We report measurements of the superconducting transition temperature, $T_c$, in CoO/Co/Cu/Co/Nb multilayers as a function of the angle $alpha$ between the magnetic moments of the Co layers. Our measurements reveal that $T_c(alpha)$ is a nonmonotonic function, with a minimum near $alpha={pi}/{2}$. Numerical self-consistent solutions of the Bogoliubov - de Gennes equations quantitatively and accurately describe the behavior of $T_c$ as a function of $alpha$ and layer thicknesses in these superconductor / spin-valve heterostructures. We show that experimental data and theoretical evidence agree in relating $T_c(alpha)$ to enhanced penetration of the triplet component of the condensate into the Co/Cu/Co spin valve in the maximally noncollinear magnetic configuration.
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