Unravelling the knotty problem of the Sun's activity

Date:
July 22, 2021
Source:
Royal Astronomical Society
Summary:
A new approach to analysing the development of magnetic tangles on
the Sun has led to a breakthrough in a longstanding debate about
how solar energy is injected into the solar atmosphere before being
released into space, causing space weather events. The first direct
evidence that field lines become knotted before they emerge at
the visible surface of the Sun has implications for our ability
to predict the behavior of active regions and the nature of the
solar interior.



FULL STORY ==========================================================================
A new approach to analysing the development of magnetic tangles on the
Sun has led to a breakthrough in a longstanding debate about how solar
energy is injected into the solar atmosphere before being released into
space, causing space weather events. The first direct evidence that field
lines become knotted before they emerge at the visible surface of the
Sun has implications for our ability to predict the behaviour of active
regions and the nature of the solar interior. Dr Christopher Prior of
the Department of Mathematical Sciences, Durham University, will present
the work today at the virtual National Astronomy Meeting (NAM 2021).


========================================================================== Researchers are generally in agreement that solar activity is caused by instabilities in giant twists of magnetic ropes threading the visible
surface of the Sun, known as the photosphere. However, there has been an ongoing debate about how these tangles form. The two dominant theories
have suggested either that coils of field lines emerge through the
photosphere from the convection zone below, or that the feet of arching
field lines wrap around each other on the surface itself and create
braids. Both mechanisms could theoretically produce effects like sunspot rotation and dramatic solar flares but, to date, no direct observational evidence had conclusively supported either scenario.

Prior and colleagues from the University of Glasgow and INAF-Osservatorio Astrofisico di Catania in Italy came up with a new direct measure of the entanglement of the magnetic field by tracking the rotation of field
lines at the points where they intersect with the photosphere. This
'magnetic winding' should manifest in different ways for each of the
two theories. Thus, applying magnetic winding to observations of the photosphere and examining the resulting patterns could enable a definitive answer to be reached for which theory was correct.

The researchers studied the magnetic winding for 10 active regions on
the Sun in observations by solar missions. In every case, the results
matched the emergence theory of pre-twisted magnetic field lines rising
up from the convection zone.

Prior explains: "The pattern for pre-twisted field lines exactly matched
the observational data we considered initially, and this has since been
found to be true for all data sets of active regions we have looked at so
far. We anticipate that magnetic winding will become a staple quantity in
the interpretation of magnetic field structure from observational data." ========================================================================== Story Source: Materials provided by Royal_Astronomical_Society. Note:
Content may be edited for style and length.


==========================================================================


Link to news story: https://www.sciencedaily.com/releases/2021/07/210722163026.htm

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