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This page hosts an interactive calculator that estimates several feature of the habitable zone (HZ) and of the 4 Gyr continuously habitable zone (CHZ).

A C code is available for download to calculate HZ and CHZ for a number of stars.

If you use the calculator or the code, please acknowledge the following paper:

Valle G., Dell'Omodarme M., Prada Moroni P.G., Degl'Innocenti S. (2013). Evolution of the habitable zone of low-mass stars. Detailed stellar models and analytical relationships for different mass and chemical compositions.

Input

The following information are required:
  • M: the mass of the star in solar unit (range: 0.70 - 1.10 Msun).
  • Metallicity: the metallicity of the star. Either Z (range: 0.005 - 0.04) or [Fe/H].
  • ΔY/ΔZ: the helium-to-metal enrichment ratio in the relation Y = 0.2485 + ΔY/ΔZ * Z (range: 1 - 3, standard value = 2).
  • To: the equilibrium temperature of the outer boundary (range: 169 - 203 K).
  • A: the albedo of the planet (range: 0.0 - 1.0, Earth = 0.3).

Output

The following information are computed:
  • dm (AU): the distance from the host star at which the maximum of habitability occurs.
  • tm (Gyr): the duration of the maximum habitability.
  • W (AU): the width of the HZ for which the habitability lasts at least one half of the maximum
  • Ri (AU): the position of the inner boundary of the CHZ, for which the habitability lasts at least 4 Gyr.
  • Ro (AU): the position of the outer boundary of the CHZ, for which the habitability lasts at least 4 Gyr.

Analytical models input

Please provide the required input and press the button "Compute...".

Metallicity: Z [Fe/H]
M (Msun) Metallicity ΔY/ΔZ To (K) A

 

WARNING: the mass is outside the range [0.7 - 1.1].
WARNING: the ΔY/ΔZ is outside the range [1 - 3].
WARNING: the temperature of the outer boundary is outside the range [169 - 203].