2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/95269The idea of a unified model for quasars and micro-quasars has been considered for a long time, despite the different environments and physical conditions where both classes of objects reside. Here we show the existence of a simple scaling law, relating the maximum size of a jet to the properties of the gas medium into which it expands. This appears to be valid for all types of hydrodynamical jets, and can be thought of as a broad unified model. The expansion velocity of the jet and the physical properties of the surrounding gas combine in such a way that a limit to the maximum extent of jets at different scales can be obtained.12 pages, 1 figure. Accepted for publication on Rev.Mex.Astron.Astrofis. Expanded versionAstrophysicstext