Orbital evolution of asteroidal moons and implication for the structure of bodies

According to Kaula’s theory (Kaula 1966, Theory of Satellite Geodesy, Blaisdell Publ., Waltham), the gravitational potential affects the motion of satellites around Earth and induces perturbations of the orbital elements (̇𝛺, ̇𝜔, ̇M). We therefore propose to study the short-term orbital evolution of asteroid moons. Currently, more than 400 moons of asteroids are known; particular attention should be given to multiple systems such as (216) Kleopatra and (130) Elektra, where the moons interact both with the central body and with each other. Using archival astrometry as well as new images from ESO/VLT/SPHERE, it is possible to measure the precession of their orbits and thus infer the internal structure of the central body. In this context, we have recently developed entirely new, precise analytical algorithms for computing light curves (the so-called polygonal algorithm) and synthetic images (’cliptracing’). See [1], Marchis et al. (2021, A&A 653, A57), Brož et al. (2021, A&A 653, A56), Brož et al. (2022, A&A 657, A76), Brož et al. (2023, A&A 676, A60), Fuksa et al. (2023, A&A 667, A189). A related topic is also addressed in the GAČR grant (25–16507S; PI D. Vokrouhlický).

For a deeper understanding, we also propose to carry out hydrodynamic simulations of collisions using the SPH method (Jutzi et al. 2015, P&SS 107, 3), particularly for asteroids associated with families, as in the study of (22) Kalliope. For this purpose, the Opensph code was developed in a previous PhD thesis ([2]; Ševeček et al. 2019, A&A 629, A122; Ševeček 2021, PhD thesis, Charles University). This code provides a comprehensive description of collision phenomena, i.e., shock-wave generation, fragmentation, ejecta, self-gravity, reaccumulation, rotation, friction, the resulting shape of the central body, its oscillations (Vernazza et al. 2019, NA 4, 136), moon formation (Durda et al. 2004, Icarus 170, 243), etc. By the way, our model of the asteroid (22) Kalliope (Ferrais et al. 2022, A&A 662, A71; Brož et al. 2022, A&A 664, A69) was spectacularly confirmed by observations with the ALMA interferometer, which detected an anomaly in the dielectric constant, consistent with the exposure of an iron core (de Kleer et al. 2024, PSJ 5, 230).

A student should have knowledge of: the Linux operating system, programming in C or Fortran, programming in Python, the ability to study related subfields (celestial mechanics, hydrodynamics), analytical skills, the ability to work independently as well as collaboratively with international experts (P. Vernazza, M. Marsset, M. Jutzi).

https://sirrah.troja.mff.cuni.cz/~mira/tmp/PhD_mesice/README_cz.pdf

References:

Brož et al. 2021, A&A 653, A56.
Brož et al. 2022, A&A 657, A76.
Brož et al. 2022, A&A 664, A69.
Brož et al. 2023, A&A 676, A60.
Durda et al. 2004, Icarus 170, 243.
Ferrais et al. 2022, A&A 662, A71.
Fuksa et al. 2023, A&A 667, A189.
Jutzi et al. 2015, P&SS 107, 3.
Kaula 1966, Theory of Satellite Geodesy, Blaisdell Publ.
Waltham. de Kleer et al. 2024, PSJ 5, 230.
Marchis et al. 2021, A&A 653, A57. Ševeček et al. 2019, 629, A122.
Ševeček 2021, PhD thesis, Charles University.
Vernazza et al. 2019, NA 4, 136.

[1] https://sirrah.troja.mff.cuni.cz/mira/xitau/
[2] https://gitlab.com/sevecekp/sph/tree/devel