Binary stellar system · 10 planets · Former home of the Alf people
Primary star — Asterra
The Asterra star system is dynamically stable and long-settled. Its primary is a cool G-type main sequence star of roughly 0.93 solar masses, with a luminosity near 0.78 Sol and an estimated age of 7.1 billion years — well into a quiet, predictable phase of its main-sequence lifetime. Its low flare rate has spared the inner worlds the periodic radiation events that disrupt atmospheric.
The system's planetary orbits are near-circular and widely spacedy. The two asteroid belts, at 2.4 and 6.8 AU, are well-bounded and shepherded by the gravitational influence of the inner gas giant Vael, whose magnetosphere and mass further shield the inner system from cometary and interstellar debris. This configuration has remained essentially undisturbed since the disruption event that reshaped Ceryn's moon population an estimated 1.3 billion years ago.
1. Keth
Keth is a tidally locked rocky world orbiting at 0.21 AU, completing one orbit every 41 standard days while keeping a single hemisphere permanently turned toward Asterra. This produces an extreme and stable hemispheric contrast: a dayside held near 620 K under continuous stellar radiation, and a nightside that settles to roughly 190 K in perpetual shadow.
The planet's low mass (0.62 Earth) and 0.78 g surface gravity, combined with its volatile-poor crust, made it useless for habitation but valuable for extraction. Mining was confined to the nightside, where the absence of direct radiation and the stable cold permitted hardened subsurface operations at depths of 300 to 1,200 meters. Facilities drew power from a mix of orbital solar collectors stationed over the terminator and compact surface reactors.
Keth was never settled in any meaningful sense. At peak operation it held fewer than 4000 permanent personnel system-wide, its highly automated infrastructure requiring minimal oversight. It functioned solely as an inner-system industrial node — among the earliest off-world footholds the Alf established.
| Operational depth | Peak population | Automation |
|---|---|---|
| 300–1,200 m | <4000 | HIgh |
Facilities: subsurface, hardened · Power: orbital solar collectors and compact reactors
2. Ytharia
Ytharia is an ocean-dominated terrestrial world and the only planet in the Asterra system known to support complex native life. Orbiting at 0.68 AU — squarely within Asterra's 0.62–0.74 AU habitable zone — it holds a mass of 1.08 Earth and a surface gravity of 1.02 g, conditions close enough to a baseline standard that the Alf evolved without the adaptations harsher worlds would have demanded. Roughly 72% of its surface is liquid water, beneath a moisture-rich ~1.4 bar atmosphere that sustains a mean surface temperature near 284 K. A modest 18.4° axial tilt drives stable, well-defined seasons rather than extremes.
Its two moons shaped the planet as much as its star did. The major moon Elaris governs Ytharia's primary tidal cycles and stabilizes its axial tilt against long-term drift. The minor moon Tirien, locked in a 2:1 resonance with Elaris, plays a smaller gravitational role but figures heavily in Alf cultural and observational tradition.
Ytharia was the historical and cultural origin point of the Alf people — the cradle from which settlement radiated outward across the system, and the seat of its political and administrative life. The Conclave Assembly convened on its surface; its orbital station served as the system's primary spaceport and customs hub. For the whole span of recorded Alf history, Ytharia was the fixed center around which the rest of the system organized itself.
That center is gone. Following the arrival of the Pursuers, Ytharia was rendered inhospitable and war-torn, stripped of the life it once held. It remains the system's origin point in memory and record only.
| Orbital altitude | Ring diameter | Peak population | Capital berths |
|---|---|---|---|
| ~42,000 km | ~11 km | ~180,000 | ~10 |
| Radius | ~1,720 km | Radius | ~720 km |
|---|---|---|---|
| Mass | 0.94 Luna | Distance | ~610,000 km |
| Distance | ~410,000 km | Period | 69.2 days |
| Period | 34.6 days | Resonance | 2:1 with Elaris |
| Base capacity | ~25,000 | Inclination | 3.1° |
3. Vael
Vael's powerful magnetosphere deflected a significant fraction of cometary and interstellar debris, contributing to inner-system stability.
4. Orthis
Several moons show evidence of subsurface oceans or cryovolcanic activity. Orthis hosted the system's primary middle-system logistics hub.
| Orbital altitude | Peak population | Annual throughput |
|---|---|---|
| ~1.8M km | ~95,000 | ~120M tons |
5. Ceryn
Orbital characteristics indicate a major disruption event approximately 1.3 billion years ago, likely responsible for Ceryn's irregular and partially captured moon population.
6. Helior
Helior marks the outer boundary of significant planetary mass in the primary system. Its sparse, frozen satellites are relics of the outer system's early formation.
7. Nysa
A frozen, isolated world at the far edge of the primary system. The lack of satellites is attributed to early orbital instability and gravitational interference from the outer gas giants.
Companion star — Carmyn
Carmyn is the red companion star of the Asterra binary system, orbiting at a wide separation that renders it a naked-eye fixture in Ytharia's night sky — a dim but constant red point, distinct from the stars of the broader field. Its slow drift across centuries of recorded observation made it a cultural and navigational reference point long before its stellar nature was understood.
C-1. Vethara
Vethara is a dense, hot terrestrial world locked in a runaway greenhouse state. Its thick carbon dioxide atmosphere traps heat from Carmyn's close proximity, producing surface temperatures hostile to any known form of life. Vethara was surveyed but never developed. It holds no strategic value beyond its role as an orbital reference marker for approach to the Carmyn system.
C-2. Pelun
Pelun is a small, heavily cratered dwarf world with minimal gravity and no retained atmosphere to speak of. Its surface is ancient and largely undisturbed — a record of early system bombardment preserved in ice and regolith.
C-3. Dorryn
Dorryn is a cold, methane-tinged gas giant occupying the far reaches of the Carmyn system. It receives very little energy from either star and sits in a state of deep atmospheric calm compared to the inner gas giants of the primary system. Its blue-grey coloration — caused by methane absorption of red wavelengths — makes it visually distinct from Vael, Orthis, or Ceryn.