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Re: (meteorobs) Interesting Question
In a message dated 98-09-12 01:06:14 EDT, you write:
Kim Hay<<
Just got home from our Astronomy meeting, and a fellow member and I
were talking about the meteor trains and the paths that stay
luminated for a few secs or longer.
Now since the answer to my question, is probably in the IMO handbook
or possibly I need to go and re-read the NAMN guide, why does the
train of a meteor last longer in some meteors than others.
Is there that much plasma in the meteor, or is the speed of the
meteor that makes the train persist?<<
Kim,
Meteors enter the earth's atmosphere at different speeds. For same sized
particles, this means they impart different amounts of energy as it rams thru
the atoms that makes up the atmosphere. The faster the meteor, the more
energy it has. As the meteor plows through the atmospheric atoms, they ionize
along the meteor's path...that is the atoms lose some electrons and become
charged particles. The process causes them to emit light. The ionized atoms
will immediately recombine with any loose electrons they encounter. This
happens quite fast. When it happens they no longer emit light. So the fastest
meteors will ionize the most atmospheric atoms. For them, the recombining
process takes a little longer to complete and thus appear to last a little
longer. I believe all meteors ionize atmospheric atoms and produce trains. But
the dimmer meteors usually ionize an insufficient number of atoms for our eyes
to perceive as persistent trains. Only the brighter one's are more noticeble
if their velocities are also sufficiently fast. I'm not sure where I've read
it, but the literature indicated that a +2 magnitude meteor will ionize a
column of atoms about a yard in diameter. Whereas a fireball with the object
about a foot in size will produce an ionized column about a 100 feet in
diameter.
I may not have the explanation 100% accurate here...but I believe it's in the
ball park?
GeoZay
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