Note that a distant star's ability to "perturb" the inner solar system is basically tidal force: it's the difference in how much the star attracts the Earth vs. the Sun, because if they are pulled by exactly the same acceleration then nothing is changed from the Earth and Sun's viewpoint.
So, the effect is proportional to 1/(distance)^3. I guess anything that zips around at ~10,000 AU would basically have zero effect on the inner solar system. And if we reduce the expected distance, the "target area" gets incredibly small.
So, the effect is proportional to 1/(distance)^3. I guess anything that zips around at ~10,000 AU would basically have zero effect on the inner solar system. And if we reduce the expected distance, the "target area" gets incredibly small.
I think we're safe for the time being. :)