Violent young Sun may have seeded life on Earth: study May 23, 2016 Life on Earth may have sprung from bombardment by a youthful Sun lashing out with flares as potent as a thousand trillion exploding atomic bombs, a study suggested on Monday. Such violence may explain how Earth became hospitable to life about four billion years ago, when the planet, and its star, were much, much colder, a research team wrote in the journal Nature Geoscience. While the Sun was about a third fainter than it is today, it was likely much more tempestuous, they found. Repeated super-flares would have smashed nitrogen (N2) molecules in the atmosphere to yield a planet-warming greenhouse gas called nitrous oxide (N2O or "laughing gas"), as well as hydrogen cyanide, which produces amino acids—the building blocks of proteins. While it is essential for all life, nitrogen in the form it would have existed in a young Earth's atmosphere is not chemically reactive, and needs to be transformed into more accessible forms. Very high temperatures can achieve this. Read more at: http://phys.org/news/2016-05-violent-young-sun-seeded-life.html#jCp
http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2719.html Prebiotic chemistry and atmospheric warming of early Earth by an active young Sun Abstract: Nitrogen is a critical ingredient of complex biological molecules1. Molecular nitrogen, however, which was outgassed into the Earth’s early atmosphere2, is relatively chemically inert and nitrogen fixation into more chemically reactive compounds requires high temperatures. Possible mechanisms of nitrogen fixation include lightning, atmospheric shock heating by meteorites, and solar ultraviolet radiation3, 4. Here we show that nitrogen fixation in the early terrestrial atmosphere can be explained by frequent and powerful coronal mass ejection events from the young Sun—so-called superflares. Using magnetohydrodynamic simulations constrained by Kepler Space Telescope observations, we find that successive superflare ejections produce shocks that accelerate energetic particles, which would have compressed the early Earth’s magnetosphere. The resulting extended polar cap openings provide pathways for energetic particles to penetrate into the atmosphere and, according to our atmospheric chemistry simulations, initiate reactions converting molecular nitrogen, carbon dioxide and methane to the potent greenhouse gas nitrous oxide as well as hydrogen cyanide, an essential compound for life. Furthermore, the destruction of N2, CO2 and CH4 suggests that these greenhouse gases cannot explain the stability of liquid water on the early Earth. Instead, we propose that the efficient formation of nitrous oxide could explain a warm early Earth.
