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What happens to coronal mass ejections?

  1. Oct 26, 2015 #1
    This thread got me wondering something: https://www.physicsforums.com/threads/kic-8462852-in-the-news.837900/page-5 Long story short: someone suggested starspots as a reason for it's weird variance. It had some problems with it, but it did get me wondering.

    I know sunspots are caused by magnetic loops pushing plasma around and when these loops collapse, large amounts of plasma gets shot of into space in a solar flare. If that material hits Earth, it can cause problems with our electronics and satellites so we watch for them.

    Other than that, I don't know much about them, what happens to all of that mass? I know that they are traveling at immense speed, and extremely hot. They're also charged and all of the particles would be charged the same way (or else they wouldn't have been stuck in the magnetic loop in the first place) so they should push themselves apart.

    Then what happens? Is most of the material at escape velocity? Does it end up in the galactic wind eventually? Also, more relevant to the other thread, if the sun threw a tantrum, how far away would that be detectable from? I would think a huge mass of hot plasma being thrown from a star should produce a noticeable cloud glowing in the IR.
  2. jcsd
  3. Oct 26, 2015 #2


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    Yes, that is correct, its gets trapped in the Earth's magnetic field, and it also causes the beautiful aurora around both the polar regions

    its speed varies greatly depending on the intensity anywhere between 800 - 3200 km/s. 3200 being an extreme. 1000 - 2000 km/s being the common range
    As they propagate out, they will slow down and will become part of the normal solar wind
    The solar wind speed and density as I type this is ...
    Solar wind
    speed: 386.2 km/sec
    density: 2.2 protons/cm3
    During a large CME, proton densities can get up to over 100 protons / cm3 which when compared to a cm3 of water is extremely low density

    The CME's and solar wind in general, are primarily composed of protons and electrons

    some of it falls back onto the sun ( this can be seen in many of the videos of CME's), the rest gets blasted out into space.

    Would be easily detected from the outer reaches of the solar system ..... but from many lightyears away ... I cant answer that

  4. Oct 27, 2015 #3


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    Few CME's happen to be emitted on an intercept course with earth [think of the odds]. Those that are, are blunted by the magnetosphere which weakens their effects at ground level. As Dave noted effects of solar emissions are most pronounced at the magnetic poles where the magnetosphere is weakest.
    Last edited by a moderator: Oct 27, 2015
  5. Oct 28, 2015 #4
    If there was a solar storm, would it make a noticeable change in surrounding solar neighborhood that could be detected light years away?
  6. Oct 28, 2015 #5
    I would think that any CME missing the earth will just keep on going, unless/until it hits something like another planetary magnetic field. What would happen when it hits the heliopause and the magnetosphere ? We do not know.
  7. Oct 29, 2015 #6


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    Any CME, regardless of if the Earth is in its path or not 99.99% of it goes right on past
    CME's are huge and any that are directed in the Earths' direction, only a tiny fraction will be intercepted by the Earths' magnetic field

    in this pic of a large CME, the Earth size in comparison would be about the size of that bright star centre right, just a few pixels


  8. Nov 2, 2015 #7
    Yes that is slightly true, but very little, if any, of the solar flare is trapped. The aurora is mainly caused by charged particles that have long been trapped in the Van Allen belts.

    The Earth's magnetic field lines converge more at lower altitudes and the trapped particles "mirror" back and forth from the North and South field convergence zones, normally turning around still high in the rare atmosphere, with little excitation of it / weak aurora. What the solar particle discharge that hits the Earth does, is make pressure on the Earth's field lines. Then the turn-a-round points for the already trapped particle can be closer to the Earth's surface - in denser but still rarefied atmosphere.

    SUMMARY: The solar flare particle pulse does not DIRECTLY cause the northern lights.

    It is interesting to note that the dominate green line, is from the meta-stable (first order forbidden) decay of an excited state of oxygen. It has a very low radiative transition probably, and when it decayed is very uncertain (compare to permitted decays). Thus by the uncertainty principle its "Delta T" is large and its "Delta E" is very small. I. e. its wave length and frequency (energy) are very precise. For an EM photon to have a precise frequency, it must have many cycles. So many that the green line photons from the aurora are more than a meter long!

    Most people, even some Ph. D. physicists, think of photons as small ball-like packets of energy. I have measured the length of some from a low pressure lamp (so their transition is usually completed before any significant collision occurs). They were 30cm long.

    How I measured the length of photons is explained here:
    Last edited: Nov 2, 2015
  9. Nov 2, 2015 #8


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    Sorry, but if that were true, then there would be bright aurora all the time

    please provide solid research papers to support your claim
    and I and dozens of others will admit error

    Instead, we get strong aurora directly associated with the occurrence of flares and CME's
    The Van Allen belts are too high up to be causing the aurora, which are happening at a much lower altitude ... around 50 - 150 km

    Everything I have so far read over the years clearly states that the Van Allen belts are fed by the geomagnetic storms that cause the aurora, NOT the other way around where the particles in the belts cause the geomagnetic storms and then the aurora

    Last edited: Nov 2, 2015
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