In the local region of the Galaxy, there is about one star system per 900 cubic light-years. I suggest using cube-shaped sectors either 25 or 50 light-years on a side. A 25-light-year sector has 6D6-4 star systems (average 17); a 50-light-year sector has 16D10+50 systems (average 138; more appropriate to generation by a computer program than by hand). Place the systems at random within the sector (roll D100/4 or D100/2 for each of the X, Y, and Z coordinates).

To find the number of stars in a system, roll (3D6/4)-1; round to the nearest whole number, and count anything less than 1 as 1.

Stars are classified into seven "spectral types", based on their temperature and colour. The types are O (blue), B (blue-white), A (white), F (yellow-white), G (yellow), K (orange), and M (red); astronomers use the mnemonic "Oh, Be A Fine Girl, Kiss Me" to remember the sequence. The seven types are each divided into ten subclasses, indicated by a digit from 0 to 9 after the spectral type (except for type O, which is only divided into five subtypes, O5 to O9). The Sun, for example, is type G2.

The vast majority of stars fall into the "main sequence", which runs from huge, bright O-type stars to tiny, dim M-type red dwarfs, with yellow dwarfs like the Sun falling almost exactly in the middle. Other types of stars are above or below the main sequence.

Red giants are a late stage in the life cycle of moderately massive stars (the Sun's mass or larger), and are denoted by a "g" prefix on the spectral type (e.g. "gM5"). Supergiants are even brighter and more massive, and are denoted by a "c" prefix (e.g. "cK0"). White dwarfs, much dimmer than most main sequence stars, are the final stage in the evolution of most stars; they are denoted by a "D" prefix, and normally no numeric subtype (e.g. "DA"). The most massive stars will end up as neutron stars or black holes (these have no spectral types, of course; the table below uses "ns" and "bh" to represent them).

For each star in a system, roll D100 two or three times on the following table, to get the general description and the specific spectral class of the star. For supergiants, giants, and main sequence stars, roll D10-1 for the numeric subtype (except for type O, which is only subdivided from 5 to 9; roll (D10/2)+4).

The stars in a system should be listed in descending order of luminosity, which you can take to be the same as the order in the table (supergiants, giants, main sequence, white dwarfs (all in order of spectral type), then neutron stars and black holes).