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Lukas
2007-Oct-19, 02:28 AM
Strahl is the german word for "ray" or "beam".

Does this (http://www.sciencemag.org/cgi/content/full/287/5461/2172) help? (search for "strahl" on this page)

Cheers

tusenfem
2007-Oct-19, 05:49 AM
The solar wind is build up of all kinds of structures, the biggest one being the Parker spiral. Although usually assumed to be just a radially outflowing plasma (electrons, protons, alpha particles etc.), which is for most cases not a bad approximation, but naturally activity on the Sun, like flares and CMEs will give rise to structures.

Strahl is part of the solar wind electrons. here (http://www-ssc.igpp.ucla.edu/ssc/tutorial/solwind_magsphere_tutorial.pdf) is a tutorial on solar wind - magnetosphere interaction by Chris Russell where he shows the electron distribution in Fig. 10. To quote him:



on page 9:
Figure 10 shows angular distributions of the solar wind electrons and cuts through these distribution functions. Sometimes the electrons can be nearly isotropic. At other times, not only is there the core and halo distribution but also a narrow field-aligned high energy beam that is called the “strahl”.

part of caption Fig. 10:
Typical two-dimensional distribution functions of solar wind electrons showing cuts
through the distribution function along the magnetic field. On the left is a distribution with a noticeable strahl component along the magnetic field.


I am not sure about strahl in the sunward direction, AFAIK it is always anti-sunward. There are various ways of producing these very fast electrons.

The structures in the SW have been know for a long time. I am not sure what you mean by "how it would change the way we interprete the role of the SW".

tusenfem
2007-Oct-19, 08:10 AM
I am not sure about strahl in the sunward direction, AFAIK it is always anti-sunward. There are various ways of producing these very fast electrons.


from the adsabs.harvard.edu/abs/2002AGUFMSH11A0387E website: (can't post link?)

We examine how the sunward moving and anti-sunward moving superthermal electrons vary with distance from the Sun and assess whether or not the source of sunward moving electrons lies between 1 and 5 AU.

thanks for the link

Ah, I see, you have to be careful here. The suprathermal electrons are not the strahl but the halo electrons. It might sound nitpicking but anywho.