(meteorobs) Hypervelocity meteors

[Pavol Habuda]

If you catch spectra of the meteor, that spectrum doesn't have 557.7 nm line.
This line doesn't belong to meteor, but hot column after it.
After meteor passes certain part of column, it takes some time to 557.7 line
to achieve maximum brightness - a few tenth of second. So, if you have 
only meteor spectrum, you don`t see 557.7 line. But in most cases, your
detector catch meteor + train light. Green line 557.7 and other
lines from train are visible in spectrum. Maybe this can be explanation.
  Second explanation, green line is good visible only between 95--110 km. 
If you have spectrum from height -- say 90 km -- green line will be missing. 
Its intensity is negligible at that heights.
Image of spectrum with green line could see here:
http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1960JRASC..54..189M&db_key=AST&page_ind=0&data_type=GIF&type=SCREEN_VIEW&classic=YES
or http://www.asu.cas.cz/~borovic/leonid.htm

I think about too small meteoroid explanation -- particle is too small 
to make changes in atmosphere to trigger filling the forbidden level in atoms.
But this seems to me not probable. Jumps in atom depends on temperature and
density, not on size of particle. And temperature of column (around 4500 K) 
don`t change much with size of particle for greater particles.


> Dear Pavol:
> 	I'm also a skeptic when it comes to these velocity claims.  With this 
> in mind, I have a question regarding your statement above re the OI 
> forbidden line at 557.7 nm.   I have seen many Perseid spectra recorded 
> on film that don't show the OI line.  On the other hand, all of my 
> image intensified spectra record this line very well.  Do you have an 
> explanation for this?
> Best regards and Happy New Year:
> Ed Majden
> 
> http://members.shaw.ca/epmajden/index.htm
> 
> 



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