From what I've read:

• 1. The Solar Wind can stop (ie. is not produced). (Ref: The Day the Solar Wind Disappeared. ).
• 2. The Solar Wind accelerates away from the Sun (ie. gets faster, the further it is from the Sun).

References:

• The [solar] wind accelerates as it moves away from the sun, like water overflowing a dam. "SOHO Reveals the Secrets of the Sun" [PDF], Scientific American, March 1997 p.45
• "... the solar wind accelerates away from the Sun" Caption at UVCS Inputs to Solar Physics CD ROM (see section Global Corona)
• "... many are hoping that SOHO will help solve several of the more puzzling riddles, such as: How the solar corona is heated; how solar wind accelerates;" in article on the Lagrangian Points // Astrophysics
• "... measurements of SOHO/LASCO, EISCAT and MERLIN [Breen et al., 2002], Helios [Schwenn et al., 1978], and Ulysses [McComas et al., 2000], indicate that the fast wind is accelerated almost to its final flow velocity within 20 Rs and a small but not negligible acceleration exists beyond 30 Rs" in Fast solar wind after the rapid acceleration in Journal of Geophysical search, Volume 109, Issue A4

I would argue that all these are consistent with an Electric Universe, but I'd be interested to hear the mainstream view.

Regards,
Ian Tresman

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Ian Tresman
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I don't answer as an expert on this, but my view of the first one is that one day the solar wind was not hitting ACE and WIND spacecraft, they are local to Earth. I don't take this as a sign that solar output of wind dropped to 2%, but rather that something interfered with the wind in our specific direction. Spacecraft that can measure solar wind, but were not in the vicinity of Earth did not detect this particular drop. Such drops are uncommon, but not unheard of. So the question is: what stopped the solar wind from common toward the Earth for a day? It is questions like this that make us study space-weather, and the sun.

Concerning the second one, the solar wind is accelerated out to about the orbit of Mercury, and then it coasts away from the sun until it hits the heliopause. What accelerates it out to Mercury? You may well ask what causes the Corona? These two phenomena certainly seem linked. As to the specifics, again, this is an interesting area of study, with plenty of research opportunities available.

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That sounds quite reasonable.

Regards,
Ian Tresman

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The solar wind can stop: On this, Antoniseb appears to be on the mark. See Interplanetary scintillation observations for the solar wind disappearance event of May 1999, H.O. Vats, et al., Journal of Geophysical Research - Space Physics 106 (A11): 25121-25124 NOV 1 2001. They were able to determine, by observing the scintillation of radio sources through the solar wind plasma, that the plasma density was anomalously low around Earth, and normal elsewhere. They conclude that "IPS and in situ measurements show that a large, tenuous, and slow plasma cloud engulfed our planet around this time, which could be because of a corotating low-density narrow stream. From the source (Sun) point of view, this was mostly a normal plasma flow in most of the interplanetary medium."

Acceleration of the solar wind: The standard theory is that the acceleration of the solar wind is a combination of thermal pressure, MHD waves (including magnetosonic waves), and ion-cyclotron waves. Thermal pressure will do most of the work for the slow solar wind, but the fast solar wind requires non-thermal mechanisms. The details are complicated, but there are a number of good books about solar physics to study (The Dynamic Sun, Bhola N. Dwivedi, Cambridge University Press, 2003 and Solar Astrophysics, P.V. Foukal, Wiley-VCH, 2004, 2nd revised edition are my favorites).

So how does the EU model explain the simultaneous acceleration of negative & positive charges?

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The point of philosophy is to start with something so simple as not to seem worth stating, and to end with something so paradoxical that no one will believe it. -- Bertrand Russell

Thanks for your comments. I've been doing some background reading on the solar wind, in particular, trying to find information on the composition and velocity of the particles, especially protons (positive ions) and electrons (negative ions).

I've found details of the composition of the solar wind that either excludes, or assumes, the number of electrons, eg. see http://www.agu.org/revgeophys/ogilvi00/node2.html (95% protons (H), 4% alpha particles (He) and 1% minor ions).

Has anyone a reference to a paper that shows (a) the measured proportion of protons to electrons (b) their velocities.

For example, the CELIAS/MTOF Proton Monitor on the SOHO Spacecraft measures protons, but not electrons.

Can anyone help?

Regards,
Ian Tresman

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Ian Tresman
plasma-universe.com

The solar wind composition webpage is only interested in chemical composition. Since electrons are not nuclei, they don't count and are not discussed. The books I referred to before give very good descriptions of the physics of the solar wind, including complete composition, in the general sense. The webpage you really want is the ACE Real Time Solar Wind Data webpage. Select the Dynamic Plots page, from which you can then select the real-time plot you want. You can get magnetic field & plasma parameters, electrons and protons.

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The point of philosophy is to start with something so simple as not to seem worth stating, and to end with something so paradoxical that no one will believe it. -- Bertrand Russell

It seems to me that a tiny proportion of the ions in the interplanetary medium come from the Stellar Winds of other stars in the galaxy (just as we receive a tiny proportion of their light, and other electromagetic radiation).

I was wondering whether anyone knows if the spacecraft sensors detecting our Solar Wind is able to descern the proportion of particles from our Sun, and the proportion from extra-Stellar Wind?

I couldn't find anything at the Solar Wind Electron Proton Alpha Monitor (SWEPAM) on the Advanced Composition Explorer (ACE) Web site, and, Ulysses' Solar Wind Observations Over the Poles of the Sun (SWOOPS) Web site.

Regards,
Ian Tresman

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Ian Tresman
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I think you'll find it generally assumed that such particles are stopped at or near the heliopause of the emitting star, and so will not be detected anywhere near us.

There are cosmic rays with near-light velocities, but they are not detected in the same way.

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I think you'll find it generally assumed that such particles are stopped at or near the heliopause of the emitting star, and so will not be detected anywhere near us.[/b][/quote]
Doesn't that mean that x-billion years worth of Solar Wind is kind of caught up in the heliopause?

Or wouldn't the Solar Wind find its way through the heliopause, in the same way that the Solar Wind finds its way through the Earth's heliopause (and causes the aurora).

Regards,
Ian

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Ian Tresman
plasma-universe.com

Our solar wind hits the heliopause and leaks away into the ISM co-moving with other ISM atoms and ions in a trail behind the sun as it moves through the medium.

Other stars have done the same contributing a small amount of matter to the ISM along the way. This is about 10^36 Hydrogen ions per second, spread over a volume of between 4 to 16 x 10^36 cubic centimeters, depending on the widest diameter of the Sun's magnetic tail. So, when the sun is going through a former path of another star a few percent of the atoms in the ISM are the same protons that that former star pushed out in its wind. Some small fraction of the ISM probably does make it through the heliopause into areas where the solar wind is denser still, and then pushes the ISM atoms/ions back out from closer in. It still will never get as close to us as Neptune.

It may be possible that some ISM is coming down the Sun's magnetic poles. Potentially a small fraction of that could be joining the wind. So, yes, a tiny fraction, during the times when we are in the trail of other stars, will be the atoms that made the solar wind from other stars.

Going back to your earlier question, I don't think it would be possible for a space craft to detect a difference between protons originating from the Sun, and those that come down the poles, enter the corona, and get sent out again. Protons are protons. The Ulysses spacecraft was/is able to detect an inbound stream coming down the poles.

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Interstellar ions cannot be realistically expected to penetrate the solar system in detectable numbers. It would be hard enough for them to penetrate the heliopause, but then they would have a 100 or so AU of "uphill" journey, bucking the outgoing flow of charge solar wind.

However, interstellar neutrall atoms can easily pass through the heliopause and solar wind, and are detected; they are distinguished as interstellar by their systematic direction of travel through the solar system, a direction that is consistent with the local motion of the sun. See The Interstellar Neutral Gas Experiment on Ulysses, M. Witte, et al., Astronomy and Astrophysics Supplement Series 92(2): 333-348, January 1992, for a description of the experiment. For more recent results, see Synopsis of the interstellar He parameters from combined neutral gas, pickup ion and UV scattering observations and related consequences, E. Möbius, et al., Astronomy and Astrophysics, v.426, p.897-907 (2004); Heliospheric conditions that affect the interstellar gas inside the heliosphere, D.R. McMullin, et al., Astronomy and Astrophysics, v.426, p.885-895 (2004); Kinetic parameters of interstellar neutral helium. Review of results obtained during one solar cycle with the Ulysses/GAS-instrument, M. Witte, Astronomy and Astrophysics, v.426, p.835-844 (2004).

The chartged solar wind does "pile up" at the heliopause, but does not remain long. It does the same thing that the charged interstellar medium does, it flows back along the heliopause towards the tail of the heliosphere (which is no more "spherical" than Earth's magnetosphere). There, it can diffuse through the much weaker magentic field.

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The point of philosophy is to start with something so simple as not to seem worth stating, and to end with something so paradoxical that no one will believe it. -- Bertrand Russell

A very small proportion of both populations of particles is swept up by orbiting bodies, still accreting in the frigid zone outside Neptune's orbit. S

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