Project description

Whether exoplanets may host life as we know it is often assessed in terms of the circumstellar  ‘habitable zone’, where liquid water could exist on the planetary surface. However, this concept is only well-defined for planets with an Earth-like atmospheric composition. Similarly, several proposed biosignatures for exoplanets (i.e., signs of the presence of life as we know it), such as dimethyl sulfide and phosphine, are molecules which on Earth are only produced by living organisms, but for which abiotic formation routes may operate on other planets. The initial goals of this PhD project are to – (i) check the robustness of the classical approach to compute habitable zone boundaries across different 1D models, (ii) develop a more consistent approach using 1D models which improves estimates of habitability compared to the classical approach and (iii) using the new approach to provide a better characterization of habitable zone boundaries going beyond simplified physical descriptions. The final goal of this PhD project is to widen the habitable zone concept to non-Earth-like atmospheres, e.g. dominated by carbon dioxide as on Venus and Mars. Providing a more comprehensive definition of habitability is necessary to establish more realistic habitable zone boundaries in the future, especially for the purpose of informing telescope target lists, and identifying the most promising candidates in the search for life beyond the Solar System.