Tides in Stars and Planets
Resonance Locking in Stellar Binaries
Resonance locking is a tidal theory where most orbital energy and angular momentum dissipation in a binary system occurs from resonances between a host body's natural oscillation frequency and the perturber's tidal potential oscillation frequency, prolonged by the host's internal evolution. Resonance locking potentially solves a number of outstanding problems related to the migration of Saturn's and Jupiter's moons, white dwarf binary system synchonization, and exciting the oscillations of heartbeat binary stars. Prof. Yanqin Wu and I applied this theory to understand how resonance locking circularizes binary star poplutions. In the first part of our work, we showed this theory efficiently circularizes binaries during their pre-main sequence evolution out to 4-5 day orbital periods. In the second part of our work, we combined eclipsing and spectroscopic binary data to show resonance locking can explain the eccentricities of short-period binaries.
Tides in Rocky Exoplanets
I have also dabbled briefly in tidal processes applied to the geophyiscs of rocky exoplanets, looking at processes which stress a rocky planet's lithosphere, which impact explanetary habitability. With Prof. Dong Lai, I calculated the maximum triaxiality a rocky planet can sustain. I showed the largest possible triaxiality for most rocky exoplanets is sufficiently large to resist the tidal torque working to synchronize the planet's spin, and capture a (short-period) planet into a spin-orbit resonance. With Dr. Amaury Triaud, I showed tidal stresses acting on short-period exoplanets can weaken the planet's lithosphere, making plate tectonics more likely.
Obliquity Tides in hot Jupiter Systems
An outstanding problem in exoplanetary science is why hot Jupiters orbiting hot stars often have high stellar obliquities (large angles between planet orbital plane and star equitorial plane), while hot Jupiters around old stars have low stellar obliquities. With Michael Poon (undergrad SURP fellow), Prof. Simon Albrecht, and I showed inertial wave tidal dissipation in cold stars, coupled with a high-eccentricity migration channel which causes the host star's stellar obliquities to form high, can explain the observed stellar obliquities. Currently, I am showing resonance locking can explain the differing obliquities between hot and cold stars.
Michael Poon, J. J. Zanazzi, & Simon Albrecht, Constraining Inertial Wave Tidal Dissipation by the Stellar Obliquities of Hot Jupiter Systems, 2021, in prep.
J. J. Zanazzi, A Tale of Two Circularization Periods, 2022, ApJL, 929, L27. PDF
J. J. Zanazzi & Yanqin Wu, Orbital Circularization of Binaries from Resonance Locking I: The Importance of the Pre-Main-Sequence. 2021, accepted to ApJ. PDF
J. J. Zanazzi & Amaury Triaud; The Ability of Significant Tidal Stress to Initiate Plate Tectonics. 2019, Icarus, 325, 55. PDF
J. J. Zanazzi & Dong Lai; Triaxial Deformation and Asynchronous Rotation of Rocky Planets in the Habitable Zone of Low-Mass Stars. 2017, MNRAS, 469, 2879. PDF