Effect of radiative heat transfer on thermocapillary convection in long liquid bridges of high-Prandtl-number fluids in microgravity

•The effect of radiative heat transfer on thermocapillary convection in high-Prandtl-number long liquid bridges is studied.•Radiative and convective heat transfers are evaluated with numerical simulations.•The radiation tends to be the dominant source of interfacial heat transfer in microgravity.•Unique secondary convection rolls due to radiation are observed.•The basic flow patterns are classified by the modified heat transfer ratio.