Mechanisms underlying period irregularity in first-overtone Cepheids

Determine the physical mechanisms responsible for the greater period erraticity observed in first-overtone Cepheid pulsators compared with fundamental-mode Cepheids.

Background

Polaris pulsates in the first overtone and exhibits unusually rapid period changes and other timing anomalies.

The authors note that overtone pulsators generally show more erratic period behavior than fundamental-mode pulsators, and that the reasons for this difference are not fully understood.