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Re: (meteorobs) Fw: continuum emission in meteor spectra
----- Original Message -----
From: "Lew Gramer" <dedalus@latrade.com>
To: "Meteor Observing Mailing List" <meteorobs@jovian.com>
Sent: Thursday, June 08, 2000 10:19 AM
Subject: Re: (meteorobs) Fw: continuum emission in meteor spectra
>
> A fireball of magnitude -3 might result from a particle as small as a few
cm.,
> That tiny particle will generally be observed from a distance of at least
50
> km, but more likely on the order of 100-300 km, and perhaps as much as
> 1000 km from the observer.
>
> The amount of thermal radiation required to register at that distance,
with
> that small an emitter is (I would guess) pretty staggering, especially if
we
> consider the significant ablation and fragmenting that the particle
probably
> undergoes in flight.
Thanks for your explanation, Lew, but it seems to me that both continuous
(thermal) and line spectra would require the same intensity at a small
source to produce the same luminance at a given distance.
> Speaking of which, folks, is it possible the continuum component in meteor
> spectra could be partly the result of thermal emission from the
surrounding
> column of atmosphere?
>
Absolutely. Hot gas emits a continuous spectrum just as hot solids do. We
see this every day when the particular exothermic chemical reaction that we
call combustion releases energy at a great enough rate to heat the
surrounding air to incandescence. We call this incandescent air a "flame",
and it does, indeed, emit a continuous spectrum.
Paul O. Johnson
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