Formation and evolution of ExoKuiper Belts

Supervisor: Dr Sebastian Marino, Senior Research Fellow

In the last two decades, the study of planetary systems has been revolutionised thanks to the discovery of thousands of exoplanets and hundreds of debris discs. Whilst exoplanet discoveries have been biased towards the inner regions, cold debris discs (extrasolar analogues of the Kuiper belt) have been crucial for constraining the outer regions of exoplanetary systems. These exoKuiper belts are made of minor bodies similar to comets that collide and generate high levels of dust that are readily detectable at multiple wavelengths.  Depending on the student’s interests and skills, I am offering up to two PhD projects in the two following areas/topics (both funded by a recently awarded ERC Starting Grant):

Area I: How do exoKuiper belts form in protoplanetary discs?

The comets that give rise to ExoKuiper belts must grow from the dust in protoplanetary discs. Whilst the formation of comets/planetesimals has been studied in detail recently, the formation of exoKuiper belts and comparison with observations has yet to receive much attention. The student will first use and extend existing software to simulate the dust evolution in a protoplanetary disc with a planet to study how exoKuiper belts form and how their structure will depend on their formation conditions. The next step will be to simulate the interaction between the planet and comets as the protoplanetary disc disperses. See Miller et al. 2021 for more details on the methods.

Area II: How does the gas released by exocomets evolve?

The collisions that produce dust in debris can also release large amounts of gas. This gas proves that the material in exoKuiper belts is icy and volatile-rich, which could be delivered to Earth-like planets in the habitable zone. In recent years significant progress has been made in trying to understand this gas, but only recently high-resolution observations of this gas became available. In this project, the student will work analysing new ALMA observations of gas in exoKuiper belts and interpreting them using existing models. In addition, this project will involve extending the existing 1D gas evolution models incorporating multiple gas species (other than CO, C and O gas) and account for 2 dimensions to explain the observations of gas. 

If you have any questions, get in touch via email. This review may be useful.