Exoplanet Dynamics

Seismic Oscillations in Gas Giants

Similar to planets in our own solar system, exoplanets could suffer impacts over their lifetime, exciting seismic oscillations.  It is postulated that the dependence of metalicity on planet mass is a result of sequential mergers of gas giants undergoing runaway accretion (Ginzburg & Chiang 2020).  Recently, I showed if the directly imaged exoplanet beta Pictoris b merged with a Neptune-mass planet in the past ~4 million years, NIRCam observations from JWST should be able to detect photometric modulations in the planet's flux.

Circumplanetary Disk or Ring Systems

A number of stars have been observed with deep dips in the star's brightness (such as J1407, PDS 110, and VVV-WIT-07), tentatively interpreted as extended circumplanetary ring systems transiting their host stars.  In order for rings to cause a transit signal, the rings must stably tilt out of the planet's orbital plane, and resist the host star's tidal force.  During my PhD, I showed a spinning planet with ring self-gravity could stably tilt an extended circumplanetary disk.  With Jessica Speedie, we used N-body integrations to show such tilted ring systems can remain stable over the system's lifetime, with gaps carved by local secular instabilities.

Image credit: Jessica Speedie

Tides in Rocky Exoplanets

Buldges on top of, and tidal stresses within, rocky planet lithospheres, affect their climates and habitability.  The maximum triaxiality a rocky planet can sustain limits the probability a planet has of being captured within a spin-orbit resonance, which affects whether the planet's rotation is synchronous or not.  Tidal stresses acting on short-period exoplanets might also weaken the planet's lithosphere, making plate tectonics more likely.

Publications

J. J. Zanazzi, Eugene Chiang, & Yifan Zhou; Seismic Oscillations after Major Mergers in Directly-Imaged, Giant Planets, in prep

Wang J., Ruffio J., Morris E., Delorme J., Jovanovic N., Pezzato J., Echeverri D., Finnerty L., Hood C., Zanazzi J. J. et al.; Detection and Bulk Properties of the HR 8799 Planets with High-resolution Spectroscopy. 2021, AJ, 162, 148. PDF 

Jessica Speedie & J. J. Zanazzi; The Stability of Extended Circumplanetary Disk and Ring Systems, with Applications to J1407b. 2020, MNRAS, 497, 1870. 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

J. J. Zanazzi & Dong Lai;  Extended Transiting Disks and Rings around Giant Planets and Brown Dwarfs: Theoretical Constraints.  2017, MNRAS, 464, 3945. PDF