A more comprehensive habitable zone for finding life on other planets

TL;DR

This paper reviews and expands the concept of the habitable zone by incorporating additional planetary and stellar factors, enhancing the ability to identify potentially life-supporting exoplanets for future space missions.

Contribution

It introduces a more comprehensive habitable zone framework that includes factors beyond classical definitions, aiding in better target selection for habitability studies.

Findings

Classical habitable zone primarily considers CO2 and H2O greenhouse effects.

Newer formulations incorporate diverse planetary and stellar processes.

Enhanced HZ models improve filtering of unlikely habitable worlds.

Abstract

The habitable zone (HZ) is the circular region around a star(s) where standing bodies of water could exist on the surface of a rocky planet. Space missions employ the HZ to select promising targets for follow-up habitability assessment. The classical HZ definition assumes that the most important greenhouse gases for habitable planets orbiting main-sequence stars are CO2 and H2O. Although the classical HZ is an effective navigational tool, recent HZ formulations demonstrate that it cannot thoroughly capture the diversity of habitable exoplanets. Here, I review the planetary and stellar processes considered in both classical and newer HZ formulations. Supplementing the classical HZ with additional considerations from these newer formulations improves our capability to filter out worlds that are unlikely to host life. Such improved HZ tools will be necessary for current and upcoming missions aiming to detect and characterize potentially habitable exoplanets.