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Magnetic fld heating corona — how?

observing solar
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#1 cloudynusr


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Posted 20 September 2019 - 12:53 PM

 Hello: two real questions here.


1) How does our sun’s magnetic field raise the corona’s temperature? I am looking for a moderately simple answer, please. While I have decent science background and can use the bay area’s many University libraries, for getting a full mathematical answer to this, I’m not,thanks.(I am aware how magnets work.)

My own thoughts on how the temperature goes up,  comprise only: a)  friction, b)  density and c) velocity. I have no rank on those, and of course I’m seeking your answers, if I was happy with mine I wouldn’t be posting.


Here’s the links generating my question.






2) I realize cloudy nights specializes in telescopes and stars in general. Do you recommend a better place to post questions such as mine?


Thank you.

#2 bobito


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Posted 20 September 2019 - 01:40 PM

The Sun's magnetic field isn't like that of Earth.  The Sun spins on its axis at varying rates simultaneously, so the magnetic field gets twisted and causes the bands we see as prominences.  These bands bring energy from inside the sun out to the corona. 


At least, that's how I understand it.

#3 Aquarellia



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Posted 20 September 2019 - 10:07 PM


I worked in the solar department of the ORB (the Royal Observatory of Brussel) when I was young, and still have good contact there.

The idea of this corona high temperature is not completely clear yet, as far as I know a new special artificial satellite, maybe an artificial planet, is dedicated to this research today ?

The last decade better hypothesis is that a type of cyclotron mecanism make the job in the corona.

Here a summary of an article https://arxiv.org/abs/1604.04788 that could help you

The full (but more complex) article PDF can be downloaded here https://www.aanda.or.../aa28392-16.pdf


For your second question, my contact in the ORB solar department is probably a good source to help you, if needed, feel free to contact me directly to be in touch with him.


Hope this helps


#4 KLWalsh


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Posted 28 September 2019 - 07:14 AM

It’s an unsolved problem.
My notion of this (fwiw) is magnetic induction heating on a vast scale. As the magnetic fields associated with the ‘surface’ of the sun, including the fields around sunspots, extend above the sun’s surface they transport a tremendous amount of energy in the ‘field lines’. When the field collapses all of that energy gets dissipated into the surrounding plasma via magnetic induction. Thus the plasma undergoes massive induction heating.

I’m not suggesting my notion is correct, but it seems reasonable to me, so long as I don’t dig into the details.
(My college physics professors would have called this ‘hand waving’ - an idea with no math behind it so pretty much useless.)

Edited by KLWalsh, 28 September 2019 - 07:15 AM.

#5 agavephoto


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Posted 23 October 2019 - 11:26 PM

This isn't an area where scientists have yet reached a general conclusion, and there are a few ideas as to why the corona is so much hotter. One idea is that the energy to heat the plasma in the corona comes from magnetic reconnection. A simplistic way of thinking about this is as follows: a magnetic field contains energy, and sometimes the field lines come together and merge, cancelling each other out. The energy that was stored in the magnetic field that has now been "cancelled out" doesn't just disappear, though ... energy is conserved. That energy goes into the plasma of the corona, heating it. There is very likely not just one physical mechanism that heats the corona, but this hopefully helps the broader understanding.

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