Volcanism and outgassing of stagnant-lid planets: Implications for the habitable zone

Left: Sketch of a mass-radius diagram indicating the mass-radius range, where the classical HZ definition can be applied (green area), the range where the HZ may be restricted due to limited outgassing (red area) and the transitional regime in-between (yellow area). The width of the transitional zone depends on the assumed composition of the mantle. Here we assume a dry peridotite composition. Black arrows indicate the influence of mass and core-mass fraction (CMF) on the transition from classical to restricted HZ definition. Right: Habitable zone without constraints (top) and without greenhouse gases (bottom) at different stellar ages 0 Gyr (red lines), 4.5 Gyr (green lines) and 10 Gyr (blue lines) using the moist and maximum greenhouse effect limits by Kopparapu et al., 2013a, Kopparapu et al., 2013b. The green and red background colors correspond to the coloured areas in the left plot.163