HARMONIC SUPERPOSITIONS OF M-BRANES

We present solutions describing supersymmetric configurations of 2 or 3 orthogonally intersecting 2-branes and 5-branes of D = 11 supergravi ty. The configurations which preserve 1/4 or 1/8 of maximal supersymme try are 2 perpendicular to 2, 5 perpendicular to 5, 2 perpendicular to 5, 2 perpendicular to 2 perpendicular to 2, 5 perpendicular to 5 perp endicular to 5, 2 perpendicular to 2 perpendicular to 5 and 2 perpendi cular to 5 perpendicular to 5 (2 perpendicular to 2 stands for orthogo nal intersection of two 2-branes over a point, etc.; p-branes of the s ame type intersect over (p-2)-branes). There exists a Simple rule whic h governs the construction of composite supersymmetric p-brane solutio ns in D = 10 and 11 with a separate harmonic function assigned to each constituent 1/2-supersymmetric p-brane. The resulting picture of inte rsecting p-brane solutions complements their D-brane interpretation in D = 10 and seems to support possible existence of a D = 11 analogue o f D-brane description. The D = 11 solution describing intersecting 2-b rane and 5-brane reduces in D = 10 to a type II string solution corres ponding to a fundamental string lying within a solitonic 5-brane (whic h further reduces to an extremal D = 5 black hole). We also discuss a particular D = 11 embedding of the extremal D = 4 dyonic black hole so lution with finite area of horizon.