World builder handbook help

T

tytalan

Cosmic Mongoose
I need some help figuring something out.
I have a single start system
F2V mass 1.46 temp 6820 Diameter 1.62 Luminosity 5.11 Mao .036 HZCO 4.68 Baseline Orbit number 4.92
(If I figure everything right)
I have a Super gas giant: Orbit 5.33 AU 3.52 with 4000 mass SAH: GLF
My questions
1) if I understand right the GG itself should have a Luminosity? What is it
2) because of its size and how close it is to the primary it’s possible for the gas giant to have its own HZCO? What is it?

how would you figure these numbers out? Please show because I’m lost.
 
It's not directly covered as luminosity, but you could derive from the Gas Giant Residual Heat formula on page 125 - Age is definitely a factor here, because it will cool with age. And then compare its diameter to one solar diameter and use the Luminosity formula on page 20 to determine luminosity for the gas giant. From that answer you can determine the HZCO from the Distance formula on the bottom of page 41. It may be inside the gas giant's surface if it's big and old.

It's unlikely to be a stable environment, because temperature will decrease with age and at that distance from the sun you're dealing with a significant amount of heat from the sun for sure and maybe the gas giant. Still, you could try to determine the temperature effects from each source individually using the first formula on page 109 for both star and gas giant at there respective distance (make sure to use the proper units) and then combining them using the second formula. If the moon's orbit has any eccentricity, then you should determine a third temperature from total seismic stress (p. 126) as well.
 
Geir said:
It's not directly covered as luminosity, but you could derive from the Gas Giant Residual Heat formula on page 125 - Age is definitely a factor here, because it will cool with age. And then compare its diameter to one solar diameter and use the Luminosity formula on page 20 to determine luminosity for the gas giant. From that answer you can determine the HZCO from the Distance formula on the bottom of page 41. It may be inside the gas giant's surface if it's big and old.

It's unlikely to be a stable environment, because temperature will decrease with age and at that distance from the sun you're dealing with a significant amount of heat from the sun for sure and maybe the gas giant. Still, you could try to determine the temperature effects from each source individually using the first formula on page 109 for both star and gas giant at there respective distance (make sure to use the proper units) and then combining them using the second formula. If the moon's orbit has any eccentricity, then you should determine a third temperature from total seismic stress (p. 126) as well.
Click to expand...
Would it make more sense if the gas giant itself was in the outer edge of the habitable zone? Having the heat from the gas giant only move the moon from a cold habitable world to a warmer one?
 
tytalan said:
Would it make more sense if the gas giant itself was in the outer edge of the habitable zone? Having the heat from the gas giant only move the moon from a cold habitable world to a warmer one?
Click to expand...
That could certainly work. The simple answer that doesn't require math is to just give it a positive DM on the Base Mean Temperature table (page 109) and call it good. You can make up a number that works.

The math way is also on that page, but first you'd have to do the whole thing of determining what temperature is added by the gas giant's 'luminosity' - computed from its temperature and diameter and the distance to the moon, which is a bit of math. Then, it has to be added using the addition equation on p. 109. Because that formula uses numbers to the fourth and fourth roots, if the temperature contribution from the gas giant is significantly less than that from the the star... it becomes basically noise.

And, you could also add a third term: the seismic factors from page 125-6. Which could become noise (say, Ganymede) or dominant (as in Io).

But it's the whole: what are you trying to accomplish? Question.

If you just want the moon to be the way you envision, there's nothing wrong with the simple DM. The math way is more for an exploratory sort of campaign where you have no preconceived notion about what you'll find and just let the the dice and a whole lot of math determine if you have a habitable world.

That's why I emphasis the whole MOARN philosophy at the front. You can make it really hard and probably accurate (even if it starts with dice rolls) or you can make easy enough to meet your goals. Doing even just a single system in full detail without a computer's help and a lot of setup takes a bunch of time.
 
Geir said:
That could certainly work. The simple answer that doesn't require math is to just give it a positive DM on the Base Mean Temperature table (page 109) and call it good. You can make up a number that works.

The math way is also on that page, but first you'd have to do the whole thing of determining what temperature is added by the gas giant's 'luminosity' - computed from its temperature and diameter and the distance to the moon, which is a bit of math. Then, it has to be added using the addition equation on p. 109. Because that formula uses numbers to the fourth and fourth roots, if the temperature contribution from the gas giant is significantly less than that from the the star... it becomes basically noise.

And, you could also add a third term: the seismic factors from page 125-6. Which could become noise (say, Ganymede) or dominant (as in Io).

But it's the whole: what are you trying to accomplish? Question.

If you just want the moon to be the way you envision, there's nothing wrong with the simple DM. The math way is more for an exploratory sort of campaign where you have no preconceived notion about what you'll find and just let the the dice and a whole lot of math determine if you have a habitable world.

That's why I emphasis the whole MOARN philosophy at the front. You can make it really hard and probably accurate (even if it starts with dice rolls) or you can make easy enough to meet your goals. Doing even just a single system in full detail without a computer's help and a lot of setup takes a bunch of time.
Click to expand...
Yea I think that’s the route I’ll go. I’m expanding out Asim for my Pirate of Drinax campaign and it came out a hot system so I thought that it would be cool if Asim is actually a moon of the Gas Giant. I also thought it would be interesting if the seasons were not determined by the planetary tilt but in stead by its orbit around the gas giant. I’m hoping to come up with an orbit around the GG that will give Asim a year around 6+ months time frame
 
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