Detailed star system generation rules

[Gee4orce]

I know this is a topic that keeps popping up.. but I just saw this linked over on RPG.net, and it was too good not to share:

http://wiki.rpg.net/index.php/RTT_Worldgen

I really hope the World Builder's Handbook takes a similar approach to this. I'd still like to see even more detail as an option: axial tilt, length of day, etc.

 

[EDG]

Ugh, no thanks. I loathe "world typing", because people invariably mash evolutionary effects into physical characteristics to make a nonsensical mess. Plus who the heck is going to remember what "Cthonian" or "Gelidian" or "Helian" means (especially if there's 20-30 definitions like that). Anything beyond "Terrestrial" (i.e. rocky/icy) and "Jovian" (i.e. gaseous) is cruft.


I'd want them to properly account for:

- Star type/size and its effect on the lifespan of the system.
- System age and its effect on the planets in the system
- Effects of jovians and companion stars on orbits and planet formation.
- Multiple star systems.
- Realistic stellar distribution and evolution (properly, not the nonsense that's previously been in Traveller).
- Habitable zone evolution.
- Hot Jupiters.
- Realistic atmospheric retention.
- orbital eccentricity
- for the love of god, throw out that Bode's Law crap when doing orbits; planets don't come in fixed orbits that are the same in every system.
- Asteroid belt formation.
- I do NOT want to see white dwarfs in close orbits around stars that have habitable planets.

 

[Infojunky]

Ugh, no thanks. I loathe "world typing", because people invariably mash evolutionary effects into physical characteristics to make a nonsensical mess. Plus who the heck is going to remember what "Cthonian" or "Gelidian" or "Helian" means (especially if there's 20-30 definitions like that). Anything beyond "Terrestrial" (i.e. rocky/icy) and "Jovian" (i.e. gaseous) is cruft.

On this I have to agree. The proliferation of nomenclature is the norm in some circles, I would like to see it kept to a minimum in our shared delusion..... I mean Game. This translates to that while I understand a fair bit of jargon across a surprisingly broad swath of science and cultural acdemia, I in not way want that to be come the norm for my hobbies, they have enough all ready.

I'd want them to properly account for:

- Star type/size and its effect on the lifespan of the system.
- System age and its effect on the planets in the system
- Effects of jovians and companion stars on orbits and planet formation.
- Multiple star systems.
- Realistic stellar distribution and evolution (properly, not the nonsense that's previously been in Traveller).
- Habitable zone evolution.
- Hot Jupiters.
- Realistic atmospheric retention.
- orbital eccentricity
- for the love of god, throw out that Bode's Law crap when doing orbits; planets don't come in fixed orbits that are the same in every system.
- Asteroid belt formation.
- I do NOT want to see white dwarfs in close orbits around stars that have habitable planets.

Dude, write it. I mean you have probably the best grasp on this of all of us. And since Mongoose has basically given us free license to produce add-on material, we should.

 

[EDG]

Dude, write it. I mean you have probably the best grasp on this of all of us. And since Mongoose has basically given us free license to produce add-on material, we should.

Oh I've got a working system... it's just that it's so complex than it can't possibly be converted to tables that humans can use (it's all software right now) - I've tried, and it's got far too much calculation and interpolation. It takes my program a fraction of a second to generate a full system, but for a human I think it would take a good hour to do the same thing.

Once I figure out how to simplify it enough without losing the realism (which is going to be tricky) then I'm sure it'll be published under the OGL. Meanwhile I'm working on some realistic systems...

 

[Infojunky]

Dude, write it. I mean you have probably the best grasp on this of all of us. And since Mongoose has basically given us free license to produce add-on material, we should.

Oh I've got a working system... it's just that it's so complex than it can't possibly be converted to tables that humans can use (it's all software right now) - I've tried, and it's got far too much calculation and interpolation. It takes my program a fraction of a second to generate a full system, but for a human I think it would take a good hour to do the same thing.

Once I figure out how to simplify it enough without losing the realism (which is going to be tricky) then I'm sure it'll be published under the OGL. Meanwhile I'm working on some realistic systems...

Cool.

Understand I am fine with the Gamest system in Scout, it is bare bones enough to work for a lot, but then there are systems that just need a better level of detail.

 

[Gee4orce]

Oh I've got a working system... it's just that it's so complex than it can't possibly be converted to tables that humans can use (it's all software right now) - I've tried, and it's got far too much calculation and interpolation. It takes my program a fraction of a second to generate a full system, but for a human I think it would take a good hour to do the same thing.

Maybe we're just being unrealistic expecting that something like this is even reasonable for someone to roll up manually with dice. I think most people playing Traveller (or at least prepping a game) are going to have access to a computer capable of running system generation . So, what I'm saying is that maybe it's not unreasonable to expect world generation to actually be something you run on a computer, not roll up with dice.

I certainly wouldn't even bother rolling up a system even with the standard rules - waaay to much like manual labour for me ! But then, I can code up a program in the time it takes to roll up maybe 10 systems manually....

As for the link I posted - each to his own. I kind of liked the world classification - it's a lot easier using a single name for a world type than 'failed jupiter' or 'a bit like venus' etc.

But, EDG, you're clearly the most qualified person around here to write up a workable generation system that's somewhat realistic. Please...

 

[EDG]

So, what I'm saying is that maybe it's not unreasonable to expect world generation to actually be something you run on a computer, not roll up with dice.

TBH this is what I'm thinking too. Unfortunately releasing software means (a) making it so that it produces usable results (right now my program churns out huge text files, so the interface needs a lot of tidying) and (b) a separate license because the OGL doesn't cover software.

But, EDG, you're clearly the most qualified person around here to write up a workable generation system that's somewhat realistic. Please...

Put it this way, it's on my mind . I just need to figure out how to balance "realistic" with "workable".

 

[10harold66]

EDG, have you posted at all on the COTI boards regarding T5?

I just received the raw PDF for T5 and am interested to see if you've 1) read it and 2) have noted if its system generation rules cover the kinds of details you were hoping to see in the World Builder's Handbook.

Happy to take this elsewhere as well (just not sure where to take it!)

 

[EDG]

EDG, have you posted at all on the COTI boards regarding T5?

I just received the raw PDF for T5 and am interested to see if you've 1) read it and 2) have noted if its system generation rules cover the kinds of details you were hoping to see in the World Builder's Handbook.

No, but I've seen T5, and I'm... unimpressed by its worldbuilding rules. At best they're as lousy as previous (non-GURPS) editions - T5 isn't going to fix anything on that front and I am distinctly uninclined to help them to do so (especially given that Marc has made it very clear that he's not interested in my input. His loss, I guess).

 

[Infojunky]

EDG, have you posted at all on the COTI boards regarding T5?

I just received the raw PDF for T5 and am interested to see if you've 1) read it and 2) have noted if its system generation rules cover the kinds of details you were hoping to see in the World Builder's Handbook.

Happy to take this elsewhere as well (just not sure where to take it!)

T5 is still mired in Scouts and MT extended systems.

And here is just, in fact a more appropriate place to trash this out than behind the proprietary walls of the T5 playtest.

 

[GypsyComet]

- I do NOT want to see white dwarfs in close orbits around stars that have habitable planets.

Too much hard stuff coming off of the pair, or more a case of the right zone (if there is one at all) being too recently occupied by one star or the other to have anything solid and useful in it?

 

[EDG]

Too much hard stuff coming off of the pair, or more a case of the right zone (if there is one at all) being too recently occupied by one star or the other to have anything solid and useful in it?

No, the problem is that the white dwarf would have been a red giant beforehand, which means it'd roast (or consume) any planets close enough to be in the habitable zone of the other star.

Not to mention that being that close in the first place is problematic - you'd get some major mass transfer going on between the stars as the giant expanded to fill its roche lobe.

It's just wrong in every way, yet for some bizarre reason book 6 likes generating white dwarfs as companions.

 

[GypsyComet]

Too much hard stuff coming off of the pair, or more a case of the right zone (if there is one at all) being too recently occupied by one star or the other to have anything solid and useful in it?

No, the problem is that the white dwarf would have been a red giant beforehand, which means it'd roast (or consume) any planets close enough to be in the habitable zone of the other star.

Not to mention that being that close in the first place is problematic - you'd get some major mass transfer going on between the stars as the giant expanded to fill its roche lobe.

It's just wrong in every way, yet for some bizarre reason book 6 likes generating white dwarfs as companions.

So about the only thing in the right zone at all would be a very recent capture, and that has its own set of problems, irregular orbits being just the most obvious. Arriving with its own atmosphere is asking too much of an already "never going to happen" case...

So, are such systems going to have planets way out on the fringes? Is there enough matter available locally to have gas giants?

 

[EDG]

So about the only thing in the right zone at all would be a very recent capture, and that has its own set of problems, irregular orbits being just the most obvious. Arriving with its own atmosphere is asking too much of an already "never going to happen" case...

Capture is very unlikely anyway. Maybe systems might catch some wandering planets on the fringes of their gravitational influence, but expecting captured planets to pop up with any regularity actually within the normal planetary system is somewhat improbable.

So, are such systems going to have planets way out on the fringes? Is there enough matter available locally to have gas giants?

They're more likely to have surviving worlds in the outer zone, but again the problem is having a WD in a close orbit without it having migrated from further out (and thus disrupting any planetary orbits close to the star).

As I said elsewhere, daryen suggested that the close WDs should all be replaced by Hot Jupiters, which nicely solves the problem all round.

 

[simonh]

..... Unfortunately releasing software means (a) making it so that it produces usable results (right now my program churns out huge text files, so the interface needs a lot of tidying) and (b) a separate license because the OGL doesn't cover software.

If it's an alternate system to the one in the TMB and generates diferent stats, I don't see how Traveller licensing is relevent. Just publish it as for generic SF roleplaying.

On the other hand to be useful I suppose it would be useful to generate trade codes that are compatible with the MGT trading system, which I suppose would require some form of Traveller license.

Simon Hibbs

 

[GypsyComet]

They're more likely to have surviving worlds in the outer zone, but again the problem is having a WD in a close orbit without it having migrated from further out (and thus disrupting any planetary orbits close to the star).

As I said elsewhere, daryen suggested that the close WDs should all be replaced by Hot Jupiters, which nicely solves the problem all round.

Since such arrangements are unlikely to have useful planetary bodies, but DO exist, this raises the question of what to do with them, particularly in the context of existing (pre-MGT) data. Not everyone will want to start from scratch, after all.

Hmm. Open question. Is a "Hot Jupiter" going to be useful in the ways Traveller assumes gas giants are useful? If not, then conversion of close dwarf companions to HJs becomes one of nomenclature on the UWP, as the "star" becomes an HJ. If they ARE useful, then they come out of the GG count, and a conversion logic tree takes on another branch...

 

[EDG]

Since such arrangements are unlikely to have useful planetary bodies, but DO exist

In reality? Well, there's plenty of nova systems out there (which are essentially what you'd get if you had a WD that close to a star), but very few (if any) with short periods. The WD of the recurrent nova RS Ophiuchi has an orbital period of 455 days, which probably puts it around the 1-2 AU mark. When Traveller talks about "close orbits" it means within Orbit 0, which is within 0.2 AU - I don't think there are any nova systems that with stars that close to eachother.

this raises the question of what to do with them, particularly in the context of existing (pre-MGT) data. Not everyone will want to start from scratch, after all.

Ditch the WDs and replace with Hot Jupiters - that's about all that can be done with them. And it removes all the problems too.

Hmm. Open question. Is a "Hot Jupiter" going to be useful in the ways Traveller assumes gas giants are useful? If not, then conversion of close dwarf companions to HJs becomes one of nomenclature on the UWP, as the "star" becomes an HJ. If they ARE useful, then they come out of the GG count, and a conversion logic tree takes on another branch...

They're probably not going to be that useful - for one thing the temperature that close to the star is going to be really high (thousands of Kelvin) and the ferocious atmospheric circulation in the HJ itself is probably going to blow ships around like paper. So it's probably just a case of renaming all the WDs as HJs instead.

 

[EDG]

If it's an alternate system to the one in the TMB and generates diferent stats, I don't see how Traveller licensing is relevent. Just publish it as for generic SF roleplaying.

On the other hand to be useful I suppose it would be useful to generate trade codes that are compatible with the MGT trading system, which I suppose would require some form of Traveller license.

Correct on both points . Still, just doing the physical side of things needn't actually be done under the OGL.

 

[BP]

...right now my program churns out huge text files...

8) - How about a peek?

 

[EDG]

8) - How about a peek?

Here's an example:

   Num Star      Age    ZMass   Mass        ZLum          Lum         Rad   Met  Pha
     3 M2 V     6.108   0.331   0.331     0.0129159     0.0129861     0.331   2   1
  
ZAMS Inner Zone =    0.110   Current Inner Zone =    0.110
ZAMS Hab Zone   =    0.220   Current Hab Zone   =    0.221
ZAMS Earth Equiv=    0.114   Current Earth Equiv=    0.114
ZAMS Outer Zone =    0.288   Current Outer Zone =    0.289

Num    AU        ecc       type    mass   density    radius       peri       aph      hill     inner     outer      4:1       3:2      migrate
 1     0.100     0.054     Rocky   0.002  5000.000  5600.000     0.095     0.105     0.001     0.091     0.110     0.040     0.076     0.220
 2     0.150     0.021     Rocky   0.004  5000.000  7200.000     0.147     0.153     0.002     0.140     0.163     0.060     0.114     0.220
 3     0.414     0.222     LGG     0.111   703.700 41550.500     0.322     0.506     0.020     0.273     0.644     0.164     0.316     0.220
 4     0.911     0.162     SGG     0.166  1601.460 36112.000     0.763     1.059     0.049     0.640     1.405     0.362     0.695     0.220
  
Orbit = 0.100 AU, Radius = 5600. km, Density = 5000. kg/m3, Mass= .002 MJ, BBTemp=  297.5 K, MMW=    8.44 , Atm=  10
Orbit = 0.150 AU, Radius = 7200. km, Density = 5000. kg/m3, Mass= .004 MJ, BBTemp=  242.9 K, MMW=    4.17 , Atm=   4