Supersymmetry Enhancement of D-p-branes and M-branes

We examine the supersymmetry of classical D-brane and M-brane configurations and explain the dependence of Killing spinors on coordinates. We find that one half supersymmetry is broken in the bulk and that supersymmetry near the D-brane horizon is restored for $p\leq 3$, for solutions in the stringy frame, but only for $p=3$ in the10d canonical frame. We study the enhancement for the case of four intersecting D-3-branes in 10 dimensions and the implication of this for the size of the infinite throat of the near horizon geometry in non-compactified theory. We found some indications of universality of near horizon geometries of various intersecting brane configurations.