1111.0694 (A. Lazarian)
A. Lazarian
Fast reconnection of magnetic field in turbulent fluids allows magnetic
fields change their topology and connections. As a result the traditional
concept of magnetic field being frozen into plasma is no more applicable.
Plasma which is at one instance can be associated with a given magnetic field
lines at the next instant is distributed along a different set of magnetic
field lines. This diffusion is enabled by reconnection and therefore is termed
"reconnection diffusion". The astrophysical implications of this concept
include many astrophysical phenomena, e.g. heat transfer in plasmas, advection
of metals in plasmas etc. However, the most dramatic implications of the
concept are related to star formation process. The reason for that is that the
existing theory of star formation was developed assuming that the decoupling of
mass and magnetic field is due to neutrals drifting in respect to magnetic
field with entrained ions, i.e. through the process of ambipolar diffusion.
This implies that if the ionization of media gets low, the coupling of mass and
magnetic field gets better. This is not true in the presence of reconnection
diffusion. As a result, the magnetic mediated star formation proceeds very
differently. The new picture of star formation can explain existing puzzles
that face the traditional theory which appeals to the ambipolar diffusion
process. I also would like to stress that the process of reconnection diffusion
is very different from a process of accumulation of matter along magnetic field
lines that the pandits of numerical star formation frequently appeal to. I
discuss how the application of the new concept changes our understanding of
star formation and its numerical modeling.
View original:
http://arxiv.org/abs/1111.0694
No comments:
Post a Comment