Composite vacuum Brans-Dicke wormholes

We construct a new static spherically symmetric configuration composed of interior and exterior Brans-Dicke vacua matched at a thin matter shell. Both vacua correspond to the same Brans-Dicke coupling parameter omega; however, they are described by the Brans class I solution with different sets of parameters of integration. In particular, the exterior vacuum solution has C-ext (omega) equivalent to 0. In this case the Brans class I solution for any omega reduces to the Schwarzschild one being consistent with restrictions on the post-Newtonian parameters following from recent Cassini data. The interior region possesses a strong gravitational field, and so the interior vacuum solution has C-int (omega) = -1/(omega + 2 ). In this case the Brans class I solution describes a wormhole spacetime provided omega lies in the narrow interval -2 -root 3/3 < omega < -2. The interior and exterior regions are matched at a thin shell made from an ordinary perfect fluid with positive energy density and pressure obeying the barotropic equation of state p = k sigma with 0 <= k <= 1. The resulting configuration represents a composite wormhole, i.e. the thin matter shell with the Schwarzschild-like exterior region and the interior region containing the wormhole throat.