Research
Below is a brief summary of my published works on extra-solar moons and giant planets, including aspects of N-body numerical modeling and orbital dynamics.
To find out more about each project, please click on the header.
I have developed an N-body integrator that is capable of handling moon problems in close planet-planet interactions, based on Mercury (Chambers 1999). The modified code treats planets realistically as oblate, and evolves planet spin with a non-secular equation of motion.
AAS nova has a very interesting summary of this work:
The Fate of Exomoons when Planets Scatter
At the early stages of the evolution of exo-planetary systems, close dynamical interactions between the giant planets lead to chaotic, unstable, and rich orbital dynamics. Moons in such systems exhibit diverse and novel dynamical behaviors, such as moons captured by a different planet, moons that turned to orbit the star, moons that are stable around ejected free-floating planets, and the most frequent outcome of all — moons ejected from the system as free-floating moons. The high frequency of moon ejection could lead to 0.01-1 free-floating exomoons per star in our galaxy.
Original paper: Innocent Bystanders: Orbital Dynamics of Exomoons During Planet–Planet Scattering Y-C. Hong, S. Raymond, P. Nicholson, J. Lunine, ApJ 2018
We placed moons around spherical planets, against a commonsensical notion that the orbital dynamics of close-in moons is dominated by the oblateness of their host planet. We observed close-in moons going unstable or acquiring high eccentricities and inclinations in a stable two-planet system mutually inclined by only 10 degrees. The cause for instability is the slowed precession of the moons' orbital plane in the absence of planet oblateness, which gives it a chance to enter the 3:2 and 1:1 resonance overlap zone or the chaotic zone around 1:1 resonance with the precession of the star's orbits (in moon hosting planet centered frame).
Original paper: Orbital Instability of Close-in Exomoons in Non-Coplanar Systems Y-C. Hong, M. Tiscareno, P. Nicholson, J. Lunine, MNRAS 2015