Star Keyboard

The spectrum cut into strips Δν wide and stacked: each mode at its frequency (up) and its frequency modulo the large separation Δν (across). Modes of one degree line up in ridges; a red giant’s dipole modes are mixed with the core’s g modes and scatter off theirs. Click a mode to show it on the star.

The surface pattern of one mode (the loudest, or the one you clicked), slowed down: bright moving out, dark moving in. It turns with the star (the lines are its equator and meridians), and the inclination tilts its axis toward you. Pole-on, the m ≠ 0 patterns average out over the disc.

Bars: each mode’s power now (the engine’s), coloured by degree l, under the model’s Gaussian envelope around ν_max (dashed); line: the live output. The bars rise and fall at random: convection drives every mode, and each forgets within its lifetime 1/(πΓ).

Hold a key and every mode flickers on its own: convection kicks it at random and it swells and fades within its lifetime, so the lines come and go like a breathing comb. Let go and each one rings down at its own linewidth; a δ Scuti star holds its few lines steady.

A Hertzsprung–Russell diagram: luminosity against temperature (hot to the left). Dots: the star on every key, along one evolutionary track; the ring: the last key played. Top keys are dwarfs on the main sequence, then subgiants, then red giants down the keyboard.