Compact supersymmetric solutions of the heterotic equations of motion in   dimensions 7 and 8
  We construct explicit compact solutions with non-zero field strength, non-flat instanton and constant dilaton to the heterotic string equations in dimensions seven and eight. We present a quadratic condition on the curvature which is necessary and sufficient the heterotic supersymmetry and the anomaly cancellation to imply the heterotic equations of motion in dimensions seven and eight. We show that some of our examples are compact supersymmetric solutions of the heterotic equations of motion in dimensions seven and eight. 
Marisa Fernandez, Stefan Ivanov, Luis Ugarte, Raquel Villacampa