Why are the 'Fixed Stars' so FIXED?

"Dr. Henri Wilson" HW@.... wrote in message
...
On Wed, 26 Sep 2007 05:32:46 -0700, George Dishman
wrote:
On 26 Sep, 11:49, HW@....(Dr. Henri Wilson) wrote:
On Wed, 26 Sep 2007 01:11:39 -0700, George Dishman
wrote:
On 25 Sep, 22:53, HW@....(Dr. Henri Wilson) wrote:
....
show as emission. What we have been discussing re
temperature is the background continuum excluding the
lines.

There is no continuum emission from the 'transparent'
layer but where there is a resonance and the opacity
is higher at that specific frequency, we see absorption.

That's a funny paragraph.
'opacity' ...'specific frequency' ...I didn't know these had the same
physical
dimensions...

Why would you imagine they would? The opacity
of the gas just above the photosphere is higher
at the specific frequency we call hydrogen Alpha
than at other frequencies between such resonances.
You even claimed you had taken pictures in H alpha.

Sorry I misread your statement...
It's OK..

I assume you read "higher than" instead
of "higher at that". No problem.

...yes..and I have been pointing out that ADoppler can cause a
considerable
shift in the planck curve.

And I have been pointing that while it _could_, we
know it _doesn't_, the actual shift is only 0.01%
and such a small shift doesn't affect temperature
determination.

If the shift is only 0.01%, so what?

So the amount of energy that falls outside a
bandpass filter from 2000 to 2400 nm because
of the shift is negligible hence the temperature
measurement based on that value is valid.

Note also that if the frequency shift were larger,
it would no longer be a black body curve but in
practice the shift is so small that is negligible.

Many stars do not exhibit black body curves so how would you now if they
were
shifted or not.

The shift is measured from specific lines,
you cannot measure a shift of 0.01% in the
continuum which is never exactly a black
body because of the finite thickness. This
is all obvious stuff Henry.

George, let's get this straight.

I think that would be a good idea, but we
have been over it several times and you
continue to ignore the numbers. Until you
start listening to my points and responding
to them, nothing will be resolved.

You say temperature is estimated by comparing the energy arriving in the
two
fliter bands and assuming a black body curve.

Almost, it doesn't assume a perfect black body
but the typical curve which is the integral
over the depth. The measurements are calibrated
for the complex shape of the filters and that
in practice absorb this effect.

I say the average light in the two bands can come from slightly different
layers with different radial velocities.

That doesn't work when you put the numbers in
though. The worst case would be if one band
was from the top of the photosphere and the
other was from the bottom. At most they are
of the order of 400km apart. The photosphere
moves by millions of km so the difference in
speed between the top and bottom is tiny, nil
if the width of the layer stays constant. If
it changed from 350km to 450km between the
times of maximum and minimum radius, that's
only a speed difference of 100km in 35 days
compared to something on the order of 30km/s
mean speed. In reality, the light comes from
almost the same depth in both bands.

ADoppler can shift the light by much
more than 0.01%

What it _might_ be is irrelevant, we know the
_actual_ shift and it is around 0.01%, my
example typical figure of 30km/s divided by c
regardless of what causes it. You can look up
the actual figure for L Car if you like.

and might easily lead to false ratios in the two bands.

As a handwaving exercise, that would appear
right but first you need to do the physics. The
degree of error is given by noting the shift is
0.01% of the frequency of the band edge and as
I showed before that is at most a fraction of a
degree. The temperature is observed to change
typically by more than 1000 degrees so an error
of less than 1 degree is completely negligible
and the temperature swing measured is valid.

I have explained all this to you several times
now so don't waste my time with more handwaving,
address the actual numbers if you still want to
argue.

George