Temporal wake
A temporal wake is an energetic phenomenon that can be created as a byproduct of a temporal vortex, insulating anything caught inside from an alteration of the timeline.

In 2373, a Borg sphere generated a temporal vortex to the year 2063, where they changed history by stopping Zefram Cochrane's first warp flight, and assimilating humanity. Having become caught in the vortex's wake, the  remained unaffected by the alteration to history, allowing the crew to follow the sphere through the vortex and able to not only restore but instigate the original timeline. ()

See also
Subspace bubble
Temporal shielding

Time travel