The Oreannen System is one of the most life-rich systems in the constellation, with five of its seven worlds having some form of ecosystem. A single planet, Oreannen-3, had an early space-faring civilization with two sentient species that would become one of the very first fully integrated Tier-1 members of the United Systems.
The Oreannen System is a single star system, the primary star designated Orean Alpha. The system has 7 planets, 6 of them rocky with 5 bearing living ecosystems, and a single Class-II gas giant.
Oreannen-2 is a warm planet mostly covered by shallow oceans and scattered rocky islands. The world does not fall within the UniSys Charter but is a popular tourism destination. True ownership is a hotly debated topic with private entities trying to exert control over the planet, often resulting in conflict and the occasional hostile takeover.
Oreannen-3 is the home world to two sentient species and a full member of the United Systems. Its main capital city, Alianis, is an important financial district within the United Systems. The planet is small, and although its atmosphere is life-supporting, the low atmospheric pressure and higher percentage of carbon dioxide make it hazardous to most non-natives visiting the world.
Oreannen-4 is a fully settled United Systems territory with several large cities including Lenparsus, Duncartus, Gontorus, and the capital, Jentarsus.
Oreannen-5 is an ice-world, its distant orbit from the parent star creating freezing temperatures across the planet. Most of the world is featureless and flat aside from the equator where a ring of extraordinarily high mountains reach far beyond the breathable limits of the atmosphere, a result of two planetoids colliding during its formation. The ecosystems of Oreannen-5 are mostly contained within the mild-temperature valleys of the massive mountain range. No settlements exist as the world is not economically viable and offers little prospect for mineral extraction.
Oreannen-6 is a high temperature lava-world boasting a collection unique species evolved to extract energy directly from the magma. The outer atmosphere forms a near impenetrable stratothermospheric shell due to the intense convention currents and deadly turbulence caused by the massive emission of thermal energy. The air is incredibly dense and hot but offers many zones of calmness near the islands of solid land surface. Together with the enormous pressure that raises the boiling point of water significantly, the reason liquid water can exist in the 160-degree centigrade surface temperatures, the conditions have led to the evolution of the most extremophilic planetary ecosystem ever discovered.
Oreannen-7 is a Class-II gas giant with a permanent eye-storm several tens of thousands of kilometres in diameter.