[Space] Multiple/Lots of Stars in one system

[scc]

Originally Posted by Brett

It's easy. The system has to be structured as a binary tree, with planets at the leaves. Each node in the tree has two orbiting objects (stars or lower nodes), and the [minimum] orbital separation of that orbit has to be at least three times the maximum, and preferrably at least four times the average, separation of the orbit of the nodes directly below it in the tree.

There are other solutions to the equations involving rosettes and so forth, but such systems are are never observed in Nature.

I sort of get that, but here's a model of my system as it currently stands, based off of the one you provided earlier, including the sixth star and excluding the two predesigned planets (those would go around stars a and b in this tree), but I don't know what I'm supposed to do with it

         3
        / \
       /   4
      /   / \
     1   c   5
    / \     / \
   /   \   f   g
  a     2
       / \
      b   e

[Agemegos]

Okay then!

Your next step is to generate orbital separations, and to get a stable (and therefore plausible) system you want

• separation (a, 2) to be at least three times separation (b, e)
• separation (c, 5) to be at least three times separation (f, g)
• separation (1, 4) to be at least three times minimum(separation(a, 2), separation(c, 5)

I would suggest that rather than rolling, you just decide to make 1-4 a distant orbit, make a-2 and c-5 wide or wide and moderate, and then make b-e one step closer than a-2 and f-g one step closer than c-5.

That done:

• Start with a (the at-least-equal-most massive star) and calculate forbidden zones based on the orbits of 2 and 4. Then generate the system of a from inner limit radius to outer limit radius, skipping over the two forbidden zones. If you want to get fancy, use the sum of the luminosities of a, b, and e between the two forbidden zones, and combined luminosity of all six stars outside the outer forbidden zone.
• Then star again with b, calculate the forbidden zones due to a and e, and generate the system of b from the inner radius limit to the inner edge of the orbital zone forbidden by a, skipping over the zone forbidden by e. If you want to get fancy, use the sum of the luminosities of b and e between the two forbidden zones.
• Then start with star e, calculate the forbidden zone due to b, and generate the system of e from the inner radius limit to the inner edge of the forbidden zone.
• Then start with star c, calculate the zones forbidden by the orbits of 5 and 1, and generate the system from the inner radius limit to the inner edge of the zone forbidden by 1, skipping over the zone forbidden by 5. If you want to get fancy, use the sum of the luminosities of c, f, and g between the forbidden zones.
• Then start with star f, calculate the zones forbidden by the orbits of g and c, and generate the system from the inner radius limit to the inner edge of the zone forbidden by c, skipping over the zone forbidden by g. If you want to get fancy, use the sum of the luminosities of f and g between the forbidden zones.
• Then start with g, calculate the zone forbidden by the orbit with f, and generate from the inner radius limit to the inner edge of that forbidden zone.

[Nemoricus]

Originally Posted by Brett

There is a problem with that: plots work on a scale of days to decades, orbital instabilities work out over a scale of centuries to millions of years, and habitable systems develop over a scale of billions of years. If any system has habitable planets in it then it must be at least billions of years too old to still have stars or even planets in unstable orbits.

All of which I am quite well aware of. The implication in my suggestion was that *something* is maintaining this unstable configuration, as otherwise it could not have lasted into the present. I apologize for not making that clearer in my original post.

The reasons and means behind it would of course be up to the GM to decide.

[RyanW]

Originally Posted by scc

         3
        / \
       /   4
      /   / \
     1   c   5
    / \     / \
   /   \   f   g
  a     2
       / \
      b   e

According to what Brett was saying, the closest distance between a and b (min a<->b) must be greater than 3x max b<->e. Min a<->c must be at least 3x greater than max c<->f. Min c<->f must be greater than max f<->g. Basically, that's why the system doesn't actually allow you to generate distant sub-companions.

[scc]

Originally Posted by RyanW

According to what Brett was saying, the closest distance between a and b (min a<->b) must be greater than 3x max b<->e. Min a<->c must be at least 3x greater than max c<->f. Min c<->f must be greater than max f<->g. Basically, that's why the system doesn't actually allow you to generate distant sub-companions.

Cool, I think I understand what I have to do now (THINK)

I'm also thinking I should generate the stats for star 6 and see if it has any companions (I think I've got enough stuff at this point to simply fiat rule NO)

[Agemegos]

Originally Posted by RyanW

According to what Brett was saying, the closest distance between a and b (min a<->b) must be greater than 3x max b<->e. Min a<->c must be at least 3x greater than max c<->f. Min c<->f must be greater than max f<->g. Basically, that's why the system doesn't actually allow you to generate distant sub-companions.

The sequence won't generate such a system, but I think it might be plausible. In terms of the sequence, a has a first companion b and second companion c (separation a-c would be rolled at +6). e is sub-companion of b (separation b-e would be rolled at -6), f is sub-companion of c (separation f-c would be rolled at -6), and g is sub-sub companion of f. The sequence doesn't do sub-sub-companions, and has no modifiers to ensure that the separation of c and f will be wide enough and that of f and g small enough to be plausible. But if you aren't rolling the separations randomly you can hand-craft them to suit. Make sure that a-c is wide enough, so that c-f can be wide enough that f-g will fit in.

[Fred Brackin]

Originally Posted by Nemoricus

This is only true if the star's outer limit is about 32 AU, which corresponds to a .8 solar mass star. For a 2.0 solar mass star, the outer limit is 80 AU, and a star has to stay outside 240 AU to have no effect.

Stars of 2 solar massses probably die too young to have Eartk-like planets.

[Agemegos]

Yeah, their life-time on the main sequence is only about 1.3 billion years, and it took Earth about 2.2 billion years to oxidise its reducing environment and start accumulating excess oxygen.

Maybe the whole thing with biogenesis, the evolution of photosynthesis, and the production of enough oxygen to transform an Ocean World into a Garden World might go a bit quicker under some circumstances. Maybe if the visible illumination were higher, as on a planet in a relatively close orbit around a star that produced comparatively more visible light and less infra-red….

But when I crunch the numbers on that it comes out touch-and-go at best for anything hotter than about A7. Perhaps it might get lucky on rapid evolution….

[David Johnston2]

Originally Posted by Brett

Yeah, their life-time on the main sequence is only about 1.3 billion years, and it took Earth about 2.2 billion years to oxidise its reducing environment and start accumulating excess oxygen.

Maybe the whole thing with biogenesis, the evolution of photosynthesis, and the production of enough oxygen to transform an Ocean World into a Garden World might go a bit quicker under some circumstances.

We can cheat with terraforming pods.

[scc]

OK, I've changed things around and had LO Clac according to the following: If a star has a companion and orbits a star itself the first stars minimum separation from it's primary is 3 times the distance that it's companion companion minimum separation is from it, then calculate average and maximum separation based on that and eccentricity.

I may still adjust the numbers, because the maximum distance between a and e can reach 480 AU and the minimum distance between a and g can fall to 450 AU, so every few million years that part of space can get interesting and there's a small chance those stars (Or should that be Suns?) may hit each other, so something may need to change there.

On the other hand the ratio between the minimum separations from a for b and c are 2.25 and I think that could be important