The discovery of extrasolar planets, especially the habitable planets to be one of the most exciting and continuous studies has developed rapidly hitherto. The habitable planet must be in a habitable zone. The habitable zone that has been modeled previously has a non-linear form by considering some parameters of albedo, temperature, surface pressure, semi-major axis, starfish mass, spectral star type, and so on. In this model, we simplify the previous model into a linear model and determine the mathematical equations for inner and outer boundaries of habitable zone, we obtain 0.54 SA for inner boundary and 1.66 SA for outer borders only considering the semi-major axis, the mass of the parent star, and spectral type of the parent star. This linear model has a high accuracy in predicting the habitable planets so that the results do not vary much with the previous non-linear models.

Keywords : Habitable zone, Habitable Planet, Linear Model, Non-linear Model, Extrasolar Planet.