2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/34360We reconsider the problem of modelling static spherically symmetric perfect fluid configurations with an equation of state from a point of view of that requires the use of the concept of principal transform of a 3-dimensional Riemannian metric. We discuss from this new point of view the meaning of those familiar quantities that we call density, pressure and geometry in a relativistic context. This is not simple semantics. To prove it we apply the new ideas to recalculate the maximum mass that a massive neutron core can have. This limit is found to be of the order of 3.8 $M_\odot$ substantially larger than the Oppenheimer and Volkoff limit.14 pages, LatexGeneral Relativity and Quantum Cosmologytext