* Tobias van Lier   (Germany)

 tobias.vanlier @ h-its.org

Uncovering Giant-Star Structure Using Asteroseismic Inversions

 

Classical observations of stars limit astronomical studies to the layers outside the photosphere of the star. The internal structure is hidden by the opacity of the stellar medium, and could in the past only be inferred using numerical models which were calibrated to match the observed surface characteristics. Asteroseismology opens a direct window to the stars' interior using global oscillations of the star (i.e. resonant waves propagating through the star), which are observable as brightness variations.

Still, linking the observed oscillations to physical properties of the star requires models that predict the behaviour of waves in the stellar medium. Asteroseismic structure inversions are a mathematical tool to infer the local difference in structure variables along the radius between a model and a real star from the difference between predicted and observed eigenfrequencies.

Structure inversions have been successfully applied to (relatively low-mass) main-sequence stars, e.g. by IMPRS-alumnus Lynn Buchele. During my PhD, I aim to also make them applicable to low-mass giant stars.

 

 

Supervisor:    Saskia Hekker    (HITS)