Researchers reveal model of Sun's magnetic field

May 22, 2013
Image of sun courtesy of NASA.

Researchers at the Universities of Leeds and Chicago have uncovered an important mechanism behind the generation of astrophysical magnetic fields such as that of the Sun.

Scientists have known since the 18th Century that the Sun regularly oscillates between periods of high and low in an 11-year cycle, but have been unable to fully explain how this cycle is generated.

In the 'Information Age', it has become increasingly important to be able to understand the Sun's , as it is the changes in its magnetic field that are responsible for '' phenomena, including and coronal . When this weather heads in the direction of Earth it can damage satellites, endanger astronauts on the and cause power grid outages on the ground.

The research, published in the journal Nature, explains how the cyclical nature of these large-scale magnetic fields emerges, providing a solution to the governing fluids and for a large astrophysical body.

The mechanism, known as a dynamo, builds on a solution to a reduced set of equations first proposed in the 1950s which could explain the regular oscillation but which appeared to break down when applied to objects with . The mechanism takes into account the 'shear' effect of mass movement of the ionised gas, known as plasma, which makes up the Sun. More importantly it does so in the extreme parameter regime that is relevant to astrophysical bodies.

"Previously, dynamos for large, highly conducting bodies such as the Sun would be overwhelmed by small-scale fluctuations in the magnetic field. Here, we have demonstrated a new mechanism involving a shear flow, which served to damp these small-scale variations, revealing the dominant large-scale pattern", said Professor Steve Tobias, from the University of Leeds' School of Mathematics, a co-author of the research.

What is more, this mechanism could be used to describe other large, spinning astronomical bodies with large-scale magnetic fields such as galaxies.

The dynamo was developed through simulations using the high-performance computing facilities located at the University of Leeds.

"The fact that it took 50 years and huge supercomputers shows how complicated the dynamo process really is." said Prof Fausto Cattaneo, from the University of Chicago's Department of Astronomy and Astrophysics.

The presence of spots on the Sun has been known since antiquity, and further analysed after the invention of the telescope by Galileo in the 16th Century. However, their cyclic nature, with periods of high activity (lots of sunspots) and low activity (few sunspots) following each other, was not identified until the 18th Century. At the start of the 20th Century it was then recognised that these sunspots were the result of the Sun's magnetic field. Since then much effort has been devoted to understanding what processes lead to the formation of sunspots and the origin of their cyclic behaviour.

Explore further: Solar flares may disrupt GPS systems, researcher says

More information: Shear-driven dynamo waves at high magnetic Reynolds number, www.nature.com/nature/journal/v497/n7450/full/nature12177.html

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User comments : 13

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cantdrive85
1.4 / 5 (11) May 22, 2013
"Magnetic reconnection is pseudoscience" Hannes Alfven

And so too is this nonsense...
anti-geoengineering
1 / 5 (6) May 22, 2013
agreed cantdrive55
fmfbrestel
5 / 5 (5) May 22, 2013
"Magnetic reconnection is pseudoscience" Hannes Alfven

And so too is this nonsense...


maybe back when Hannes was still alive (died in 1995) but there have been multiple direct observations of magnetic reconnection.

observation around the sun: http://www.azonan...ID=26419
observation around the earth: http://www.nasa.g...wer.html
observation in a laboratory: http://adsabs.har....6.1743J

All of those observations took place after your "authority" died.

cantdrive85
1 / 5 (6) May 22, 2013
My "authority" discovered the processes behind "magnetic reconnection" over 70 years ago. The various interactions of plasma double layers is the process involved therein, what astrophysicists are trying to do is reinvent the wheel, poorly at that.

http://www.thunde...heel.htm
Fleetfoot
5 / 5 (5) May 23, 2013
My "authority" discovered the processes behind "magnetic reconnection" over 70 years ago.


But he didn't manage to understand out how the dynamo effect worked. Science moves on and the pioneers, not matter how good in their day, are left behind. Alfven didn't have the possibility of using the numerical simulation power available today.

You are constantly whining that science ignores plasma effects, well this article is clear proof that you don't know what you are talking about. A great deal of effort over many decades has gone into this breakthrough.
cantdrive85
1 / 5 (6) May 23, 2013
You are constantly whining that science ignores plasma effects, well this article is clear proof that you don't know what you are talking about. A great deal of effort over many decades has gone into this breakthrough.


LOL! When they do acknowledge plasma effects, it's clear proof they don't know what they're talking about. Frozen-in magnetic fields and "reconnection" are truly pseudoscience, yet these are tried and true "plasma effects" among astrofizzlecists. Alfven didn't understand how the standard dynamo worked because he knew how circuits work, and he knew that the dynamo was nonsense. Alfven's magnetosheric circuit still is the best most accurate model we have of solar magnetospheres.
Fleetfoot
5 / 5 (4) May 23, 2013
You are constantly whining that science ignores plasma effects, well this article is clear proof that you don't know what you are talking about. A great deal of effort over many decades has gone into this breakthrough.


LOL! When they do acknowledge plasma effects, it's clear proof they don't know what they're talking about.


It's clear YOU don't know what you're talking about.

Frozen-in magnetic fields and "reconnection" are truly pseudoscience,


Yet they are observed and the problem for 50 years has been how to model the way they work.

Alfven didn't understand how the standard dynamo worked because he knew how circuits work, and he knew that the dynamo was nonsense.


Funny how every power station on the planet finds they work just fine.
cantdrive85
1 / 5 (4) May 23, 2013
Those dynamos require an input of electrical energy to sustain them, not just mixing conductive fluids. When I refer to the "dynamo" in planetary regards I'm referring to the pseudoscience of mixing conducting fluids to create a magnetic field.

Yet they are observed and the problem for 50 years has been how to model the way they work.

Ummm, nope. Not even close. For 50 years pseudoscientists have been ignoring and misinterpreting processes that were discovered 80 years ago by Langmuir and Alfven.

The theoretical belief that allows pseudo-astrophysicists to theorize of "frozen magnetic fields" is based upon the belief that plasma is a perfect conductor. This is a spurious POV, one that ignores 80 years of laboratory plasma experiments. Astrofizzlecists however don't have any compunction to ignore such research, especially since acknowledging such a notion would be career suicide.
cantdrive85
1 / 5 (4) May 23, 2013
Thanks to Alfven we now know that there can be voltage differences between different points in plasmas. He pointed this out in his acceptance speech when receiving the Nobel Prize for physics in 1970. The electrical conductivity of any material, including plasma, is determined by two factors: the density of the population of available charge carriers (the ions) in the material, and the mobility of these carriers. In any plasma, the mobility of the ions is extremely high. Electrons and ions can move around very freely in space. But the concentration of ions available to carry charge may not be at all high if the plasma is very low pressure or diffuse. In short, although plasmas are excellent conductors, they are not perfect. It therefore follows that weak electric fields can exist inside them, and magnetic fields are NOT frozen inside them.

He explicitly pointed this out 40 years ago, yet as with most of his life, the non experts choose to ignore him.
Fleetfoot
5 / 5 (1) May 25, 2013
Those dynamos require an input of electrical energy to sustain them, not just mixing conductive fluids.


In the Sun, that would be the fusion energy released at the core, something the EU cranks deny exists.

.. based upon the belief that plasma is a perfect conductor.


Strawman, plasma is not a superconductor.

Astrofizzlecists ...


Your views may mature when your age reaches double figures.
Fleetfoot
5 / 5 (1) May 25, 2013
In short, although plasmas are excellent conductors, they are not perfect. It therefore follows that weak electric fields can exist inside them,..


Sure.

and magnetic fields are NOT frozen inside them.


You seem to be confusing weak voltages applied to a resistance with magnetic fields. They are not the same. Air is a good insulator, aluminium is a good conductor but wrap a bar magnet in cooking foil and it still picks a pin, the magnetic field passes through both.
HannesAlfven
1.6 / 5 (7) May 25, 2013
It's really incredible the extraordinary lengths that the astrophysical community will go to in order to avoid constructing a second electrodynamic model for the universe that does away with dark matter and dark energy (the problems they claim to be attempting to solve ...). One guesses that behind the public facade of confidence, there are whispers and fears that the entire theoretical structure could collapse if those alternative models were ever constructed and shown to work as well as they likely can. But, rather than just build them, so that we have something to compare their ideas against, they would prefer to just defend their existing models -- as if the very notion of building a second model is some sort of hostile attack.

These are the games that people play with science. Science itself is something very different.
HannesAlfven
1.6 / 5 (7) May 25, 2013
Re: "there have been multiple direct observations of magnetic reconnection ..."

From http://electric-c...nder.pdf (Don Scott's Rejoinder) ...

"Actually 'magnetic reconnection' has never been observed. What has been observed is the release of large amounts of energy from magnetic fields in which it was previously stored."

Re: "... observation around the earth: http://www.nasa.g...wer.html"

What about THEMIS' other observation?

From http://www.nasa.g...hts.html ...

" "THEMIS encountered its first magnetic rope on May 20," said Sibeck. "It was very large, about as wide as Earth, and located approximately 40,000 miles (70,000 km) above Earth's surface in a region called the magnetopause." ... There, the rope formed and unraveled in just a few minutes, providing a brief but significant conduit for solar wind energy."

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