Heglum was a very light, synthetic gas used in dirigibles. Sometimes found inside of nebulae, it quickly bonded to a starship's sublight drives. Ships passing through heglum clouds need to undergo regular drive scrubbing in order to remain at optimal performance.
- Galaxy Guide 2: Yavin and Bespin
- Galaxy Guide 2: Yavin and Bespin, Second Edition
- "Home"—The Kathol Rift
- The Complete Star Wars Encyclopedia