So, once upon a time I hacked Omer's python program to create a star system generator.
Yeah, there's not much left of the original at this point besides the def for dice rolls.
Anyway, it pulls from 2300 and Gurps Space, a couple other sourcebooks I found on the webs, and posts and comments here as well.
Right now the process is something like:
- pull star data to calculate snow line, inner and outer limits, BBT for stuff in orbit.
- figure out a starting point for planets. Either a big gas giant or the inner/outer edge.
- place successive worlds using resonances -- I think I stole this idea from Brett? 1.41, 1.59, etc
- roll up diameters, and then figure out density, etc.
- determine various world characteristics based on BBT and zone -- icy cores and lower density for outer, atm types, etc. I have some mods for tide-locked worlds to strip water and atmosphere down a bit -- with Gurps Space as a guideline.
Couple things I want to do differently.
1) thinking about instead of diameter, generating world mass. If I set up the ranges and odds correctly, then I can allow for a very slim chance of a gas giant in the inner system. Is there a minimum mass for an inner system GG to survive? The nice thing about computers is I can create dice-unfriendly ranges. To allow for a reasonable chance of garden worlds, I might add some mass cheats based on local BBT. Of course in the outer zone worlds are going to be either significant multiples of earth mass, or tiny fractions (moons). But inward from the snow line anything goes, really.
1a) If I want to think about orbital resonances, I assume I need to factor in eccentricity, yeah? Multiply 1.59 by the 1.02 eccentricity or similar?
2) Not entirely happy with figuring out atmospheres. Right now it's a GURPS-space thing, tied to gravity, but influenced by size. Mars-size worlds are guaranteed not to have more than a trace atm, at least in the inner system. And I wonder if that's so likely. No chance of a Mars with magnetic field and volcanism to keep a few hundred millibars around?
Of course my hacker skills aren't nearly good enough to deal with multi-star systems. Usually what I do is run the program, then go and, for example, delete worlds in Alpha Centauri A/B further out than ~3AU. And then there are systems with close-orbiting pairs, like, um... G208-044, I think? I'd have to do that manually.
The other tricky one is subgiant stars. Like Mu Herculis and Delta Pavonis. They're both presumably a lot hotter than they used to be. Not a big deal for barren rocks, but worlds in the hab and middle zone might look a little different.
Plus there's the A-type stars like Vega and Sirius. I assume that whatever's orbiting them probably hasn't even cooled yet.
Anyway, if anyone has suggestions, I'll share the file if I can make some productive changes.