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The Sun: a new emission mechanism produced by galactic cosmic rays
The Sun illuminates by emitting continuously in the entire energy band of the electromagnetic spectrum. However, based on current theories, not all the emission that we see from the Sun is as expected. Prof. Elena Orlando of the University of Trieste has just discovered the existence of a new emission mechanism from the Sun that extends from radio frequencies to gamma energies. This new emission mechanism is produced by galactic cosmic rays, i.e. highly energetic charged particles arriving from outside our solar system. Prof. Orlando discovered that, as they approach the Sun, these particles spiral into the Sun's magnetic field and emit energy through the synchrotron process. Observations of this energy in radio, X-rays, and gamma rays reveal important information about the Sun and its surrounding environment. The work was published in the Astrophysical Journal [1] in February this year, and it has been followed by a press release from the American Astronomical Society (https://aasnova.org/2023/02/22/new-phenomena-on-the-quiet-sun/).
This is not her first discovery about the Sun. In 2008 Prof. Orlando obtained the first image of the sun at high gamma energies [2] when as yet no continuous emission from the Sun had ever been observed. The discovery confirmed her prediction two years earlier when she theorized an additional mechanism of continuous high-energy emission that had never been hypothesized before [3], discovering a new way to study our star.
[1] “A New Component from the Quiet Sun from Radio to Gamma Rays: Synchrotron Radiation by Galactic Cosmic-Ray Electrons,” Elena Orlando et al 2023 ApJ 943 173. doi:10.3847/1538-4357/acad75
[2] Orlando & Strong 2008, “Gamma-ray emission from the solar halo and disk” A&A 480, 847
[3] Orlando & Strong 2007 “Gamma rays from halos around stars and the Sun” Ap&SS 309, 359 42.
Last update: 08-02-2023 - 09:18