The orbital radius (in au) compatible with a given time interval that the planet spends in the habitable zone (tHZ) plotted for brown dwarfs of different masses. The dotted, unbroken, and dashed black curves correspond to brown dwarf masses of 10 MJ, 40 MJ, and 70 MJ, respectively, and the dotted, unbroken, and dashed red lines are their respective Roche limits.