Thursday, July 22, 2021

Space weather events

A new approach to analyzing magnetic tangles in the Sun has illustrated how energy is injected into the solar atmosphere before going out into space, causing space weather events.

Dr. Christopher Prior, from the Department of Mathematical Sciences at Durham University, presented the research at the British National Astronomy Meeting (NAM 2021).

Researchers agree that solar activity is caused by instabilities in giant twists of magnetic strings that thread the visible surface of the Sun, known as the photosphere. However, there has been an ongoing debate about how these tangles are formed. The two dominant theories have suggested that the spirals of field lines emerge through the photosphere from the convection zone below, or that the feet of the arched field lines wrap around each other on the surface itself and create braids.

In theory, both mechanisms could produce effects such as sunspot rotation and dramatic solar flares, but to date, no direct observational evidence has conclusively supported either scenario.

Prior and colleagues at the University of Glasgow and the INAF-Osservatorio Astrofisico di Catania in Italy proposed a new direct measure of magnetic field entanglement by tracking the rotation of field lines at the points where they intersect the photosphere. This "magnetic winding" should manifest itself in different ways for each of the two theories. Therefore, applying the magnetic winding to the observations of the photosphere and examining the resulting patterns could lead to a definitive answer as to which theory was correct.

The researchers studied the magnetic winding of 10 active regions of the Sun in recent observations from spacecraft and found that the results were consistent with the emergence theory of twisted magnetic field lines rising from the convection zone.

Prior explains: "The pattern of the twisted field lines previously matched exactly the observational data that we initially considered, and this has since been found to be true for all active region data sets that we have analyzed thus far. We anticipate that the magnetic winding will become a basic quantity in the interpretation of the magnetic field structure from the observational data. "

Simulation of twisted magnetic field lines emerging through the photosphere, the visible surface of the Sun. - D. MACTAGGART ET AL.

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