Octonionic gravitational instantons

We construct eight-dimensional gravitational instantons by solving appropri ate self-duality equations for the spin-connection. The particular gravitat ional instanton we present has Spin(7) holonomy and, in a sense, it is the eight-dimensional analog of the Eguchi-Hanson 4D space. It has a removable bolt singularity which is topologically S-4 and its boundary at infinity is the squashed S-7. We also lift our solutions to ten and eleven dimensions and construct fundamental string and membrane configurations that preserve 1/16 of the original supersymmetries. (C) 1998 Elsevier Science B.V. All ri ghts reserved.