[Space] Various Star System Generation Thoughts and Questions

[Agemegos]

Originally Posted by Nemoricus

2. The third star of a trinary system must orbit at a distance greater than that of the second star, but no hard rules are given for how much greater.

It is the +6 modifier on the roll for orbital separation for second companions that is supposed to handle this.

The maximum separation of a subcompanion must be no more than one-third its closest approach to any other star. If it exceeds that, its maximum separation is multiplied by 1/3.1 and its other orbital parameters adjusted accordingly, for the same reasons as in 2.

It is the -6 modifier to the roll for orbital separation of sub-companions that is supposed to handle this.

From the tables on page 105, the closest one star may approach its primary is 0.04 AU, and so I think that it would be appropriate to boost the minimum separation of a star to this value

It would better reflect the physical processes involved to remove the companion and add its mass* to the primary. There is no effect in Nature that moves companion stars outwards as their primaries swell.

(* Caution! An astronomer might come along and tell you that something more violent would in fact occur.)

2. The luminosity based inner limit can be inside the star for cool giant stars, specifically for giant stars cooler than about 3950 K. This can result in a planetary orbit being placed inside the star, especially if it is an epistellar gas giant. Contrary to my general inclination to preserve objects when possible, in this case I think it most convenient to declare that the planet is destroyed.

Indeed. Even if the outer parts of the red giant aren't actually hot enough to evaporate silicates such as enstatite drag from the stellar material will cause the planet to lose orbital speed and it will spiral in to the centre of the red giant.

In particular, what should be done if the snow line exists between the limits of the zone or if it exists inside of the zone's inner limit?

Start placing orbits just inside the outer limit and work your way inwards? That's how I read the fifthe paragraph of Step 22 (p.108).

[Nemoricus]

Originally Posted by Brett

It is the +6 modifier on the roll for orbital separation for second companions that is supposed to handle this.

It is the -6 modifier to the roll for orbital separation of sub-companions that is supposed to handle this.

Supposed to, yes, but it will fail often enough that I have to ensure that it won't happen. For two stars at distant separation, it is entirely possible that the second star will roll an orbital radius smaller than that of the first companion, for example.

Before I instituted those rules, 3 star systems in every hundred had orbital conflict problems

It would better reflect the physical processes involved to remove the companion and add its mass* to the primary. There is no effect in Nature that moves companion stars outwards as their primaries swell.

Indeed not, but physical laws are not the motivation behind my choice. Instead, it is an attempt to remain faithful to the tendency in the rules to favor preserving an object over having catastrophe befall it. See the rules for star orbits, planets that end up placed in forbidden zones, and moon orbits for examples.

Start placing orbits just inside the outer limit and work your way inwards? That's how I read the fifthe paragraph of Step 22 (p.108).

That is what I intend to use for placing the orbits within a zone if the snow line exists beyond its outer limit or if it has the No Gas Giant arrangement. The question is more one of what to do for the gas giant arrangement for each orbital zone.

My present inclination is to randomly determine the gas giant arrangement for each zone and treat results of epistellar gas giants as eccentric for outer zones. If the snow line exists within the orbital zone, it is used to place the gas giant as normal, except that it is not be inside of the inner edge of a zone. If the snow line exists inside of the zone's inner limit, the gas giant is placed at the inner limit. The rest of the orbits are then generated as normal.

[Nakawaros]

That is what I intend to use for placing the orbits within a zone if the snow line exists beyond its outer limit or if it has the No Gas Giant arrangement. The question is more one of what to do for the gas giant arrangement for each orbital zone.

My present inclination is to randomly determine the gas giant arrangement for each zone and treat results of epistellar gas giants as eccentric for outer zones. If the snow line exists within the orbital zone, it is used to place the gas giant as normal, except that it is not be inside of the inner edge of a zone. If the snow line exists inside of the zone's inner limit, the gas giant is placed at the inner limit. The rest of the orbits are then generated as normal.

I did it a bit more simply: I test to see if any of the "range" for the arrangements are available, if not, it generates as per the flags and simply places no first gas giant.