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Re: (meteorobs) Fwd: How fast do Meteors go?
Lew; Look on page 121 in McKinley. He has a different formula and discusses
the reliability of these formulae.
McKinley also to "dustball" which I presume is one of these nebulous
meteors. How common or maybe I should say how rare are nebulous meteors?
Lew Gramer wrote:
> Robert, your interpretation makes a lot of sense. But it assumes that Marco
> didn't define his terms correctly. Marco's original post says:
>
> >log M(m)=2.98-0.44m-3.89log V[inf]-0.67log(sin h)
> >
> >in which m=magnitude, M=mass in kg, V[inf] is speed (infinite, not
> >geocentric) and h is the zenith distance of the radiant.
>
> In other words, Marco defines M as meteoroid mass, not meteor magnitude.
>
> Now in your interpretation, we would then assume M(m) means "mass as a
> function of magnitude", so that the magnitude could be derived as a log
> of some god-awful power of 10 (based on Vinf and h) divided by the mass!
>
> 0.4 m = log [ exp(2.98-3.89logVinf-0.67log(sin h)) / M ]
>
> Lordy... Does that make any sense? It may: but aren't there any second-
> order terms in this magnitude function then?? Shoot, I'm going straight
> home tonight to check through my copies of Oepik and D.W.R. McKinley! :)
>
> As for that funky "Vinf" term, Robert, it was discussed last Summer: it
> is the atmospheric entry velocity of the meteor, which takes into account
> not only the meteoroid's orbital velocity relative to Earth (which seems
> to be called 'Vgeo'), but also the Earth's gravitational attraction on the
> meteoroid, and Earth's rotational velocity - and maybe other things, too?
>
> Clear skies,
> Lew Gramer
>
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