the sun’s energetic particles towards the Earth and found that they had the same “fingerprint” as plasma, located low in the sun’s corona, close to the central region of the sun’s atmosphere, the chromosphere.

Co-author Dr. Stephanie Yardley (UCL Mullard Space Science Laboratory, MSSL) said: “In our study, we have for the first time observed exactly where solar energy particles come from on the sun. Our evidence supports theories that these highly charged particles originate from plasma that have been kept down in the atmosphere of the sun by strong magnetic fields, these energetic particles, once released, are then accelerated by eruptions moving at a speed of a few thousand kilometers per second.

“Energy particles can get to Earth very quickly within minutes to a few hours, where these events last for several days. At the moment, we can only provide forecasts for these events as they take place, as it is very challenging to predict these. events. before they occur. By better understanding the sun’s processes, we can improve forecasts, so that when a major solar storm hits, we have time to act to reduce risks. “

Main author Dr. David Brooks (George Mason University and Honorary Associate Professor at UCL MSSL) said: “Our observations provide a tempting insight into where the material that produces solar energy particles comes from in a few events from the last solar cycle. We are now starting a new solar cycle , and once it gets started, we will use the same techniques to see if our results are generally true, or if these events are somehow unusual.

“We’m lucky because our understanding of the mechanisms behind solar storms and the sun’s energetic particles is likely to advance more 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. the sun than any spacecraft has been before. “

In the study, scientists used measurements from NASA’s wind satellite located between the sun and the earth to analyze a series of solar energy particle currents, each lasting at least one day, in January 2014. They compared this with spectroscopy data from JAXA-powered Hinode spacecraft. (The EUV Imaging Spectrometer aboard the spacecraft was built by UCL MSSL and Dr. Brooks is a member of the Mission Operations 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 plasma was limited close to the top of the sun’s chromosphere. These locations were at the “footing points” of warm coronal loops – that is, at the bottom of loops with magnetic field and plasma extending into the Sun’s outer atmosphere and back again.

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

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

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

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

A strong radiation storm alarm was issued at the time by the NOAA / NWS Space Weather Prediction Center, but the energetic solar particle event is not known to have caused any disturbance in the Earth’s atmosphere, although computer systems on the Hinode spacecraft itself recorded several particle hits. .

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

Coronal holes below the maximum of the sun

More information:
“The source of the largest solar particle events from superactive region 11944” Scientific progress (2021). advances.sciencemag.org/lookup …. .1126 / sciadv.abf0068

Provided by University College London

Citation: Source of Hazardous High Energy Particles in the Sun (2021, March 3) Retrieved March 3, 2021 from https://phys.org/news/2021-03-source-hazardous-high-energy-particles-sun.html

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