Here is a summary of some of the PhD projects on offer for a student to start in 2023:
Dust growth in self-gravitating discs
With the recent exciting discoveries of gaps and rings in protoplanetary discs, it is becoming clearer that planet formation happens quickly, and likely begins when the discs are very young – in what we call self-gravitating discs. Previous work shows that dust tends to collect in the spiral arms of these young discs, but a big unknown is whether the dust grows enough to form planets. The aim of this project is to simulate the growth of dust in self-gravitating discs to understand if planets can form in young discs.
Fragmentation of self-gravitating discs
Young massive discs — known as self-gravitating discs — are expected to become unstable and break apart into giant gas balls in the outer regions. These may ultimately evolve into giant planets or brown dwarfs. There are various elements of disc fragmentation that still need to be explored in detail. For example, we have recently found that a fragmenting disc can trigger more fragments to form in the inner part of a disc — a process called Triggered Fragmentation. But how prevalent is this process in real discs? In addition young stars form in clusters and so interactions with nearby stars is possible. Can the interaction with an external perturber cause a disc to fragment? And since stars have varying masses, how likely is it that a disc will fragment around different mass stars to form planets or stellar companions?
The impact of warps on planet formation (co-supervised with Rebecca Nealon)
While we often think of protoplanetary discs as flat structures (i.e. a bit like a dinner plate), this is not necessarily the case. There is strong theoretical and observational motivation for warped or misaligned discs, where the orientation of the disc changes as a function of its distance from the star. We also expect that most discs will experience a warp in their lifetime. However, how warps interact with existing disc processes like dust and gravitational instabilities is poorly understood. Does the presence of a warp contribute to dust collection and thus planet formation? Or do they prevent dust collection? Can warps be responsible for the formation of misaligned planets? Does this picture change if we include fragmentation and growth?
With exciting new observations of protoplanetary discs constantly appearing, this research field is fast-developing. Therefore the above projects may evolve over time. In addition I welcome potential students to contact me if they are interested in a particular area that is not listed above but which fits generally within my research field.