[SPACE 4e] System Design help? (star systems that is...)

[Pragmatic]

Originally Posted by Ze'Manel Cunha

What about the double planet suggestion I made, along with a third world in a separate orbit?

And what discounts the idea of three habitable large moons around a gas giant?

Could you do a "trial run" through these scenarios?

That is, I'm interested, and would like to see how it's done by the rules, so that I can apply it to my own star-building. :) So if you can provide examples of how you'd go through the rules and achieve these, I'd appreciate it. Even broad instructions would be helpful.

Thanks!

[Pomphis]

For the moons around a GG you simply put a GG in the life zone and give it 3 standard size terrestrial moons (unlikely to be rolled randomly, but possible). Then you develop the moons like any other Terrestrial. The GG is only there to anchor them in a single orbit. They may well be tidelocked to the GG, but as they still orbit the GG, they will not be tidelocked relatively to the star, so tidelocking will not make them uninhabitable. So the GG may also provide protection against tidelocking.

[Ze'Manel Cunha]

For the double planet, I prefer doing one bigger, usually about 0.2-0.4G bigger, this makes the sattelite "planet" almost a moon, except the two planets actually both orbit around a center of mass which then orbits around the star, so only one orbit around the star is taken up.

The two planets are likely tidally locked to each other and at least 1-2 million miles apart, but there's no reason they wouldn't rotate around their center of mass in a stable orbit, while the center of mass orbits the sun.

This then allows you to have the third planet in the life zone some 100 million miles or so away from the center of mass of the double planet.

For other effects on the system, just consider the total mass of the two planets as if it were one larger planet in the center of mass orbit.