Planetary Profile: Duskara

Name: HD Xanthea (colloquial: “Xanthea’s Star”)
Spectral Type: M0–M1 main-sequence star (a red dwarf at the warm end of its class)
Mass: ~0.55 Solar masses
Luminosity: ~0.05–0.06 Solar luminosities
Estimated Age: ~4–5 billion years
Activity: Quiet for a red dwarf, but still prone to flares that feed Duskara's auroras and disrupt communications
Habitable Zone: Close-in orbits, where planets are tidally locked

Planet Name: Duskara
Orbital Distance: ~0.17 AU from HD Xanthea (varies slightly with eccentricity)
Orbital Period: ~34.7 Earth days, one Cycle (synchronous rotation leads to tidal locking)
Stellar Flux: Roughly twice what Earth receives from the Sun
Rotation: Tidally locked (one hemisphere faces the star constantly)
Axial Tilt: Minimal (≤ 1°), little to no seasonal variation

Diameter: ~1.00–1.05 × Earth’s diameter
Mass: ~1.00–1.10 × Earth’s mass
Surface Gravity: ~0.95–1.05 g (near Earth-normal)
Escape Velocity: Similar to Earth’s (slightly higher or lower depending on precise mass/radius)

Day Side:
- Surface Temperatures: ~150–220°C, hottest around the substellar point
- Brutal stellar flux, extreme UV and particle radiation
- Frequent dust storms in transition zone
- Minimal or no standing water at the surface
Night Side:
- Surface Temperatures: ~−100 to −150°C (variable by region)
- Permanently dark or in deep twilight from scattered auroras
- Glacial ice sheets, occasional geothermal vents or volcanic hotspots
- Some pockets of life in subterranean areas warmed by geothermal heat

Width: ~200–300 km band encircling the planet (about 40,000 km long)
Settled Arc: About 6,000 km of the belt (Daŋa-Hai, the Living Edge), where night-side glaciers supply water; the remainder is unsettled
Temperature Range: Generally −5°C to +40°C, depending on proximity to day or night side
Atmospheric Dynamics:
- Strong, persistent winds due to stark temperature gradient
- Frequent superstorms where hot and cold air masses meet
Habitable Zone: Nearly all surface settlements and farmland lie here; major cities form linear chains along temperate corridors

Composition (approx.):
- ~76–78% Nitrogen (N₂)
- ~20–22% Oxygen (O₂)
- ~1–3% Argon / other inert gases
- Trace amounts of CO₂, H₂O vapor, and exotic molecules
Surface Pressure: ~0.9–1.1 bar (near sea-level Earth equivalent)
Radiation & Weather:
- Enhanced stellar radiation on the day side; partial protection via thick atmosphere
- Robust wind circulation redistributing heat and moisture from day to twilight regions

Primary Water Reservoirs:
- Subterranean aquifers, glacial deposits on the night side
- Collection of atmospheric moisture in twilight and day-night transition storms
Surface Water:
- Present mainly in the form of rivers or small seas in the deeper parts of the twilight belt
- Lake- or river-like bodies fed by precipitation and geothermal springs
Geology:
- Tectonically active regions produce geothermal vents, crucial for night-side warmth
- Abundant mineral deposits in dayward highlands, mined by robotic systems

A dry world: Duskara has no oceans. With little water vapor in the air, the greenhouse effect stays weak, and the planet avoids the runaway heating that would sterilize a wetter world at this distance from its star.
Water locked in the night: Nearly all of Duskara's water sits frozen on the night side, with the carbon dioxide that freezes out beside it. Glaciers creep toward the Nightward Edge and melt there, feeding the rivers, aquifers, and storms of the belt. They reach the belt only along one arc of the ring, which is why the settled world is an arc and not a ring. This is why water is scarce, and why night-side ice matters so much.
Wind as heat engine: The thick atmosphere carries day-side heat across the terminator and returns cold air beneath it. The eternal wind and the storm walls are the visible face of that circulation, and they keep the belt between −5°C and +40°C.
Magnetic shelter: A strong planetary magnetic field turns aside most of the star's flare radiation. What gets through lights the auroras.

Native Flora & Fauna:
- Adapted to low light, high winds, or subterranean niches
- Some species show bioluminescence or specialized thermal regulation
- Deep-cave ecosystems rely heavily on geothermal/chemosynthetic processes
Human Settlements:
- Concentrated in twilight belt, forming linear “wind-hardened” cities
- Cave-dwelling communities near geothermal vents on night side
- Careful agriculture (vertical farming, hydroponics) in stable twilight microclimates