Asteroseismology

Remarks

Example: for solar-like oscillators, the large separation $\Delta\nu$ between modes of consecutive radial order scales as $\Delta\nu \propto \sqrt{M / R^3}$. Here $M$ is the mass and $R$ the radius. Together with the frequency of maximum power, $\Delta\nu$ gives estimates of $M$ and $R$. The reason is that $\Delta\nu = \big(2 \int_0^R dr / c(r)\big)^{-1}$ is the inverse of the sound crossing time, which scales as the dynamical time $\sqrt{R^3 / (G M)}$. Non-example: measuring the radius of a star by interferometry alone is not asteroseismology, because no oscillation frequencies are used. The case of the Sun is called helioseismology.