Ravi Kumar Kopparapu

Research Associate
Department of Geosciences -- The Penn State University

443 Deike Building
University Park, PA 16802
Phone: 225.678.0058


  

             Habitable Zones for 1 Earth mass planet                                                                           Habitable Zones for multi-mass planets


Calculation of Habitable Zones

Enter stellar effective temperature and luminosity (Default is Sun).

If you don't know the luminosity, just enter Teff and keep luminosity = 0.

That will give you just Habitable stellar flux boundaries.


(If you want to calculate HZs for a number of stars, download this fortran code) . Table of Coefficients can also be downloaded.


(A python version of the code (courtesy John Armstrong at Weber State, is also available).


After entering the values in each box, just click inside each box to obtain the results.


Teff (K) Stellar Luminosity (solar units)


Conservative habitable zone limits (1 Earth mass) Stellar flux compared to the Sun HZ distance from the star (AU)
Inner HZ - Runaway Greenhouse limit
Outer HZ - Maximum Greenhouse limit


Optimistic habitable zone limits (1 Earth mass) Stellar flux compared to the Sun HZ distance from the star (AU)
Inner HZ - Recent Venus limit
Outer HZ - Early Mars limit



The following limits are for 5 Earth mass and 0.1 Earth mass planets. The inner edge of the HZ (in the units of stellar fluxes) moves closer to the star by about +7% for a 5 Earth mass planet, compared to the inner edge for an Earth mass planet (see above table). For a 0.1 Earth mass planet, the inner edge moves away from the star by - 10%, compared to the inner edge flux for an Earth mass planet. The outer edge of the HZ does not change in any appreciable way. So for the outer edge, use the 1 Earth mass (conservative and optimistic) limits.


CAVEAT: We assume that for these planets, the background Nitrogen gas pressure scales according to the planetary gravity. We should caution that volatile delivery to a planet is stochastic in nature, and may be a weak function of planetary mass. Still, this is the best assumption we can make in the absence of a rigorous theory of how planetary volatile content varies with planet mass. So, please keep this in mind when using the following limits. See Kopparapu et al.(2014) for more details.

Conservative habitable zone limits (5 Earth mass) Stellar flux compared to the Sun HZ distance from the star (AU)
Inner HZ - Runaway Greenhouse limit


Conservative habitable zone limits (0.1 Earth mass) Stellar flux compared to the Sun HZ distance from the star (AU)
Inner HZ - Runaway Greenhouse limit



If you use this calculator or the FORTRAN code, please cite the following publications:

"Habitable Zones Around Main-Sequence Stars: New Estimates" by Kopparapu et al.(2013), Astrophysical Journal, 765, 131    arXiv link

"Habitable Zones Around Main-Sequence Stars: Dependence on Planetary Mass" by Kopparapu et al.(2014), Astrophysical Journal Letters, 787, L29    arXiv link