Talk abstract details
Impact of Large-Scale Magnetic Fields on Stellar Structure and Evolution
The influence of large-scale magnetic fields on stellar structure and stellar evolution is semi-analytically considered. The classical set of stellar evolution equations is modified owing to the presence of a magnetic field. The field is derived for a given axisymmetric azimuthal current using a Grad-Shafranov approach, and is non force-free, acting thus directly on the stellar structure by modifying the hydrostatic balance. We discuss the relative importance of the various terms associated with the magnetic field in the mechanical and thermal balances before implementing its effects in a 1D stellar evolution code in a way that preserves its geometrical properties. Our purpose is illustrated by two cases : (i) the case of a 7 MG strength field burried below the tachocline in a solar-like star, and (ii) the case of an inner field in an A-type star matching at the star’s surface with an external potential and multipolar magnetic field. The modifications on the internal structure introduced by such fields are deduced, and the resulting multipolar gravitational moments are obtained.