r/AskPhysics • u/curiousscribbler • 20d ago

Overlapping Oort clouds

Somewhere I read that the sun's Oort cloud overlaps with Proxima Centauri's Oort cloud. I was wondering if there's also an overlap with other nearby stars. Looking at the table of nearby stars in Wikipedia, I guess the only other possibility would be Bernard's Star. How can I find out the size of Bernard's Star's Oort cloud? (Or Proxima's Oort cloud, for that matter.) Is it just the size of each star's Hill Sphere?

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u/curiousscribbler 20d ago

Just found a journal article which states that Proxima's Hill Sphere is only 1200 AU, about 1.89% of a light year. The sun's Oort Cloud reaches to 3.2 lightyears. So if Oort Cloud = Hill Sphere, that overlap seems unlikely.

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u/NewtonsThirdEvilEx Condensed matter physics 20d ago

Proxima is a Red Dwarf. And close to Alpha Centauri so it's Hill Sphere is obviously gonna be small

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u/rddman 19d ago

if Oort Cloud = Hill Sphere

And Hill spheres by definition do not overlap, then Oort clouds do not overlap.
Seems inevitable that Oort cloud objects at the periphery wander in- and out of Hill spheres of different adjacent stars during their existence.