The solar wind is swirly

Dec 19, 2012
Tiny turbulent swirls in the solar wind.

(Phys.org)—Using ESA's Cluster quartet of satellites as a space plasma microscope, scientists have zoomed in on the solar wind to reveal the finest detail yet, finding tiny turbulent swirls that could play a big role in heating it.

Turbulence is highly complex and all around us, evident in water flowing from a tap, around an aircraft wing, in experimental fusion reactors on Earth, and also in space.

In the stream of charged particles emitted by the Sun – the solar wind – turbulence is thought to play a key part in maintaining its heat as it streams away and races across the Solar System.

As the solar wind expands, it cools down, but to a much smaller extent than would be expected if the flow were smooth.

Turbulence arises from irregularities in the flow of particles and , but understanding how this energy is transferred from the large scales where it originates, to the small scales where it is dissipated, is like trying to trace energy as it is transferred from the smooth, laminar flow of a river down to the small turbulent eddies formed at the bottom of a waterfall.

In a new study, two of the four Cluster satellites have made extremely detailed observations of plasma turbulence in the solar wind.

They were separated by just 20 km along the direction of the plasma flow and operated in 'burst mode' to take 450 measurements per second.

By comparing the results with , scientists confirmed the existence of sheets of electric current just 20 km across, on the borders of turbulent swirls.

"This shows for the first time that the solar wind plasma is extremely structured at this high resolution," says Silvia Perri of the Universita della Calabria, Italy, and lead author of the paper reporting the result.

Cluster previously detected current sheets on much larger scales of 100 km in the magnetosheath, the region sandwiched between Earth's – the – and the that is created as it meets the solar wind.

At the borders of these turbulent eddies the process of 'magnetic reconnection' was detected, whereby oppositely directed field lines spontaneously break and reconnect with other nearby field lines, thus releasing their energy.

"Although we haven't yet detected reconnection occurring at these new, smaller scales, it is clear that we are seeing a cascade of energy which may contribute to the overall heating of the ," said Dr Perri.  

Future missions such as ESA's Solar Orbiter and NASA's Solar Probe Plus will be able to determine whether similar processes are also in play closer to the Sun, while NASA's Magnetospheric Multiscale mission will specifically probe the small-scale regions where reconnection can occur.

"This Cluster result demonstrates the mission's unique capability to probe universal physical phenomena, in this case pushing the mission's instrument measurement capabilities to their limit to unlock features at small scales," comments Matt Taylor, ESA's Cluster Project Scientist.

"Future multi-spacecraft missions will make very detailed studies of these small-scale plasma phenomena and provide further context to our Cluster measurements."

Explore further: Bacteria manipulate salt to build shelters to hibernate

More information: Perri, S. et al., Detection of small scale structures in the dissipation regime of solar wind turbulence. Physical Review Letters, 8 November, 2012

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rubberman
1 / 5 (2) Dec 19, 2012
"At the borders of these turbulent eddies the process of 'magnetic reconnection' was detected, whereby oppositely directed field lines spontaneously break and reconnect with other nearby field lines, thus releasing their energy."

You can't "break" an EM field, but yes they do couple. Voyager also detected these "magnetic bubbles" and a highly turbulent region at the termination shock, and this visulization is great! The acceleration and heat generation has been previously explained.

http://www.rdmag....-mystery


GSwift7
3 / 5 (4) Dec 19, 2012
Voyager also detected these "magnetic bubbles" and a highly turbulent region at the termination shock


Yes, but please note that the above article is talking about the bow shock in front of the Earth, not the bow shock in front of the solar system. These are things happening inside the solar system, in the solar wind. Conditions in the interstellar medium are an entirely different story.
rubberman
3 / 5 (4) Dec 19, 2012
Actually GS, there was an article on physorg this summer regarding the shape of the heliosphere and the lack of a bow shock associated with it and the interstellar medium, I'll try and find it to link as I am sure I saved that one, but the jist was that there isn't a magnetotail like the earth has. The magnetic turbulence that voyager detected was on our side of the magnetic highway between it and the termination shock. The "breaking" of the field lines they refer to and the eddies at the bow shock of the earths EM field have a different driving process than those just inside the Heliosheath, although I am sure they would image the same way. I should have been more specific with regards to the regions I was referencing, sorry about that.

It boils down to the velocity of the solar "wind" in the two locations.
rubberman
3 / 5 (4) Dec 19, 2012
Same paper but not the physorg abstact.

http://www.scienc...91.short

This paper theorizes that it is due to the heliosphere travelling at less than magnetosonic speed through the ISM...I'll go one better and say it is because the heliosphere isn't moving through the ISM, it is moving with it as would happen if you suspend a magnetic bubble inside a magnetic web, the entire region has the same inertial reference frame.
rubberman
3 / 5 (4) Dec 19, 2012
IBEX is my favourite measurement satelite...but only by a a touch.

http://ibex.swri.edu/

Logically, the IBEX ribbon they speak of will turn out to be the interaction not only from solar "wind" on our side of the Heliosheath, but varying fields on the ISM side as well. Voyagers readings can confirm this after it penetrates the ISM, depending on how long it remains functional in that enviroment. The info. from these two devices along with our myriad of solar observation satelites should lead to an improved model of the heliosphere that takes the Solar Dipole (north/south) EM field into account emanating from the suns poles. This missing component, along with the "eddies" explains the lack of a magnetic highway in the current heliospheric model.
rubberman
1 / 5 (2) Dec 19, 2012
Sorry for the flood guys.
cantdrive85
1.5 / 5 (8) Dec 19, 2012
"Magnetic reconnection is pseudo-science" Hannes Alfven

And there is no "bow shock" in a plasma environment, it is instead called a double layer. The release of energy is from an exploding double layer, not "reconnection". Hannes Alfven pointed this out quite clearly in his Nobel acceptance speech, but as with in the past he has been largely ignored.
Read Current free double layers;
http://www.thunde...apter-5/

And Current carrying double layers;
http://www.thunde...apter-7/
cantdrive85
1.5 / 5 (8) Dec 19, 2012
Also note the cellular and filamentary characteristics of the inset image, all should have been expected if the proper application of plasma physics were employed.
rubberman
2.6 / 5 (5) Dec 19, 2012
CD85, the terminology is semantics, like solar "wind" or your favourite...."GAS". The study is on the physical relationship and the interactions inside the plasma and at the various field boundaries. Photons and electrons are waves not particles as observed in various double slit difraction experiments, but for the sake of discussion electrons have been referred to as particles for a very long time, so why mince words....
cantdrive85
1.5 / 5 (8) Dec 19, 2012
The misrepresentation due to "semantics" leads to misunderstanding of the phenomenon. And it was my understanding that science needs to be very specific in it's nomenclature. Just as we don't call ice a liquid, we also shouldn't label plasma a gas. If something is what it is, why call it something it isn't? It leads to confusion and misunderstanding among both the people who are studying it as well as the layman.
rubberman
3 / 5 (4) Dec 19, 2012
In some respects it definitely does lead to misunderstanding...I wind up tripping over terminology myself sometimes and yes science is supposed to be specific, i have run into some order parameters when researching that make me cringe...you should read the article on IBEX I linked, there is some good stuff in there and some no so sound logic...being able to separate the two helps.
GSwift7
3 / 5 (4) Dec 20, 2012
and say it is because the heliosphere isn't moving through the ISM, it is moving with it as would happen if you suspend a magnetic bubble inside a magnetic web, the entire region has the same inertial reference frame


That seems plausible. I think that once Voyager gets into the ISM, we'll have a better idea of what to look for next. That might mean building a specialized observatory, or sending a dedicated probe into the ISM with instruments specifically designed to answer whatever questions the Voyagers leave us with.

I tend to think that the ISM will teach us some things about quantum theory. The ISM is a region where quantum effects might be observed in bulk. We can't mimic that environment here on Earth, since we can't get anywhere near that level of vaccum. It might be interesting to try some fundamental experiments there.
rubberman
3 / 5 (4) Dec 20, 2012
Agreed GS. The more tech we can throw out there for the purpose of measurement and observation, the better our understanding will be. I really hope I am still kicking when the types of missions you mentioned come to fruition. There are certain aspects of the ISM which I think we'll find through voyager such as the structure in the cross section of plasma above, just larger. It may take voyager a year to record directional changes in the ISMF, or I could be way off and the region could be complete chaos...or very quiet. But given the existence of the magnetic highway I doubt that. The order of magnitude increase without a change in directionality can only come from a combination of coupling fields and an influx of charged particles from the stagnation region.
GSwift7
3 / 5 (4) Dec 20, 2012
It may take voyager a year to record directional changes in the ISMF, or I could be way off and the region could be complete chaos...or very quiet


I think that we have already seen evidence that it is chaotic. Remember that Voyager moved into and back out of the boundary zone several times before moving beyond it. That seems to indicate that the boundary shifts forward and backwards a lot. We know the solar wind is fairly constant at that distance, as well as the solar magnetic fields. Voyager measured that. So the only thing that could make the boundary region shift around so much would be variations from the other side. If we're moving 'with' the ISM, then it must be very turbulent. If we're moving 'through' it, then it must be either turbulent, varrying in density, or both. I'm leaning towards the 'both' option.
rubberman
3 / 5 (4) Dec 20, 2012
Voyager hasn't made the ISM just yet. That chaotic region was after the termination shock when the charged particles slow to sub-sonic velocities and it encountered regions that the voyager team described as "magnetic bubbles".

http://science.na...urprise/

It's kind of ironic that this linked article talks about the previous model of the suns EM field as the arcing dipole structure, they will actually have to re-incorporate this aspect of the field into the model as this article was written in June 2011 and at that point only the radial field components and the foam had been observed. Dec 04th Voyager entered the "Magnetic highway". So, to the "new model" shown in the link, the "foam" has an EM "skin" between it and the ISM. I would agree 100% that there will be deformations as an assumed constant force on either side of the skin over time is not a logical assumption.
Whydening Gyre
1 / 5 (5) Dec 23, 2012
Does anyone else here see the fluid dynamics aspect of this sort of info? Sounds suspiciously like Aether Theory is making an endaround play...
cantdrive85
1 / 5 (3) Dec 23, 2012
Does anyone else here see the fluid dynamics aspect of this sort of info? Sounds suspiciously like Aether Theory is making an endaround play...

Fluid dynamics doesn't apply to plasma.
"The fluids states of gas and liquid are treated with the Navier-Stokes equation whereas plasmas are treated with the Boltzmann and Maxwell equations."

http://plasmauniv...derstand
Whydening Gyre
1 / 5 (5) Dec 23, 2012
Does anyone else here see the fluid dynamics aspect of this sort of info? Sounds suspiciously like Aether Theory is making an endaround play...

Fluid dynamics doesn't apply to plasma.
"The fluids states of gas and liquid are treated with the Navier-Stokes equation whereas plasmas are treated with the Boltzmann and Maxwell equations."

http://plasmauniv...derstand

I don't care how someone may calculate it's actions - it still acts in a fluid LIKE manner.
cantdrive85
1 / 5 (2) Dec 24, 2012
Does anyone else here see the fluid dynamics aspect of this sort of info? Sounds suspiciously like Aether Theory is making an endaround play...

Fluid dynamics doesn't apply to plasma.
"The fluids states of gas and liquid are treated with the Navier-Stokes equation whereas plasmas are treated with the Boltzmann and Maxwell equations."

http://plasmauniv...derstand

I don't care how someone may calculate it's actions - it still acts in a fluid LIKE manner.

No, not really. It is FAR more complex and not at all fluid "like" at all. The essential point to bear in mind when considering space plasma is that it often behaves entirely unlike a gas. The charged particles which are the defining feature of a plasma are affected by electromagnetic fields, which the particles themselves can generate and modify. Fluids are not self organizing/modifying in this manner. I know I'm splitting hairs here, but it's really apples and oranges.