« on: 01/06/2019 16:25:50 »
If Proxima b is bigger than the earth, it may have a bigger magnetosphere, could this trap water?The size of a planet has nothing to do with its magnetic field, which is generated by its spinning core. One of the issues with orbiting so close to the star is that the planet is going to be tidally locked so that it rotation and orbit have the same period. Since Proxima b takes about 11 days to orbit, it would also take 11 days to rotate. The slower rotation doesn't bode well for generating a strong field.
We can compare Mercury and Venus, the latter is close to the Sun and has a very thick atmosphere. Smaller than the Earth, yet inside maybe more Iron?
It is estimated that Proxima loses mass to solar wind at a rate about 1/5 of that of our Sun, but Proxima b is only about 1/20 of the distance from its star than the Earth is from the Sun. This ends up with the Solar wind being more than 80 times stronger for Proxima b than it is for the Earth.
While this does not completely rule out Proxima b from having a viable biosphere, it does but it at very long odds.
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