Asterra System

Asterra System is a binary star system and the former home of the Alf people. It comprises the primary star Asterra and its distant red companion Carmyn, which together hold ten planets across two stellar groups. For the whole span of recorded Alf history, the system was the cradle and center of their civilisation, anchored on the ocean world Ytharia.

The system is dynamically stable and long-settled, but no longer inhabited. Following the arrival of the Pursuers, it was overrun and abandoned; its worlds are silent and its infrastructure inactive. Asterra endures as the historical origin point of the Alf in record and memory only.

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 and biological development in more active systems.

The system's planetary orbits are near-circular and widely spaced. 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.

A-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 4,000 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.

Mining operations

Operational depth	Peak population	Automation
300–1,200 m	<4,000	High

Facilities: subsurface, hardened · Power: orbital solar collectors and compact reactors

A-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 station

Orbital altitude	Ring diameter	Peak population	Capital berths
~42,000 km	~11 km	~180,000	~10

Moons of Ytharia

	Elaris (Major)	Tirien (Minor)
Radius	~1,720 km	~720 km
Orbital distance	~410,000 km	~610,000 km
Orbital period	34.6 days	69.2 days
Notable	Base capacity ~25,000	2:1 resonance · 3.1° inclination

A-3. Vael

Vael is the innermost gas giant, orbiting at 3.1 AU with a mass of 1.4 Jupiter — the most massive body in the system after Asterra itself. Its powerful magnetosphere extends some 9 million kilometers and deflects a significant fraction of cometary and interstellar debris before it can reach the inner system. Together with its gravitational shepherding of the 2.4 AU asteroid belt, Vael acts as the inner system's primary shield, a passive guardian whose presence was a quiet precondition for Ytharia's long climatic stability.

A-4. Orthis

Orthis is the system's second gas giant, orbiting at 7.6 AU with a mass of 1.1 Jupiter and encircled by the most extensive — and most striking — ring system in the system, spanning some 140,000 kilometers of bright, finely structured bands. Several of its 30-plus moons show evidence of subsurface oceans or cryovolcanic activity, making them points of long-standing scientific interest. Orthis hosted the system's primary middle-system logistics hub: an orbital station moving roughly 120 million tons of material annually, anchoring asteroid and moon mining operations across the region.

Orbital station

Orbital altitude	Peak population	Annual throughput
~1.8M km	~95,000	~120M tons

A-5. Ceryn

Ceryn is the third gas giant, orbiting at 14.2 AU with a mass of 0.7 Jupiter. Its defining feature is its moon population — over 45 satellites, many on irregular, inclined, or retrograde paths that mark them as captured bodies rather than native ones. These orbital characteristics point to a major disruption event approximately 1.3 billion years ago, the same disturbance referenced in the system's deep history; whatever passed through or struck the outer system left Ceryn with a scattered, chaotic retinue that has yet to fully settle.

A-6. Helior

Helior is the outermost gas giant, orbiting at 38 AU with a mass of 0.4 Jupiter — the smallest of the system's four giants and the marker of its outer planetary boundary. Beyond Helior, significant planetary mass gives way to the cold and the dark. Its handful of sparse, frozen satellites are relics of the system's early formation, undisturbed and little studied, orbiting at the quiet edge of Asterra's reach.

A-7. Nysa

Nysa is a small, cold terrestrial world on a distant, irregular orbit averaging 62 AU, taking roughly 490 years to circle Asterra once. Its path is markedly eccentric and inclined relative to the system's orbital plane — a sign that Nysa never settled into the stable, near-circular order that governs the inner worlds. With a mass of 0.41 Earth and a surface gravity of 0.55 g, it retains only a trace atmosphere below 0.1 bar, frozen gases held against a mean surface temperature near 35 K. It has no moons; the same early orbital instability and gravitational interference from the outer gas giants that warped its path would have stripped or scattered any satellites it might once have held. Isolated and all but inert, Nysa marks the lonely far edge of the inhabited system — the last named world before the long dark out to Carmyn.

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. Its position has since taken on renewed significance as the first designated waypoint for Project Exodus.

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.

Comparison

Bodies of the Asterra binary system

Body	Star	Type	Orbital radius	Period	Mass	Mean temp	Moons
Keth	Asterra	Rocky	0.21 AU	41 d	0.62 Earth	~620 / 190 K	0
Ytharia	Asterra	Ocean terrestrial	0.68 AU	286 d	1.08 Earth	~284 K	2
Vael	Asterra	Gas giant	3.1 AU	5.4 yr	1.4 Jupiter	—	40+
Orthis	Asterra	Gas giant	7.6 AU	20.9 yr	1.1 Jupiter	—	33
Ceryn	Asterra	Gas giant	14.2 AU	53.6 yr	0.7 Jupiter	—	40+
Helior	Asterra	Gas giant	38 AU	~235 yr	0.4 Jupiter	—	12
Nysa	Asterra	Cold terrestrial	~62 AU (ecc.)	~490 yr	0.41 Earth	~35 K	0
Vethara	Carmyn	Venusian	0.08 AU	~18 d	0.81 Earth	~720 K	0
Pelun	Carmyn	Dwarf world	0.41 AU	~194 d	0.018 Earth	~145 K	1
Dorryn	Carmyn	Cold gas giant	4.8 AU	~38 yr	0.6 Jupiter	~52 K	17

Status

The Asterra system no longer shows any signs of life. All infrastructure is inactive — no power, no supply lines, no personnel. Ytharia, once the system's historical and cultural heart, is now inhospitable and war-torn. Carmyn remains a navigational reference point for Project Exodus planning, but the system as a whole stands silent and abandoned.