The Beta Stromgren system was an uninhabited star system in Sector 25434. The system was in space claimed by the Romulan Star Empire.

A Federation long-range unmanned probe, Vega Nine probe, had charted this system, which lay 23 parsecs beyond the limits of manned exploration at the time. This system was destroyed in 2366 when its primary, Beta Stromgren, became a supernova. (TNG: "Tin Man")

"STRUM-gren" was the pronunciation for the system's name from the script pronunciation guide. [1]
According to Star Trek: Star Charts ("United Federation of Planets II") and, the Beta Stromgren system was located in the Beta Quadrant.