Absorption lines are unaffected by Doppler shift.

Paul B. Andersen wrote:
Androcles wrote:
"Mike Ruskai" wrote in message
news | On or about Sat, 15 Oct 2005 18:15:56 GMT did "Androcles" Androcles@
| MyPlace.org dribble thusly:
|
| "The spectral class [of stars] is determined by the relative
positions
| and intensities
| of the absorption lines, and these are unaffected by a Doppler shift."
| 'Nuff said, nobody could top that, not even Tom Roberts with his
| observation
|
| It's a completely correct statement. Though it does require that one
| be familiar with the term "relative", understand what it means, and
| grasp the rather significant effect upon meaning it has in the above
| statement.
|
| Absorption lines as a whole are *SHIFTED*, not spread out, which is a
| paraphrase of what's said above.
| --
| - Mike


Let there be a line at 500 nm and a line at 1000 nm.
The associated frequencies will be (according to conventional stupidity)
3.0E+08 /500.0E-09 = 6.08E+14 Hz
3.0E+08 /1000.0E-09 = 3.0E+14 Hz

Let these frequencies be Doppler-shifted (red) to 4.0E+14 Hz and 2.0E+14
Hz.
The lines will then appear at
15.0E-07
7.5E-07

1500 nm - 750 nm = 750 nm
1000 nm - 500 nn = 500 nm

So they are Doppler shifted by 0.5. Z = -0.5.
That is a blue shift.

Wavelength 1000 nm to wavelength 1500 nm is blue shift?
Wavelength 500 nm to wavelength 750 nm is blue shift?



Colour blind, Androcles?

Blatantly obviously you are.
Algebra-blind as well, as you've now demonstrated.
Androcles

"Paul B. Andersen" wrote:

snip

My statement:
"The spectral class of a star is determined by the relative
positions and intensities of the absorption lines,
and these are unaffected by a Doppler shift."
is true.

But as you have demonstrated it is possible to misinterpret
it given that you are ignorant of the conventional meaning
of Doppler shift.

In general it should go without saying, with *any* scientific
statement about "relative" properties, that the relevant measurements
are made in (or converted to) an appropriate common scale for comparison.

--
Odysseus

On Thu, 20 Oct 2005 01:25:30 GMT, Odysseus
wrote:

"Paul B. Andersen" wrote:

snip

My statement:
"The spectral class of a star is determined by the relative
positions and intensities of the absorption lines,
and these are unaffected by a Doppler shift."
is true.

But as you have demonstrated it is possible to misinterpret
it given that you are ignorant of the conventional meaning
of Doppler shift.

In general it should go without saying, with *any* scientific
statement about "relative" properties, that the relevant measurements
are made in (or converted to) an appropriate common scale for comparison.

Did you wish to comtribute something useful?
Are you just pointing out that Andersen is an idiot?

We already know that.



HW.
www.users.bigpond.com/hewn/index.htm
see: www.users.bigpond.com/hewn/variablestars.exe

"Sometimes I feel like a complete failure.
The most useful thing I have ever done is prove Einstein wrong".