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Re: (meteorobs) What I think I know (and don't know) ...



> If I unsderstand
> right dist trails lag behind the comet with the lag being proportional to
> the time elapsed since the trail's formation.

No, that's not so simple. Particles are ejected at a certain speed, 
causing an initial  shift in semimajor axis (delta a0) and thereby 
changing the orbital period with respect to the comet. This
process forms the trail.  Gravitational perturbations by the major 
planets will now further affect the orbital periods, causing a further 
delay or accellaration of the particles. The effect of this 
can be quite dramatic and can delay or speed up 
particles. This makes things much more complicated. 

It has to be said that the delta a0 values for the 
2001 and 2002 encounters are not very different
from those having previously caused storms. For
instance, for 2001 the value was nearly identical
to that of 1966. That serves as an argument that
the trail sections we encounter in 2001 and 2002
should be quite densely populated. 

If I recall it right, in 1969 we encountered a trail and observed
quite low rates, but in that case the delta a0
value  was MUCH larger  than 
for historically storm producing trail sections; 
and this is the reason for the quite low particle
density in that distant trail section. 

Thus it appears that delta a0 and not the number
of passed years since comet perihelon 
passage matters when it comes to 
Leonid storms. 

>Have any unusual rates been
>observed during the 'off' years?

So 2001 and 2002, at least according
to the classical dust trail model, are far
from being an "off year". 



Hartwig



H. Luethen
h.luthen@botanik.uni-hamburgdot de
priv: Behnstr. 13, D-22767 Hamburg
lab: Institut fuer Allgemeine Botanik, Ohnhorststr. 18
     D-22609 Hamburg, Germany
Tel: 0049 (0)40-3800551 priv
     0049 (0)40-428-16-337



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