To call Erebus-Nyx (official designation E-N-Beta-2) a hell-world is not at all hyperbolic; it is, in fact, something of an understatement.
Caught between the massive blue giant of H-Erebus and the brown dwarf of H-Nyx (The Night Star) as they try to tear material from each other's cronona is not a nice situation for a planet to exist in. In fact, were it not for the near-impossible existence if the ravaged world of Tarteros right between the orbits of these two stars, Erebus-Nyx might not exist at all.
Boiled sterile during the 'summer' (when closest to H-Erebus) and frozen solid in 'winter' (when closest to H-Nyx) nothing can live on its ravaged surface which is also in regular techtonic chaos due the tidal forces exerted when in proximity to its massive main star.
When the Ark arrived here in EA 2064, two thirds of those aboard died with the first local day, the rest learned to live below ground very quickly indeed.
Erebus City was first built hurriedly from material salvaged from the Ark (not even the terraforming engines of the Phanes Spears could have helped, several were attempted and no-one knows what happened to them), then with more of an eye to defense when the skoulkisme worms were discovered.
After many more deaths, it was the discovery of a curious mineral known as Nyx' Breath that saved them. Building a shell of thisa round the city hid them from the vicious armoured worms that could grow as large a a small spaceship.
The same material, known as Oneirium to the wider Empyraeum has a number of remarkable properties, though 'as light as breath' it is durable, tolerating sheer forces that would snap even mithril alloys to pieces. It is also highly resistent to extremes of both heat and cold, reflecting the latter while slowly radiating the former.
The locals, who call themselves Erebusians, see this blue-glowing mineral as a blessing from Nyx herself.
So too do they defend the eyes their ancestors gave them by dabbling with illegal genetic manipulation. Able to see in near total darkness (any strong light attracts the tunneling worms), they glow with a milky-blue radience that is easy to find unsettling.
Hard men and women used to privation and trained from birth to be as silent and move as ghosts, many Erebusians have found themselves in the employ of the ONI, or Office of Naval Intelligence in these latter, troubled days. They make for natural spies and covert operatives.
Official Designation: E-N-Beta-2
Solar System : Erebos-Nyx Binary
Orbit: 2.3 Gaian Years
Rotation: 63 Gaian Hours
Diameter: 30,030 km (18.652 milia)
Atmosphere: Oxygen, nitrogen mix with strong percentage of phosphene, carbonic and sulphuric acid rain
Orbital Position: 2nd planet in system, on parallel orbit with planet Talos
Population: 73.1 Million
Colonised: EA 2064
Industry: Sole known source of Oneirium
Climate: Surface uninhabitable
Max. Temperature: 650 degrees
Min. Temperature: -220 degrees