The photosphere was an outer layer of stars that radiated light. The nuclear fusion supported temperature around 5,500 °C in the outer area. During the Great Hyperspace Disaster, when the Hetzal system came under threat from hyperspace debris, a liquid Tibanna tank was set on a collision course with the system's largest sun. As the star was R-class, a collision could ignite a rare chemical reaction which would wipe out all life in the system, leading the Jedi to undertake an effort to change the tank's course. The tank eventually entered the star's outer photosphere, but only grazed the star, emerging heated but otherwise intact.