M - type star

M - type stars are the most common stars in the universe, known as red dwarfs. Their mass is below 40% of the mass of our sun, Sol. Their luminosity is very dim and red in color. These stars have very long lifetime because they burn their hydrogen slowly. An Earth-like planet would be in a torch orbit. A Habitable Zone exists around the vast majority of red dwarfs.

The star
Red dwarfs can be divided into two main groups: flare stars and more stable, " friendly " stars. One good example of a flare star is UV Ceti, while one more friendly star is Barnard's Star. Around a flare star like UV Ceti (see image to right), flares can reach huge dimensions, increasing stellar energy output by many times in only a few seconds. Solar spots can form anytime and decrease luminosity by a few times. This will be a nightmare for settlers trying to make a new Earth here. On the other hand, Barnard's Star is far more friendly, but not safe. It still blows flares, terrorizing its planets, but such events are far more rare.

The light of a red dwarf is different from the light generated by Sol. Ultraviolet light is almost absent, so an ozone layer might not be needed. X-rays are generated mainly within flares. Majority of light comes into infrared. Visible light is more into the red spectra. Visible light might be up to 1 000 000 times less powerful then the Sol. For Barnard's Star, it is 0.000441, however infrared light is about 10 times more intense.

Solar winds are very small, except for the flare periods.