Star and Planet Classification

Federation Planetary and Stellar Classification

I've decided to adapt Star Trek's classification systems. The Federation classification systems provide standardized categorizations used in Starfleet surveys, astrometric databases, and exploration logs. Stellar classes describe host stars and their habitable zones, while planetary classes detail surface conditions, atmospheres, and habitability. Together they form the basis for evaluating worlds and their potential for life.

Stellar Classification (Host Stars)

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

The mnemonic for spectral types is "Oh Be A Fine Girl/Guy, Kiss Me" (OBAFGKM). Sol (Earth's Sun) is G2V: a yellow main-sequence star.

Core Spectral Classes

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

Added to spectral type (e.g., G2V):

V — Main-sequence/dwarfs (most common for habitable systems)
III — Regular giants
II — Bright giants
I — Supergiants (Ia most luminous, Ib less)
0 / Ia+ — Hypergiants (extremely luminous, rare)
IV — Subgiants
VI — Subdwarfs
D — White dwarfs

Sub-classes / Modifiers

Main-Sequence — Stable hydrogen-fusion core (V class default)
Giant / Supergiant — Evolved, expanded radius
Dwarf — Small, long-lived
Peculiar — Unusual composition (e.g., carbon-rich)
Variable — Pulsating or eruptive
Binary / Multiple — Part of multi-star system

Planetary Classification

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)

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

See also: Habitable zone, Class M, Hertzsprung-Russell diagram
Non-canon expansions: Star Trek: Star Charts
Shorthand examples: G8V (stable yellow dwarf), VCM-O-T (Verdant Class M Oceanic-Temperate)