PI: Laura Currie

All stars transport at least some of their energy by convection but one issue when modelling stellar convection is that it occurs over a vast range of spatial and temporal scales and so simulation over stellar timescales is not possible. Therefore, stellar structure models rely on parametrisations of the convection. Commonly used is mixing length theory (MLT) which essentially relies on prescribing the temperature gradient necessary for convection to carry a given flux. However, convection is affected by rotation, density stratification and magnetism and as yet we do not have a full, quantitative understanding of the interaction of these physical effects with convection. Previous work (Barker et al. ApJ, 2014; Currie et al. MNRAS, 2020) showed that many aspects of convection are well captured by a MLT extended to account for rotation. However, this work did not incorporate the important effects of a background density stratification. Using simulations performed on DiRAC’s Data Intensive at Leicester (DIaL3), we are attempting to address this limitation with our latest work. Preliminary results from our project suggest that a strong density stratification leads to a depth-dependent relationship between the temperature gradient required to carry a given flux and the rotation rate, unlike in unstratified cases. This is a result of the vertical asymmetry introduced by the density stratification. Figure 1 shows snapshots of the vertical velocity and entropy from an example simulation. The asymmetry introduced by the density stratification is especially visible in the snapshot of entropy where strong plumes can be seen descending from the top boundary.