2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/175365It is proven that in Vaidya spacetimes of bounded total mass, the outer boundary, in spacetime, of the region containing outer trapped surfaces, is the event horizon. Further, it is shown that the region containing trapped surfaces in these spacetimes does not always extend to the event horizon.33 pages, 4 figures, minor corrections for publicationGeneral Relativity and Quantum Cosmologytext