Our home galaxy isn’t as hospitable to life as you might think. Cosmic radiation, supernova explosions, and collisions with small galaxies make much of the Milky Way too hellish for biology. But a detailed new simulation locates quiet and fertile neighborhoods, including a surprising locale: wispy streams of stars flung far beyond the main body of the Milky Way. To support life as we know it, planets must have liquid water and orbit in the right place in their solar systems, not too close and not too far from their star. Similarly, life will not emerge or survive for long near the centers of galaxies. Here, the high density of stars means that at any given time several could be exploding, frying off a planet’s ozone layer and exposing any surface life to deadly ultraviolet rays.
So in the new study, researchers led by physicist Duncan Forgan of the University of St. Andrews in Fife, U.K., focused on the regions far from a galaxy’s center. They used computer simulations to model an entire Milky Way–like galaxy and its neighbors, the Andromeda and Triangulum galaxies. They then simulated the distribution of gas, stars, and planetary systems within those whorls of stars. Finally, they allowed these galaxies to evolve over billions of years, while mapping out their evolving habitable zones. “We’re the first to look at how the history of galaxies affects their habitability,” Forgan says.
0 Comments