![]() "The lessons that we are learning for the Sun we'll take to other stars," says Dupree. Solving this persistent mystery will have applications far beyond the Sun, says solar researcher Dr Andrea DuPree of the Harvard-Smithsonian Center for Astrophysics. They also created simulations to confirm that the physics made sense. The sound waves had been considered incapable of reaching the surface to add energy, and therefore heat, to the corona.īut by combining observations made with the SOHO and TRACE spacecrafts, along with solar observing instruments at Antarctica and the Canary Islands, the team was able to make a pretty good case for it. "They allow us to tap into the energy reserves of the Sun's interior." There's a lot of leakage of sound waves being caused by the constant jostling of the Sun's magnetic field, McIntosh says. It was this leaking that was seen using the Magneto-Optical filters at Two Heights (MOTH) instrument in Antarctica. The seismic energy escapes into the corona when the Sun's magnetic field tilts enough for them to leak out. Instead, the waves carry a remarkable 200 watts per square metre, he says, and are more like seismic waves. "They're not your garden variety sound waves," McIntosh says. The two biggest surprises are that sound waves reach beyond the interior of the Sun, and that they have the power to warm things up. He and Dr Scott McIntosh of the Southwest Research Institute announced their discovery this week during the meeting of the American Astronomical Society in Honolulu. ![]() "It's a combination of the Sun's magnetic field and sound waves," says De Pontieu. The secret source of the corona's extreme heat has long been suspected of hiding either in the violent magnetic contortions of the plasma all over the Sun, or in the powerful subsonic sound waves that pulse through our closest star.īut it turns out it's not an either-or situation, say the researchers. "This has been a mystery since it was discovered in the last century," says Dr Bart De Pontieu, a research scientist at Lockheed Martin Solar & Astrophysics Lab in California. ![]() To scientists this has never made much sense, since it's in the depths of the Sun where all the white hot nuclear reactions take place. Scientists have known for decades that it is many times hotter than the chromosphere beneath it. The mystery is the oft-cited million-degree corona of the Sun - the outer layer of the Sun that can be seen around the Moon during total solar eclipses. Roman towns aligned with Sun, Science Online, Ī combination of technology and careful observation may have solved a 100-year-old mystery about how the Sun works.Deadly parasite threatens California sea otters. The Sun in 3D, just put on specs, Science Online, Generation of solar spicules and subsequent atmospheric heating.It's the Sun, but not as we know it, Science Online,.Parker Solar Probe has three detailed science objectives: Trace the flow of energy that. & Schwenn, R.) 147–150 (Pergamon, Oxford, 1992). Parker Solar Probe provides a statistical survey of the outer corona. Interplanetary Dynamical Process (Interscience, New York, 1963). in Wave Propagation in Random Media (Scintillation) (eds Tatarskii. I estimate the size of the smallest filamentary structure within coronal holes to be about 1km at the Sun, approximately three orders of magnitude smaller than the smallest filamentary structures observed in images of different wavelengths 2,10–12. Here I argue that these features are the manifestation of a transition from small ray-like or filamentary structures in the corona that rotate with the Sun to turbulent density irregularities convecting with the solar wind. Two specific features that have proved difficult to explain are an abrupt increase in anisotropy of the irregularities close to the Sun 5–7, and a break in the power-law spectrum describing the density fluctuations 8,9. Radio measurements have established many of the characteristics of the density fluctuations in the corona and solar wind, but the fundamental nature of these structures is not yet fully understood 3,4. The structure can be investigated directly by imaging at optical and shorter wavelengths, or indirectly through the effects of changing electron density on the propagation of radio waves (scattering and scintillation). KNOWLEDGE of the structure of the Sun's corona is important for our understanding of how this high-temperature plasma is heated, and of the processes involved in the acceleration of the solar wind 1,2.
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