Magnetic fields and differential rotation on the pre-main sequence

Maps of magnetic field topologies of rapidly rotating stars obtained over the last decade or so have provided unique insight into the operation of stellar dynamos. However, for solar‐type stars many of the targets imaged to date have been lower‐mass zero‐age main sequence stars. We present magnetic maps and differential rotation measurements of two‐higher mass pre‐main sequence stars HD 106506 (∼10 Myrs) and HD 141943 (∼15 Myrs). These stars should evolve into mid/late F‐stars with predicted high differential rotation and little magnetic activity. We investigate what effect the extended convection zones of these pre‐main sequence stars has on their differential rotation and magnetic topologies.