Localized traveling-wave states in binary-fluid convection

We report on convection in horizontal layers of an ethanol-water mixture in a rectangular and an annular container heated from below. When the tempearature difference ΔT exceeds a critical value, localized regions of traveling-wave convection evolve via a backward bifurcation in both geometries and coexist with the conduction state for a range of ΔT. The size, shape, wave number, and frequency of the localized states are reproducible and geometry independent. The coexistence range stands in contrast to systems with a potential, where droplets of a given phase are not stable for first-order transitions at fixed values of the thermodynamic fields.