Beta Niobe

Beta Niobe was the primary of the Beta Niobe system. This star went supernova in 2269, destroying its only planet, Sarpeidon. The star occupied the same space as the parallel antimatter universe star, Amphion. Beta Niobe was located in the Alpha Quadrant. Its location in the Milky Way Galaxy was depicted on a Federation star chart in 2293. (, production art)

History
In 2269, hours before the star went nova, the USS Enterprise (NCC-1701) arrived to warn the native species of Sarpeidon of their impending doom. However, they found that, all the inhabitants had evacuated using a time portal known as the Atavachron, into various eras of the planet's past. 

While en route to planet Babel in 2270, the Enterprise passed near Beta Niobe. They detected an alien ship racing for the center of the Beta Niobe nova at warp 36. The Enterprise attempted to tractor the ship in an effort to prevent it from its apparent suicide course. Both ships were taken into the center of the nova where they passed through into the parallel antimatter universe. 

Background information
There have been three conflicting accounts on the location of Beta Niobe. While all the accounts are canon, we assume the location depicted in the star chart was the correct one and retconned the previous statements, as it was the latest of the accounts.


 * The first is from the episode "All Our Yesterdays" where Spock states Beta Niobe to be millions of light years away from Vulcan. This distance figure suggests Beta Niobe was in another galaxy.
 * The second account is the large star chart table in the episode "The Counter-Clock Incident" which displays the position of Beta Niobe in relation to Earth in the Milky Way Galaxy. The graphic depicts Beta Niobe on the other side of the galaxy approximately 50 thousand light years away from Earth in what is later on in Star Trek established to be the border region of the Delta and Gamma Quadrants.
 * The third account was from the star chart "The Explored Galaxy" that was first seen in the episode  of Star Trek: The Next Generation. The chart depicted Beta Niobe close to Ariannus and as far away from Earth as the Romulan Neutral Zone for example. Beta Niobe was located between the Tholian Assembly and Romulus, both of which were identified in  as being located in the Alpha Quadrant. The chart, first seen chronologically in Star Trek VI: The Undiscovered Country, set in 2293, was also seen in several Star Trek: The Next Generation and Star Trek: Deep Space Nine episodes set in the 24th century.