Twisting Classical Solutions in Heterotic String Theory

We show that, given a classical solution of the heterotic string theory which is independent of $d$ of the space time directions, and for which the gauge field configuration lies in a subgroup that commutes with $p$ of the $U(1)$ generators of the gauge group, there is an $O(d)\otimes O(d+p)$ transformation, which, acting on the solution, generates new classical solutions of the theory. With the help of these transformations we construct black 6-brane solutions in ten dimensional heterotic string theory carrying independent magnetic, electric and antisymmetric tensor gauge field charge, by starting from a black 6-brane solution that carries magnetic charge but no electric or antisymmetric tensor gauge field charge. The electric and the magnetic charges point in different directions in the gauge group.