Habitability from Tidally-Induced Tectonics

• Published in: arXiv.org
• Main Authors: Valencia, Diana, Vivian Yun Yan Tan, Zajac, Zachary
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 19.03.2018
• Subjects: Atmospheric models; Carbon; Carbon content; Carbon dioxide; Carbon sequestration; Dynamic stability; Habitability; Initial conditions; M stars; Negative feedback; Outgassing; Physics - Earth and Planetary Astrophysics; Planet detection; Planets; Plate tectonics; Recycling; Stability analysis; Subduction (geology); Tidal effects; Vehicle emissions; Weathering
• DOI: 10.48550/arxiv.1803.07040

The stability of Earth's climate on geological timescales is enabled by the carbon-silicate cycle that acts as a negative feedback mechanism stabilizing surface temperatures via the intake and outgas of atmospheric carbon. On Earth, this thermostat is enabled by plate tectonics that sequesters outgassed CO2 back into the mantle via weathering and subduction at convergent margins. Here we propose a separate tectonic mechanism -- vertical recycling -- that can serve as the vehicle for CO2 outgassing and sequestration over long timescales. The mechanism requires continuous tidal heating, which makes it particularly relevant to planets in the habitable zone of M stars. Dynamical models of this vertical recycling scenario and stability analysis show that temperate climates stable over Gy timescales are realized for a variety of initial conditions, even as the M star dims over time. The magnitude of equilibrium surface temperatures depends on the interplay of sea weathering and outgassing, which in turn depends on planetary carbon content, so that planets with lower carbon budgets are favoured for temperate conditions. Habitability of planets such as found in the Trappist-1 may be rooted in tidally-driven tectonics.