Andrew Bunting

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Andrew Bunting

Grad Student

I am working on modelling the tidal interaction between a star and a close planetary companion, to investigate how the spectrum from the star will be affected. As the tidal perturbation to the star will be small compared to it's own gravitational potential, the tidal potential can be expanded in terms of spherical harmonics, and the lowest order time-varying term (the l=2, m=2 term) produces a corresponding time-varying oscillation in the star. As the surface of the star moves in and out, this produces extra motion on top of motion as it orbits the system's centre of mass, which could be detectable in the spectrum of the star.

This could be used to replicate observed systems, such as Pegasi 51, and to therefore test our models of stellar interiors (as the oscillations are not just at the surface, but throughout the whole star). With increasingly sensitive radial velocity measurements being planned for upcoming missions, the number of systems for which these kind of oscillations could be observed is likely to increase rapidly.