Harsh ultraviolet radiation flares from red suns, once thought to destroy surface life on planets, might help uncover hidden biospheres.
Their radiation could trigger a protective glow from life on exoplanets called biofluorescence, according to new Cornell University research.
Maybe such life forms can exist on other worlds too, leaving us a telltale sign to spot them," said co-author Lisa Kaltenegger, associate professor of astronomy and director of the Carl Sagan Institute Astronomers generally agree that a large fraction of exoplanets—planets beyond our solar system—reside in the habitable zone of M-type stars, the most plentiful kinds of stars in the universe.
M-type stars frequently flare, and when those ultraviolet flares strike their planets, biofluorescence could paint these worlds in beautiful colors.
Credit: Cornell University "Such biofluorescence could expose hidden biospheres on new worlds through their temporary glow, when a flare from a star hits the planet," said Kaltenegger.
The astronomers used emission characteristics of common coral fluorescent pigments from Earth to create model spectra and colors for planets orbiting active M stars to mimic the strength of the signal and whether it could be detected for life.
In 2016, astronomers found a rocky exoplanet named Proxima b—a potentially habitable world orbiting the active M star Proxima Centauri, Earth's closest star beyond the sun—that might qualify as a target.