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PostPosted: Thu Aug 21, 2008 7:24 am 
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For the past few years I've been working on an ultrarealistic planetary system generator (in FORTRAN) - unfortunately the nature of the program means that it's not going to be released to the public for years (if ever - but first I'd have to get it all working fully, then convert it all to Java, and probably add graphics stuff too). But for now at least I can show off some results.

Anyway, I've finally worked out a few really annoying and large bugs that have been stalling the project for months, so here's a couple of results. I haven't quite finished the rocky worldgen routines (I just got the size done), but I'll use the modified MGT system that I made for the MGT playtest for their UWPs:

There's a lot of info in here, most of which is generated by the program. The rest is generated by some spreadsheets that I have to calculate temperatures, tidelocking etc.

First block: Stellar data - (row number), Star type/size, age (in Ga), initial stellar mass (in Sols), current stellar mass (in Sols), initial luminosity (in Sols), current luminosity (in Sols), Radius (in Sols), Metallicity, Evolutionary Phase

Second block: initial orbital zone boundaries (at initial luminosity) in AU, current orbital zone boundaries in AU (inner, habitable, earth equivalent orbit, outer zone). It's a bit confusingly worded, so this is how it works: the inner zone extends out to the distance shown in "Inner Zone", the habitable zone extends from that distance to the "Hab Zone" distance, (the Middle Zone is by implication between the "Hab Zone" distance and the "Outer Zone" distance), and the Outer Zone extends beyond the "Outer Zone" distance.

third block: Orbital data - (planet number), semimajor axis (AU), orbital eccentricity, type (1=SGG, 2=LGG, 3=Hyperjovian, 4=Rocky, 5=belt), mass, density, radius (rockies have all these set at 0 for now), perihelion (AU), aphelion (AU), hill sphere radius (AU), inner limit (AU), outer limit (AU), 4:1 orbital resonance (AU), 2:1 orbital resonance (AU), orbital migration ratio.

fourth block: UWPs for rocky planets.

fifth block: Fluff descriptions.

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PostPosted: Thu Aug 21, 2008 7:24 am 
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Code:
  Num Star      Age    ZMass   Mass        ZLum           Lum         Rad   Met Pha
    73 G0 V     4.064   1.048   1.048     0.9180110     1.2904449     1.071   2   1
 
ZAMS Inner Zone =    0.789   Current Inner Zone =    0.926
ZAMS Hab Zone   =    1.580   Current Hab Zone   =    1.856
ZAMS Earth Equiv=    0.958   Current Earth Equiv=    1.136
ZAMS Outer Zone =    2.429   Current Outer Zone =    2.880
 
Num    AU        ecc       type      mass     den       rad        peri       aph      hill     inner     outer      4:1       2:1      migrate
 1     0.200     0.072     4.000     0.000     0.000     0.000     0.186     0.214     0.001     0.182     0.216     0.079     0.126     0.842
 2     0.360     0.068     4.000     0.000     0.000     0.000     0.336     0.384     0.001     0.330     0.388     0.143     0.227     0.842
 3     0.576     0.005     4.000     0.000     0.000     0.000     0.573     0.579     0.002     0.568     0.584     0.229     0.363     0.842
 4     1.094     0.079     4.000     0.000     0.000     0.000     1.008     1.181     0.003     0.991     1.191     0.434     0.689     0.842
 5     6.263     0.027     3.000     8.312 10976.350 70017.000     6.095     6.430     0.853     2.684     8.989     2.485     3.945     0.842
 6    11.273     0.084     2.000     0.221   560.300 56320.500    10.324    12.222     0.458     8.034    13.596     4.474     7.101     0.842
 7    22.546     0.079     2.000     0.149   988.400 40850.500    20.763    24.330     0.803    16.748    26.738     8.947    14.203     0.842
 8    38.328     0.069     1.000     0.183  1734.060 36280.000    35.700    40.957     1.462    28.390    45.343    15.210    24.145     0.842

Rockies:
1  X7B0000-0
2  X400000-0
3  X400000-0
4  AA858BA-A (Temperate) Ri Ga



First, here's what turns out to be a pretty habitable system, not too different to our own solar system!

The primary star is a solo G0 V, somewhat brighter and a little more active than our own sun, and has a similar metallicity. It's about halfway through its main sequence lifespan (its total lifespan is a bit shorter than Sol's) but generally pretty stable. It's got a bit brighter since it formed, which has pushed its orbital zones outwards from their initial locations (not to the detriment of any of its planets though).

The planetary orbits are pretty stable and not very eccentric. The jovians did start out a little further from the star and migrated inwards by about 84% of their initial distances, but stopped before they could mess up rocky planets in the inner system.

Planet 1: Tidelocked Greenhouse Hellhole. It's pretty much exactly like Venus, but even hotter and tidelocked (with earthlike density). This close to the star the atmosphere might be a bit thinner, but the base temperature (without greenhouse effect) is still about 664 K. There's ferocious winds from the dayside to nightside that keeps the planet at a uniform temperature, probably around 800-900 K. Not a nice place to be.

Planet 2 and 3: Pretty much identical rockballs. Both worlds are tidelocked rockball with no atmospheres, though the inner world is somewhat denser than the outer one.

Planet 4: Jackpot! Somewhat larger and denser than Earth (8000 km radius) and with a surface gravity of 1.37G, this planet is half covered by oceans and has a dense, breathable atmosphere and earthlike temperature extremes. It is geologically active world with plate tectonics and volcanoes, and probably a large moon too (which seems to be a necessity for life). At just over 4 billion years old, it's a few hundred million years younger than Earth - and when Earth was 4 billion years old we were in the Cambrian era and complex life was just starting!. However, I'll say that this planet's a bit more advanced than that, and already has a decent biosphere in land and sea (roughly equivalent in complexity to the Permian era on Earth), so there's oxygen in the air, lots of sea life, amphibians, reptiles and dinosaur equivalents on land. The air is about 10% O2, with about 85% N2 and 5% Helium (which makes for somewhat vivid aurorae), but the dense atmosphere increases the oxygen pressure enough for it to be breathable unaided by humans. A few hundred million people call this world home, and enjoy a high TL and have a fully functional starport and shipyard.

Planet 5: About 5 AU further out from our habitable world orbits a monstrous hyperjovian. Weighing in at over eight jupiter masses (crammed into a body that's the same size as Jupiter, so it's much denser), this planet's gravitational influence ejected a LGG from the system that was in an orbit between it and the rockies (which explains the large orbital gap). The hyperjovian emits a lot more radiation than it receives from its primary star, and early in its history was certainly warm enough to drive off ice in the inner part of its protojovian disk - its moons are therefore likely to be rocky bodies, and given the jovian's mass they can potentially be the size of full blown planets (up to size 6-8). However, the moons themselves will be very cold and ice-covered (surface temperature is around 120 K).

Planets 6 and 7: These two Hydrogen Giants (LGGs) have unusually low densities, and are very similar to (but slightly smaller than) Saturn in the Sol system. They also have moons and probably spectacular ring systems. The second giant is just on the borderline of being classed as an SGG.

Planet 8: The outermost planet is a large Icy Giant (SGG) somewhat larger than but similar to Neptune in the Sol system. It's 4000 km smaller than Planet 7, but it's so dense than it's actually more massive than the inner planet. Like Neptune, it's wracked by storms and probably has a small family of moons.


One thing you should note though - this sort of system is pretty rare in my worldgen. I'll be posting some more examples of the more common ones, but here we have a relatively rare star (a G V), that's about the right age for habitable planets, that doesn't have jovians in the wrong places screwing things up, that actually has a large planet in its habitable zone, which also has managed to generate a breathable atmosphere. There's a lot of things that could prevent a habitable planet from forming in a system, but this one happens to have - entirely by chance - got everything conspiring to allow a habitable planet to form.

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PostPosted: Thu Aug 21, 2008 8:28 am 
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First: I do not know if it is okay that I post here - if not, just move the post, please. :oops:

An ultra-realistic system for world and system building would of course be most welcome. :)

A feature that might make it even more useful could be the ability to check existing systems
and planets for serious errors and problems. For example, I have quite a number of systems
and worlds in my setting, created with GURPS Space, and I had to use some handwaving to
arrive at the results I wanted. It would have been very nice to have a program that could
have given me hints as to which of my handwavings were implausible or plain silly.

Of course, I do not know how realistic others want their worlds and systems to be, but I think
that a good way to check (and modify, if necessary) already existing stuff might be welcome
to others, too.


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PostPosted: Thu Aug 21, 2008 8:36 am 
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rust wrote:
First: I do not know if it is okay that I post here - if not, just move the post, please. :oops:


Well I'll be posting more here, but I'm OK with general comments about realistic worldbuilding here :). I was largely posting to show what I've got so far, and also to generate some interest in the physical processes I'm basing it on (so if you want to ask questions about what I've done and why it works like that then feel free).


Quote:
A feature that might make it even more useful could be the ability to check existing systems
and planets for serious errors and problems. For example, I have quite a number of systems
and worlds in my setting, created with GURPS Space, and I had to use some handwaving to
arrive at the results I wanted. It would have been very nice to have a program that could
have given me hints as to which of my handwavings were implausible or plain silly.


TBH it really comes with experience - make more systems, ask questions, read papers, and eventually enough sinks in that you can eventually see what is silly and what isn't :). The GURPS worldgen systems are pretty good (First In was good, haven't tried the new GURPS Space 4e one yet but it seems realistic from what I've seen). However, if I was to convert my program into RPG dice tables it'd be pretty darn complicated (if my program was all in table form it'd take you a long time to roll up a system!)!


Quote:
Of course, I do not know how realistic others want their worlds and systems to be, but I think
that a good way to check (and modify, if necessary) already existing stuff might be welcome
to others, too.


Well, it's really up to the individual. Some prefer realism, others prefer to ignore it. Obviously I prefer realism - and I think that the system I presented in my post above is ample proof that "realistic" doesn't necessarily equate to "boring".

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PostPosted: Thu Aug 21, 2008 9:27 am 
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EDG wrote:
The GURPS worldgen systems are pretty good ...


Well, if you say so, their results are good enough for my setting. :D

I would of course like to give you some meaningful feedback on your system, but all I can say is
that its results look very good and quite interesting - I lack even the basic knowledge to say more.


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PostPosted: Thu Aug 21, 2008 10:37 am 
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wibble :shock: :D

Teh Evill Dokta strikes again :mrgreen:


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PostPosted: Thu Aug 21, 2008 1:40 pm 
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Hey, mods! Spam poster above! :o

EDG, I saw you made some comments about moons, but they don't show in your output. Have you got your program generating them yet? I ask because I'm a bit of a sattelitophile :?: I probably use moons as RPG backdrops as much as I do planets.

Looking forward to seeing some of the nastier outcomes, too. :twisted:

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PostPosted: Thu Aug 21, 2008 3:18 pm 
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No moons yet. Once I get the physical stuff done for the rockies I'll see what I can do. It can't generate multiple star systems yet either (that introduces a whole raft of problems, like having to figure out unavailable orbits, but that's on the development list for later too).

I'll post some more typical results tonight.

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PostPosted: Thu Aug 21, 2008 10:57 pm 
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It looks really good...

You wouldn't by any chance be willing to share the source code would you?

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PostPosted: Thu Aug 21, 2008 11:03 pm 
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The code table is screwed from where I'm sitting. Can you post a txt file of it up at a URL, EDG?


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