Turbulent dynamo models for solar-like stars

Building a unified theory for solar and stellar dynamos

How the Sun generates its magnetic fields remains enigmatic, when the full picture of the turbulent convection zone is accounted for. Phenomenological dynamo models exists, that capture the behaviour of the global solar magnetic field, but it is doubtful whether they do so for the correct reasons. This is because the standard procedure is to neglect turbulent effects, or selectively pick some that could be relevant, and still do not break the agreement with observations. Here direct numerical simulations, solving for the full set of MHD equations, trying to push towards the solar parameter regime, are of vital help.

In our group we have developed one of the most sophisticated solvers to produce such simulations, our speciality being the data-analysis tools built hand in hand with the MHD solver. These enable us to directly measure all the turbulent transport coefficients relevant to the dynamo problem in various different parameter regimes. Very recently, we have completed a successful proof-of-concept chain of directly modelling and measuring the turbulent quantities from the MHD models of turbulent convection, and inputing them back into a global-scale reduced simulation, to recover the behaviour of the full scale simulation in the simpler one. This PhD project is about applying the same techniques on even better MHD models of the solar convection zone, including physical effects not accounted before. The aim is to produce the first physically self-consistent model of the solar dynamo, accounting for all the relevant turbulent effects. This project fits into and will fundamentally contribute to the development of a unified dynamo theory encompassing all stellar activity branches.

We are looking for a candidate with a keen interest and some experience in numerical modelling in astro- or space plasmas. Knowledge of the theoretical background (for example, a subset of courses in fluid dynamics, hydrodynamics, magnetohydrodynamics, plasma physics etc) or expertise in numerical methods and parallel computing are expected. Practical experience in either is a strong bonus.

A computer model of a fast-rotating solar-like star with dynamo action.

This PhD project will be funded under the ERC CoG grant "UniSDyn"

How to apply

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