Circumstellar Ring Megastructure Image from Phil B The rotating surface of Ouaddai ringworld would tear itself apart, because the centrifugal forces are greater than the strength of any conventional materials; but a ring of massive particles push inwards to counteract this massive pressure. This means that the ringworld can be built without the use of magmatter.

A relatively small ringworld around a white dwarf star

Ouaddai (Wadi) - Data Panel System: Ouaddai Primary: Eggen/Greenstein 471 white dwarf Region: Inner Sphere; 50.5ly from Sol, Constellation Cetus Planets Ouaddai Ring - Habitable Megastructure

Bonaventure 10 a.u. orbit (lethian cinderworld) (dismantled to build circumstellar ring).

Auozou 15 au orbit (lethian cinderworld)

Image from Steve Bowers The Ouaddai Ring is two million kilometres in diameter, and surrounds a white dwarf star which is roughly the same diameter as Earth.

The development of oil reserves in the early 21st century c.e. in the Republique du Tchad financed extensive solar powered nanotechnology and ecological management programs; by the third century AT the Republique was involved in developing asteroid resources from Near Earth Orbit to the moons of Uranus. When the Technocalypse attacked, many of the Republique's NEO'S were lost or declared independence; before long the Republique was limited to a single moon of Uranus, Oberon.Following the Great Expulsion , a hastily constructed interstellar craft, the, was launched in 654 AT (with the assistance of GAIA's boostbeams) and allowed several thousand vitrified colonists to escape to Epsilon Eridani , in the Eridanus League . This ship arrived in 744 AT. However this nearby system was soon crowded with refugees from Earth; by 900 AT. the Bismillah was rebuilt and set off again for the white dwarf star E/G 471, 40 light years further on.In the current era, E/G 471 is a white dwarf system, but one and a half billion years ago it was a class F star on the main sequence; by one billion years before present it had swollen into a red giant, and then began to expel its atmosphere in a ferocious stellar wind, forming a spherical planetary nebula around the now shrunken central star. The closest planets to the star were destroyed in this process, but the outer two gas giants were smothered in silicon and carbon soot, and although they lost much of their volatiles they still retained hydrocarbon compounds when the central star finally shrank to a white dwarf. It was to these carbon rich worlds the colonists of thewere drawn.During the First Federation period this cluster of semi-independent colonies, now called the Ouaddai League, became advanced in the design and construction of carbon-shelled structures. Building a series of rotating habitats around the dwarf and the two cinderworlds, the Republique colonists recaptured the musical lifestyle developed long ago on Oberon. Later contact with the Sophic League and the Stellar Umma led to a rich spiritual development among the enhanced and augmented sections of society.The ring itself is constructed of carbon nanotube weave, but even this strongest of conventional materials would have been torn apart by centrifugal force if it were not for the additional weight of the counter-rotating mass particle beams pressing inwards toward the star. The mass stream consists of iron particles, all that remains of the core of the dismantled planet Bonaventure, which are accelerated in efficient magnetic tubes until they are stationary with respect to the central star; these massive particles exert no centrifugal force themselves, but balance the outward pressure of the rotating surface. This has allowed the construction of a ringworld with respectable surface gravity using conventional materials instead of magmatter (an ultratech material which was not available when construction started on this ring).The inner surface is covered with an Earth-like artificial environment, which receives artificial sunlight emitted by the power collection swarm surrounding tiny white dwarf in the centre, an object only 9000 km across. A ring shaped filter cuts out the most harmful UV rays emitted by this still quite hot dwarf star. Every night the phased array emitters on the power collection swarm redden then go dark to simulate a day-night cycle; the quality of the resulting sunlight falling on the ringworld surface is remarkably similar to that received on Old Earth.From 4800 to 7600 a.t. Ouaddai Ring culture was predominantly Mortalist , largely because of close ties with other similar Sophic League and Umma worlds; both the nearbaseline humans and the posthumans of that world rejected excessive life extension and digital immortality, but chose freely to die of old age, and to go forward into a supposed afterlife which had no physical connection with our own existence. A series of schisms and power struggles, some ferocious and bloody, eventually allowed the immortalists of the Materialist Tendency to practice transcendental uploading; the society of today is a mixture of mortalism, materialism and cosmopolitanism.