Citation/Abstract

Let S ₁ be a Del Pezzo surface of degree one over a number field k, and let [Special characters omitted.] denote the base-change of S ₁ over the algebraic closure k¯ of k. We establish a criterion for the existence of a non-trivial element of order five in the Brauer group of [Special characters omitted.] in terms of certain Galois stable configurations of exceptional divisors on this surface.