Aucafidus is a trojan planet. It orbits at the L4 Lagrange point of its companion gas giant, Subralis (HD 28185 b). Both planets share one orbit around the main sequence star HD 28185 (HIP 20723, SAO 149631). Locals know this star as Biculus.

Aucafidus is home to an estimated 25 billion sentient beings. About 5 billion live on the surface, in roughly 2 million cities on the southern continent. The other 20 billion live in the three orbital bands. The surface resembles Earth in many ways. Gravity reaches 1.27 times the gravity of Earth, and the atmospheric pressure is nearly double. The planet has no natural satellite.

Key Facts

Type
Terrestrial Trojan Body
Satellites
none natural, three artificial orbital bands
Affiliation
Multitude
Colonized
~250kya (from archaeological records)
Population
25 billion entities (5 billion on the surface, 20 billion in the orbital bands, including 3.47 billion infomorphs)

Astronomy and Orbit

Aucafidus and Subralis occupy the same orbit around Biculus. Aucafidus leads the gas giant by 60 degrees at the L4 Lagrange point. This trojan configuration gives long-term orbital stability. The gas giant also shapes the outer reaches of the system.

Semimajor axis
1.031 ± 0.060 AU
Eccentricity
0.070 ± 0.040
Periastron
0.956 AU
Apastron
1.102 AU
Inclination
0 degree
Period of revolution
1.0484 earth years (382.928 earth days, 407.14 aucafidian days)
Synodic rotation period
81261.94 seconds (22:34:22, 0.941 earth days)
Sidereal rotation period
81062.84 seconds (22:31:03, 0.938 earth days)
Axial tilt
24.6 degrees

Physical Characteristics

Radius
5734 km
Mass
6.1213E+24 kg
Density
7.78 g/cm^3
Surface gravity
12.43 m/s^2 (1.27 g)

Aucafidus has an exceptionally large iron-nickel core. The core makes up nearly half of the planet by volume. This core generates a strong magnetic field. A strong field is crucial for a planet that harbors life. The large core also gives Aucafidus a slightly greater mass and a much higher density than Earth. The planet is smaller than Earth, yet its surface gravity reaches 12.43 m/s².

Atmospheric Characteristics

Pressure
1.98 bar
Composition
18% (356 mbar) oxygen, 81.6% (1616 mbar) nitrogen, 0.4% (8 mbar) other gases.

The atmosphere holds nearly twice the pressure of the atmosphere of Earth. The surface gravity is also higher. Together these two factors give the surface a distinctly heavy feel. The oxygen-rich composition supports the native biosphere and its humanoid inhabitants.

Biosphere and Climate

The surface of Aucafidus resembles the surface of Earth in many respects. It hosts a rich native biosphere. The axial tilt of 24.6 degrees produces seasonal cycles comparable to the cycles of Earth. These seasons play out across the two continents of the planet.

Aucafidus has no natural satellite, so it lacks lunar tides. The oceans respond only to weaker solar tides. This gives the shorelines an unusually stable ecology. The large iron-nickel core also generates a strong magnetic field. This field shields the biosphere from stellar radiation. This protection is crucial for a planet that harbors life.

Settlement Overview

The 25 billion inhabitants of Aucafidus live in two very different realms. One realm is the planetary surface. The other is a set of three artificial orbital bands that encircle the planet.

The Surface

Roughly 5 billion beings live on the surface. They concentrate in roughly 2 million cities across the southern continent. The southern landmass is the administrative and cultural heart of Aucafidus. It is a mosaic of gleaming urban centers integrated with verdant vegetation. It is also the launchpad for travel to the orbital bands. The northern continent stands in contrast. It is a vast wildlife reserve. Sentient presence there is limited to research facilities and eco-tourism outposts.

The two-continent philosophy, the decentralized AI governance, and the connection to the orbital bands are described in Aucafidus: The Surface.

The Orbital Bands

The other 20 billion entities live in three orbital bands. These ring-shaped megastructures encircle the planet in place of natural satellites. The First Band is tethered to the equator. It hosts a diverse post-scarcity biosphere of transplanted species. The Second Band is coplanar with the orbit of the planet. It is a high-tech society of humanoids, robots, and synthetic life. The Third Band aligns with the terminator of the planet. It endures perpetual twilight, sustained by artificial sunrises, and thrives on tourism. Across the three bands live 16.53 billion physical inhabitants (11.03 billion on land, 5.51 billion at sea). A further 3.47 billion infomorphs live in the computing infrastructure of the bands.

Each band has its own society, environment, and infrastructure. Aucafidus: The Orbital Bands describes them in detail.