Line sources in Brans-Dicke theory of gravity

We investigate how the gravitational field generated by line sources can be characterized in Brans-Dicke theory of gravity. Adapting an approach previously developed by Israel who solved the same problem in general relativity we show that in the Brans-Dicke theory case it is possible to work out the field equations which relate the energy-momentum tensor of the source to the scalar field, the coupling constant omega and the extrinsic curvature of a tube of constant geodesic radius centered on the line in the limit when the radius shrinks to zero. In this new scenario two examples are considered and an account of the Gundlach-Ortiz solution is included. Finally, a brief discussion of how to treat thin shells in Brans-Dicke theory is given. [S0556-2821(99)04720-7].