[Space] Making a solar system with 3 (semi-) habitable planets?

[vicky_molokh]

Originally Posted by Flyndaran

I thought the exclusion zone would be about the no closer than .14 A.U. no matter the ratios.

Isn't the exclusion zone the greater of the two? (I think by now I'm too sleepy to remember stuff and follow the discussion. Goodnight all.)

[Flyndaran]

Originally Posted by vicky_molokh

Isn't the exclusion zone the greater of the two? (I think by now I'm too sleepy to remember stuff and follow the discussion. Goodnight all.)

Yes, but you could always manually shove the ratios to the smallest you feel comfortable with. If that's tighter than 1.4 ratio, it doesn't take much hand waving. The data on real systems is still too sparse to make many absolute statements.

[Anthony]

Originally Posted by vicky_molokh

Aren't exclusion zones roughly comparable to to Orbit×1.4 and Orbit/1.4? (I.e. vaguely less, such that at a ratio of 1.4 is more-or-less safe from the other orbital body's gravity.) I thought those numbers come from laws of astrophysics, not made up in G:Space. Are they real-life or not?

They are empirically observed ratios, and scale in some way with the mass of the planet, since Ceres fails to clear its orbit.

[Flyndaran]

Originally Posted by Anthony

They are empirically observed ratios, and scale in some way with the mass of the planet, since Ceres fails to clear its orbit.

Calling Ceres a planet is a bit of a leap. When you compare extraplanetary bodies to states in size it shouldn't be called a planet, in my humble opinion.

[dataweaver]

One possibility to consider is to put a brown dwarf in the primary's bio-zone (make it no more that 4% of the primary's mass, and aim for the upper limit of star sizes that have a decent chance of habitable worlds). This would create a set of five libration points that could potentially have planets (because a planet's mass is insignificant compared to a brown dwarf), and they would potentially be habitable (because a brown dwarf isn't hot enough to cause problems). A case might even be made that planets could naturally form in such spots, since the whole point of libration points is that matter found there doesn't get swept away by the two bodies' gravitational influences.

The L4 and L5 points are your best bet in this regard, since any other objects in the system that might interfere will most likely be dealt with by the brown dwarf; the L1, L2, and L3 points have a much greater risk of having their orbits perturbed by other objects in the system, so you'd have to make sure that no other worlds are close enough to cause them problems.

As well, the L1, L2, and L3 points are likely to have heating problems: the L1 and L3 points will be closer to the primary than the brown dwarf; and while I haven't worked the numbers, I suspect that the reduced distance is likely to make any planets found there too hot to be habitable.

And an L2 world would face the opposite dilemma: not only would it most likely be outside of the primary's bio-zone, but it would very likely be perpetually in the brown dwarf's shadow. This would make for an interesting world; but not a habitable one.

And finally, the brown dwarf itself would be in the primary's biozone, and so would any of its satellites. I know you didn't want moons; but the difference between "moon" and "planet" is a somewhat fuzzy one, based in part on whether the thing you're orbiting is a planet or a star: a Jupiter-sized object isn't going to have any planets orbiting it simply because it isn't big enough to manage it. A brown dwarf, being somewhere between a planet and a star, is potentially massive enough that its larger satellites might qualify as planets. I wouldn't put more than one such satellite there; even that much strains credulity. But between that one and the L4/L5 planets, you probably could manage three habitable worlds in one system.

[RyanW]

Originally Posted by dataweaver

But between that one and the L4/L5 planets, you probably could manage three habitable worlds in one system.

Habitable brown dwarf Trojans? Pretty cool idea, and one I wouldn't have thought of.

[Langy]

Originally Posted by vicky_molokh

Aren't exclusion zones roughly comparable to to Orbit×1.4 and Orbit/1.4? (I.e. vaguely less, such that at a ratio of 1.4 is more-or-less safe from the other orbital body's gravity.) I thought those numbers come from laws of astrophysics, not made up in G:Space. Are they real-life or not?

Those aren't actually from the laws of physics or anything, just how our own solar system turned up. It's called the Titius-Bode Law or Dermott's Law. As you can see on the 'actual data' section of the page, it's not perfect, and isn't really an accepted rule for people in that scientific field - the planetary science journal Icarus doesn't even allow people to publish articles trying to improve it any more.

[Flyndaran]

Some form of harmonics should apply to other systems. But what numbers those have to be is anyone's guess.

[Daigoro]

Would it be acceptable for the outermost planet to get most of its heat from volcanism rather than insolation?

[vicky_molokh]

Originally Posted by Daigoro

Would it be acceptable for the outermost planet to get most of its heat from volcanism rather than insolation?

I don't think Garden worlds can get a noticeable part of their heat from volcanism. AFAIK only hydrographics meaningfully affect BBT of Garden worlds.