I wrote this for my players way back in the early days before GDW & Digest Group incorporated stellar information
in their gaming modules. There is some information given here that you will not find in the Traveller products
that will enhance your play.
In man's conquest of space he will almost always try to find an area to inhabit that is as similar to his home world as possible. The reasoning behind this is that it will be less costly if one need not employ expensive equipment to insure ones survival. One must not however disregard the fact that this cost may be worth the gain through mining royalties etc.. In Dole's book "Habitable Planets For Man", he outlined the types of worlds and star systems that would be likely to produce habitable planets and the types of planets that humans would be able to populate easily. Most stars will have an ecozone that if a planet falls within, it will be likely to be able to produce life and/or be able to support human life.
A planet to qualify as Imperium standard must have the following characteristics:
1) Primary stellar mass greater than .7 sol and less than 1.4.
2) The radius of the planet must be from 3090-4950 miles.
3) The planetary rotation must be within 3-96 hours.
4) It must have a surface G of less than 1.5 and an axial tilt less than 81 degrees.
To determine the length of a year in 24 hour days use the following equation: y=L(43)(SM)
Where L is the light minute distance from the planet to the sun (radius), 43 is a constant(stellar luminosity gradient), and SM is the stellar mass. A standard light minute is 17,997,907 KM. In most star faring societies the light minute will be a standard unit of measure for ub-light distances due to its universal nature (the distance travelled by light in one minute).
The following chart will provide the data necessary to compile the areas that are habitable and their charateristics:
class mean lumin. temp R ecosphere mass kelvin KM inner outer
f0 1.54 4.46 7060 974455 15.1 21.8 1 1.47 3.85 6930 939653 14 20.2 2 1.4 3.02 6650 904851 12.5 17.9 3 1.84 2.82 6640 877009 11.9 17.3 4 1.28 2.32 6425 849168 10.9 15.7 5 1.24 2.07 6320 828287 10.3 14.8 6 1.18 1.72 6170 797348 9.4 13.55 7 1.14 1.55 6120 765643 8.9 12.8 8 1.10 1.37 5990 751722 8.4 12 9 1.06 1.22 5900 730841 7.9 11.4 g0 1.02 1.04 5780 702999 7.3 10.5 1 .985 .956 5710 689079 7 10.1 2 .955 .814 5545 675158 6.4 9.3 3 .930 .694 5380 661237 5.9 8.6 4 .9 .61 5300 640356 5.6 8.1 5 .87 .525 5160 626435 5.3 7.5 6 .85 .501 5160 612514 5.2 7.3 7 .825 .408 4955 598594 5.2 6.6 8 .8 .363 4870 584673 5.1 6.2 9 .775 .316 4760 570752 5.1 5.8 k0 .75 .282 4685 556831 5 5.5 1 .73 .252 4610 542910 4.9 5.2 2 .705 .219 4560 528990 4.8 5.0 3 .68 .2 4470 515069 4.7 4.9 4 .655 .162 4300 501148 4.6 4.8 5 .63 .145 4240 487227 4.5 4.7 6 .6 .123 4130 473306 4.4 4.5 7 .57 .105 4050 453817 4.3 4.4 8 .54 .09 3865 441985 4.2 4.3 9 .505 .073 3830 423192 4.1 4.2 m0 .47 .059 3720 407183 4 4.1 1 .435 .049 3600 389782 3.9 4 2 .38 .032 3350 365421 3.8 3.9 3 .33 .023 3210 341059 3.8 3.9 4 .27 .015 2990 316698 3.7 3.8 5 .22 .012 2935 292337 3.6 3.7
mass 1=1.991 times 10 to the 33rd grams, luminosity 1=standard. Temperature is in degrees kelvin, R is the radius of the star in kilometers, and the inner and outer ecosphere boundaries are in light minutes.
For example: The survey scout Donosev enters a new star system to carry out a system scan. The star is of type
g3 and measures 5324 degrees kelvin in temperature and having a standard mass for that type star. Deep radar detects
6 planets as well as a number of smaller bodies in orbit around the primary. Scanners maintain that one of
the planets falls within the ecosphere being some 6.45 light minutes out from the star. Further investigation reveals
that the planet has the following characteristics: UPP-X764???-1 The log will read the UPP as it stands as
well as the captains notes - this planet appears to be in an early stage of developement, no industrial centers
noted and no space travel evident. Population and government types can be determined with further study. I would
advise status RED for this planet and careful xenological study to determine if contact would be harmful. The planet
appears to be Imperium Standard, having a 32 hour day, no moons and an approximately 250 24 hour day year. We are
now proceeding to the next system rimward. Captain's log 245-1104.
This system of charting will enable players to determine the probability of good mining in an area and the chance
of meeting human-type xeno's. The following breakdown gives the star type with its major component of composition:
Most star atlases will give the stellar types, composition, temperatures, and other vital statistics. The most
prevelent type of star is type m with k and g being next. the most rare are types o, b, and n. N type
stars are known for heavy duchai crystal deposits on their planetary masses. When applying this to already
charted systems (i.e. the Spinward Marches) the planets that are rich, agricultural and generally of standard
type will have stars outlined in the body of the chart and will always fall within the ecozone. Airless worlds,
planets with exotic or unfit atmospheres may or may not fall within the ecozone, depending upon referee choice.
This system should help make your worlds more real and will help your play of Traveller attain a more realistic
nature.