2024-02-13 21:36:22
Keavin Moore, doctoral student at iREx, recently completed his doctorate at McGill University. He summarizes his research project here.
Artist’s concept showing DG CVn, a binary system composed of two red dwarf stars. Credit: NASA Goddard Space Flight Center/S. Wiessinger
Life as we know it, organic life on Earth, depends on the presence of liquid water. Although Earth orbits a so-called “yellow dwarf” star, the Sun, most stars in the universe are red dwarfs, smaller and less bright. Around these small stars orbit a large number of planets likely to support life. We hope to study and understand them better in the near future. However, red dwarfs are more active, and the radiation and particles they emit put the planets around them at risk of losing their atmosphere. During my PhD, I created a model that combines what is known from astronomy, atmospheric science and geophysics to study rocky planets around red dwarf stars and explore the presence of water – and therefore the potential habitability – of these worlds.
My first project focused on how water moves between the interior and surface of an Earth-sized planet, driven by things like plate tectonics. The model showed that water might be stored in the planet’s mantle (the middle layer of a rocky terrestrial planet, between the core and the surface), which would prevent it from being lost into space. This might eventually lead to a stable liquid ocean on the surface. We then improved the model to make it more complex and more general.
Credit: Kevin Moore
The next version of the model took into account the first stage of a planet’s evolution, when it is extremely hot. At this point, an ocean of molten silicates (rocks) extends from the planet’s surface to its core, where water is soluble. This ocean acts as a shield, preventing water from escaping into space. Our simulations suggest that this long-lived reservoir might significantly improve the chances of habitability of planets around red dwarfs.
Finally, as part of the work of two undergraduate interns, whom I supervised as part of their end-of-study project, we studied the influence of the mass of a planet on its habitability. Large planets retain water better, but sometimes a large part of it is trapped in the planet’s mantle, which is not conducive to the habitability of the surface.
Our simulations provide a solid basis for further research into the habitability of rocky planets around red dwarfs and highlight the importance of studying planets as complete systems.
To know more
Keavin completed his doctorate at McGill between 2018 and 2023, under the supervision of Professor Nicolas Cowan of iREx. His thesis will be available soon.
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