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Re: (meteorobs) Interesting Question
Hi Everyone!!
>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?
>I hope someone can answer this, as this member is giving at talk next
>month on Terrestial Impacts, and I would like to answer his question,
>as I did not know why?
>Thanks in advance
>Kim
Hi Kim
From my information and reading in the past it is indeed ionization and re-combination that produces the persistant train seen
after a (usually brighter and faster) meteor is wittnessed.
Excitation raises electrons to a higher energy level, this is only stable for a short time, the excess energy given to both
particles of the meteoroid and the atmosphere (due to ablation of the meteoroid in the atmosphere) is lost very quickly and
re-radiated as light. This is what causes the meteor we see.
Ionization and Re-combination is only present in higher energy collisions. Ionization occurs when an electron is completly
stripped from an atom altogether. Re-combination occurs when a the positively charged atoms capture the free electrons to become
neutral again. This process also leads to the emission
light. We see this as a persistant train after the initial meteor is gone. Depending on the energy of the
collision, this can take seconds to minutes, depending on how much of the atmosphere and meteoroid
particles which were ablated are ionized.
A few figures on the subject to.
For slow meteors lght emission accounts for 0.01 % of the energy produced, ionization only 0.001%
For fast meteors, 0.1% of the energy goes to light, 0.005% goes into ionization.
I hope I have remenbered all this correctly, anyone out there who has any more info, I woould be interested too !
Adam Marsh
Asst Director, ASV Meteor Section.
Melbourne, Australia.