Mode trapping in evolved stars

What you are seeing: a buoyancy-frequency glitch (sharp localised variation of $N$ ) imprints a periodic modulation on the g-mode period spacing $\Delta P(P)$ . The modulation amplitude $A$ measures glitch strength; the modulation period $P_{\rm trap}$ measures the glitch position.

Figure 1. Period-spacing diagram with mode trapping.

Π_1 (s)80

A0.20

P_trap (s)350

WHAT TO TRY

Vary each control and watch the rail readouts respond.
Compare the diagnostic plot against the live scene.