Superhabitable Planets Around Mid-Type K Dwarf Stars Enhance Simulated JWST Observability and Surface Habitability

In our search for life beyond the Solar System, certain planetary bodies may be more conducive to life than Earth. However, the observability of these `superhabitable’ planets in the habitable zones around K dwarf stars has not been fully modeled. This study addresses this gap by modeling the atmospheres of superhabitable exoplanets. We employed the 1D model $\mathtt{\text{Atmos}}$ to define the superhabitable parameter space, $\mathtt{\text{POSEIDON}}$ to calculate synthetic transmission spectra, and $\mathtt{\text{PandExo}}$ to simulate $\text{JWST}$ observations. Our results indicate that planets orbiting mid-type K dwarfs, receiving $80\mathrm{\%}$ of Earth’s solar flux, are optimal for life. These planets sustain temperate surfaces with moderate $C{O}_2$ levels, unlike those receiving $60\mathrm{\%}$ flux, where necessarily higher $C{O}_2$ levels could hinder biosphere development. Moreover, they are easier to observe, requiring significantly fewer transits for biosignature detection compared to Earth-like planets around Sun-like stars. For instance, detecting biosignature pairs like oxygen and methane from $30$ parsecs would require $150$ transits ($43$ years) for a superhabitable planet, versus over $1700$ transits ($\sim 1700$ years) for Earth-like planets. While such observation times lie outside of $\text{JWST}$ mission timescales, our study underscores the necessity of next-generation telescopes and provides valuable targets for future observations with, for example, the $\text{ELT}$.