Tidal and Spin Evolution
Pure point-particle Newtonian gravity gets you pretty far in astronomy, but it doesn’t get you all the way. Much of my work centers around the interplay between tidal dissipation, spin axis evolution, and the aforementioned Newtonian gravity that governs the dynamics of the system.
In the presence of resonances, or close matches in characteristic frequencies of a system, fascinating behavior can emerge. One example is the extreme axial tilt of Uranus, one of the enduring problems in solar system science. In Lu & Laughlin (2022), we show that a spin-orbit resonance driven by the migration of the hypothetical Planet 9 is theoretically capable of generating this obliquity.
Recently I led a case study of the HAT-P-11 system, one of the most-studied and well-characterized exoplanet systems best known for a pair of planets on unusual eccentric and misaligned orbits. In Lu et. al (2024) we present a feasible formation scenario for this system involving violent planet-planet scattering followed by von Zeipel-Kozai-Lidov oscillations and tidal circularization.
Relevant Publications:
- Lu et. al (2024), In Review
- Lu et. al (2023), ApJ 948 41
- Lu & Laughlin (2022), PSJ 3 221