Nineveh and Tyre, two worlds in the devastated Caph system
A Cinder System is a solar system that has been ravaged by expansion, energy demands and populations run amok. Often they are dead and include a dying or dead star, black hole or some other "disfigured" solar body.
Planets in such a system have often been disassembled, leaving behind only poor quality asteroids or abandoned habitats and other structures which have been ravaged by the effects of a mega-collapse. These systems are often filled with "dust" and other fine particulate heavy matter of iron, lead and other common heavy elements. Sometimes gold and uranium or other valuable materials are found as well making the system marginally valuable to those that wish to sift through many cubic light hours of space. Wreckage fields are quite frequent due to violence associated with the collapse. There will almost always be no life beyond prokaryote and other microscopic lifeforms clinging to life in small pockets of habitable space in the system, but exceptions have been reported.
Systems have been known to collapse into Cinder Systems because of cataclysmic outside events such as aggressive self-replicating swarms, artificial supernovae such as the Gehenna Event or other major disruption to the energy or resource cycle of a star system. In some cases these prime causes are not the force which causes the calamity that causes collapse to occur, but rather begin a chain of events that causes the system to rapidly devolve into a Cinder System. Most often though, it is due to an energy or matter crunch forged by unregulated technological or reproductive expansion. When the population or technological level reaches a certain critical mass, it will begin a series of internal events that will ultimately destroy the entire civilization in the system, and consume almost all energy and viable resources left.
Not all Cinder Systems are completely destroyed, but have been left scarred and ravaged by the violence that occurred. On occasion a star may flare strongly or go nova inside an inhabited suprastellar shell or dyson swarm, killing most of the inhabitants and shattering the megastructure. This leaves a massive, encompassing debris field with a wild star or large stellar body in the middle. Some survivors may be found in isolated sections, but without rescue help, they are often dead within months or a few years if not found.
This almost never happens with Archai running the system, but there are the extra rare exceptions to this. More often than not, it happens to those Baseline-equivalents and Superbrights who believe that they are smarter and better than the transapients who rule them back home. In their hubris, they can experience such problems unless drastic, and often horrific measures are implemented. Sometimes the solution is worse than the problem.
There are rumors that sometimes Archai will deliberately cause Cinder Systems to happen for their own purpose. Population control, technological control, meme warfare, creating an example to keep their sophonts in line or thousands of other reasons. Some even believe that Archai sometimes force Cinder Systems to occur and before the collapse happens, begin exiling their unwanted prisoners to the system to help hasten the collapse and then slam the door so no one can escape. This effectively deals with unruly populations and troublesome polity groups. Often though, the root cause is something simply overlooked and caught too late.
These are colonization ghost stories used to frighten populations from half baked, or reactionary schemes to escape and cause future trouble for their former homestars. Very little goes on in a Cinder System. Scavengers often pick through the largest and most dramatic of these stellar graveyards. Pirates are known to live here and there among the wreckage but mostly they are left alone. Rumors abound about secret technology and conspiracies on why the calamity occurred.
Since the destruction of a system in this order can cause wormholes to collapse, high toposophic archai who sense a Cinder System occurring often if possible move their wormholes (including wormhole buses!) and will sometimes let them reluctantly collapse after moving their mouths farther out of their system as to avoid damage. Usually they pull the wormholes out of the collapsing system long before this occurs as to preserve the buses and wormholes and prevent risk to their systems back home.
Every once in a while, Archai will leave beamrider routes or wormhole links through a Cinder system as a reminder to people passing through to stay in line. This could be viewed as a galactic version of the "crossroads gallows" of ancient Earth. This is often a grim reminder to those who fancy rebellion, that their star can be made into a Cinder System as well if their Master is angered.