A multi-parameter approach to exoplanet habitability
type: CreativeWork
description: Upcoming telescopes will be able to remotely detect potential biosignatures in exoplanet atmospheres and discover signs of life beyond our Solar System. To make the most of the limited observational resources available, target selection has focused on 'habitable worlds' defined as rocky bodies orbiting their host stars at a distance where stellar radiation is suitable for the presence of surface liquid water and enough surface gravity to sustain an atmosphere. With the ever-increasing number of detected exoplanets, we might end up with hundreds of planets that suit these criteria and are accordingly all equally likely to host life. Therefore, we must rethink our classification of what makes a planet habitable. This thesis investigates multiple factors such as planetary magnetism, tectonic activity, surface pressure, and surface temperature that affect habitability. Evidence from the solar system suggests that, unlike Venus and Mars, the presence of a significant magnetic dipole moment and the maintenance of a long-term carbon cycle aided by plate tectonics has assisted in preserving liquid water on Earth's surface. Modelling the magnetic dipole moments of detected rocky exoplanets reveals that 44% +/- 13% of the planets in the circumstellar habitable zone have a negligible magnetic dipole moment. Subsequently, an investigation into tidally induced tectonic activity on the detected rocky exoplanets suggests that 57% +/- 14% of the planets in the circumstellar habitable zone reside within the optimum regime for internal heating, with 14% +/- 2% likely to have tidally driven mobile lid tectonic activity that would help in maintaining the presence of surface liquid water and could be comparable to plate tectonics on Earth. The research conducted on magnetism, tectonics, and tides has revealed many Earth-centric assumptions and biases that still exist in current models. Thus, I develop a primary classification system to characterise the detected rocky exoplanets based on…
abstract: Upcoming telescopes will be able to remotely detect potential biosignatures in exoplanet atmospheres and discover signs of life beyond our Solar System. To make the most of the limited observational resources available, target selection has focused on 'habitable worlds' defined as rocky bodies orbiting their host stars at a distance where stellar radiation is suitable for the presence of surface liquid water and enough surface gravity to sustain an atmosphere. With the ever-increasing number of detected exoplanets, we might end up with hundreds of planets that suit these criteria and are accordingly all equally likely to host life. Therefore, we must rethink our classification of what makes a planet habitable. This thesis investigates multiple factors such as planetary magnetism, tectonic activity, surface pressure, and surface temperature that affect habitability. Evidence from the solar system suggests that, unlike Venus and Mars, the presence of a significant magnetic dipole moment and the maintenance of a long-term carbon cycle aided by plate tectonics has assisted in preserving liquid water on Earth's surface. Modelling the magnetic dipole moments of detected rocky exoplanets reveals that 44% +/- 13% of the planets in the circumstellar habitable zone have a negligible magnetic dipole moment. Subsequently, an investigation into tidally induced tectonic activity on the detected rocky exoplanets suggests that 57% +/- 14% of the planets in the circumstellar habitable zone reside within the optimum regime for internal heating, with 14% +/- 2% likely to have tidally driven mobile lid tectonic activity that would help in maintaining the presence of surface liquid water and could be comparable to plate tectonics on Earth. The research conducted on magnetism, tectonics, and tides has revealed many Earth-centric assumptions and biases that still exist in current models. Thus, I develop a primary classification system to characterise the detected rocky exoplanets based on…
author: McIntyre, Sarah
language: en_AU
date published: 2023
date modified: 2026-07-24T01:07:22Z
provider: Australian Catholic University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Australian Catholic University

PropertyValue
property ID: Handle
value: http://hdl.handle.net/1885/286534