When we pass one of these areas, we send a probe, that will stay there. Earth, and our solar system in gener

everything in our arm of the galaxy is moving at the same rate (more or less) as we are (including the empty space between thinks, so to speak) - so we won't "pass a low mass ares", sorry :)

More broadly - to "park a probe" in space and "leave it there" would need it to escape our solar system, and THEN shed the entire angular speed of this arm of the galaxy, reaching I don't-know-what escape velocity in so doing and travelling an un-imaginable distance from us first :)

I don't have the maths to explain the numbers but I'm pretty sure the reaction mass needed to do both these things (at least... ) would be astonishing...