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Astronomy
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A new study identified 37 recently active volcanic structures on Venus. The study provides some of the best evidence yet that Venus is still a geologically active planet. A research paper on the work, which was conducted ...
Space Exploration
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When a solar flare filled with charged particles erupts from the sun, its magnetic fields sometime break a widely accepted rule of physics. The flux-freezing theorem dictates that the magnetic lines of force should flow away ...
Astronomy
May 22, 2013
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(Phys.org) —ESA's Herschel space observatory has provided the first images of a dust belt – produced by colliding comets or asteroids – orbiting a subgiant star known to host a planetary system. The team of scientists ...
Astronomy
Apr 9, 2013
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Scientists have used powerful X-rays from the Linac Coherent Light Source (LCLS) at the SLAC National Accelerator Laboratory, to study and measure, in atomic detail, a key process at work in extreme plasmas like those found ...
Plasma Physics
Dec 12, 2012
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By diving into the sun's corona, NASA's Parker Solar Probe has ruled out S-shaped bends in the sun's magnetic field as a cause of the corona's searing temperatures, according to University of Michigan research published in ...
Astronomy
Jul 30, 2024
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In a new study published in The Astrophysical Journal, a researcher from The University of Alabama in Huntsville (UAH), a part of the University of Alabama System, explores critical aspects of a phenomenon called kinetic ...
Astronomy
Jul 29, 2024
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Is it possible for nanoparticles to go through the digestive system and deliver medicine directly to the brain tissue? Researchers from Michigan State University say yes, and their latest findings are expected to benefit ...
Bio & Medicine
Apr 19, 2024
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A corona is a type of plasma "atmosphere" of the Sun or other celestial body, extending millions of kilometers into space, most easily seen during a total solar eclipse, but also observable in a coronagraph. The Latin root of the word corona means crown.
The high temperature of the corona gives it unusual spectral features, which led some to suggest, in the 19th century, that it contained a previously unknown element, "coronium". These spectral features have since been traced to highly ionized iron (Fe-XIV) which indicates a plasma temperature in excess of 106 kelvin. The fact that the Sun has a million degree corona was first discovered by Gotrian in 1939 and Bengt Edlén in 1941 by identifying the coronal lines (observed since 1869) as transitions from low lying metastable levels of the ground configuration of highly ionized metals (the green FeXIV line at 5303 Å, but also the red line FeX at 6374 Å).
Light from the corona comes from three primary sources, which are called by different names although all of them share the same volume of space. The K-corona (K for kontinuierlich, "continuous" in German) is created by sunlight scattering off free electrons; Doppler broadening of the reflected photospheric absorption lines completely obscures them, giving the spectral appearance of a continuum with no absorption lines. The F-corona (F for Fraunhofer) is created by sunlight bouncing off dust particles, and is observable because its light contains the Fraunhofer absorption lines that are seen in raw sunlight; the F-corona extends to very high elongation angles from the Sun, where it is called the Zodiacal light. The E-corona (E for emission) is due to spectral emission lines produced by ions that are present in the coronal plasma; it may be observed in broad or forbidden or hot spectral emission lines and is the main source of information about the corona's composition.
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