Related topics: sun

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Scientists discover volcanoes on Venus are still active

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New clue to solving the mystery of the Sun's hot atmosphere

The elemental composition of the Sun's hot atmosphere known as the 'corona' is strongly linked to the 11-year solar magnetic activity cycle, a team of scientists from UCL, George Mason University and Naval Research Laboratory ...

Astronomers unveil the magnetic field of the solar corona

While the world has been dealing with the coronavirus pandemic, researchers at the University of Hawaiʻi Institute for Astronomy (IfA) have been hard at work studying the solar corona, the outermost atmosphere of the sun ...

Eclipse science along the path of totality

Leading U.S. solar scientists today highlighted research activities that will take place across the country during next month's rare solar eclipse, advancing our knowledge of the Sun's complex and mysterious magnetic field ...

Experts discover heavenly solar music (w/ Video)

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Understanding coronal mass ejections

(PhysOrg.com) -- The corona of the sun is the hot (over a million kelvin), gaseous outer region of its atmosphere. The corona is threaded by intense magnetic fields that extend upwards from the surface in loops that are twisted ...

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Corona

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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