FU Orionis eruptions and the formation of close binaries

The discovery of close pairs of stars where both are FU Orionis objects poses important constraints on the triggering mechanism for these dramatic eruptive events among pre-main sequence stars. It is argued here that FUor eruptions are signposts of the last stages of orbital evolution as a close binary is being formed. In this view, FUors represent an evolutionary phase immediately following the formation of Herbig-Haro jets.