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Circumstellar Habitable Zone


Possible Nomenclature:

  • Exclusion - No planets
  • Epistellar - Very hot
  • Hot - Hot
  • Inner - Inner
  • Standard - Goldilocks / Gaian
  • Outer - Outer
  • Cold - Cold
  • Winter - Very cold

Inhospitable Region

This region is generally considered to be too hot for life. It is close to the star, and planets are either baked rock balls or hot jovians.

Exclusion (X)

The first, innermost, zone is generally considered too hot to support solid planets of any type. Temperatures tend to be above 6000K.

Epistellar (E)

Planets this close are rare, and temperatures are above 1000K. Planets in this zone are generally tidally locked to their star. Only jovian planets can retain an atmosphere in this zone, though smaller, young worlds may retain them briefly during planetary formation.

Hot (H)

This region is too hot for surface water to exist, and planets that form here will not have an atmosphere. Smaller worlds which have migrated inwards may still retain an atmosphere.

Goldilocks Region

This is the region around a star most likely to have liquid water and life.

Inner (I)

The inner zone is warmer than ideal, but it's possible for conditions to allow water and life. Planets can retain an atmosphere here, which may allow enough reflection of heat to cool the world down.

Middle (M)

The middle zone is just about right for surface water and life.

Outer (O)

Temperature: 150K - 250K
Distance: 185 Mkm - 500 Mkm

The outer zone is colder than ideal, but a thick atmosphere with greenhouse effects can ensure surface water is possible. Smaller worlds which don't retain an atmosphere will tend to be too cold.

Both Mars and most of the Belt are considered part of the Outer zone.

Snow Region

This is the outer part of the system, where ice is more common than water. Surface life is almost unheard of this far out from a star, and liquid water is only possible through gravitational heating.

Cold (C)

Temperature: 75K - 150K
Distance: 500 Mkm - 2 Gkm

The cold zone is well beyond what even optimistic estimates allow for surface water. Life may be possible out here, in sub-surface oceans in the moons of gas giants, but such life is not surface based.

Both Jupiter and Saturn fall into this zone.

Stygia (S)

Temperature: 50K - 75K
Distance: 13 AU - 30 AU

Stygia is the name given to the outer part of the system where planets are most likely to be found. Beyond this planetary sized objects tend to be rare. It is frigid and cold, and the parent star will often not be much more than a bright point of light.

Uranus falls into this zone, with Neptune right on the outer edge.

Tartarus (T)

Temperature: 50K and below
Distance: 30 AU +

The outer edge of the system, generally filled only with balls of ice and snow. Beyond this lay Kuiper Belts and Oort Clouds.

worldgen/systems/chz.txt · Last modified: 2019/08/12 08:46 by sam