Re: Solar absorption lines

Hi William,

Thanks for your reply.

The light emitted by a hot, dense substance forms a continuous
spectrum.

You give an excellent description of the concepts required to
understand a spectrum. Alas, I already understand all this
(though I wasn't familiar with the term "flash spectrum") &
my question is still not answered.

The fault is mine, however. I'm finding it difficult to formulate
my problem in words.

I'm familiar with quantisation of photons & energy levels of atoms
& how atoms can absorb & re-emit photons, etc.

What I'm trying to understand is _what_ causes the absorption lines.
Obviously, atoms in the chromosphere can absorb specific wavelengths
of the continuum. BUT, they're not absorbed forever. Indeed, a fraction
of a second later the atom re-emits a photon (and as you point out the
"flash spectrum" is proof of this).

& _unlike_ interstellar gas/dust which can scatter photons from
extra-solar stars away from an observer, the chromosphere can't
scatter photons away from the observer. (Well, as I describe
earlier in this thread, individual photons can be scattered away,
but they're compensated for by other atoms scattering photons
_toward_ the observer.)

Consult a dictionary for the meaning of convolve while you are at it.

I think my usage is correct. It is a derivative of the technical term
"convolution". See: http://en.wikipedia.org/wiki/Convolve

Though, I agree, colloquial use of the term means something different.

Scott.
.

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