Star Generator Formulas v1.00
*****************************
This is the first draft of a doc file that list all the formulas I used
in Star Generator v1.53a. I hope that it's better understandable than my
chaotic code. I didn't include the Alien Generator Formulas, perhaps in
the future...
These formulas were based mainly on 2300 AD and MegaTraveller rules, and
on the Accrete program. With time they will change and will become more
accurate, but for now they contain some randomness.
If these formulas look like chinese to you (even it's sometimes a little
nebulous for me...), you could always e-mail me at
aina@geocities.com (or aina@usa.net). Be patient for the answer, I could only
check my mails once per week.
*********************************************
I NOTES:
--------
* Dices:
dX means rolling a dice with X sides, so 3d6 means rolling 3 six-sided
dices.
* World types:
1 Ice Ball
2 Rock
3 Gas Giant
4 Hot House
5 Failed Core
6 Asteroid Belt
7 Chunk
8 Arid
9 Steppe
10 Terran
11 Jungle
12 Ocean
13 Desert
14 Glacier
15 Nickel-Iron
16 Stony
17 Carbonaceous
18 Icy
19 Ring
20 Brown Dwarf
* Unusual planet characteristics
1 'Extreme Vulcanism'
2 'Atmos. Contaminants'
3 'Meteors Storms'
4 'High Radiation Level'
5 'Violent Storms'
6 'Microbes'
7 'Orbital Conjunction'
8 'Rugged Terrain'
9 'Retrograde Rotation'
10 'Unstable Climate'
11 'Orbital Eccentricity'
12 'Unstable World'
13 'Strong Magnetic Field'
14 'Cloud Cover'
15 'No Axial Tilt'
16 'High Tides'
17 'Tidal Lock'
18 'Extreme Axial Tilt'
19 'Int. Lifeforms'
20 'Semi-Int. Lifeforms'
21 'High Humidity'
22 'Low Humidity'
23 'Corrosive Atmosphere'
24 'Insidious Atmosphere'
*********************************************
II STAR(S):
-----------
* Star creation: procedure star_creation
d10 Number of stars
1-4 1
5-8 2
9-10 3
d1000 spectral class d1000
(Gaia off) (Gaia on)
1 20 % Pulsar 1
80 % A II
2 20 % Black Hole 2
80 % A II
3-19 M II 3-12
20-45 A II 13-29
46-79 M III 30-39
80-99 F IV 40-59
100-209 F V 60-209
210-450 G V 210-709
451-700 K V 710-909
701-900 M V 910-950
901+ F VII NA
NA M V (main star) 950+
NA F VII (companion)
Modifier to d1000: +(b-1)*200 b=1 for main star
b=2 for the first companion
b=3 for the second companion
The companion size cannot be higher than the main star, if it's higher
replace the companion spectral class by the one just lower than the
main star. For example if the main star is a G V star, its companion
couldn't be a F V star, so replace the F V star by a K V star.
F VII, A II, Pulsar and Black Hole cannot have companion(s).
Decimal classification=d10-1 (no classification for F VII stars)
Spectral class Mass Luminosity
A II 14-0.3*dec 2200-160*dec
M III 6.3+0.31*dec 470+22*dec
F IV 2.5-0.05*dec 19-0.7*dec
F V 1.7-0.07*dec 8.1-0.7*dec
G V 1.04-0.01*dec 1.32-0.08*dec
K V 0.82-0.034*dec 0.42-0.038*dec
M V 0.48-0.027*dec 0.04-0.0039*dec
F VII 0.8 0.001
M II 20+dec 117000+2400*dec
with dec=decimal classifaction of the star
Distance between the main star and his companion:
d6 distance
(in 0.1 A.U. unit)
1 d950+50
2-6 d90+10 (if Gaia parameter On minimum distance=50)
if main star mass>2 then distance=d950+50
if main star mass>10 then distance=d700+300
Star age:
main_sequence_life=1000*mass/luminosity
if main_sequence_life>5 then star age=d50+10
else star age=random(main_sequence_life-10)+10
* Orbit creation : procedure orbit_creation
(returns the number of planets around stars and their orbit radius)
Spectral class Number of planets
F V 1d10 (Gaia On : d8+2)
G V 3d6 (Gaia On : 4d4+2)
K V 2d6
M V 1d6
Initial orbit of the first planet = 1d10
(orbit radius are given in 0.1 A.U.)
Untenable orbits (planet cannot exist due to the high temperature)
initial orbit should be superior to sqrt(lux)/10
Subsequent orbits:
1d10 Multiplier Multiply the previous robit
1 Empty orbit by the multiplier to determine
2 1.3 subsequent orbit radius. If
3 1.4 empy orbit, roll 1d6:
4 1.5 1-2 no more planets
5 1.6 3-6 Asteroid belt with
6 1.7 a subsequent orbit
7 1.8 multiplier of 1d9/10+1.1
8 1.9 (minimum orbit radius=2)
9 2.0
10 2.1
Maximum allowed orbit radius:
Single star: 400*star mass
Multiple stars: distance to companion/3
* Star system creation (Misc): main program star.pas
lux:=star luminosity+Sum of(companion_luminosity/(sqrt(companion_dist/10)))
note: the distance between the two companions of the primary star
is considered equal to the sum of the distance of
companions to primary star.
lux : effective luminosity of the star(s)
Innerzone 0 to 8.2*sqrt(lux) A.U.
Lifezone 8.2*sqrt(lux) to 12*sqrt(lux)
Outerzone 12*sqrt(lux) to the end of stellar system
*********************************************
III ASTEROID BELT
-----------------
* Asteroid Belt creation: main program star.pas
2d6-1 Belt width (in A.U.) Dices modifiers: Asteroid belt orbit radius < 1.5 A.U. : -3
1 0.01 1.5 A.U < orbit radius < 20 A.U. : -1
2 0.05
3 0.1
4 0.1
5 0.5
6 0.5
7 1
8 1.5
9 2
10 5
11 10
2d6 World type Density
2-4 Nickel-Iron d3/10+1
5-7 Stony d3/10+0.6
8-11 Carbonaceous d3/10+0.2
12 Icy d6/10
Dices modifiers: Innerzone :-4
Outerzone :+2
*********************************************
IV PLANETS:
-----------
* Planet creation (Misc): main program star.pas
If planet diameter>299999 then world type=Brown Dwarf
Gas Giants and Brown Dwarfs doesn't have mineral ressources
If Hydrography>0 and atmosphere componants different of Vacuum or
Nitrogen/Hydrogen then 8.3 % chance of water tainted (2d6>10)
* Diameter determination: procedure diametre_calcul
Core: (outerzone) 1 Rocky
2-6 Icy
(innerzone) Rocky
(lifezone) Rocky
For Rocky worlds:
diameter density
(outerzone) and (innerzone) Xd6*1000+d999 d10/10+0.3 (X=1d6)
(lifezone) (d8+8)*1000+d999 d6/10+0.7
For Icy worlds:
density=d6/10
diameter: d6 1 d6*1000+d999
2 2d6*1000+d999
3 3d6*1000+d999
4 5d6*1000+d999
5 6d6*1000+d999
6 8d6*1000+d999
* Gravity determination : procedure gravity_calcul (procunit.pas)
Snowball if Icy Core and one of these cases:
density=0.1 and diameter>39000
density=0.2 and diameter>30000
density=0.3 and diameter>26000
density=0.4 and diameter>23000
density=0.5 and diameter>21000
density=0.6 and diameter>20000
If Snowball diameter=diameter*1d10
gravity=pi*density*(diameter/1000)*169/6765
mass=pi*density*cube(diameter/2000)/813.9
* Atmosphere type determination: procedure atmos_calcul
gravity atmosphere
less than 0.1 Vacuum
0.1-0.5 30 % Thin
40 % Very Thin
30 % Vacuum
0.5-0.8 10 % Standard (30 % if Gaia On)
70 % Thin (50 % if Gaia On)
10 % Very Thin
10 % Vacuum
0.8-1.3 20 % Dense
50 % Standard (80 % if Gaia On)
10 % Thin (0 %)
10 % Very Thin (0 %)
10 % Vacuum (0 %)
1.3-2.0 70 % Dense
20 % Standard
10 % Thin
more than 2.0 Dense
(or Mass>2)
* Atmospheric Pressure: function press_calcul (procunit.pas)
aux=gravity*(0.9+d20/100)
Atmosphere Pressure
Very Dense aux*100
Dense aux*1.25
Standard aux
Thin aux*0.5
Very Thin aux*0.1
Vacuum 0
* World type determination: procedure word_calcul
atmosphere core world type
Vacuum Rocky Rock
Vacuum Icy Ice Ball
Very Thin Rocky Rock
Very Thin Icy Ice Ball
Thin Rocky Desert
Thin Icy Ice Ball
Standard Rocky Hot House (Innerzone)
Failed Core (Outerzone)
Inhabitable (Lifezone)
Standard Icy Ice Ball
Dense Rocky Hot House (Innerzone)
Failed Core (Outerzone)
Inhabitable (Lifezone)
Dense Icy Gas Giant
Hot House and Gas Giant have automatically Massive atmospheres.
Worlds with a diameter less than 1000 kms are Chunks.
If the diameter is zero the world is an Asteroid Belt.
Inhabitable world :
Dice World Dice
(Gaia factor Off) (Gaia factor On)
1-4 Glacier 1
5-8 Terran 2-8
9-10 Hot House 9-10
* Hydrography and Water Type determination: procedure water_calcul (procunit.pas)
World type Water type
Ice Ball,Desert Ice
Rock Rare Ice
Gas Giant,Brown Dwarf Crystals
Failed Core,Glacier Ice Sheets
Chunk (Lifezone,Outer Zone) Rare Ice
others None
Water type Hydrography
Rare Ice 1
Crystals 1
Ice d5*10+d10
Ice (Desert) (d5*10+d10)/4
Oceans (3d4-3)*10+d10
Ice Sheets (3d4-3)*10+d10
Hydrography World Terran Types
1-19 Arid
20-49 Steppe
50-79 Terran
80-89 40 % Terran
60 % Jungle
90-100 Ocean
* Oxygen pressure determination: function oxygene_calcul
hydrography/10 oxygene_table
0 5
1 10
2 12
3 14
4 16
5 18
6 19
7 20
8 22
9 24
10 26
If world_type=(Arid,Steppe,Terran,Jungle,Ocean) then
oxygen_pressure=oxygene_table*gravity/100
If world_type=Glacier then oxygen_pressure=(oxygene_table*gravity)/300
If atmospheric_componant is not Nitrogen/Oxygen then
oxygen_pressure=oxygen_pressure/5
* Atmospheric Components: function compos_atmos
World type Componants
Hot House Carbon Dioxyde
Gas Giant,Glacier,Brown Dwarf 70 % Methane/Ammonia/Hydrogen
30 % Hydrogen
Ice Ball,Failed Core 50 % Ammonia
50 % Methane
Arid,Steppe,Terran,Jungle,Ocean 80 % (70 % if dense atmos) Nitrogen/Oxygen
20 % (30 % if dense atmos) Exotic
Desert 70 % Carbon Dioxyde
30 % Exotic (see Exotic table)
Chunk None
Miscleanous modificators:
If Thin atmosphere then automatically the main componant is Carbon Dioxyde.
If Vacuum atmosphere then automatically there's no componant.
Exotic atmospheres table:
25 % Nitrogen
10 % Carbon Dioxyde
5 % Fluorine/Carbon Dioxyde
5 % Nitrogen/Carbon Dioxyde
5 % Chlorine/Carbon Dioxyde
10 % Chlorine
10 % Flourine
10 % Exotic
5 % Nitrogen/Chlorine
10 % Methane/Ammonia
5 % Fluorine/Nitrogen
* Orbit period determination: function orbit_calcul
period= sqrt(cube(orbit/10)/mass)*365
with cube: expression raised to the 3rd power
orbit: planet orbit in .1 A.U.
mass : stellar mass
sqrt : square root of the expression
* Rotation period determination: procedure rotation_calcul (procunit.pas)
j=1.18E-19
K=0.19
K=0.66 for Brown Dwarves and Gas Giants
K=0.33 for world with oceans and satellites
angular_velocity=sqrt(j*planet_mass*5.98E27/(K*sqr(planet_diameter*5E4)))
aux1=6.28/(3600*angular_velocity)
aux2:=(exp(0.27*ln(10/orbit)))/mass_stellar
rotation period=aux1*aux2
notes: sqr: expression raised to the 2nd power
orbit: planet orbit in 0.1 A.U.
sqrt : square root of the expression
if orbit<(9*mass_stellar) then rotation period=2
if rotation period<=2 then
rotation period=24*orbit period
if eccentricity>100 then
rotation period:=(1-eccentricity/1000)*rotation period/(1+eccentricity/1000)
planet is in resonance
if rotation period>orbit period*24 then
rotation period=24*orbit period*24
planet is in resonance
* Eccentricity determination: function eccentricity_calcul
2d6 eccentricity (in .001 unit)
2-7 0
8 d5
9 d5+5
10 d5+10
11 d5+15
12 d6: 1 d5+20
2 d25+25
3 d50+50
4 d100+100
5 d50+200
6 d600+200
* Axial tilt determination: function axial_tilt_calcul
X=2d6
X
2-11 axial tilt=2d6-2+(X/2-1)*10
12 axial tilt=38+d4*10+2d6
* Average surface temperature determination: function temp_calcul
lux=effective luminosity of the star(s)
green_effect=greenhouse effect
energy_abs=energy absorption of the world
atmosphere energy_abs green_effect
Vacuum 0.8-d50/1000 1.05
Very Thin 0.8-d50/1000 1
Thin 0.8-d190/1000 1
Standard 0.8-d190/1000 1
Dense 0.7-d200/1000 1.1
Massive 0.7-d200/1000 1.15
if Hydrography<10 then energy_abs=energy_abs+0.1
if world_type is Hot House then green_effect is 1.15
temperature=sqrt(sqrt(lux)/(orbit/10))*340*energy_abs*green_effect-273
Maximal temperature:
Glacier -15
Gas Giant -25
Brown Dwarf -25
Minimal temperature:
Hot House 40
Arid 40
Ocean 5
Jungle 20
Terran 10
Steppe 25
* Night and day temperature variation determination
atmosphere day_table day_max night_table night_max
Vacuum 0.2 5 0.2 0.05
Very Thin 0.4 4 0.5 0.1
Thin 0.5 2.5 1 0.15
Standard 0.6 1.5 3 0.3
Dense 0.8 0.8 8 0.5
Massive 1 0.1 20 0.8
Day variation temp=day_table*lux/sqrt(orbit/10)*rot/2
Max variation=(avg_temp+273)*day_max*lux/sqrt(orbit/10)
A temperature cannot be superior to 2000 ø C.
Night variation temp=night_table*rot/2
Max variation=(avg_temp+273)*night_max
variables: orbit : planet orbit radius in .1 A.U.
lux : effective luminosity of the star(s)
avg_temp: average surface temperature in ø C
* Mineral ressources determination:
mineral X(mine_k in the program)
Metal ore 70
Radioactive ore 40
Precious metal 10
Raw crystals 30
Precious gems 10
Asteroid belt are considered like a planet of 5000 km diameter.
Rings are considered like a planet of 700 km diameter and a density of
d10/10+0.3
aux1=diameter*density/200 (maximum value=120)
mineral_ressource=aux1+1dX-60 (minimum value=1)
if mineral_ressource>X then
mineral_ressource=X+(mineral_ressouce-X)/5
maximum value for mineral_ressource is 100
* Unusual characteristics determination: procedure unusual_calcul
. Rocky core and satellite(s) present:
1.33 % (1d75=1) chance of "Extreme Vulcanism"
If there's Extreme Vulcanism and atmosphere is thin or higher,
60 % chance of Atmospheric Contaminants. In this case atmospheric
componants could change:
Carbon Dioxyde ------> Carbon Dioxyde/Sulfur Dioxyde
Chlorine ------> Chlorine/Disulfur Dichloride
Flourine ------> Fluorine/Sulfur Tetrachloride
If there's Extreme Vulcanism, 40 % chance of Unstable World.
. If atmosphere thin or higher: 1.33 % (1d75=1) chance of Atmospheric
Contaminants
. Meteor Storms: 1.33 % (1d75=1) chancce
. If atmosphere is Very Thin or Vacuum: 10 % chance of High Radiation
Level
. High Radiation Level: Radioactive ore/3 % chance
0.5 % chance for miscleanous reasons (like nuclear
war...)
. Violent Storms: 3.33 % (1d30=1) if atmosphere is thin or higher.
16.66 % (1d6=1) if axial tilt<4
. Microbes : 2 % (1d50=1) if atmosphere is thin or higher
. Orbital Conjunction: 0.5 % (1d200=1)
. Rugged Terrain : 2 % (1d50=1) should have a rocky core and the world
type should be different of Ocean planet.
. Unstable Climat: 2 % (1d50=1) if atmosphere is thin or higher
. Cloud Cover : 16.6 % (1d6=1) if atmosphere is standard or higher
. High Tides : 16.6 % (1d6=1) if hydrography>50, and if ocean and
satellites are present.
. Extreme Axial Tilt : if axial tilt>50. In this case, 50 % chance of
Strong magnetic field.
. No Axial Tilt : if axial tilt<5.
. Strong Magnetic Field : 3.33 % (1d30=1)
10 % (1d10=1) if rotation period<15
. Tidal Lock : if the planet is in resonance with its star.
. Orbital Eccentricity : if eccentricity>0.250. In this case if Rocky core
then Extrem Vulcanism, with 70 % chance of
Atmospheric Contaminants if atmosphere is Standard
or higher.
. if water type=Ocean : water vapor=exp(0.698*(temperature-15))*hydrography/(0.007*gravity)
if water vapor>30000 then High Humidity
if water vapor<0.2 then Low Humidity
. Life chance determination:
Life chance Life chance
'Extreme Vulcanism' -5 Terran +25
'Atmos. Contaminants' -5 Jungle +25
'Meteors Storms' -5 Ocean +25
'High Radiation Level' -15 Arid +5
'Violent Storms' -5 Steppe +5
'Microbes' -5 Desert -45
'Orbital Conjunction' -20 Glacier -45
'Unstable Climate' -10 Failed Core -55
'Orbital Eccentricity' -5 others -200
'Strong Magnetic Field' -10 Life chance
'No Axial Tilt' +10 Nitrogen/Oxygen 0
'High Tides' -5 others -10
'Extreme Axial Tilt' -15
Life chance= 1d100 + modifiers
If Life chance> 49 then Semi-Intelligent Lifeforms present
If Life chance> 74 then Intelligent Lifeforms present
. Corrosive Atmosphere : If atmosphere componant<>(None,Nitrogen/Oxygen,
Carbon/Dioxyde,Methane) and
(Average temperature+ Day variation temp)>50.
. Insidious Atmosphere : If atmosphere componant=(Nitrogen,Methane/Ammonia
/Hydrogen,Hydrogen) and
(Average temperature+ Day variation temp)>100.
If High Radiation Level.
*********************************************
V SATELLITES:
-------------
* Number of satellites: function satellites_calcul
world type satellites
Gas Giant 2d6
Brown Dwarf d6: 1 d6-3 (minimum=0)
2-6 0
Others d6-3 (minimum=0)
* Orbital radius of satellites : function moon_orbit
(given in planetary diameters of the parent planet)
d10
1-3 factor=1
4-6 factor=2
7-10 factor=3
if diameter=0 then factor=1 (rings)
factor moon orbit
1 d7+3 (rings: 1d3)
2 d10*5+10
3 d10*10+60
* Satellites creation (Misc): procedure moon_creation
Diameter=(1d10-4)*1000+d999 km
If Diameter<0 then Diameter =1000
If the satellite diameter is higher than its mother planet diameter
divide its diameter by 2 until it's inferior to its mother planet
diameter.
Outerzone : 83.3 % Icy core (density=1d6/10)
16.7 % Rocky core (density=1d10/10+0.3)
Innerzone, Lifezone : Rocky Core
For temperature determination luminosity=luminosity+0.1 if
mother planet is Brown Dwarf.