Vol. 528In section 7. Stellar structure and evolution

V1309 Scorpii: merger of a contact binary

The authors present a strong case for the first observation of the initial stages of merger for a contact binary, an essential element in testing evolutionary scenarios for the end stages of common envelope binaries. These systems are thought to be the progenitors of rapidly rotating evolved stars, but the physical process is essentially the same as would happen in systems driven to merger by any of a variety of mechanisms (e.g. gravitational wave emission, magnetic breaking, spiraling within the common envelope).