Beta Niobe was a star and system. The Beta Niobe star went supernova in 2269.
The star was orbited by several planets, including Sarpeidon, which were destroyed when the star went nova. (TOS episode: "All Our Yesterdays", TOS novel: Yesterday's Son)
Radiation emitted by Beta Niobe, as well as the Minara supernova, threatened many nearby systems for years to follow, including Verzhik, which was particularly badly damaged in 2279. (TOS - Mere Anarchy eBook: The Darkness Drops Again)
One of the planets contained a Federation colony in the mid-23rd century. In 2259, Dmitri Valtane, the son of Larisa and Nikolai Valtane, was born there. (ST video game: Starship Creator)
In the antimatter universe, the sun Amphion was its counterpart. (TAS episode: "The Counter-Clock Incident")
In the Kelvin timeline, the interstellar community had discovered Beta Niobe by 2262. Independents from the Neutral Zone were allowed passage to Beta Niobe from the New Berlin system. (TOS video game: Fleet Command)