Close extrasolar encounter

[Dominatus]

Our solar system is translating up and down through the galactic plane, I think at something like 62 million years to get from one edge to the other. Other stars also show this behavior. My question is this... What if another star system passed close by ours? Not through our system, which is astronomically unlikely. Just near enough to us for it's gravity to have some noticeable effect, such as tugging on the sun just a little bit... This star could be a red giant, a pulsar, a neutron star, a more or less massive star than our own. It may even be a black hole.

Doesn't matter gravity, make it up. I want to see what the effects would be. How close it would have to pass to disrupt orbits, and at what point would it destabilize the system so slightly that things begin to go wrong, ie setting in motion events that lead to the ejection or collision of planets in-system. Even moons getting thrown out or colliding.

It would be really awesome if this were simulated in Universe Sandbox 2. (I don't know how well this would work as I haven't played the game yet, just watched videos on it) The star-heading-directly-at-us cliche has been overused, this is why I want to know how a much more likely event could offset things.

[Hannu]

I tested many years ago this with my own simulator. If I remember right, Jupiter sized object had to come quite close (hundred AUs) to have noticeable effect in short period (hundreds of years). My simulator was not accurate enough to simulate longer time periods. Largest position errors of planets was within few tenths of a percent of Nasa Horizon's values more than 300 years, but after that errors increased dramatically as you can expect from initial value sensitive system. I simulated 8 planets and Earth's Moon. Without Moon the timescale could have been much longer but I wanted to test my algorithm with harder system (it was a hobby project with standard Runge-Kutta 4, not fine science). Stars are order of 1000 times more massive than Jupiter and effect is proportional of distance squared, so normal star should be within thousands of AUs to have immediate effect. Such encounters are extremely rare events even in stellar timescales.

On the other hand, it seems that for example climate of the Earth is sensitive to much smaller effects in orbital parameters. And there may be some long scale effects or unstabilities. It is extremely difficult to simulate the solar system during very long periods. And if you want to take moons into account it will be much mode demanding. I do not even know how long periods the state of the art algorithms can simulate. If I remember, Horizon had predictions to 1000 year or something like that.

[magnemoe]

This should affect the orth cloud object far more than the inner planets.

Some speculations that the 60 million year interval between major mass extinctions might be related to this as it causes more comets.

The late heavy bombardment is visible on moon, it happened some hundred years after earth was formed and is belived to be an disturbance in the cuppier belt probably because Neptun was stabilizing in orbit, might also be an larger planet getting ejected.

Nothing even close to it later.