The Alcyone star system is composed of a yellow star and two white dwarfs orbiting two blue giants.  The two white stars lost their battle with gravity thousands of years ago and shed much of their mass into gaseous clouds surrounding them.  Full of heavy metals and the remains of shattered planets, those nebulas are better refueling stations than even the giants.  And the star system’s manufacturing centers send miners there too.  It is a very rich star system.