Astronomy Reference: Habitable Zones, Stellar Classification, Planet Types
Type: Developer Guidance — Real-World Science Reference Material Status: Reference material (general astrophysics, not Maf-specific canon) — preserved per creator's request as developer reference
Overview
General real-world astronomical reference material generated as developer tooling for world/planet generation — habitable zone calculation formulas, stellar classification data, and planet type taxonomy. Not Maf-specific canon; usable as a developer's toolkit for building out plausible star systems, planets, and habitable zones throughout the game.
Habitable Zone (HZ) Formulas
Based on the Kopparapu et al. (2013) model, simplified for practical use. Constants (1.1 and 0.53) can be adjusted for a more conservative or optimistic habitable zone (accounting for factors like cloud feedback or planetary atmosphere).
Method 1 — from stellar luminosity (L = luminosity in solar units, Sun = 1):
- Inner edge (AU) = √(L / 1.1)
- Outer edge (AU) = √(L / 0.53)
Method 2 — from stellar temperature and radius (when luminosity isn't directly known):
- Calculate luminosity: L = R² × (T / 5778)⁴, where T = star's effective temperature in Kelvin, R = star's radius in solar radii, and 5778 K is the Sun's temperature.
- Plug L into the Method 1 formulas above.
Worked example: A star with T = 5000 K and R = 0.9 solar radii: L = 0.9² × (5000/5778)⁴ ≈ 0.481. Inner HZ ≈ 0.662 AU, Outer HZ ≈ 0.952 AU.
Excel implementation: with stellar temp in cell A1 and stellar radius in A2 —
- Luminosity (A3):
=A2^2 * (A1/5778)^4 - Inner HZ boundary in AU (A4):
=SQRT(A3/1.1) - Outer HZ boundary in AU (A5):
=SQRT(A3/0.53)
Stellar Classification Table
| Spectral Type | Temp (K) | Color | Mass (☉) | Radius (☉) | Luminosity (☉) | Lifespan (yrs) | Example |
|---|---|---|---|---|---|---|---|
| O | 30,000–60,000 | Blue | 16–>100 | 6.6–>15 | >30,000× | ~1–10 million | Zeta Puppis |
| B | 10,000–30,000 | Blue-white | 2.1–16 | 1.8–6.6 | 25–30,000× | ~10–100 million | Rigel (B8Ia) |
| A | 7,500–10,000 | White | 1.4–2.1 | 1.4–1.8 | 5–25× | ~500 million | Sirius A (A1V) |
| F | 6,000–7,500 | Yellow-white | 1.04–1.4 | 1.15–1.4 | 1.5–5× | ~2–4 billion | Procyon A (F5IV–V) |
| G | 5,200–6,000 | Yellow | 0.8–1.04 | 0.96–1.15 | 0.6–1.5× | ~10 billion | Sun (G2V) |
| K | 3,700–5,200 | Orange | 0.45–0.8 | 0.7–0.96 | 0.08–0.6× | ~15–30 billion | Alpha Centauri B (K1V) |
| M | 2,400–3,700 | Red | 0.08–0.45 | 0.1–0.7 | 0.01–0.08× | ~100+ billion | Proxima Centauri (M5.5V) |
Notes: Spectral type subdivisions run 0 (hottest) to 9 (coolest) within each letter class (e.g., G2 is hotter than G8). Luminosity class (Roman numerals) indicates evolutionary stage: I = supergiant, III = giant, V = main sequence (our Sun is G2V). The Sun is a G-class main-sequence star, NOT an M-class star — a common misconception, since M-dwarfs (like Proxima Centauri) are far more numerous in the galaxy despite being cooler and dimmer, and dominate exoplanet habitable-zone research because their HZs sit much closer in.
White dwarfs and giants: also chartable by temperature range, though full tabulated data for these categories wasn't completed in this source session.
Planet Type Classification
By Composition
- Terrestrial (rock and metal): Earth, Mars, Venus, Mercury. Subtypes: Super-Earths (rocky, larger than Earth but smaller than Neptune), Sub-Earths (smaller than Earth, still rocky).
- Gas Giants (mostly hydrogen/helium): Jupiter, Saturn. Subtypes: Hot Jupiters (close-orbiting, very hot), Cold Jupiters (farther out).
- Ice Giants (water/ammonia/methane ices): Uranus, Neptune.
By Mass (NASA/ESA-style classification)
| Planet Type | Mass (Earth Masses) | Notes |
|---|---|---|
| Sub-Earth | < 0.8× Earth | Small rocky |
| Earth-sized | 0.8–1.25× Earth | |
| Super-Earth | 1.25–2× Earth | Rocky, possible thin atmospheres |
| Mini-Neptune | 2–10× Earth | Rocky core + thick gas envelope |
| Neptune-like | 10–50× Earth | Ice-rich, deep atmospheres |
| Gas Giant | > 50× Earth | Mostly H/He |
| Brown Dwarf* | ~13–80 Jupiter masses | Not a true planet (substellar) |
Brown Dwarfs
Substellar objects that form like stars (gravitational collapse of gas) but lack sufficient mass to sustain hydrogen fusion. Mass range: roughly 13–80 Jupiter masses (~0.01–0.08 solar masses). Can fuse deuterium (heavy hydrogen) if above 13 Jupiter masses. Very low luminosity, glowing mostly in infrared; surface temperatures ~300– 3,000 K. Use spectral classes L, T, and Y (cooler than the M class).
Is Jupiter a brown dwarf? No. Jupiter would need roughly 13x its current mass to begin deuterium fusion (the brown dwarf threshold), and roughly 80x its mass to become a true hydrogen-fusing star. It has no spectral class (planets don't) and formed from a planetary disk, not a collapsing gas cloud like stars/brown dwarfs do.
Appearances
- Creator-provided detail (ChatGPT export, "Maf Starfleet Battles Discussion")