What happens to asteroids in resonances? - Supervisor: Apostolos “Tolis” Christou
The AOP solar system group is carrying out frontline astronomical research in the origin and evolution of the solar system and its small bodies. Recent highlights include: the discovery that the tenuous atmosphere of Mercury is modulated by impacts with debris from periodic comet Encke (Christou, Killen et al, GRL, 2015); using the moons of the giant planets to constrain key events in early solar system evolution (Li and Christou, AJ, 2017; AJ, 2020); and quantifying the evolution of Mars and Earth Trojan asteroids by collisions and radiation forces (Christou et al, Icarus, 2017; Icarus, 2020; Christou & Georgakarakos, MNRAS, 2021). Work by our group
recently showed that Yarkovsky non-gravitational forces cause significant orbit changes or even escape for asteroids in the 1:1 resonance with Mars – the so-called Trojans – while the physical bodies themselves may break apart due to YORP spin-up, creating clusters of resonant asteroids. Outcomes of YORP-induced disruption are observed elsewhere, as orbital clusters of Main Belt asteroids (Pravec et al, 2010) and the active shedding of material (eg (6478) Gault, Hui, M-T et al, MNRAS Lett., 2019). In a wider context, correlations between asteroid orbits and sizes point to size-dependent orbit evolution (Bolin et al, Icarus, 2017; Dermott, Christou et al, Nature Astr., 2018; Dermott et al, MNRAS, 2021).
In this project we want to quantify resonant orbit and/or spin evolution of asteroids and their debris under non-gravitational radiation-driven forces, applying our findings to different settings, make predictions and interpret observations. Breaking up of resonant or co-orbital asteroids near the Earth’s orbit may form compact orbital clusters (de la Fuente Marcos & de la Fuente Marcos, MNRAS Lett., 2019), contribute to debris structures observed at the orbits of the Earth (Dermott et al, Nature, 1994) or, more recently, Venus (Jones et al, Science, 2013; Pokorny & Kuchner, ApJ, 2019). Outside the solar system, any debris in resonance with close-in exoplanets would evolve significantly and rapidly, giving rise to features that may betray the presence of the planetary body. The successful applicant will collaborate with Dr Christou in attacking this multi-faceted problem. The scope and direction of the resulting PhD project will depend primarily on the student’s individual inclinations. Work methods will include, but are not necessarily limited to, intensive N-body numerical simulations. Some familiarity in the areas of dynamics, statistical methods or numerical analysis will be seen as an advantage.
For further information contact Apostolos.Christou@armagh.ac.uk