Helios Delta

Helios Delta is a reddish main sequence star of spectral class K2V and has a mass of 0.74. It was the last of the four systems to be settled by the Colonials. It and Helios Gamma orbit a common barycenter maintaining a separation of 70 SU. Helios Delta is less massive and is farther from the system's barycenter. It completes an orbit once every 456 years.

• Planets and Other Astronomical Bodies
  • Phoebe - A small world with a high surface temperature and thin atmosphere.
  • Styx - A planet with a dense, reducing atmosphere of carbon dioxide and sulfides.
  • Aeolus asteroid belt - This asteroid belt features gaps, likely caused by tidal influences with Hestia and its two orbital companions.
  • Aerilon, Hestia, and Canceron - These planets share the same orbit.
    • Hestia - The smallest gas giant in the Cyrannus star system, Hestia only has a diameter of 47,000 km. It has 17 moons, the largest of which, Kronos and Rhea, share the same orbit.
  • Aquaria - An arctic world, with the most inclined orbit of all the Twelve Colonies.

This system is unique in the fact that Aerilon, Hestia, and Canceron share the same orbit. The two colonies are positioned at Hestia's Lagrangian points, meaning that the gravitational pull of Helios Delta and Hestia are balanced, allowing two smaller bodies (Aerilon and Canceron) to share the same orbit in a "fixed" position, maintaining the same distance apart at all times. Aerilon sits at the (leading) L4 point, and Canceron at the (trailing) L5 point.

• Ragnar - A gas giant with a diameter of 138,000 km, orbits the entire Helios Gamma and Delta system in a 899.75 year period. It is about 110 SU away from the central barycenter. The Colonials use the planet as host to Ragnar Anchorage, an orbital refueling station and naval armory that distills hydrocarbons from the planet's upper atmosphere. It has one moon, Sigurd. During the Fall of the Colonies, Ragnar was used as cover by the battlestar Galactica, and later her fleet, after escaping the destruction of Caprica. It would be the last world of the Cyrannian system that most of the surviving Colonials would lay eyes on. Hours after arriving, Galactica took the gathered fleet, and fled the system, never to return.