What happens to asteroids in resonances? - Supervisor: Dr 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. 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 distant moons of the giant planets to time key events in early solar system evolution (Li and Christou, Astron. J., 2017); and constraining the production and loss of Mars Trojan asteroids by collisions and radiation forces (Christou et al, Icarus, 2017; Icarus, 2020). Our research is grant-aided by the UK Science and Technology Facilities Council (STFC).
Work done by our group (Christou, Icarus, 2013; Borisov et al, MNRAS, 2017; Christou et al, Icarus, 2020) shows that the Yarkovsky effect causes significant orbit changes or even escape for asteroids in the 1:1 resonance with Mars – the so-called Trojans – while the physical bodies themselves 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) while correlations between asteroid orbits and sizes point to size-dependent orbit evolution (Bolin et al, Icarus, 2017; Dermott, Christou et al, Nature Astronomy, 2018).
In this project we want to quantify resonant asteroid orbit and/or spin evolution under non-gravitational 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) and give rise to meteor showers. Outside the solar system, any debris co-orbital 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, with the scope and direction of the resulting PhD project depending 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