Singularity-formation zone

Singularity-formation zone or SFZ was the term used by the USS Odyssey (NCC-81302) personnel for regions of black holes and gravitational shear caused by the use of Omega molecule technology. (Star Trek: Odyssey)

While trapped in the Andromeda Galaxy the Odyssey crew discovered the Kelvan's use of Omega molecules had an unknown side effect—the creation of zones where singularities appeared spontaneously and nearby stars went nova. As the habitable regions of the galaxy became limited, a war of attrition broke out between the Kelvans and Archein and the Archein began their invasion of the Beta Quadrant of the Milky Way Galaxy. Experimentation with Omega molecules in the Alpha Quadrant caused similar damage. (Star Trek: The Helena Chronicles)

Odyssey developed a technology for repairing the subspace damage that causes the zones. When they returned to the Beta Quadrant they used their subspace-repair technology to prevent the Romulan system star from going nova. ("Tossed Upon the Shore")

Star Trek (2009) timeline
In an alternate timeline, Odyssey failed to return and the Romulan homeworld was destroyed by a supernova, despite attempts by Spock to use red matter to mitigate its effects.