Non-rigid precession of magnetic stars

Abstract

Stars are, generically, rotating and magnetised objects with a misalignment between their magnetic and rotation axes. Since a magnetic field induces a permanent distortion to its host, it provides effective rigidity even to a fluid star, leading to bulk stellar motion which resembles free precession. This bulk motion is however accompanied by induced interior velocity and magnetic field perturbations, which are oscillatory on the precession timescale. Extending previous work, we show that these quantities are described by a set of second-order perturbation equations featuring cross-terms scaling with the product of the magnetic and centrifugal distortions to the star. For the case of a background toroidal field, we reduce these to a set of differential equations in radial functions, and find a method for their solution. The resulting magnetic-field and velocity perturbations show complex multipolar structure and are strongest towards the centre of the star.

41 pages, 11 figures, 3 tables. Accepted for publication in MNRAS

References in corpus (4)

• The Breaking Strain of Neutron Star Crust and Gravitational Waves
• Magnetic White Dwarfs
• Instability of Magnetic Equilibria in Barotropic Stars
• Investigating the magnetic inclination angle distribution of $\gamma$-ray-loud radio pulsars

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• Distorted surfaces of magnetic helium-peculiar stars: An application to a Cen
• Deciphering Accretion-Driven Starquakes in Recycled Millisecond Pulsars using Gravitational Waves
• Evolution of Crab Pulsar: Magnetic Inclination Angle and Spin