Alpha Centauri B is a Hertzsprung-Russell main sequence K1-type star that is one of the two principal stars of the Alpha Centauri System. It is smaller and dimmer than the Sun, and radiates a "phosphorescent bloodshine" light in Thebes's atmosphere, giving the appearance that "rills of human blood streaked across the horizon" and that the skies were "bloodshot, swollen". The time when only Alpha Centauri B would shine in Thebes's skies would be dubbed "night time" for Thebes because of the lesser intensity of Alpha Centauri B's light compared to the more luminous Alpha Centauri A.