OK, I'm developing a planetary system around Alpha Centauri B (yes, another fiction-related question), and I want it to have two "Earthlike" planets (a truly Earthlike planet and a Snowball Earth-like planet). The system I've got so far looks like this:
Alpha Centauri B - ~.94 Sol masses
Inner planet - ~.8 Earth masses - .73 AU orbit
with a moon like ours
Outer planet - ~.8 Earth masses - 1 AU orbit
also with a moon like ours.
The inner planet was taken from Solstation's estimate of where a planet orbit ACB would have Earthlike conditions, and the outer planet is just inside the outer radius of the point where CO2 clouds start to form in the atmosphere (I just don't want the headache of worrying about a climate with CO2 clouds).
The thing that worries me is that this is a little closer than Earth and Venus in the solar system - Venus orbits at .72 AU. Intuitively I think it shouldn't make that much of a difference - it's only a matter of .01 AU - but I don't know and that bothers me.
Is it possible to check the stability of this system? Does anyone know how?
PS, there's also a Venus-like .7 Earth mass planet in a .4 AU orbit and a Mars-like planet in a 1.5 AU orbit, but I didn't think that'd make much of a difference.