Coronal loop: Difference between revisions

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Latest revision as of 12:30, 30 May 2025

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The strong interaction of the magnetic field with the dense plasma on and below the Sun's surface tends to tie the magnetic field lines to the motion of the Sun's plasma; thus, the two ''footpoints'' (the ___location where the loop enters the photosphere) are anchored to and rotate with the Sun's surface. Within each footpoint, the strong magnetic flux tends to inhibit the convection currents which carry hot plasma from the Sun's interior to the surface, so the footpoints are often (but not always) cooler than the surrounding photosphere. These appear as dark spots on the Sun's surface, known as [[sunspot]]s. Thus, sunspots tend to occur under coronal loops, and tend to come in pairs of opposite [[magnetic polarity]]; a point where the magnetic field loop emerges from the photosphere is a North [[magnet|magnetic pole]], and the other where the loop enters the surface again is a South magnetic pole.

Coronal loops form in a wide range of sizes, from 10the minimum observable scale (< 100&nbsp;km) to 10,000&nbsp;km. There is currently no accepted theory of what defines the edge of a loop, which is embedded in a general corona that is itself strongly magnetized. Coronal loops have a wide variety of temperatures along their lengths. Loops at temperatures below 1&nbsp;[[megakelvin]]&nbsp;(MK) are generally known as cool loops; those existing at around 1&nbsp;MK are known as warm loops; and those beyond 1&nbsp;MK are known as hot loops. Naturally, these different categories radiate at different wavelengths.<ref>{{cite journal

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