Donald Brownlee and David Ward proposed a "galactic" version of this concept based on the metallicity and the frequency of supernovae. Expanded notions of this concept consider alternative solvents such as ammonia or methane, which can exist at lower temperatures. This concept is relatively narrow for red dwarfs because of frequent stellar flares (10[1])stripping away gas, compounded with the likelihood of tidal locking. In 2016, (10[2])Proxima Centauri b (10[1])was discovered (10[1])as the closest known object in this region. This region spans between 0.9 and 1.5 astronomical units from the Sun, (10[3])although for hotter stars it is farther away. This region encompasses orbits where stable (10[1])bodies of liquid water could exist on a planet's surface. For 10 points, name this zone around a star in which life can potentially exist. ■END■