Wednesday 24 Feb 2016: Seminar: Asteroseismology and the structure of core helium burning stars
Dr Tom Constantino - University of Exeter
Physics, 4th floor 14:00-15:00
Recent advances in asteroseismology allow us to make new inferences about the internal structure of stars. One of the most promising discoveries is the detection in red giants of mixed oscillation modes, which propagate as gravity waves in the core and pressure waves in the envelope. We use these observations to probe the uncertain mixing at convective boundaries in core helium burning stars. In models, feedback from convective overshoot can lead to the development of a 'semiconvection' zone outside the convective core that can extend the lifetime of the phase by up to a factor of two. We complement the asteroseismology study by determining the horizontal branch and AGB lifetimes of globular cluster stars from star counts in HST photometry.