Applied Maths Seminar: Lecoanet -- Measuring Core Stellar Magnetic Field using Wave Conversion

Title: Measuring Core Stellar Magnetic Field using Wave Conversion 

Speaker: Dr.  Daniel Lecoanet, Princeton, USA https://www.princeton.edu/~lecoanet/ 

Date: March 1st, 2pm 

Abstract: By studying oscillation modes at the surface of stars, astrophysicists are
able to infer characteristics of their deep interior structure.  This was first applied
to observations of the Sun, but recently space-based telescopes have measured
oscillations in many other stars, leading to many new mysteries in stellar structure and
evolution.  Recent work has suggested that low dipole oscillation amplitudes in evolved
red giant branch stars may indicate strong core magnetic fields.  Here we present both
numerical simulations and analytic calculations of the interactions of waves with a
strong magnetic field.  We can solve the problem very accurately by using the WKB
approximation to reduce the 2D PDE into a series of ODEs for different heights.  We find
that magnetic fields convert the buoyancy-driven waves observable at the surface of the
star to magnetic waves, which are not present at the surface, in agreement with
observations.  

Seminars are held at 2:00 pm on Wednesdays in the Access Grid Room (Carslaw Building,
8th floor).  


Applied Mathematics Seminar http://www.maths.usyd.edu.au/u/SemConf/Applied.html