Star Classes Your navigation instruments and HUD will often describe stars as being of a particular class. When you select a remote target, your HUD will display something like, "UNKNOWN STAR / CLASS S06". The number given tells you what kind of star you have selected, and learning these codes will prove invaluable when trying to find a particular kind of stars (It's especially important to remember that Grey Giants are class S06, as these are the stars that emit the lithium ions you use for fuel). There are eleven different classes of star: