Dozens of Habitable Worlds in One System?

I want to know if this is physically possible. So at first I thought I was nuts. Then I started reading about Hill Radii, and googled left and right. Turns out a Hill Sphere is the region around an astronomical body where it is dominant in regards to attracting satellites. The Sun has a Hill "Sphere" of sorts, but close enough to Earth, the Earth's Hill Sphere is dominant.

$r_H = a(1-e)\sqrt[\leftroot{-2}\uproot{2}3]{\frac{m}{3M}}$

which simplifies to

$a\sqrt[\leftroot{-2}\uproot{2}3]{\frac{m}{3M}}$

for circular orbits, where e is eccentricity, a is the semimajor axis of the smaller object's orbit around the larger body, and m and M are the masses of the smaller and the larger object, respectively.

It occurs to me that as M grows larger and larger, the area where the gravitation of the mass-m orbiter dominates over the larger M shrinks more and more, and the degree to which planets perturb their neighbors shrinks and shrinks.

So here's the idea:

• One supermassive black hole (think > 100,000 $M_{\odot}$)
• Orbiting that, place One (1) coorbital-ring system of 7+ sun-like stars, a safe distance from the black hole, in a stupidly stable orbit.
• Farther out, a whole coterie of dozens (hundreds?) of worlds orbiting within say 0.1 AU of each other, their Hill Radii safely shrunk to the point where they barely interfere with each other.

Potential downsides:

• Planets may get tidally locked, and may get a bit, uh, unspherical.
• Despite doing the math, I still have a hard time believing that the planets would not perturb each other.

Potential upsides:

• At really ridiculously low Hill Radii, you could (have not done the math) have coorbiting planets, and have them almost touching. A Niven ring made out of planets.
• If the perturbations really bother you, just add more suns to the Sun-ring, and push the Goldilocks zone out to multiple AU.

But this could never just happen naturally! Well, duh.

posted almost 6 years ago

Serban Tanasa‭

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