RESEARCH

Asteroseismology is the field to study stellar internal structures by using surface oscillations. Thanks to space telescopes missions (e.g. CoROT, Kepler), our understanding about star interiors is proceeded. However, there are many phenomena that cannot be interpreted by the recent stellar physics and the vast amount of observational data has not been fully utilized. We have theoretically investigated the newly discovered phenomenon, resonance between the inner core and the outer layer in the oscillations of γ doradus stars, a fast rotating 1.2-1.8 solar mass star. We have found that these phenomenon can be utilized to study the structure around the boundary between the inner and outer layers (Paper URL).

The angular momentum transport of magnetized stellar winds spins down solar-type stars, including the Sun (magnetic braking). The property of spin-down of solar-type stars has been actively studied by theoretical models and numerical calculations. While previous models based on the assumption of rigid body rotation can roughly explain the observed trend of stellar rotation, there are some contradictions between models and observations.

We proposed a simple model to track the spin-down of solar-type stars that takes into account differential rotation and discussed its properties. As a result, we pointed out that the observed trend can be resolved naturally by considering the effect of differential rotation (Paper URL).

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