Dust plays a significant role in the composition and evolution of the universe. Until recently, scientists believed dust is mainly formed in the atmosphere of asymptotic giant branch (AGB) stars. In the last decades however, observations have revealed significant dust masses in very old galaxies. In these galaxies the stellar populations are too young to have produced so much dust via AGB stars. To explain the dust excess in the early universe, core-collapse supernovae (CCSNe) have been suggested as effective and dominating producers of dust. Unfortunately, CCSNE do not only produce dust, they also destroy it. How much exactly is still unclear.
At UCL, we use the hydrodynamics code AstroBEAR to model the supernova remnant and the dust destruction processes within. Using the latest parameter constraints we produce estimates for the amount of dust able to survive these extreme conditions long enough to transition into the interstellar medium.
An object travelling through a gaseous medium experiences drag forces pointing in the opposite direction to the object’s movement. These drag forces include the hydrodynamic drag force (due to momentum exchange) and the dynamical drag force (due to the gravitational interactions between the object and an overdense wake of material forming behind it).
For my MSc thesis in 2016, I examined the supersonic movement of non-gravitating and gravitating spheres through gaseous media for varying adiabatic indices and varying Mach numbers. The analysis includes, but is not limited to, examinations of the resulting density profiles, shock distances, and the individual forces acting on the system. The obtained results indicate a clear dependence of the standoff distance on the Mach number and adiabatic indices. This enabled us to obtain an analytical approximation of the standoff distance as a function of either the adiabatic index or the Mach number.
In late 2014 the Japan Aerospace Exploration Agency (JAXA) launched the unmanned spacecraft Hayabusa 2, which arrived at its destination, the asteroid 1999 JU3, in 2018. Hayabusa 2 released a lander, developed by the German Space Agency (DLR), onto the asteroid surface.
The subject of this bachelor’s thesis carried out in 2014 was the study of the bouncing behaviour of said lander colliding with the regolith covered asteroid surface at a velocity of
|v| ≈ 0.1 ms .This will be accomplished using a smooth particle hydrodynamics (SPH) code.
Several numerical test runs were performed, confirming the integrity of the code and revealing the unlikeness of the lander significantly distorting the asteroid surface at low velocities. Subsequently simulations with varying numbers of SPH particles, asteroid surface densities, lander rotation angles and angles of incident were executed and evaluated with respect to the coefficient of restitution.