Re: 3-star system mechanics

From: Michael S. Lorrey (
Date: Wed Feb 23 2000 - 08:05:38 MST

Tim Ventura wrote:

> The three-star system is intriguing when you think about what the orbit of any planets must be like--it would seem offhand (of course I'm no physicist) that the energy from the combined three suns would cook the living heck out of anything on the planet's surface--you'd think that the people in the movie would get at least three times the exposure to solar radiation, which would be immediately unhealthy, at the very least. I suppose they might get less if the planet orbited farther out from the suns, though.

>From what I've read, most binary and trinary systems are rather spread out. Alpha Centauri, for example is actually a trinary system with two sun like stars in relatively close proximity (I think the distance between is somehwere about the distance of Pluto from the sun), while the third companion, Proxima Centauri, which is currently closer to earth, is between .1 to .2 light years out from it companions.

Pluto receives extremely little energy from our sun. The sun is only a few times brighter on Pluto than Venus is from earth. Given this, I would say that while each star may have a few close companion planets, they are not likely to have any jovian types in outer orbits. The premise of Pitch Black, that the planet in question is a moon of a jovian type, is not likely IMHO. It was placed there more for the opportunity for hot visual effects and scenery than for scientific accuracy.

> I'd bet that based on the assumed requirements for an M-class star, you could theoretically calculate the mechanics of the stable 3-star system without needing much information to go on. What I mean is that with 3 stars in such close proximity to each other, the solar orbits would almost seem self-defining.....if there was an exception to the orbit, the stars would have collided long before then. THEN, if you know what the solar orbital mechanics are, I'm sure that there could only be a very few different ways that a planet could orbit around one or more of these stars in a stable manner. And whoila! The mechanics are so complicated (at least to my tired brain tonight) that you end up with the self-defining system.

They are typically like the Centauri system, with two close companions, and a third in a wide orbit.

Mike Lorrey

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