06:26 GMT19 January 2021
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    Scientists have for the first time associated solar flares occurring around the edge of the sun with high-energy gamma-rays on the star’s visible side.

    Using NASA's Fermi Gamma-ray Space Telescope, in combination with its Solar Terrestrial Relations Observatory (STEREO), an international team of scientists has been able to link gamma-ray emissions with behind-the-limb eruptions.

    The STEREO spacecraft was monitoring the far side of the Sun during three rare explosive incidents that occurred in 2013 and 2014. Only 20 minutes after a massive solar flare was spotted in October 2013, Fermi's Large Area Telescope (LAT) observed a spike in gamma-ray emissions on the star's near side, lasting about half an hour.  The other two powerful flares detected by STEREO were also followed with similar long-lasting gamma-ray emissions.

    In each case, billion-ton clouds of plasma from the Sun were thrown out into space. Scientists believe that some of the charged particles remained attached to the magnetic-field lines running across the solar surface, traveling to the Sun's visible side before slamming back into the surface and releasing powerful gamma-rays.

    Co-author of the study Nicola Omodei, a researcher at Stanford University in California, presented the findings on January 30 at an American Physical Society meeting in Washington DC.

    "Fermi is seeing gamma-rays from the side of the sun we're facing, but the emission is produced by streams of particles blasted out of solar flares on the far side of the Sun," the scientist said in a statement.

    "These particles must travel some 300,000 miles [500,000 km] within about 5 minutes of the eruption to produce this light," she suggested.

    The Fermi telescope has detected emissions from over 40 solar flares since its launch in 2008. STEREO observations have increased those capabilities, according to study co-author Melissa Pesce-Rollins, a researcher at the National Institute of Nuclear Physics in Italy.

    "Observations by Fermi's LAT continue to have a significant impact on the solar physics community in their own right, but the addition of STEREO observations provides extremely valuable information of how they mesh with the big picture of solar activity," the researcher said.    


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    eruption, gamma ray, Sun, space
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