Assuming three-dimensional grid points one parsec apart, and a general separation between stars of about 4 parsecs, the GM may roll 2d to determine what lies at each grid point. Add 1 to the roll in a cluster or core area. 2-9 – Empty space. 10 – Possible unusual item; roll one die. If the result is a 6, go to the Unusual Stellar Objects table (p. 149). Otherwise, there is nothing here. 11+ – Star system. Note that this is a very time-consuming method of building a star map, unless you program a computer to do it for you. See p. 148 for an alternate method of placing worlds
As many as one in three star systems may be a multiple star. Roll 2d to deter- mine how many stars there are in the sys- tem, adding 2 to the roll if the area is in a cluster or galactic core: 2-9 – Single star. 10 – Double star. 11 – Triple star. 12+ – Four or more stars – a double rotating around a double or triple, for instance – GM’s decision!
Stars fall into four size classes: main- sequence stars (average-sized stars like our own sun, and the most common), smaller dwarfs and subdwarfs, larger giants, and huge supergiants. Roll 3d: 3-5 – White dwarf (Class D). 6 – Subdwarf star (Class VI). 7-17 – Main-sequence star (Class V). 18 – Giant star; roll 3d again: 3 – Class I supergiant. 1 in 3 chance of Class Ia (the largest); 2 in 3 chance of Class Ib. 4 – Class II large giant. 5-12 – Class III giant. 13-18 – Class IV subgiant.
To determine type of a main-sequence star (Class V), roll 3d: 3 – O (Blue). 4 – B (Blue-white). 5 – A (White). 6 – F (Yellow-white). 7 – G (Yellow). 8 – K (Orange). 9-18 – M (Red). Clearly, the small, M-type red stars are by far the most common.
To determine the type of a giant, sub- giant, or supergiant star, roll 2d: 2 – O (Blue). 3 – M (Red). 4, 5 – B (Blue-white). 6-9 – K (Orange). 10-12 – A (White). Certain giant stars do not seem to exist. Ignore and re-roll the following results: O- II, O-III, O-IV and M-IV. Also ignore any Blue or Blue-white result if you are mapping an area of space other than a spiral arm or young cluster. Giant stars of types F and G are very unusual – they exist, but they are much too rare to show on a random table.
Roll 1d for a subdwarf’s color: 1 – G (Yellow). 2 – K (Orange). 3-6 – M (Red)
To generate a random “unusual object” in interstellar space, roll 3d. Supernovae, huge black holes, zones of improbability (p. 164), and white holes are too uncom- mon to appear randomly on a three-die table; the GM must place these unique objects intentionally if he wants them to exist. 3 – Neutron star. 4 – Black dwarf (no planets). 5 – X-ray star. 6, 7 – Brown dwarf, with planet-size moon(s). 8, 9 – Lost planet (gas giant). 10-13 – Lost planet (terrestrial). 14 – Flare star (red M-type). 15 – SS Cygni catastrophic vari- able; roll 2d for number of months between bursts. 16 – Center of nova shell. 17 – Center of small dark nebula; roll 1d for diameter in parsecs. 18 – Roll on Very Unusual Stellar Objects table (below).
3 – Antimatter system. 4 – Planetary nebula; diameter 1d × 0.1 pc. 5 – Pulsar. 6 – Center of dark nebula with T Tauri protostars condensing; roll 1d for diameter of nebula in parsecs, 1d for number of protostars. 7 – Black dwarf, with planets. 8 – Center of large dark nebula; roll 3d for diameter in parsecs. 9, 10 – Black hole of average stellar mass. 11 – Nova. 12 – Black hole of 10 times average stellar mass. 13 – X-ray burster. 14,15 – Natural wormhole to some- where. 16 – Star enclosed by Dyson sphere (p. 162). Star will be type F through M. 17 – Center of huge dark nebula; roll 6d for diameter in parsecs. 18 – Neutron star/pulsar surrounded by supernova remnant.