Coexisting traveling waves and steady rolls in binary-fluid convection

I present experimental observations of a new state of convection in an ethanol-water mixture with separation ratio {ψ}=-0.020 in a narrow, annular container. Increasing the Rayleigh number to about 1% above the onset of convection causes the system to evolve from the erratic state called ``dispersive chaos'' into a regime in which bursts of traveling waves coexist with a persistent region of steady convective rolls. Remarkably, the traveling-wave bursts appear at regular intervals. Equally remarkably, the burst frequencies of the two oppositely directed traveling-wave components are different. Evidence for the reflection of traveling waves at the boundaries of the steady-roll region is seen.