Ran (Epsilon Eridani) System, The

Early colony system near Sol

Ran System (Epsilon Eridani)
Image from The Astronomer
The planets of the Ran System; Dufa, Hroenn, Bara, Unn, Ægir, Hefring and Himinglaeva

System Ran (Eridan Ran) -Data Panel

Primary Ran, Epsilon Eridani
Location- Distance from Sol: 10.502 ly (J2000)
- Constellation: Eridanus
Reached: 595 AT by the Kelkemesh, a Gengineer Republic starship, followed by the Mayari from the Cislunar Alliance in 603, and the Cinnabar from the Martian Union in 607.
StarNames: Ran, Epsilon Eridani, 18 Eridani, Gliese 144 (GJ 144), HD 22049, HIP 16537, HR 1084, JD 1452
Physical characteristics:
- Mass: 1.553E+30 kg (0.781 x Sol)
- Radius: 577,893 km (0.831 x Sol)
- Luminosity: 0.381 x Sol (bolometric)
- Temperature: 4,975 Kelvin
- Spectral type: K2V.
- Rotation period: 11.2 days
- Age: 800 million years
PlanetsThe star and its planets are named after Ran, Ægir, and their daughters.
1) Dufa: Videntian Sulfoli-Terrestrial Lapi-Minervan Azo-Cytherean
Semi-major axis = 0.197 AU, Orbital period = 36.14 days, Eccentricity = 0.019, Mass = 0.526 x Earth, Radius = 0.823 x Earth
2) Hroenn: Videntian Acidi-Terrestrial Lapi-Ydratian Aqua-Cytherean
Semi-major axis = 0.336 AU, Orbital period = 80.50 days, Eccentricity = 0.024, Mass = 0.773 x Earth, Radius = 0.930 x Earth
3) Bara: Tholi-Terrestrial Lapi-Rhean Ocea-Thermal Aqua-Gaian
Semi-major axis = 0.534 AU, Orbital period = 161.3 days, Eccentricity = 0.026, Mass = 1.141 x Earth, Radius = 1.064 x Earth
4) Unn: Hydro-Terrestrial Lapi-Rhean Estua-Tepidal Aqua-Gaian
Semi-major axis = 0.712 AU, Orbital period = 248.3 days, Eccentricity = 0.027, Mass = 0.407 x Earth, Radius = 0.774 x Earth

- First Ran Asteroid Belt: 1:4 to 1:2 mean motion resonance with Ægir
Inner radius = 1.40 AU, Outer radius: 2.22 AU

5) Ægir (Epsilon Eridani b): Ammo-Jovian Hydrogeo-Barian
Semi-major axis = 3.52 AU, Orbital period = 7.47 years, Eccentricity = 0.12, Mass = 1.19 x Jupiter, Radius = 11.608 x Earth

- Second Ran Asteroid Belt:
Inner radius = 8 AU, Outer radius: 20 AU

6) Hefring: Cryoazuri-Neptunian Geli-Jotunnian Hydrogeo-Barian
Semi-major axis = 26.19 AU, Orbital period = 151.7 years, Eccentricity = 0.035, Mass = 18.59 x Earth, Radius = 4.715 x Earth
7) Himinglaeva: Metho-Jovian Hydrogeo-Barian
Semi-major axis = 47.83 AU, Orbital period = 374.2 years, Eccentricity = 0.1, Mass = 34.80 x Earth, Radius = 7.241 x Earth

- Third Ran Asteroid Belt:
Inner radius = 52 AU, Outer radius: 76 AU

Image from The Astronomer
Dufa, a Cytherian (Venus-like) world in this system.


WormholesOrdered by age since first opened
Vast Horizon (3,800 m) to Nova (Tau Ceti)
Two Sides of the Same Walkway (1,300 m) to Keid (40 Eridani)
Aegir and Fimafeng
Image from The Astronomer
Ægir and its Io-like moon, Fimafeng


Ran is orbited by seven planets - four terrestrials, one neptunian, and two jovians.

Both Dufa and Hroenn are Cytherean worlds, with thick atmospheres consisting mainly of carbon dioxide and water vapor, respectively. Volcanic eruptions are very common on both worlds, although planetary engineering allowed these eruptions to be controlled, preventing damage to the surface settlements.

The surface of the next two worlds - Bara and Unn - were shrouded by the tholin haze layer characteristic of young worlds, but the details below it were slightly different. Bara and Unn were AquaGaian-type worlds. Bara, the larger planet, is almost completely flooded, with few volcanic islands jutting out of the ocean. Unn, the smaller one, is also drier, with only roughly half of its surface covered with water bodies. In the Current Era, both worlds have been transformed to various degrees, although none of them are habitable to baseline humans. Microbiotic biospheres were present on both Bara and Unn, and have been integrated into the foundation of the biospheres that inhabit the two planets in the Current Era.

Ægir is by far the largest planet of the Ran system, with a mass of around 1.2 Jupiters and a semimajor axis of 3.39 AU. In many ways it strongly resembled a younger version of Jupiter of Solsys, and its epithet in many cultures, especially those descended from the colonists affiliated with the Gengineer Republic, can be roughly translated to 'New Jupiter' or 'Young Jupiter'. Ægir was orbited by three large satellites known as Fimafeng, Eldir, and Gerd, as well as a large number of asteroidal moons.

In the Current Era, the planet and its moons have been transformed into a Jupiter brain, home of the system's S4 overseer. Waste heat from the Jupiter brain is used to power the civilizations inhabiting the surrounding Matrioshka micronode.

Finally, the two cold worlds - Hefring, and Himinglaeva, are located near the edge of the two outer debris belts, and serve to shepherd them.

For more details of the history of the Ran system, see this page.

Image from The Astronomer
Hefring, a cold ice giant on the edge of this system.
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Development Notes
Text by M. Alan Kazlev, revised by QwertyYerty 2018
Further amended by The Astronomer and Dangerous Safety 2021
Initially published on 24 October 2001.

Renamed in December 2015 in line with new IAU nomenclature
Other planets in this system renamed in 2021 by The Astronomer