Artist’s impression of the planet orbiting the red dwarf star Proxima Centauri. Credit: ESO
Dimitra Atri, an astrobiologist with the Blue Marble Institute of Space Science, has run simulations of planet Proxima b, an exoplanet circling the star Proxima Centauri, which could possibly support life. Last August, a team of scientists identified a planet circling Proxima Centauri—at 4.2 light-years away, the red dwarf is the closet star to our own sun and the discovery of a planet in its Goldilocks zone excited the astronomy community because it represented the possibility extraterrestrial life. Since that time, Atri has created and run simulations meant to measure the impact of stellar flares on the planet and whether they might be enough to prevent or allow life to exist on the planet.
Proxima b has been considered a good candidate for supporting life—initial reports suggested it has a rocky surface, is close in size to Earth and circles its star closely enough to receive adequate warmth. On the other hand, it also could face extinction-level events on a periodic basis via stellar flares spewing radiation across its surface. Such stellar flares are more worrisome for a planet like Proxima b because it is much closer to its star than Earth is to the sun—it is actually even closer than Mercury is to our sun. It does not burn up, however, because the star is much cooler than the sun.
To discern if Proxima b might be capable of supporting life, Atri had to take into account 3 main factors—the type and size of stellar flares, various thicknesses of the planet’s atmosphere and the strength of its magnetic field. He reports that if Proxima b turns out to have an atmosphere similar to Earth’s, life on the surface could very well survive most of the flares occurring on its star. Conversely, if it does not, or if it has a weak magnetic field, then any life on the planet would likely be snuffed out by large stellar flares.
http://mnrasl.oxfordjournals.org/content/465/1/L34
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