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Published December 2017 | Submitted + Published
Journal Article Open

Heartbeat stars, tidally excited oscillations and resonance locking

Fuller, Jim ORCID icon


Heartbeat stars are eccentric binary stars in short-period orbits whose light curves are shaped by tidal distortion, reflection and Doppler beaming. Some heartbeat stars exhibit tidally excited oscillations and present new opportunities for understanding the physics of tidal dissipation within stars. We present detailed methods to compute the forced amplitudes, frequencies and phases of tidally excited oscillations in eccentric binary systems. Our methods (i) factor out the equilibrium tide for easier comparison with observations, (ii) account for rotation using the traditional approximation, (iii) incorporate non-adiabatic effects to reliably compute surface luminosity perturbations, (iv) allow for spin–orbit misalignment and (v) correctly sum over contributions from many oscillation modes. We also discuss why tidally excited oscillations (TEOs) are more visible in hot stars with surface temperatures T ≳ 6500 K, and we derive some basic probability theory that can be used to compare models with data in a statistical manner. Application of this theory to heartbeat systems can be used to determine whether observed TEOs can be explained by chance resonances with stellar oscillation modes, or whether a resonance locking process is operating.

Additional Information

© 2017 The Author Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2017 August 14. Received 2017 August 14; in original form 2017 June 14. Published: 18 August 2017. I am grateful to Susan Thompson for providing the data in Fig. 1, and to the anonymous referee for a thoughtful report. I thank Rich Townsend and Zhao Guo for helpful discussions. This research was supported in part by a Lee DuBridge Fellowship at Caltech, the National Science Foundation under grants AST-1205732 and PHY-1125915 and the Gordon and Betty Moore Foundation through grant GBMF5076.

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Published - stx2135.pdf

Submitted - 1706.05054.pdf


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August 19, 2023
October 17, 2023