Enriques surfaces with eight nodes

Abstract.

A nodal Enriques surface can have at most 8 nodes. We give an explicit description of Enriques surfaces with 8 nodes, showing that they are quotients of products of elliptic curves by a group isomorphic to or to acting freely in codimension 1. We use this result to show that if S is a minimal surface of general type with p _g =0 such that the image of the bicanonical map is birational to an Enriques surface then K ² _S =3 and the bicanonical map is a morphism of degree 2.