Solar Explosions Spark Controversy


Nowhere in the Solar System are conditions more extreme than the Sun. Every second it converts millions of tons of matter into energy to create the intense levels of heat and light we expect of our local star. Study the Sun in different wavelengths and its violent nature can really become apparent. The STEREO satellite has been studying the Sun at a wavelength of 304Å and the results support a controversial solar theory.

Coronal Mass Ejections (or CMEs) are common on the Sun and they have a very real impact to us here on Earth. The solar explosions expel trillions of trillions of tons of super hot hydrogen gas into space, sometimes in the direction of the Earth. Traveling at speeds up to 2,000 kilometers per second it takes just a day for the magnetized gas to reach us and on arrival it can induce strong electric currents in the Earth’s atmosphere leading not only to the beautiful auroral displays but also to telecommunication outages, GPS system failures and even disturbances to power grids.

Solar flares, to use their other name, were first observed back in 1859 and since then, scientists have been studying them to try to understand the mechanism that causes the eruption. It has been known for some time that the magnetically charged gas or plasma is interacting with the magnetic field of the Sun but the detail has been at best, elusive.

In 2006, the international satellite STEREO was launched with the objective of continuously monitoring and studying the CMEs as they head toward the Earth and its data has helped scientists at the Naval Research Laboratory (NRL) in Washington, D.C., start to understand the phenomenon.

Using this new data, scientists at the NRL compared the observed activity with a controversial theory that was first proposed by Dr James Chen (also from the NRL) in 1989. His theory suggested that the erupting clouds of plasma are giant ‘magnetic flux ropes’, effectively a twisted up magnetic field line shaped like a donut. The Sun being a vast sphere of gas suffers from differential rotation where the polar regions of the Sun and the equatorial regions all rotate at different speeds. As a direct result of this, the plasma ‘drags’ the magnetic field lines around and the Sun and it gets more and more twisted up . Eventually, it bursts through the surface, taking some plasma with it giving us one of the most dramatic yet potentially destructive events in the Universe.

Dr Chen and a Valbona Kunkel, a doctorate student at George Mason University, applied Dr. Chen’s model to the new data from STEREO and found that the theory agrees with the measured trajectories of the ejected material. It therefore looks like his theory, whilst controversial may have been right all along.

Its strange to think that our nearest star, the Sun, still has secrets. Yet thanks to the work of Dr. Chen and his team, this one seems to have been unraveled and understanding the strange solar explosions will perhaps help us to minimise impact to Earth based technologies in years to come.

Mark Thompson is a writer and the astronomy presenter on the BBC One Show. See his website, The People’s Astronomer, and you can follow him on Twitter, @PeoplesAstro

29 Replies to “Solar Explosions Spark Controversy”

  1. I didn’t know that this theory was “controversial”. I mean, a rising magnetic field dragging plasma with it, recombining at the bottom and buggering off into space — well, that’s the idea I have always heard about it. Maybe I am just too young and too new in astrophysics (just started my PhD work) and didn’t witness the debates about it.
    What I know is that at my university a group tries to reproduce solar flares in their lab. And that seemed to be exactly a reproduction of that mechanism (I don’t know their current status, it’s been a while since I have talked to or heard from someone of that group…)

  2. Paul Bellan’s plasma group at caltech have also been doing laboratory simulations of Solar prominences, see their Laboratory simulation of solar prominences web page. See also:

    James Chen, Valbona Kunkel, “Temporal and Physical Connection Between Coronal Mass Ejections and Flares”, The Astrophysical Journal, Volume 717, Number 2 (Abstract)

    Chen, James; Kunkel, Valbona, “Dynamics of Solar Coronal Mass Ejections: Theory and New SECCHI Observation”, American Physical Society, 2009 APS April Meeting, May 2-5, 2009, abstract #K1.009 (Abstract)

    Scientists unlock the secrets of exploding plasma clouds on the sun“, November 8, 2010

  3. Just watched a show on Nat’l Geo that chatted up the Earth/Sun mag. field relationship. To show the earth’s mag. field, one researcher built a giant magnetic rotating sphere filled with liquid Sodium then energized it. It was fascinating to observe the growth of magnetic flux tubes organized into long thin eruptive channels. These tubes self-organized into twisted strands from the core outward. It was mentioned that convection creates electrical charges (MHD) in these flux tubes or channels and were oft times located at ‘hot spots’ in the earth’s crust. The South Atlantic Anomaly was also briefly mentioned as an area where the flux tubes may have become ‘nullofied’ by interactions with the underlying magnetic structures?

  4. “Every second it converts millions of tons of matter into energy” – are you sure about this? since childhood i remember the sun converts 4 tons of matter into energy per second.

  5. Or…. 4.28 billion kg of mass gets converted to energy every second! At least that is according to modern physics.

    Electro-gravitational multiverse functions anyone?

  6. I’m with DrFlimmer, the overall process doesn’t seem controversial. IIRC the “kink healing” mechanism (which I can’t remember the name of at the moment) that is believed to kick particles is hard to get the right kick out of theoretically, but that is “mere detail”. 😀

    But hey, any data that test a hypothesis is good data!

    the magnetically charged gas or plasma

    There is no magnetic charge.

    [Well, I guess if you decouple Maxwell’s equations and you are really anxious to explain B-to-H behavior “in a similar manner” as the electric field you can introduce it in a ad hoc model despite the basic B field being divergence free and so explicitly rejecting charge. It’s not particularly helpful to understand the physics though.]

    @ Renoor:

    Encyclopedias, my dear fellow, encyclopedias:

    The proton–proton chain occurs around 9.2 × 10^37 times each second in the core of the Sun. Since this reaction uses four free protons (hydrogen nuclei), it converts about 3.7 × 10^38 protons to alpha particles (helium nuclei) every second (out of a total of ~8.9 × 10^56 free protons in the Sun), or about 6.2 × 10^11 kg per second.[37] Since fusing hydrogen into helium releases around 0.7% of the fused mass as energy,[38] the Sun releases energy at the mass-energy conversion rate of 4.26 million metric tons per second, 384.6 yottawatts (3.846×10^26 W),[1] or 9.192 × 10^10 megatons of TNT per second.

    [Wikipedia, happily jumping all over the sensible number of significant digits because *conversions can have more significant digits*! It is a US tradition, I believe.]

  7. Chen’s model is basically how I have always thought of these solar flares. Magnetic field lines in the charged particle plasma get wound up and the energy density increases. Eventually the solar medium lack the pressure required to contain this and the magnetic field lines with its plasma load erupt from the solar surface.

    How can it be any other way?


  8. >there is no charge separation in the solar wind.

    I think there is evidence of at least three different kinds of charge separation in the interplanetary medium:

    The heliospheric current sheet

    The Interplanetary electric field which is orientated north/south.

    And although not quite the same thing, the ambipolar electric field in our results corresponds to a potential drop of about 900 V from the sun to 1 AU” (ref)

    Of course in all cases, quasi-neutrality means that in the electric wind, contains equal numbers of positive and negative charges, though I don’t think that any of these are what Lars was discussing.

  9. Well,in the first place YOU CAN’T HAVE A MAGNETIC FIELD WITHOUT AN ELECTRIC CURRENT !!! Hello-oo.

    Secondly, there’s NO SUCH THING AS MAGNETICALLY CHARGED PROTONS !!! Hello-oo again, is there anyone in there who can think rationally ?

    What’s happening is there is an electric field surrounding the Sun all the way out to the Heliopause (or Heliosphere), the positively charged particles accelerate away from the Sun due to the increasingly negative electric field as they get farther away from the Sun. The motion of charged particles IS AN ELECTRIC CURRENT. As such electric currents cause magnetic fields to arise near them.
    This is the origin of your so called ‘magneitic flux tubes’. Electric currents (streams of ions or electrically charged particles moving away from the Sun) cause magnetic fields to form around them simultaneously with their motion.

    To wit:

    The Electric Field has Three causative sources:

    1 – the charge density
    2 – the time derivative of the charge density
    3 – the time derivative of the electric current density

    The Magnetic Field has Two causative sources:

    1 – the electric current density
    2 – the time derivative of the electric current density

    The prominent presence of [derivative J over derivative t] and [the derivative of J over derivative t], in the formulas, indicate that the time derivative of the electric current density is the primary causative agent of both electric and magnetic fields, with the charge density and its time derivative being of equal prime importance in electric fields.

    Thus: electric and magnetic fields are always simultaneously created by the same time-variable electric current with its charge density also modulating the intensity of the electric field.

    “There is a widespread belief that time-variable electric and magnetic fields can cause each other, but an analysis of Maxwell’s equations does not support this belief. It is true that whenever there exists a time-variable electric field there also exists a time-variable magnetic field, but neither Maxwell’s equations (and also as reformulated by Oliver Heaviside) nor their solutions indicate an existence of causal links between electric and magnetic fields.

    Therefore: an electromagnetic field is a dual entity, always having an electric and a magnetic component simultaneously created by their common source:
    time-variable electric charges and currents.”

  10. The so-called “controversy” in the title seems to be journalistic overdrive. Or maybe Dr James Chen is advertising his stuff as controversial for better attention! He’s anyway using his own theory for this new observation, so he doesn’t really need to advertise.

  11. @ Lars

    I know I shouldn’t do this, because I will cause a lot of noise, but:

    Maxwell’s equations support both a constant electric as well as a constant magnetic field. They can exist without a source, actually. rot(B)=div(B)=0 can be solved and the solution obeys Maxwell’s equations and is therefore possible. If it’s realistic is another question — but it’s not forbidden by the equations in the first place.

    Btw: The idea that there is a large electric field extending from the sun to the heliosphere is flawed and not supported by (in-situ) observations and measurements. In fact: the solar wind contains equal amounts of positive and negative charges and both flow away from the sun with the same velocity! That was proven by the Ulysses spacecraft and others. Thus, there is no charge separation in the solar wind, and therefore no electric field which WOULD separate the charges!


  12. >it takes just a day for the magnetized gas to reach us and on arrival it can induce strong electric currents in the Earth’s atmosphere leading not only to the beautiful auroral displays but also to telecommunication outages, GPS system failures and even disturbances to power grids.

    It seems the author ought to include “potential effect on weather systems” in the above paragraph. As the Earth’s magnetosphere is charged by these violent ejections, it seems logical an impact on the upper air currents ultimately occurs, thereby amplifying weather systems etc.

  13. Several comments here were held up in the Pending queue for longer than usual; sorry about that.

  14. @ iantresman

    May that be as it is. My point is still valid, because there is no large scale electric field pointing radially away to or from the sun.

  15. >here is no large scale electric field pointing radially away to or from the sun.

    Not only is there charge separation, but the heliospheric current sheet has a large scale radial electric field component. However, it is of tiny magnitude.

    In their paper, !”MHD simulation of the three-dimensional structure of the heliospheric current sheet “, Israelevich et al write: “The existence of the radial component of the electric current flowing toward the Sun is revealed in numerical simulation. The total strength of the radial current is 3x10E9 Amps” (ie. 3 Giga amps.) But the current density is only about 10E-10 amps/m^2.

    The heliospheric current sheet has also been described as”the biggest thing in the heliosphere”(ref)

    Interestingly, “For solar wind velocities between 300 and 400 km s?1 the helium velocity exceeded the hydrogen velocity by 5 km s?1 on the average”.(ref), but I am unable to find a comparison with electron velocities; do you have one?

  16. the gravitational field of a point mass and the electric field of a point charge are structurally similar. For a positive charge the direction of the electric field points along lines directed radially away from the location of the point charges, and in the opposite direction for a negative charge. Wikipedia says electric current flows deep within the sun, and that the sun is an excellent electrical conductor governed by the laws of MHD.
    the solar wind positive charged H+ plasma essentially infinite conductivity is electricallly charged pointing radially away from the sun. Voltage involves electric fields just as magnetism involves magnetic fields. Voltage is the “dual” of magnetism, the EM duality that causes widespread confusion. Voltage is not an electric current. Voltage fields reach across outer space, but cannot be measured in outer space DRFUMMER, because voltage is relative and the sun cannot have a certain voltage nor a certain distance to extend an electric field radially away to or from the sun. Single points and single objects don’t “have distance” and don’t “have voltage.” voltage causes the attraction between opposite charges.

  17. @Jean Tate

    Is there a message queue? Is there moderation? I only ask because all my previous messages appeared instantaneously, whereas now, they are either not appearing, or are queued. If the latter, why not display a message noting that a comment has been received, and will appear shortly?

  18. It seems that messages containing several links to other websites are withheld. Perhaps individuals can be whitelisted if they have demonstrated that they are not abusing links.

  19. I don’t think we should be discussing speculative theories.

    But concerning your astrophysics of the solar wind, as I mentioned above, a large scale electric field does affect the solar wind electrons and ions differently, producing the heliospheric current sheet. This is observed. I provide some references in another post, which for some reason have not yet appeared here.

    Charged particles in a plasmas do not necessary respond only in the way you describe (“accelerate one species and decelerate the other”). As Dr. David P. Stern says in his article on “Particle Drifts in Space“:

    “In a conductor such as a wire, electrons move from (-) to (+), while ions (if they are free to move), are pushed in the opposite direction, (+) to (-). In space, on the other hand, the the entire plasma is moved sideways, perpendicular to both magnetic and electric field lines. No steady electric current results from the electric field, and both ions and electrons advance in the same direction.”

  20. ExB drift sounds correct.

    Why are the heliospheric current sheet electric fields not large scale? You may be right, but I’d like to understand more.

  21. @ JimHenson

    The idea of EU is that the sun is on a potential relative to the heliosphere and/or the ISM. Thus, there should be a radially extending electric field between the sun and the heliosphere. That’s the idea.
    Concerning the solar wind: It contains equal amounts of charges. It does not only contain protons or heavier nuclei, it also contains electrons and is overall neutral. If there would be a large scale electric field from the sun to the heliosphere we would see the effect. Because it would accelerate one species and decelerate the other. This is NOT observed. Hence, there is no large scale electric field from the sun to the heliosphere.

  22. As I see it, what you describe is the ExB drift.

    And btw: My first answer was to Lars, who gave the speculative idea (of the charged sun). All I did was refuting it for good reasons. I know that there are electric fields in space. But they are on small scales compared to the whole solar system. That’s it, I don’t see why we even need to discuss this.

  23. >The heliospheric current sheet is primarily caused by a polarity change in the interplanetary magnetic field.

    Indeed, but why is the associated electric field not “large scale”?

    1. Israelevich et al write “The existence of the radial component of the electric current flowing toward the Sun is revealed in numerical simulation. The total strength of the radial current is 3x10E9 Amps” (ref)

    2. The heliospheric current sheet has also been described as”the biggest thing in the heliosphere”. That seems quiet large scale to me.

    I’m not interested in whether the Sun is charged.

  24. >You can have a current without an electric field

    You are quite right. I assumed, mistakenly, that the radial current in the heliospheric current sheet, must have an associated electric field. It doesn’t. As Dr. David P. Stern writes on “Particle Drifts in Space“.

    “.. electric currents often flow in space without any voltage driving them. No electric field is involved–the magnetic field is doing it all, when it has the appropriate structure”.

  25. The heliospheric current sheet is primarily caused by a polarity change in the interplanetary magnetic field. This sheet is similar to the sheet that surrounds the earth. I don’t know if those sheets contain electric fields. There is no need for them in the first place.

    Btw: Your link concerning the “interplanetary electric field” states a noteworthy fact: The electric field is only observable for an observer at rest relative to the solar wind. If you fly with the solar wind, there is no electric field. This is an effect of the Lorentz transformation.

    But / And still:

    This is no hint for a charged sun. (Just emphasizing again, what this is all about. I don’t see the point of bringing up topics that just lead sideways, and do not directly support the points made originally by Lars and/or myself.)

  26. the sun is not charged because the solar wind plasma undergoes charge exchange at the heliosphere ribbon, which I believe is a large plasma sheath ~100AU that surrounds the solar system in a DL double layer. The sheath seperates the solar systems plasma from the intersteller and intergalactic plasma, because the density & temp of plasmas are scalable in 14 known sizes! the electrical neutral atoms ENAs that are produced by charge exchange fly off into interstellar or intergalactic space, and the solar wind is deflected by either the ISM or IGM magnetic fields back to the solar system in a U-turn style. This is my original idea of a new solar system model and it does not change the likelyhood that gravity fuses elements in the sun. The sun may have had an EM source, because huge charged molecular clouds and protostars condense over vast distances, because plasmas attractive force increments increase with distance practically exponential compared to gravit. EM attracts/repels proportional to the distance, but weaker gravity only attracts the SQAURE of the distance. Gravity holds stars together, but is the weaker force to Em responsible for forming huge cosmological structures.

  27. 1.) I’ve searched through the paper and found no hit for “electric field”. The connection between an electric current and an electric field is not necessarily given. You can have a current without an electric field. All you need is a changing magnetic field (changing with respect to position) — that is to say: the curl of B should not vanish. Then you get an electric current, but not necessarily an electric field (dE/dt in Maxwell’s equation can still be zero!). Since the magnetic field does not a have a curl that is zero, we gain an electric current in the current sheet. But not necessarily an electric field. If there is one (that follows the entire structure!), it might be considered “large scale”. However, it does not necessarily exist, and I don’t think it does.
    But I am not an expert here, and I could be wrong with the last statement.

  28. could stars like the sun not be colliding and remain very far apart in the galaxy despite gravity between stars, because the electric current flowing in the 10,000 km thick current sheet extending beyond the orbit of pluto, is a large scale current sheet that repels other stars?

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