I posted similar questions a few days ago, and got "answers" that did not help. I really need somebody with a good knowledge of the pertinent physics.

I have written a VB application which computes the positions of objects acting under the influence of gravity. I am using classical equations, not general relativity equations.

First question relates to objects light years apart. Should I make corrections for such distances, which are not necessary for objects closer to each other? If corrections are required, do you know of a book or Web site which provides equations/algorithms?

Second question is more complex. It relates to two systems based on 3 massive stars (20 solar masses each). In both systems the three stars are initially equally spaced on a circle around the origin in the XY-Plane. They have initial velocities which result in their maintaining almost circular orbits around the origin and in the XY-Plane. The following two systems are based on this 3-Star system.

The first has a fourth star (5 solar masses) which is initially motionless on the Z-Axis about 1-2 light hours from the origin. Obviously, the fourth object will accelerate toward the origin and pass the 3 circling stars. It will then decelerate and reverse direction, again passing through the three circling stars.

The second system has a fourth star which is initially at the origin with a significant velocity along the Z-Axis. It will obviously reach some maximum distance from the origin, stop, and then accelerate toward the circling stars. When the fourth objects stops, this system seems very similar to the initial condition of the first system.

I expected these systems to be similar to each other, with the differing initial conditions causing them to start at different places in essentially similar histories.

My VB application indicated that in the first system, the three stars orbiting the Z-Axis moved off the XY-Plane in the direction of the initial velocity vector of the fourth object. They continue moving ever farther from the XY-Plane and seem unlikely to return to it. It seems as though they stole momentum from the fourth object.

My VB application indicates that in the second system, the three stars stay near the XY-plane. At least they do not move as far from the XY-Plane as for the first system.

If my application is correct, my intuition about these systems was seriously in error. While not surprised that my intuition was wrong, I was surprised at how bad it was.

My second question is: Could my application have some error, and my intuition be not so far off the mark? Other simulations indicate that the application is correct, but I do not have any independent data for use in verifying my results.

If you are a physicist with some pertinent knowledge, might you have a worthwhile opinion on the above? I would appreciate reliable advice.