I thought Alpha Centauri bb was a rocky planet just a bit larger than Earth.. It doesn't really matter. All stars have planets and our m class star is a pretty common star type. It's perfect for evolving life over billions of years. steady, not too warm, not too intense.. just a nice bright glow. I watched Blue Planet 2 last night (The Deep). it seems life can pretty much exist anywhere. There are fish living at the absolute bottom of the Mariana Trench.. 50 jumbo jets worth of pressure per square inch.. it was thought impossible.. until now !

Cheers for the links.. I wish more people would respond with links !!