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 first goal of this PhD project are to widen the habitable zone concept to non-Earth-like atmospheres, e.g. dominated by carbon dioxide as on Venus and Mars. Comparison with exoplanet catalogs will then provide new insights into how many planets may host life as we know it.  Second, we aim to study the dependence of proposed biosignatures on atmospheric pressure, temperature, and redox state. The boundary conditions for the models will be drawn from state-of-the-art exoplanet observations, e.g. with the James Webb Space Telescope (JWST). In a third step, the spectroscopic fingerprints of robust biosignatures at optical and near-infrared wavelengths will be determined, and compared with observations with JWST as well as the METIS instrument on the e-ELT, which is expected to start operations by 2028.

Additional specifications

We look for a candidate with an M.Sc degree in Astronomy, Chemistry, or Planetary Science. Familiarity with (exo)planetary atmospheric chemistry and/or molecular spectroscopy is recommended.