vonHardenberg: The Star classes in-game are actually based on the real-life stellar classification system. Mechanically, however, it's like this:
- Yellow star systems are the most common and begin with F or G.
- Red star systems begin with M or K, and can only be accessed with Warp Reactor Sigma.
- Green star systems begin with E and can only be accessed with Warp Reactor Tau.
- Blue star systems begin with O or B, and can only be accessed with Warp Reactor Theta.
Numbers and letters behind usually specify temperature (the higher the number, the cooler the star in relation to others in it's class) and anomalies (which probably do not translate to anything in-game - lacking empirical data here).
Red, Green and Blue star systems tend to have better resources, and supposedly blue ones also have a higher base chance of life on the planets.
However, that's "tendencies", and since the RNG plays a large role in resource allocation, pretty much everything can be found everywhere.
The "route planner" features will ONLY use yellow stars. Also, black holes will always dump you into a yellow star system, regardless of your installed hyperdrives.
That did the job. Thanks.