The orbital radius (in au) compatible with a given UV abiogenesis lifetime (in Gyr)—the interval over which an Earth-like planet receives sufficient UV flux for prebiotic chemistry leading to abiogenesis—plotted for brown dwarfs of different masses. The dotted, unbroken, and dashed black curves correspond to brown dwarf masses of 20 MJ, 40 MJ, and 70 MJ, respectively, and the dotted, unbroken, and dashed red lines are their respective Roche limits.