From a University College, London Press Release – Solar winds triggered by magnetic fields
Solar wind generated by the sun is probably driven by a process involving powerful magnetic fields, according to a new study led by UCL researchers based on the latest observations from the Hinode satellite.
Scientists have long speculated on the source of solar winds. The Extreme Ultraviolet Imaging Spectrometer (EIS), on board the Japanese-UK-US Hinode satellite, is now generating unprecedented observations enabling scientists to provide a new perspective on the 50-year old question of how solar wind is driven. The collaborative study, published in this month’s issue of Astrophysical Journal, suggests that a process called slipping reconnection may drive these winds.
Deb Baker, lead author from UCL Mullard Space Science Laboratory, says: “Solar wind is an outflow of million-degree gas and magnetic field that engulfs the Earth and other planets. It fills the entire solar system and links with the magnetic fields of the Earth and other planets. Changes in the Sun’s million-mile-per-hour wind can induce disturbances within near-Earth space and our upper atmosphere and yet we still don’t know what drives these outflows.”
“However, our latest study suggests that it is the release of energy stored in solar magnetic fields which provides the additional driver for the solar wind. This magnetic energy release is most efficient in the brightest regions of activity on the Sun’s surface, called active regions or sunspot groups, which are strong concentrations of magnetic field. We believe that this fundamental process happens everywhere on the Sun on virtually all scales.”
Images taken in February 2007 from the EIS instrument showed that hot plasma outflows are due to a process called slipping reconnection. At the edges of active regions where this process can occur, a slow, continuous restructuring of the magnetic field leads to the release of energy and acceleration of particles in the Sun’s hot outer atmosphere, known as the corona. Slipping reconnection is the first theory to explain how observed outflows from the Sun can be located over areas of a single magnetic sign, something previously considered improbable.
Computer models of the Sun’s magnetic field were used to identify regions where slipping reconnection could occur. The locations proposed by the computer model were compared with measurements of the speed of the gas coming from the solar corona. The comparison showed the gas was moving outward at up to 100,000 mph, 1,000 times the wind speed in a hurricane, over the possible slipping reconnection regions.
The study was carried out by the UCL Mullard Space Science Laboratory, Observatoire de Paris, Konkoly Observatory in Hungary and Instituto de Astronomía y Física del Espacio in Argentina. Deborah Baker is funded by a Science and Technology Funding Council (STFC) studentship.
Hinode is a Japanese mission developed and launched by the Institute of Space and Astronautical Science (ISIS) and Japanese Aerospace Exploration Agency (JAXA), with the National Astronomical Observatory of Japan (NAOJ) as domestic partner and NASA and STFC (UK) as international partners. It is operated by these agencies in co-operation with the European Space Agency (ESA) and Norwegian Space Centre (NSC).
Data that served as the basis for the magnetic modelling was provided by the Solar and Heliospheric Observatory (SOHO) Michelson Doppler Imager (MDI) consortium. SOHO is a project of international cooperation between ESA and NASA.
See the Research paper in The Astrophysical Journal
Leif Svalgaard (19:37:55) :
Glenn (18:37:51) :
So does the technology exist to directly test if a moving stream of charged particles produces no current in the absence of a magnetic field?
“Of course it does, you can buy it at radioshack.”
(I’ll read the rest of your post later, first one thing at a time)
Does this mean that you agree that a moving stream of charged particles does produce an electrical current without external magnetic field influence? Or that a direct test exists. I’m just trying to get you to say what you mean straight out.
What can be had at radioshack that shields a moving plasma from all magnetic fields? I’m curious, sounds like a good science project, maybe I could figure out how to harness nuclear fusion or something.
I love having solar physicists on this blog as much as the next man (great resource), but man that’s a big horse you are on dude. I personally find myself skipping through any blog where Leif dominates, particularly when it get’s nasty (bummer really as I’m probably missing out on some good data or discussion to learn from in between the nastiness). I really don’t understand why a scientific discussion can’t be had without insults. In my opinion, if someone has a weak argument, by all means point it out, show the facts or data, but POLITELY disagree…get off the horse, let’s be polite. Let’s not poke each other with sticks out of the gate…
If someone is an idiot (probably me), the data or the argument will show it. Let that speak for itself.
That’s where this country is going, pure nastiness. Two people of differing political views (or scientific for that matter) can’t even sit at the same table and have a discussion regarding differing beliefs. It used to be in this country, that people respected differing views…not belittled them. Snip if you like, but you should really tell ALL involved and instigating parties to tone it down, regardless of perceived status.
Entrenched positions in science never lead to progress, instead belief systems take over and each side defends their model violently as if they were defending some sort of quasi-religious cult.
This thread is a classic example of two entrenched positions being defended. The laws af physics are clear. a conductor moving through a magnetic field produces an electric current, conversely an electric currant moving through a conductor produces a magnetic field. Both aspects need to be considered before any physical process can be understood. A blinkered approach will always fail – as in all areas of science, the observers position is crucial to a full understanding of events.
However, we still have much to learn about magnetism and electricity. We still have no real understanding of the mechanism of gravity, and I have a hunch that only by understanding how these three forces interact will real progress be made.
Wanting to investigate how solar wind is driven, has lead me down divergent paths. While not completly on topic, I’m struggling to agree with this statement:
“We show that a strong toroidal magnetic field stored at or below the overshoot part of the tachocline leads to a pileup of fluid at high latitude, owing to the poleward magnetic curvature stress which has to be balanced by an equatorward latitudinal hydrostatic pressure gradient.”
Prolateness of the Solar Tachocline Inferred from Latitudinal Force Balance in a Magnetohydrodynamic Shallow-Water Model (Mausumi Dikpati et al 2001)
http://www.iop.org/EJ/article/0004-637X/552/1/348/52682.html
Now, I’m goin out on a limb here, but I would think that multi-decadal variances of poloidal convection, especially in reference to diverging with and running under the tachocline region, would make plasma ebb and store more greatly. I would further rationalize that magnetic flux being regenerated and the release of the fluid involved would also increase the storage above and below the convection zone, creating a bulge, so to speak.
I say this because I would think the return of flux through the hydromagnetic dynamo would be a greater factor than the return of magnetic flux, back to the surface.
Anyone care to share on this?
Yes, I read the Yamada paper, but I don’t see where it adds to the other “magnetic reconnection” papers (if there are specific issues, please raise them).
We still have four elements addressed:
Electric field
Magnetic field
Current density
Plasma flow velocity
Failure to address any one of these elements leads to a failure to explain the physical reality in total.
Here is an abstract of a paper that backs my position.
Driving Currents for Flux Rope Coronal Mass Ejections
“We present a method for measuring electrical currents enclosed by flux rope structures that are ejected within solar coronal mass ejections (CMEs). Such currents are responsible for providing the Lorentz self-force that propels CMEs. Our estimates for the driving current are based on measurements of the propelling force obtained using data from the LASCO coronagraphs aboard the SOHO satellite. We find that upper limits on the currents enclosed by CMEs are typically around $10^{10}$ Amperes. We estimate that the magnetic flux enclosed by the CMEs in the LASCO field of view is a few $\times 10^{21}$ Mx.”
http://arxiv.org/abs/0810.4210
So, my explanation is not hanging out there by itself.
Dr. Svalgaard presents this statement: “the electric field accelerating the charged particles derives from plasma moving across the earth’s dipole magnetic field lines”
And attributes it to Dr. Anthony Peratt’s website:
http://plasmascience.net/tpu/TheUniverse.html
Problem is I can’t locate the quote.
The closest I can find is this:
Electric Fields
Electric Fields—The Source of Particle Acceleration in Cosmic Plasma
“The acceleration of a charged particle is achievable only by means of an electric field. An electric field can arise from a number of processes that include the motion of plasma across magnetic fields lines, charge separation, and time varying magnetic fields.”
http://plasmascience.net/tpu/elec_fields.html
Perhaps it is in another location on the website, but I was unable to locate after searching.
Dr. Anthony Peratt, per the website: “Regardless of scale, the motion of charged particles produces a self-magnetic field that can act on other collections of particles or plasmas, internally or externally.”
http://plasmascience.net/tpu/elec_currents.html
Gosh, I sure would like to track down that quote Dr. Svalgaard provided…
I found the quote presented by Dr. Svalgaard from Dr. Anthony Peratt’s website.
“Here, the electric field accelerating the charged particles derives from plasma moving across the earth’s dipole magnetic field lines many earth radii into the magnetosphere.”
It was in the section: Electric Currents and Transmission Lines in Space, at the subsection: Electrical Discharges in Cosmic Plasma
http://plasmascience.net/tpu/elec_currents.html
After carefully reviewing the above section, I stand corrected:
The section makes this statement: “All plasma clouds may be considered a system: they are coupled by electrical currents (charged particles beams) they induce in each other. These beams are the source of energy transfer from large, slow moving plasma to smaller plasma regions that may release the energy abruptly or cause local plasmas to pinch to the condense state.”
I take this statement to mean that the plasma flow, itself, while emanating a magnetic field, “…the motion of charged particles produces a self-magnetic field…”, does not express an electric current, rather, the contact of “plasma clouds” with differing physical properties causes electric currents, which in turn will effect the “contacting” plasma regions, “clouds” because of the generation of electric currents.
I was in error.
However, Dr. Peratt points out, “The acceleration of a charged particle is achievable only by means of an electric field.”, this would suggest that the electric field is the driver of so-called “magnetic reconnection.
Magnetic fields increase the current density and presumably plasma flow velocity (which would seem to contradict the above statement).
Dr. Anthony Peratt, per the website, “Except in very limited circumstances, all cosmical plasmas carry electric currents that constitute the sources of the magnetic field.”
This seems contradictory.
But perhaps, this phrase needs to be looked at: “All plasma clouds may be considered a system: they are coupled by electrical currents (charged particles beams) they induce in each other.”
Almost all plasma regions are “coupled” with other plasma regions with differing physical properties, therefore, there will be electrical currents in the plasma regions as a result of their interaction at the point of physical contact.
And these induced electrical currents can have wide-ranging impacts far from the source of the induced electrical currents.
Tenuc (02:04:49) :
“Entrenched positions in science never lead to progress, instead belief systems take over and each side defends their model violently as if they were defending some sort of quasi-religious cult.
This thread is a classic example of two entrenched positions being defended. The laws af physics are clear. a conductor moving through a magnetic field produces an electric current, conversely an electric currant moving through a conductor produces a magnetic field. Both aspects need to be considered before any physical process can be understood. A blinkered approach will always fail – as in all areas of science, the observers position is crucial to a full understanding of events.
However, we still have much to learn about magnetism and electricity. We still have no real understanding of the mechanism of gravity, and I have a hunch that only by understanding how these three forces interact will real progress be made.”
tenuc, I associate with your comment and to the extent that I fell afoul of its injuctions, I was in error.
Addendum:
Generation of large scale electric fields in coronal flare circuits
Submission August 6, 2009
“A large number of energetic electrons are generated during solar flares. They carry a substantial part of the flare released energy but how these electrons are created is not fully understood yet. This paper suggests that plasma motion in an active region in the photosphere is the source of large electric currents. These currents can be described by macroscopic circuits. Under special circumstances currents can establish in the corona along magnetic field lines. The energy released by these currents when moderate assumptions for the local conditions are made, is found be comparable to the flare energy. ”
http://arxiv.org/abs/0908.0813