The Laurentian system was a star system.
With the bulk of Starfleet otherwise engaged in the system in 2258, a number of other ships stationed at Earth, including the USS Enterprise, were mobilized to respond to a distress call from Vulcan, which was under attack by the Narada. After the destruction of Vulcan, acting captain Spock planned to regroup with the rest of the fleet in the Laurentian system to balance the terms of the next engagement with the Narada. This plan was halted, however, when James Kirk took command, and ordered a pursuit of the Narada toward Earth. (Star Trek)