08-30-2014, 12:57 PM
Some points to consider:
1) At a given distance, a more massive planet is going to become tidally locked with respect to its star sooner than a less massive world.
2) If the planet has an indigenous biosphere, it might be helpful for the captured rotation to precede or coincide with (more or less) the emergence of life, so that evolution has only one rotation period to contend with.
3) An issue with habitable tidally-locked planets is that at least 100 millibars (CO2 equivalent) of "greenhouse" gases are required to prevent the day-side atmosphere from condensing out on the night-side.
4) The sub-stellar "hot spot" on the surface directly beneath the primary star's zenith will be substantially warmer than the surrounding terrain; the "hot spot" is not a fixed point, as the planet is (slowly) rotating beneath the zenith. The path described around the globe is determined by the world's orbital inclination and axial tilt.
5) The atmosphere will circulate more or less radially from high above the "hot spot" to the "cold pole" on the opposite side of the planet, where it will begin its return journey in the form of surface winds blowing back towards the "hot spot." Clouds will stream away from a clear region above the "hot spot" and condense soon after crossing the terminator.
Putting these together with the basic plan you described, the most straightforward solution is to place the planet in a low-eccentricity orbit just beyond the primary star's liquid water zone; to preclude the mass of the planet from growing far past your stated preferences, an orbit around the red dwarf star might be preferable.
Radtech497
1) At a given distance, a more massive planet is going to become tidally locked with respect to its star sooner than a less massive world.
2) If the planet has an indigenous biosphere, it might be helpful for the captured rotation to precede or coincide with (more or less) the emergence of life, so that evolution has only one rotation period to contend with.
3) An issue with habitable tidally-locked planets is that at least 100 millibars (CO2 equivalent) of "greenhouse" gases are required to prevent the day-side atmosphere from condensing out on the night-side.
4) The sub-stellar "hot spot" on the surface directly beneath the primary star's zenith will be substantially warmer than the surrounding terrain; the "hot spot" is not a fixed point, as the planet is (slowly) rotating beneath the zenith. The path described around the globe is determined by the world's orbital inclination and axial tilt.
5) The atmosphere will circulate more or less radially from high above the "hot spot" to the "cold pole" on the opposite side of the planet, where it will begin its return journey in the form of surface winds blowing back towards the "hot spot." Clouds will stream away from a clear region above the "hot spot" and condense soon after crossing the terminator.
Putting these together with the basic plan you described, the most straightforward solution is to place the planet in a low-eccentricity orbit just beyond the primary star's liquid water zone; to preclude the mass of the planet from growing far past your stated preferences, an orbit around the red dwarf star might be preferable.
Radtech497
"I'd much rather see you on my side, than scattered into... atoms." Ming the Merciless, Ruler of the Universe