Christopher Crochett in Science News June 29, 2017 summarizes the possibilities and problems for life on planets near M dwarf stars, the “…darlings in the search for life.”
The planetary problems–early excessive heat, close orbits, sun flares, and difficultyholding onto water–all caused by their host M dwarf stars, are obvious, so I’ve summarized the good news here:
So far, dozens of the 200 planets found near M dwarfs are in their suns’ habitable zones, where liquid water exists.
Most M dwarfs are “cool and tiny,” many the size of Jupiter, about half as hot as our sun.
M dwarfs live a long time (about 12 trillion years) since they burn their “nuclear fuel” slowly. This is plenty of time for life to find some way to appear, if it can.
M dwarfs often have lots of small planets.
Though M dwarfs’ planets suffer their sun’s intense early brightness and UV radiation that could strip away any water, oxygen, or nitrogen, Earth’s history provides some hope. Our oceans came back after the blast that whipped away our water and created our moon by venting water and gases from deep within the mantle.
Even if a planet is locked so that one ...