When stars go nonlinear: large amplitude tides and stellar oscillations (video)
Nevin Weinberg, Associate Professor of Physics, MIT
Tides significantly impact the structure, evolution, and fate of many types of close binary systems, including short-period exoplanets, stellar binaries, and coalescing binary neutron stars. In many of these systems, the tide's amplitude is so large that it cannot be treated as a small, linear perturbation to the background star. In this talk, I will show that nonlinear effects can greatly enhance the rate of tidal dissipation and thus the rate of binary evolution. As examples, I will describe how nonlinear tides influence the orbital decay of hot Jupiters and the gravitational-wave signal of coalescing binary neutron stars. I will also discuss the nonlinearity of oscillation-modes in red giants, which are excited by turbulent motions within the stars' convective envelope. The rich oscillation spectra observed by the CoRoT and Kepler space missions, and soon TESS, has yielded a wealth of information about the internal and global properties of thousands of red giants.