Prof Adrian Barker (on behalf of the team) University of Leeds

Here are a few science highlights in the third year of our project.

Neutron stars have the strongest magnetic fields in the Universe. We model magneto-thermal evolution of neutron stars starting with realistic initial configuration. This magnetic field configuration was produced via the Tayler-Spruit dynamo at the proto-NS stage. The angular momentum is transferred from fallback material. The surface temperature distribution as well as external magnetic fields are shown in figure. Our results show that the external magnetic field is formed by individual arcs. The footpoints of these arcs could be heated by magnetospheric currents and could be responsible for persistent X-ray emission of low-B magnetars. (Work undertaken by Andrei Igoshev and Rainer Hollerbach and collaborators.)

Gravitational tidal interactions are important in extrasolar planetary and binary star systems. For example, dissipation of tidal flows excited in giant planets by their stars (much like the tidal flows excited in Earth’s oceans by the Moon and Sun) is thought to cause evolution of planetary orbital eccentricities, perhaps explaining why hot Jupiters with orbital periods shorter than 10 days are primarily circular. We use DIal3 to model the excitation and dissipation of tidal waves in magnetised convective envelopes of giant planets with short orbital periods around their stars, for which both nonlinear fluid effects and magnetic fields are important. Our most recent results have explored the interaction of tidal flows with planetary magnetic fields, where we have found complicated interactions between the magnetic field and fluid flows. This figure shows the initial magnetic fields lines in a meridional slice through the planet (top left), the induced azimuthal magnetic field and meridional field lines (bottom left and both middle panels) and the differential rotation (zonal flows; both rightmost panels) inside the body for various field strengths (report here as Le values). Sufficiently strong magnetic fields (larger Le values) can substantially inhibit tidally-induced differential rotation and modify tidal energy transfers. (Work undertaken by Aurélie Astoul and Adrian Barker.)