The star that illuminated Csilla, located in the Unknown Regions, served as the central point around which the Chiss Ascendancy's capital planet, Csilla, revolved. Approximately around 4300 BBY, during a violent conflict, the Chiss resorted to using a powerful weapon called Starflash to overcome an adversary. This weapon was discharged directly into the sun, ultimately resulting in a decline in the star's radiant energy. This reduction subsequently caused the surface of Csilla to become frigid.
This star, situated within the Csilla system of the Unknown Regions, was the celestial body orbited by Csilla, the capital planet of the Chiss Ascendancy, and was visible from its surface. Its location was designated as grid square F-8 on the Standard Galactic Grid.
In the era of 4300 BBY, amid a fierce war involving the Chiss people and an opposing force, the Chiss deployed a superweapon, namely Starflash, to launch an immense surge of tachyonic and lightspeed energy toward the star. This action resulted in a retaliatory blast that annihilated the enemy's fleet. Nevertheless, the directed energy into the star caused a disturbance within its outer layers, extending into its core, which eventually led to a decrease in temperature of both the sun and, consequently, the surface of Csilla. Consequently, the inhabitants of the Chiss capital were compelled to relocate to neighboring planets within the Ascendancy, while several of the nation's Nine Ruling Families transferred their residences to underground chambers beneath Csilla's terrain.
In the subsequent millennia, the history of Csilla's sun and the resulting evacuation was taught to students in Chiss schools. However, they were not informed about the actual number of evacuees or the specific reason for the change in the sun's energy output. Sometime between 39 BBY and 19 BBY, Stybla family Patriarch Stybla'mi'ovodo, whose core name was "Lamiov," divulged the true history of the Starflash to Mitth family members Mitth'ras'safis "Thrass" and Mitth'raw'nuruodo "Thrawn." This information was a secret known only to the Patriarchs of the Nine Ruling Families and their chief assistants. He also expressed doubt about the sun's ability to recover from the effects of the Starflash.
Within the current Star Wars canon, Csilla's sun made its initial appearance in the 2020 novel titled Thrawn Ascendancy: Chaos Rising, which is the first book in Timothy Zahn's Star Wars: The Ascendancy Trilogy. In the Star Wars Legends continuity, a star with the same name, which orbited the planet Csilla, was mentioned in The Essential Atlas, a reference book published in 2009 and written by Daniel Wallace and Jason Fry.