(Brian Tung) wrote in message ...
Abdul Ahad wrote:
Firstly, how does one go about making such future positional guesses
and secondly, how long has Alpha Centauri been in close proximity to
the Sun? Is there any projections as to how long Alpha Centauri will
stay this close?

To put it another way, if the Sun is a golf ball in San Francisco, then
alpha Centauri is another one (or two golf balls and a marble) in Los
Angeles, and Sirius is a slightly larger racquetball, accompanied by an
incredibly dense BB pellet, in Boise. Picture that for a moment, and
ask yourself how likely it is that they will interact with one another.
And remember, they move in three dimensions, not two.

Your scale illustration is a good one, makes it easier to picture
distances in every day terms. Of course, the inverse square law
governing gravitational interactivity dictates that for a system such
as Sirius which is twice as far away from the Sun as Alpha Centauri,
the force of gravity will be only a quarter as strong (other things
like relative masses, being equal). So you'd expect the Sun and Alpha
Centauri to interact 4 times as strongly between one another, compared
to the strength with which each one interacts with the Sirius system.

So I would say, from a perspective of gravitational interactivity, the
Sirius system is relatively *far removed*... but you have every right
to disagree of course!

So if Alpha Centauri is not gravitationally *connected* with the Sun,
are you saying that its just another passing star system? Is there a
3D model available to show the projected distances separating Sun from
Alpha Centauri on a time-series basis like this:-

Epoch: Distance:
================================================== ============
Now - 1 million years ?
Now - 500,000 years ?
Now - 100,000 years ?
Now 4.3 LY
Now + 1 million years ?
Now + 500,000 years ?
Now + 100,000 years ?

Its important I think...

What you require is accurate astrometry, and this has all been done
previously--most recently by the Hipparcos mission.

What about extrasolar planet detection efforts around Alpha Centauri,
to your knowledge?

Thanks for sharing your thoughts.

Abdul Ahad