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

dataweaver · 04-03-2012, 07:38 PM

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.

04-03-2012, 07:38 PM	#29
dataweaver Join Date: Aug 2004	Re: [Space] Making a solar system with 3 (semi-) habitable planets? 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.