The orbital architectures of short-period exoplanet systems are shaped by tidal dissipation in their host stars. For low-mass M dwarfs whose dynamical tidal response comprises a dense spectrum of inertial modes at low frequencies, resolving the frequency dependence of tidal dissipation is crucial to capturing the effect of tides on planetary orbits throughout the evolutionary stages of the host star. We use nonperturbative spectral methods to calculate the normal mode oscillations of a fully convective M dwarf modeled using realistic stellar profiles from MESA. We compute the dissipative tidal response composed of contributions from each mode, as well as nonadiabatic coupling between the modes, which we find to be an essential component of the dissipative calculations. Using our results for dissipation, we then compute the evolution of circular, coplanar planetary orbits under the influence of tides in the host star. We find that orbital migration driven by resonance locking affects the orbits of Earth-mass planets at orbital periods Porb ≲ 1.5 days and of Jupiter-mass planets at Porb ≲ 2.5 days. Due to resonantly driven orbital decay and outward migration, we predict a dearth of small planets closer than Porb ∼ 1 day and similarly sparse numbers of more massive planets out to Porb ∼ 3 days.
Published March 1, 2024
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Tidal Migration of Exoplanets around M Dwarfs: Frequency-dependent Tidal Dissipation
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© 2024. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Acknowledgement
This material is based on work supported by the National Science Foundation Graduate Research Fellowship under grant No. DGE-1745301, and by NASA through grant 20-XRP20 2-0147.
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Additional details
- ISSN
- 1538-4357
- National Science Foundation
- NSF Graduate Research Fellowship DGE-1745301
- National Aeronautics and Space Administration
- 20-XRP20 2-0147
- Caltech groups
- Astronomy Department, TAPIR, Walter Burke Institute for Theoretical Physics