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habitable planets orbiting M dwarfs

I would also think the coriolis (which arises from the Earth's rotation) would be overwhelmed by the gravity well that is tidally locking the planet. Your atmosphere (and probably your planet) would be very egg-shaped, I would think, alos. [/QB]
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Why should it be egg-shaped? Titan is tidelocked to Saturn, and its atmosphere isn't egg-shaped any more than its surface is (ie, they may both be distorted by tides, but the atmosphere isn't hugely more eggshaped than the surface is).

The E atmosphere is an impossibility anyway.
 
Right, Liam! Wasn't thinking game mechanics! :D

OK, Mal. I was thinking of the mass difference between gases and solids. I wouldn't think it would be very egg-shaped - just enough to provide some interest. But, why would the *E* atmos be an impossibility?
 
Well, I shant steal Mal's thunder here--we had this discussion down on the TNE-1248 playtest board/forum, and Mal's input was crucial to the planetary collapse system that was amalgamated out of it.

Game mechanics wise, with 2d6-7 + planet's size, the best atmosphere you could *roll* up for the habitable 0-orbit on a maximum size 3 world is 8 (Dense)--and that goes for any star that has a 0-orbit habitable zone [2d6 -7, and -2 for orbit 0].
 
Originally posted by Fritz88:
But, why would the *E* atmos be an impossibility? [/QB]
Click to expand...
Because it just doesn't happen. If you've got so much of a tidal force that the atmosphere is stretched out to be 'egg-shaped' then the solid body has to be egg-shaped along with it too. And the description in the books is nonsense, you simply can't get an egg-shaped world while the atmosphere stays spherical - it'd be distorted along with it.
 
Why does the planet have to be so close as to bake the sun side? Can we place the world out a bit more to bring the temp down a bit?
 
Because the tidal forces that lock a planet to a star are big enough to do that when you're close to it. And the habitable zones of M V stars are very close to them (well within 1 AU) which means any planets there have to be tidelocked. And usually, once you get the sun in a fixed spot overhead then the temperature has to increase and you will inevitably end up with a 'baked' dayside.
 
Mal, query: is it possible for an egg-shaped body to have a non-conformal atmosphere; ie, atmosphere is more spherical than world.

What size would an egg-shaped world cease being feasible due to own mass pulling it into a roughly spherical shape?
 
Originally posted by Aramis:
Mal, query: is it possible for an egg-shaped body to have a non-conformal atmosphere; ie, atmosphere is more spherical than world.
Click to expand...
Nope, not remotely possible. The atmosphere follows the shape of the body.

What size would an egg-shaped world cease being feasible due to own mass pulling it into a roughly spherical shape?
Click to expand...
Well, 400 km diameter is usually the size quoted for self-gravity to make a body spherical. Io is about 1800 km radius, getting stretched to buggery by Jupiter, and its equatorial radius (1826.25 km) is only 14 km greater than its polar radius (1812.2 km), which while still a fairly large oblateness wouldn't be enough to make any kind of difference to an atmosphere.
 
So the only feasible way to have an ellipsoidal atmospere would involve spins produced artifically? (Thinks about the measured oblateness of jupiter.)
 
Originally posted by Aramis:
So the only feasible way to have an ellipsoidal atmospere would involve spins produced artifically? (Thinks about the measured oblateness of jupiter.)
Click to expand...
There isn't a feasible way to produce an ellipsoidal atmosphere on a terrestrial world. Jupiter and Saturn are oblate because they have atmospheres that are thousands of kilometres thick and are fluid beneath that, and are rotating fairly rapidly.
 
A lot of them do. That may render many of them uninhabitable. Alternatively, it may do a lot to turn oxygen in the atmosphere to ozone. I think there are scenarios where life could be allowed to form and survive/adapt to flares though. Submarine life may not be affected so much, for example.
 
Don't forget we have the 3:2 spin coupling of Mercury to mix things up. They'd have long diurnal cycles compared to Earth and Mars, but not so long as to be deadly.
 
we don't know how common that sort of coupling is though, it may be just due to mercury's eccentric orbit. Though that itself may be due to its proximity to Sol....
 
Great work guys!

Certainly gives us "writing" types something to figure in when doing system details/ fleshing Out the nitty-gritty stuff!

Thanks Mal, Straybow, & Mr Hopper!

/me returns to typing on other things crunchy for traveller...
 
Um, something else. A fix that I have often done for worlds orbitting M dwarfs that are larger that what would be normally allowed for that orbit, I have just placed a gas giant in the habitable zone and had the world be a moon of it. Is this realistic? Would a gas giant get stripped of its moons if it were that close? What about tidal effects between the gas giant and the star, how would they effect the moon's habitability?
 
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