Tau Ceti or Al Nánamat is a very ancient Human system in the Terran core only 12 light years from Earth. Tau Ceti 3 was one of the first worlds terraformed after Mars and was a center of Cymek machine culture during and after the fall of the Second Empire. Unfortunately, about 5000 years ago a massive meteor storm overwhelmed the planet's defenses resulting in the deaths of many millions and the collapse of the artificial ecosystem. It's been airless since, abandoned to the billions of wild robots that were left behind.
Wavium crystal mining is still a major concern in the the debris disk surrounding the star and thousands of asteroid mining settlements remain there including Syntrál, the seat of the wealthy Ket of the system's governor and Sughu City, the most decadent city in the Old Core.