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What is the net electric charge (in magnitude and sign) of the Sun and its corona?

Emilio Pisanty
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VYT
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2 Answers2

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According to this post and references there, the charge of the Sun is positive, the magnitude is estimated as 77 Coulombs, or about 1 electron per million tons of matter.

The reason for this is that

The net global charge on the Sun comes about because electrons, being rather less massive than protons, are more able to escape the sun as part of the solar wind. The net charge achieved is a result of the balance between the forces that eject the solar wind, which push electrons more efficiently then protons, and the attractive force on the electrons of the net positive charge that results. Equilibrium of these forces establishes the allowed net charge.

Emilio Pisanty
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akhmeteli
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    @honeste_vivere: I respectfully disagree with your estimate. An electric field of a point charge $q$ at a distance $r$ is $q/(4\pi\epsilon_0 r^2)$. When I substitute $q=77$, $\epsilon_0=8.85\times 10^{-12}$, $r=7\times 10^8$ (the Sun radius, SI units everywhere), I get $1.4 \mu V/m$. – akhmeteli May 03 '16 at 01:33
  • Yes, you are correct... I forgot to square the $8 \ R_{s}$ factor. My colleagues eventually corrected my mistake. – honeste_vivere May 03 '16 at 12:20
  • I have added some updates to my answer explaining why the Neslusan, [2001] paper in the link in your answer is incorrect at: http://physics.stackexchange.com/a/253491/59023. – honeste_vivere May 04 '16 at 13:18
  • @honeste_vivere: Your update does not look very convincing: so the model does not describe dynamic phenomena well, this does not mean it does not describe static phenomena. So what charge does the newer model predicts? So far I just see your conclusions about neutralization. Or is it the authors' conclusion? – akhmeteli May 05 '16 at 00:44
  • It is true that the static model does predict a ~70 C charge but the sun is not static. The Neslusan, [2001] model cannot explain the observed velocity distribution functions nor the observed supersonic solar wind. Those two points are quite fatal to that model, I think. – honeste_vivere May 05 '16 at 12:31
  • @honeste_vivere: I am afraid your comment does not address my questions. – akhmeteli May 06 '16 at 00:11
  • The exospheric models predict the multi-component electron distributions that we see and a supersonic solar wind. I do not think the exospheric models predict a net charge though... – honeste_vivere May 06 '16 at 12:21
  • @honeste_vivere: I am not a native English speaker, so I am not sure if you mean "exospheric models have no prediction for the net charge" or "I believe exospheric models predict zero net charge". However, in the first case, exospheric models do not contradict my answer, and in the second case, the fact that my answer contradicts your "opinion", rather than some fact, cannot be "fatal" for my answer. – akhmeteli May 07 '16 at 14:59
  • Your answer does not produce a supersonic solar wind nor can the P-R model produce the observed components of the electron velocity distributions. Those are the fatal flaws to which I referred. Nothing to do with my opinions... – honeste_vivere May 08 '16 at 13:45
  • @honeste_vivere: If the model has drawbacks, it does not necessarily mean it is useless. If it does not describe the phenomena that you mention, it does not necessarily mean that it does not reasonably describe the net charge. In your opinion, it does not, but this is your opinion, not a fact. I suspect the exospheric models do not give any predictions for the net charge at all (otherwise you would probably mentioned such predictions), so we do what we can with what little we have. And I don't quite understand why my answer should have produced supersonic solar wind. OP only asked about charge – akhmeteli May 08 '16 at 17:19
  • The problem is that you do not get results consistent with observations precisely because your model allows the star to charge up. I agree, the model is not completely useless. However, I cannot think of a situation where a star would be in hydrostatic equilibrium. – honeste_vivere May 09 '16 at 12:41
  • @honeste_vivere: Again, you cannot offer theoretical or experimental results giving a different value for the net charge, so let us agree to disagree:-) – akhmeteli May 10 '16 at 00:31
  • Is 77 C a ridiculously tiny charge for such a massive object? It's like one tenth of a single AA battery. – lolmaus - Andrey Mikhaylov Sep 06 '17 at 15:55
  • @lolmaus-AndreyMikhaylov : I am afraid I don't understand your comparison - there is no significant charge in a battery. A battery contains chemical energy. 1 C is a huge charge. – akhmeteli Sep 07 '17 at 00:45
  • @akhmeteli I had visited the Wikipedia page for Coulomb, and it says a 1C is equal to ~0.3mAh. – lolmaus - Andrey Mikhaylov Sep 07 '17 at 06:08
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    @lolmaus-AndreyMikhaylov : Yes, I do understand this, but that does not mean that there is a charge comparable to 1 C in a battery at any moment in time. The energy there is in the form of chemical energy. – akhmeteli Sep 07 '17 at 14:00
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    @akhmeteli fyi I've just asked Are there measurements of, or experimental limits to the residual charge of the Sun? – uhoh Oct 28 '17 at 20:20
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Utilizing the accepted number 3.8427 x 10^26W. The charge of the Sun is 2.948124982 x 10^13 As. While the Amp is 1.00995716 x 10^12 A, the volt 3.804814 x 10^14 Kgm2/As3. VA = W and V/A = 376 Ohms. Which is the background impedance of vacuum space. The power is derived from the equation P= oeAT. From which the solar constant of 1366 W/m2 is derived. q = sq.rt.WF/m(4Pir)2/c = As A = qc/4Pir = Amp V = q/4PiF/mr = Kgm2/As3 W = q2c/F/m(4Pir)2 = Kgm2/s3

ROBERT DUNN
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    We do have MathJax here that makes your equations look better. You can search 'notation' in [help] for details, if you aren't familiar with it. – Kyle Kanos Jan 03 '19 at 21:46