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Star and Planet Classification

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Stellar Classification

The Federation classification systems provide standardized categorizations for celestial bodies encountered during exploration. The stellar system describes the host star's spectral type, luminosity, and implications for planetary environments, while the planetary system focuses on surface conditions, atmosphere, hydrosphere, and habitability.

These systems are used in Starfleet survey logs, astrometric databases, and first-contact reports. Stellar classes determine the stability and width of habitable zones, directly influencing which planetary classes are likely to form.

Stellar Classification (Host Stars)

Stellar type heavily influences planetary habitability and classification. G and K main-sequence stars are optimal for Class M worlds.

Class Color Temperature (K) Key Spectral Features Prevalence Typical Planets/Habitability Notes Examples (Canon/Expanded)
O Blue-violet >30,000 Ionized helium (He II), weak hydrogen Very rare Unstable radiation; unlikely habitable zones Rigel analogs
B Blue-white 10,000–30,000 Neutral helium, moderate hydrogen Rare Short lifetimes; hot Jupiters or barren worlds Rigel (B8Ia)
A White 7,500–10,000 Strong hydrogen (Balmer lines) Uncommon Moderate habitability potential Sirius (A1V)
F Yellow-white 6,000–7,500 Metals (Ca II, Fe) prominent Common Good for life; stable habitable zones Procyon (F5IV-V)
G Yellow 5,000–6,000 Hydrogen + metals; Sun-like Common Ideal for Class M planets Sol (G2V)
K Orange 3,500–5,000 Strong metals, some molecules Very common Long-lived; superhabitable potential Alpha Centauri B (K1V)
M Red <3,500 Titanium oxide (TiO), molecular bands Most common Very long-lived; close-in habitable zones possible Proxima Centauri (M5.5Ve)

Luminosity Classes

  • V — Main-sequence (dwarfs, most habitable systems)
  • III — Giants
  • I — Supergiants
  • etc. (see full list in separate stellar classification article if needed)

Planetary Classification (Core Classes)

Class Designation Key Traits Location/Zone Typical Diameter (km) Age (billion years) Life Potential Examples (Canon/Expanded)
A Geothermal Partially molten, volcanic, hydrogen compounds atmosphere Ecosphere/Cold 1,000–10,000 0–2 None Janus VI (conjectural)
B Geomorteus Molten surface, thin toxic atmosphere (helium/sodium) Hot 1,000–10,000 0–10 None
C Geoinactive Frozen barren rock, no atmosphere Cold Varies Varies None
D Barren/Plutonian Airless rock/ice dwarf Outer system Small Varies Minimal Regula
H Desert Arid, high-radiation, limited water Hot/Ecosphere Varies Varies Hardy/adaptable Tau Cygna V
J Gas Giant Hydrogen/helium envelope, storms, rings Cold Massive Varies Non-humanoid (possible in layers) Jovian analogs
K Adaptable Thin CO₂ atmosphere, dome-habitable Ecosphere Varies Varies Primitive
L Marginal Borderline habitable, often arid/sparse vegetation, higher CO₂ Ecosphere Varies Varies Limited
M Minshara/Terrestrial O₂/N₂ atmosphere, 20–80% water, temperate, shirt-sleeve habitable Ecosphere 10,000–15,000 3–10 Abundant (humanoid common) Earth, Vulcan, Qo'noS
N Reducing/Sulfurous Thick toxic atmosphere (Venus-like) Hot Varies Varies Limited
O Pelagic 80%+ global ocean, minimal land Ecosphere Varies Varies Aquatic dominant
P Glaciated/Cryoterrestrial 80%+ ice cover, breathable but cold Ecosphere/Cold 10,000–15,000 3–10 Hardy vegetation/animal
T Ultragiant Massive gas supergiant, near-stellar ignition Cold Enormous Varies None
Y Demon Toxic, extreme heat (>500 K), sulfuric deserts, thermionic discharges Hot Varies Varies Lethal "Demon" class

Planetary Sub-classes (Modifiers)

Sub-classes stack as prefixes or parentheticals (e.g., Verdant Oceanic Class M). They refine core classes, especially M.

Common for Class M

  • Verdant — Hyper-lush vegetation: dense forests, expansive grassy plains, high biodiversity and O₂ from photosynthesis. Superhabitable traits.
  • Oceanic — High hydrosphere (75–90% water): massive oceans, archipelagos, mega-lakes, river deltas. Transitional to Class O.
  • Arid — Low water (20–40%), deserts/savannas dominant.
  • Temperate — Balanced mild climate, gentle seasons, varied biomes.
  • Glacial — Cold-biased with ice caps/tundra but breathable.
  • Pelagic — Near-ocean (80–95% water), scattered land.

Other examples

  • Molten (A/B) — Active lava oceans.
  • Frozen (P/C) — Deep ice, subsurface potential.
  • Turbulent (J/T) — Extreme storms/rings.

Example: Verdant Class M (Oceanic-Temperate)

Verdant Class M (Oceanic-Temperate sub-class) (shorthand: VCM-O-T)

This variant represents a superhabitable lush terrestrial world with amplified greenery and water features.

  • Core Class: M (Minshara)
  • Sub-classes: Verdant, Oceanic, Temperate
  • Atmosphere: 78% N₂, 21–22% O₂ (elevated), trace gases
  • Hydrosphere: 75–85% (massive oceans, mega-lakes, wetlands)
  • Land Biomes: Rolling grassy plains, dense temperate forests, river-fed lakes
  • Climate: Warm-mild (15–22°C avg.), high precipitation, gentle seasons
  • Gravity: ~0.9–1.1 g
  • Diameter: 10,000–15,000 km
  • Age: 3–10 billion years
  • Habitability: Superhabitable; high biodiversity, fertile soils, no major extremes
  • Life: Abundant carbon-based flora/fauna; potential sapients

From orbit: A deeper-blue marble with emerald continents veined by rivers/lakes amid azure seas. Ideal for colonization; priority for ecological surveys.

Relationship Between Stellar and Planetary Classes

  • G/K main-sequence stars → Best for Verdant, Oceanic, Temperate Class M
  • M dwarfs → Common for Glaciated or Pelagic variants (tidal locking possible)
  • O/B types → Often associated with Class J gas giants or Y demon worlds

Appendices

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