The Oroseira System: The Young and the Old
Overview
At the center of an irregular protoplanetary nebula, Oroseria is a system in the last stages of death. This wide binary consists of an intermediate-mass red giant and a main-sequence star, both of which host relatively small systems of massive planets. Only the smaller Columbia hosts life, residing on several moons surrounding the massive habitable-zone gas giant Oreaster. Though the system lies near the massive Tommotia Cluster, it is nearly 100 times older and is certainly unrelated.
Complex life has existed in the system for just shy of 200 million years. Despite this short timescale, the small distance between its six habitable moons means that it has managed to colonize all of them save the acidic Sideros (though often only in the form of extremophiles). As the system is only 2.44 billion years old this might seem unusual, but on Earth the Francevillian Group of Gabon preserves evidence of possible complex life when our planet was similar in age to Oroseira. The Francevillian fossils disappear after a drop in oxygen levels, but it is conceivable that Oroseira had more luck with its first evolutionary radiation.
Oroseira’s most complex terrestrial ecosystems are no more developed than the patchwork forests of the late Devonian of Earth. Nevertheless, sapient life exists in the form of a giant millipede-like species. While they seem to be naturally evolved, neither their sapience or their civilization is natural. No evidence of their activity is observed in strata more than 400 years old and they subscribe to a primitive, quasi-Aristotelian model of science despite crossing the stars. The reason for these anomalies seems relatively clear, as the Oroseirans are ruled by an alien theocrat belonging to one of the Six Great Clades: an un-aging, velvet worm-like civilizational parasite hailing from the distant moon Chrysoprase. This creature seems to be responsible for uplifting the species to sapience and providing them the means to traverse the void but also inhibits technological and sociological development in order to secure the divine reverence it needs to complete its life cycle.
The First Sun: Vredefort, Titanian Opisthotonos
Unlike most other stars in life-hosting systems, Vredefort is a dying star. It began its life as a blue-white A-type star, losing around 20% of its mass and swelling into a red giant nearly 300 times larger than the Sun after exhausting its supplies of hydrogen and helium at the end of its ~2 billion year main-sequence lifespan. Having run up the red giant branch twice, it is nearly finished with its life as it slowly shrinks and heats up in preparation for its final days. The ailing star has become a highly unstable Mira variable, swelling and shrinking as its nuclear fires flicker and shedding its outer layers in a dusty funeral shroud that cloaks the system in darkness. Over the next few thousand years, it will lose around half its present mass until its bare core shines through as a dead, exhausted white dwarf.
Vredefort only has one planet, the eccentric super-Jupiter Acanthaster. This depauperate arrangement suggests that the star formed with additional planets but ejected all but one into deep space through mutual instabilities. Acanthaster and Columbia are too distant to directly interface with the stellar surface, but their gravity jerks Vredefort around and warps shells of solar wind into complex and irregular shapes, portending the formation of a complex planetary nebula from its remains.
Little more can be said about the planetary system of Vredefort, as even in Acanthaster’s heyday 500 million years ago it was not impressive in comparison to the likes of Oreaster. While additional planets may have existed close to Vredefort as it was then, these worlds, if there were any, have long been swallowed by the giant.
Planets of Vredefort
-
Witness the end of a system of worlds. This massive super-Jupiter’s eccentric orbit and depauperate satellite system are relics of a narrow encounter with a sibling planet in the distant past, one that proceeded to kick its remaining siblings into interstellar space. Alone by its own design and with a sun on the brink of death, soon it will be all that remains of its erstwhile family.
Acanthaster steeps in the blood of shattered worlds.
The Second Sun: Columbia, the Erstwhile Survivor
Compared to its partner Vredefort, Columbia is a much more conventional star. This F8 white star, at only 15% more massive than the Sun, has a considerably longer lifespan than its partner and thus has a bit more than half of its lifetime remaining. It is presently a quiet star but this was not always so; unusual enhancements in certain metals suggest it consumed one or more Jupiter-sized planets in its early days. Columbia’s stellar wind bores holes in the carbonaceous dust cloak of Vredefort, though the high density of the red giant’s extended envelope causes severe truncation of its heliosphere.
Columbia’s planetary system is massive but relatively compact, with five volatile-rich worlds packed in a space twice the radius of Earth’s orbit. Three-quarters of this mass is in the massive super-Jupiter Oreaster, at around 5 times the mass of Jupiter. Beyond the planets is a born-again protoplanetary disk consisting of around a Jupiter-mass of volatile, carbonaceous material ejected from Vredefort, which may one day form into a new series of planets.
Sungrazers
The Sungrazers are a pair of scorched planets that represent an unusual end-state Hot Jupiter system. The inflated Jupiter-mass planet Culcita is quite typical for its kind, but distinguishes itself with the existence of Botryllus - a massive, molten super-Earth companion slightly interior to its orbit. The existence of Botryllus suggests planetary migration in Columbia’s system has been gentle despite the presence of several massive planets, allowing a massive wake to form ahead of the giant that later condensed into its companion. This gentle migration does not mean the planets themselves are gentle at all, for both are so irradiated by their sun that they belch millions of tonnes of vaporized surface material into deep space every second.
Members of the Sungrazers
-
Observe a world on the brink. This molten super-Earth completes an orbit in less than a day as its boiling oceans of magma stream out into space as a comet-like tail. Highly stable, it rarely shifts in its orbit nor its hellish surface conditions, maintaining its primordial appearance for as long as it shall live.
Botryllus seethes with primordial rage unleashed by solar glare.
-
Investigate an unusual world close to stardom. This scorched giant’s anomalous bloating may be the result of limited deuterium fusion in the water-rich core of the planet as it is heated by tides and magnetic interactions, despite it being far below the ordinary mass of a brown dwarf.
Culcita keeps its secrets near.
Columbian Intermediary
Beyond the scorching interior of Columbia’s planetary system is a large gap in which a pair of small worlds dwell. Sub-Neptune Aquilonastra and melted aquaria Ciona populate this region at present but neither world seems to be native; both are volatile-rich worlds originating from far beyond the ice line. The formation of this region may have resembled that of the asteroid belt in the Solar System, with material tossed outward by Culcita combining with material tossed inward by Oreaster, assembling together to form a hybrid
Members of the Columbian Intermediary
-
Fly by a Neptunian world ravaged by cosmic forces. The shattering of a pair of Vesta-like moons ringed this small gas giant in russet bands of dust. Though the collision is long in the past, debris still wanders the system as golden grains of deep-mantle olivine.
Aquilonastra bears testament to a violent history.
-
Swing by a world misplaced, sent to the searing interior of the Columbian division from its home out in the icy barrens beyond. Forming from volatile-rich material accumulating before the giant Oreaster, its boiling oceans are crushed under a nitrogenous atmosphere that keeps them largely liquid.
Ciona paints a choking parody of life.
Columbian Exterior - Sole Member Series
As the most massive and most habitable of all the worlds of Oroseira, Oreaster occupies a lonely zone between the bustling interior of Columbia and the far reaches of Vredefort. Though alone in its size, this region is not truly empty; Vredefort shepherds huge clouds of co-orbiting asteroids just like Jupiter does in our Solar System, while its outer resonances are occupied by swarms of asteroids and dwarf planets going all the way out to the rejuvenated disk at the edge of Columbia’s gravitational well.
Members of the Columbian Exterior
-
Journey to a microcosm of planetary diversity trapped in the immense pull of a jovian titan. This massive world has accrued a hyper-diverse collection of satellites, from scraps of dust and rock to acidic deserts to drowned ocean worlds. Few but the Authors concentrate variety so intensely.
Oreaster wheels through the sky with its celestial entourage.
