I propose a simple, fully explicit habitability coefficient (C) for exoplanets based on (i) stellar irradiance at the planet, (ii) orbital-frequency penalization as a proxy for extreme proximity effects, and (iii) a multiplicative factor intended to summarize atmospheric and surface-water suitability in the spirit of classical habitable-zone modeling. The final score is normalized to C ∈ 0,1 and is easy to compute from basic orbital and stellar parameters. This note is intended as a transparent, reproducible toy model. It should be interpreted as a heuristic ranking metric (useful for prioritization) rather than a validated predictor of biosignatures. The model includes a complete Python implementation.
Márcio Barbosa (Sat,) studied this question.