On 16 Feb 2007 00:56:32 -0800, "George Dishman"
wrote:

On 15 Feb, 22:55, HW@....(Henri Wilson) wrote:
On 15 Feb 2007 00:41:00 -0800, "George Dishman"
wrote:
On 14 Feb, 23:29, bz wrote:
HW@....(Henri Wilson) wrote :
On Wed, 14 Feb 2007 11:25:05 +0000 (UTC), bz
wrote:
HW@....(Henri Wilson) wrote in
m:

If they travel far enough to bunch up and show variation in brightness,
they will travel far enough (at different speeds) to be coming from
different directions by the time the arrive here.

After all, they start out from different places in the sky. The slow ones
come from the side of the orbit where the star is going away from us. The
fast ones come from the side of the orbit whewre the star is approaching
us.

My guess is that the process would essentially
unify the speeds within a few tens of hours so
the displacement might not be detectable directly.
Last year Henry was tallking of tens or hundreds
of light years but now he is saying the effect
of bunching is too fast if anything, so I'm not
sure what his view is now.

I have to explain why the extinction rates for contact binaries with very short
periods and high speeds appear to be a lot faster than those required for slow
moving stars in long period orbits.

The gas stripped from one by the other may be
higher in those cases.

I don't believe that light speed unification is dependent solely on the amount
of matter present. I think the gravity fields of the source pair might have a
lot to do with the initial extinction.

No, gravity acts to oppose unification but it's
a very small effect.

Similarly, why don't all spectroscopic binaries
show extreme variability?

Because the distance/velocity combination is in the wrong range.

Which ones have you analysed?

You might say that the light has not traveled far enough yet for it to
bunch up, but then you are contradicting the idea that the velocities unify
rapidly.

More likely he will say the speeds unify so fast
there is no time for the bunching to cause
significant brightness variation. Again that comes
down to the value he chooses for extinction distance
as a function of density.

It's complicated George. For one thing, the effect appears to depend on orbit
period. ...which stands to reason because obviously the light emitted by a star
traveling towards us right now cannot unify with light that WILL BE emitted in
say 8 months time when the star is moving away.

Of course it should, the ISM hasn't changed in
that time. The distance should be independent
of the orbital parameters but probably dependent
on the type of star which will influence the
density of the stellar wind.

'Unification' is not like conventional 'extinction' even though I often call it
'extinction' for convenience.
..

On the other hand, the extinction rate for short period contact binaries is
very high. The required unification distance can be less than 1 LY.

Let's see what you get for J1909-3744.

If I know the details of the dwarf I might be able to tell you something.


George