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Old March 29th 07, 01:32 AM posted to sci.physics.relativity,sci.astro
Henri Wilson
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Default Why are the 'Fixed Stars' so FIXED?

On 28 Mar 2007 06:27:41 -0700, "George Dishman"
wrote:

On 28 Mar, 11:40, HW@....(Henri Wilson) wrote:
On 28 Mar 2007 02:16:59 -0700, "George Dishman" wrote:
On 28 Mar, 08:10, HW@....(Henri Wilson) wrote:



The diagram would be like this:

g h --- O


+
B

The pulsar sends one pulse from g and the next from h,
it is orbiting round the barycentre B and the observer
is at O. Obviously there is a v*cos(theta) term for
other parts of the orbit, it is the distance change
in the direction of the line of sight that matters.

I have
incorporated that by adding an Rsin(x) term to the star distance. It is
generally negligible.


It will certainly be small but it is not negligible, it
will produce a 45 degree phase shift when the ADoppler
is about 93 parts per million too and in fact we know
that the VDoppler is probably larger than the ADoppler
_except_that_ the phase can be changed by the effect you
describe at the top of the post regarding an elliptical
orbit looking circular.


I think I had it right before.
The distance for 45 deg phase difference is about 0.0007 LY.
It is independent of velocity.



"When a true genius appears in the world, you may know
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--Jonathan Swift.