The story gets even more dangerous. M-dwarfs have been known to have much more powerful flares than sun-like stars, partly due to their very strong magnetic fields. Without knowing how often these flares go off, or how many M-dwarfs have flaring storms, it is even harder to estimate the likelihood of extraterrestrial life.
Enter, once again, the Hubble Space Telescope.
A survey of M-dwarfs that was originally used as a planet finding expedition found new life in a search for the incidence of stellar flares. 215,000 red dwarfs were imaged over just seven days, and 100 flares were found, several from the same stars, and some from stars billions of years old.
This is crucial in the search for complex life, as it took billions of years to evolve on Earth. Wouldn't it just be awful to come all that way to have a super-flare wipe out your planet's atmosphere?
The team was able to note that stars that already varied in brightness periodically were more vulnerable to having such outbursts. So, that parameter may help in ruling out the most dangerous environments for life.