Earth Similarity Index with two free parameters

TL;DR

This paper introduces an Earth Similarity Index with two adjustable parameters optimized to match Mars's similarity to Earth, and applies it to various planets and exoplanets to assess their Earth-likeness.

Contribution

The paper proposes a new Earth Similarity Index with two free parameters optimized for Mars, providing a refined method to evaluate planetary similarity to Earth.

Findings

Optimized parameters m=0.8 and T=0.8 yield ESI values comparable to previous studies.

Several exoplanets are identified as having ESI close to the Earth similarity threshold.

The method highlights planets with potential Earth-like characteristics.

Abstract

We have derived Earth Similarity Index (ESI) with two free parameters m and T. These free parameters are optimized with the consideration that the planet Mars is almost similar to the Earth. For the optimized values of free parameters, the interior-ESI, surface-ESI and ESI for some planets are calculated. The results for m = 0.8 and T = 0.8 are compared with the values obtained by Schulze-Makuch {\it et al.} (2011). We have found that the exoplanet 55 Cnc f is within 10% away from the threshold value T. The exoplanets HD 69830 c, 55 Cnc c, 55 Cnc f, 61 Vir d and HIP 57050 b are found to have ESI within 10% from the threshold value.