This Side of Science

Around 70 percent of the stars in our Galaxy are classified as M dwarfs, which are slow-burning stars that last for 40-100 billion years (compared to our G-class Sun’s 10 billion year lifespan).  So chance would have it that our galactic neighbors are circling around an M dwarf.  But since M dwarfs burn cooler than our own Sun, Earth-like planets would have to orbit much closer to the star, even closer than Mercury is to the Sun.  This worries astrobiologists, since these stars are very violent and unpredictable, especially in their early lives, and send out high-energy particles and solar flares that could have fatal consequences to life on these planets.

But recently, a group of researchers led by Astrobiologist Antigona Segura of UNAM in Mexico City created a computer model to learn how a solar flare would affect an Earth-like planet very close (astronomically speaking) to a young M dwarf.  It turns out that the solar flare was not as dangerous as previously thought.  The UV radiation from the M-dwarf’s upper atmosphere actually resulted in a thicker ozone layer in the planet’s atmosphere.  The UV radiation split molecules of oxygen to create more ozone than it destroyed.  The ozone layer then protected the planet’s surface.  With its surface guarded the planet would have an easy 100 billion years to evolve life. (More here)

Credit ESO