Trenhal
Planetary Overview
Trenhal is the second planet in the Eidolon Star System, orbiting at a distance of 0.32 AU (approximately 47.9 million kilometers) from its parent star. Slightly larger than Helex, with a radius of 4,800 kilometers and a mass around 0.47 Earth masses, Trenhal is a terrestrial world dominated by intense volcanic activity and a dense, corrosive atmosphere. The planet's elevated surface temperatures and sulfurous clouds render it a hostile environment, yet one of great scientific interest for its dynamic geology and atmospheric chemistry.
Trenhal rotates slowly, completing one rotation roughly every 92 hours. Its rotation is not synchronized with its orbit, leading to uneven thermal distribution and complex atmospheric circulation patterns.
Atmospheric and Thermal Characteristics
The planet's surface temperature averages around 585 K, with localized hotspots near active volcanic regions. Its relatively high albedo of 0.18 reflects some of the incoming stellar radiation, though this is offset by a substantial greenhouse effect from the dense atmosphere.
Trenhal's atmosphere is primarily composed of carbon dioxide (68%) and sulfur dioxide (18%), with nitrogen (9%), argon (3%), and trace gases rounding out the mix. This composition creates an opaque, choking atmosphere, thick enough to exert a pressure 2.7 times that of Earth at sea level.
| Gas (Formula) | Percent |
|---|---|
| Carbon Dioxide (CO₂) | 68% |
| Sulfur Dioxide (SO₂) | 18% |
| Nitrogen (N₂) | 9% |
| Argon (Ar) | 3% |
| Other | 2% |
The sulfurous haze, combined with trace hydrothermal emissions, results in frequent lightning activity and photochemical reactions in the upper atmosphere, forming transient sulfuric acid droplets and yellow-orange clouds.
Geological and Surface Features
Trenhal's surface is defined by widespread volcanism, with numerous shield volcanoes, fissure vents, and expansive basaltic plains. Lava channels several hundred kilometers long intersect the terrain, feeding into caldera basins and lava seas. Tectonic activity is pronounced, with rift zones and fault scarps suggesting active mantle convection.
Impact craters are relatively sparse compared to more geologically quiescent bodies, suggesting a young and frequently resurfaced crust. Areas of high reflectivity correspond to silica-rich deposits possibly formed through chemical weathering or volcanic distillation processes.
Seismic and Magnetic Properties
Trenhal exhibits strong but localized magnetic anomalies, likely linked to subsurface magma flows rather than a global magnetic field. Seismology indicates persistent low-frequency tremors consistent with active volcanism and tidal flexing.
Orbital and Gravitational Context
With an orbital eccentricity of 0.019 and inclination of 1.6 degrees, Trenhal maintains a stable, near-circular orbit. It resides well within the gravitational influence of Eidolon, but distant enough from Helex and Orvenya to avoid significant perturbation.
Moons
Trenhal hosts two natural satellites:
Volmir is a rocky moon approximately 820 kilometers in radius, orbiting at a distance of 54,000 kilometers. It is heavily cratered with visible tidal stress fractures. Subsurface brine pockets are hypothesized beneath the crust, though unconfirmed.
Karesh is a smaller, likely captured asteroid 230 kilometers in radius, with a tumbling rotation and dark, carbonaceous surface. It occupies a more eccentric orbit at 138,000 kilometers and is suspected of emitting intermittent piezoelectric radio signals.
Summary
Trenhal is a geologically active, superheated terrestrial world with a dense and chemically complex atmosphere. It offers valuable opportunities for studying sulfur-based geochemical cycles, volcanically induced atmospheric dynamics, and the interplay between planetary geology and atmospheric evolution. While uninhabitable by Earth standards, its volatile-rich environment and active surface processes make it a compelling subject for planetary science.
Maps
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Trenhal - Surface Map
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Trenhal - SOI
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