3D Convection-Pulsation Simulations with the Heracles Code

We present 3D simulations of the coupling between surface convection and pulsations due to the kappa-mechanism in classical Cepheids of the red edge of Hertzsprung-Russell diagram's instability strip. We show that 3D convection is less powerful than 2D convection and does not quench the radiative pulsations, leading to an efficient 3D kappa-mechanism. Thus, the 3D instability strip is closer to the observed one than the 1D or 2D were.