The solar corona, invisible to the human eye, except for the moment when it appears for a short time as a plasma halo during a solar eclipse, remains a mystery even to scientists who study it. Located 2,000 km from the surface of the star, the corona is more than 100 times hotter than the lower layers, which are much closer to the thermonuclear reactor in the Sun's core.
A team of physicists led by Gregory Fleischman of the New Jersey Institute of Technology (USA) recently uncovered a phenomenon that will help to find out which physical mechanisms heat the upper atmosphere to 500 thousand degrees Celsius and above.
NASA's Solar Dynamics Observatory found areas in the corona where levels of heavy metal ions were elevated - magnetic flux tubes.
Their bright images, taken in the extreme short-wave ultraviolet range, show that the concentration of charged metals is 5 times or more higher than the concentration of one-electron hydrogen ions in the photosphere.
Iron ions are located in so-called "ion traps", which are located at the base of coronal loops, arches of electrified plasma driven by lines of magnetic fields. The existence of these "traps" means that there are high-energy coronal loops, devoid of iron ions, which, therefore, were not detected in the extreme ultraviolet light range. Only metal ions produce emissions that make them visible.
Observations suggest that the corona may contain even more thermal energy than studies in the extreme ultraviolet range suggest.
There are various theories that explain the scorching heat of the crown. For example, some scientists speculate that magnetic field lines connect in the upper atmosphere and eject explosives. energy. The energy waves enter the corona, where they are converted into heat energy.
Scientists note that before figuring out how energy is produced in the corona, it is necessary to map it and quantify the thermal composition.
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Metal ions enter the corona when solar flares of various sizes destroy traps and they evaporate in a flow loop in the upper atmosphere.
The bursts of energy in solar flares and accompanying forms of explosions occur when magnetic field lines with their powerful underlying electrical currents bend. The strongest of explosions cause space weather - radiation, energy particles and magnetic fields that are ejected from the surface of the Sun.
Scientists can now measure the vectors of the photospheric magnetic field, from which the vertical component of electric currents is calculated and at the same time the emissions of extreme ultraviolet radiation that produce heavy ions are calculated.
Scientists at the Big Bear Solar Observatory at New Jersey Institute of Technology have captured the first high-resolution images of magnetic fields and plasma streams that originated deep below the sun's surface. Thanks to the images, the researchers were able to trace the evolution of sunspots and magnetic currents from their appearance in the chromosphere to their spectacular appearance in the corona as glowing loops.
Extreme ultraviolet emissions can only be observed from space. The Solar Dynamics Observatory aboard the spacecraft launched in 2010 measures both the magnetic field and extreme ultraviolet emissions from around the Sun.
Findings about the temperature structure of the corona and whether it allows the sun to transfer more heat into the solar system are the subject of future research, scientists say.