Solar Prominence

Missions, Solar Astronomy, sun

Solar Explosions Spark Controversy

8 Nov , 2010 by

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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

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DrFlimmer
Member
DrFlimmer
November 8, 2010 7:14 AM

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…)

iantresman
Member
November 8, 2010 10:19 AM

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

Aqua4U
Member
November 8, 2010 8:14 AM

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?

renoor
Member
renoor
November 8, 2010 8:59 AM

“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.

Aqua4U
Member
November 8, 2010 9:57 AM

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?

Torbjorn Larsson OM
Member
Torbjorn Larsson OM
November 8, 2010 12:49 PM
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… Read more »
Lawrence B. Crowell
Member
Lawrence B. Crowell
November 8, 2010 7:15 PM

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?

LC

iantresman
Member
November 9, 2010 7:27 AM

>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.

lars
Member
lars
November 8, 2010 11:53 PM
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… Read more »
Dilip G Banhatti
Member
November 9, 2010 3:30 AM

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.

DrFlimmer
Member
DrFlimmer
November 9, 2010 6:26 AM
@ 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… Read more »
2stepbay
Member
2stepbay
November 9, 2010 7:57 AM

>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.

Jean Tate
Member
November 9, 2010 12:35 PM

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

DrFlimmer
Member
DrFlimmer
November 10, 2010 9:21 AM

@ 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.

iantresman
Member
November 11, 2010 2:39 AM
>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… Read more »
jimhenson
Guest
jimhenson
November 11, 2010 2:49 AM
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. http://www.en.wikepedia.org/wiki/Solar_dynamo 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… Read more »
iantresman
Member
November 11, 2010 3:34 AM

@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?

iantresman
Member
November 11, 2010 3:37 AM

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.

iantresman
Member
November 11, 2010 8:51 AM
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… Read more »
iantresman
Member
November 11, 2010 10:27 AM

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.

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