Interstellar exchange of massive objects is difficult across several light years. But as the stars orbit the galaxy the distances between them change. I don't find data for neighbor star distances which covers more than a couple of a hundred thousand years. I can imagine that it is difficult to trace their orbits further given todays uncertainties in distance measurements. But I'm interested in a purely statistical/geometrical estimation of how frequent nearby Sun-star passages have been.

• How many times has a star come closer than, for example, 1 light year from the Sun since it formed?
• How well mixed have the nearest stars become over time? What fraction of them have followed the Sun since formation and made multiple passages?

I suppose that 1 light year's distance is enough to cause disturbances in the Oort cloud and likely exhange comets.

Interstellar exchange of massive objects is difficult across several light years. But as the stars orbit the galaxy the distances between them change. I don't find data for neighbor star distances which covers more than a couple of a hundred thousand years. I can imagine that it is difficult to trace their orbits further given todays uncertainties in distance measurements. But I'm interested in a purely statistical/geometrical estimation of how frequent nearby Sun-star passages have been.

• How many times has a star come closer than, for example, 1 light year from the Sun since it formed?
• How well mixed have the nearest stars become over time? What fraction of them have followed the Sun since formation and made multiple passages?

I suppose that 1 light year's distance is enough to cause disturbances in the Oort cloud and likely encourage comets.

Interstellar exchange of massive objects is difficult across several light years. But as the stars orbit the galaxy the distances between them change. I don't find data for neighbor star distances which covers more than a couple of a hundred thousand years. I can imagine that it is difficult to trace their orbits further given todays uncertainties in distance measurements. But I'm interested in a purely statistical/geometrical estimation of how frequent nearby Sun-start passages have been.

• How many times has a star come closer than, for example, 1 light year from the Sun since it formed?
• How well mixed have the nearest stars become over time? What fraction of them have followed the Sun since formation and made multiple passages?

I suppose that 1 light year's distance is enough to cause disturbances in the Oort cloud and likely exhange comets.

Interstellar exchange of massive objects is difficult across several light years. But as the stars orbit the galaxy the distances between them change. I don't find data for neighbor star distances which covers more than a couple of a hundred thousand years. I can imagine that it is difficult to trace their orbits further given todays uncertainties in distance measurements. But I'm interested in a purely statistical/geometrical estimation of how frequent nearby Sun-star passages have been.

• How many times has a star come closer than, for example, 1 light year from the Sun since it formed?
• How well mixed have the nearest stars become over time? What fraction of them have followed the Sun since formation and made multiple passages?

I suppose that 1 light year's distance is enough to cause disturbances in the Oort cloud and likely exhange comets.