Title:Surprising Impacts of Gravity Waves

Speaker:Prof. Jim Fuller (California Institute of Technology)

Date:Thursday, July 11, 2019, 02:00pm

Venue:South 727, Mong Man-wai Science Technology Building


Abstract:Gravity waves are low frequency fluid oscillations restored by buoyancy forces in planetary and stellar interiors. Despite their ubiquity, the importance of gravity waves in evolutionary processes and asteroseismology has only recently been appreciated. For instance, Kepler asteroseismic data has revealed gravity modes in thousands of red giant stars, providing unprecedented measurements of core structure and rotation. I will show how gravity modes (or lack thereof) can also reveal strong magnetic fields in the cores of red giants, and I will demonstrate that strong fields appear to be common in intermediate-mass stellar cores. The slow core rotation measured for red giants informs angular momentum transport models, allowing us to predict the spin rates of compact objects (spoiler alert: they usually spin slowly). In the late phase evolution of massive stars approaching core-collapse, vigorous convection excites gravity waves that can redistribute huge amounts of energy within the star. I will present preliminary models of this process, showing how wave energy redistribution can drive outbursts and enhanced mass loss in the final years of massive star evolution, with important consequences for the appearance of subsequent supernovae.