About Me

I am a 3rd Year PhD Student at the Institute of Astronomy, University of Cambridge, working with Professor Cathie Clarke.

Research

I study protoplanetary discs, where planets form around young stars.

Image of GW Lup: DSHARP survey (Andrews et al., 2018)

Publications

Find my complete list of publications here:

SAO/NASA ADS
Orcid

Although I originate from Devon, since 2015 I have lived in Cambridge, where I studied Natural Sciences for my BA and MSci degrees, specialising in astrophysics.

I also enjoy doing outreach and public engagement; for several years now I have been part of the committee of Cambridge Hands-On Science (CHaOS), a student-run group which runs hands-on roadshow events in schools and public events around the country.

In what spare time remains, I enjoy heading out into the countryside for long walks, or relaxing with a cryptic crossword.

Email:
ads79@cam.ac.uk

GitHub:
https://github.com/AndrewSellek

Disc environments evolve through a number of competing processes; my particular interests are on the secular (i.e. long term) evolution, addressing questions such as:

  1. What is the origin of any winds that are removing material; does photoevaporation affect discs in important ways?
  2. How long are the resulting protoplanetary disc lifetimes; how is this affected by their surroundings?
  3. Where does their material end up – on the star, blown away in a wind, or in planets?

Broadly speaking, I tackle these questions in two ways.
– Firstly, by seeking to improve our physical understanding of photoevaporative winds including what heats and cools them, and what controls the structure of these thermal winds.
– Secondly, by investigating how photoevaporative winds compete with other evolutionary processes in the disc such as viscous accretion and radial drift of dust by combining models of these effects in a forward modelling process to try to reproduce trends we see in demographic surveys of protoplanetary discs.

Some recent highlights (as of June 2021) of papers that I have published during my PhD include:

The general applicability of self-similar solutions for thermal disc winds

Sellek, Clarke and Booth (2021)

We extend previous self-similar models, considering in particular the effects of temperature gradients, which only make small differences, and elevated wind bases, which are more important. We explain results of hydrodynamics simulations – which generally agree well with our solutions – in terms of space-filling, and consider implications for [Ne II] line profiles.

A dusty origin for the correlation between protoplanetary disc accretion rates and dust masses

Sellek, Booth and Clarke (2020)

We consider how the radial drift of dust grains lowers disc masses enough to better explain this correlation, and find that a fairly weak photoevaporative wind is needed to reproduce low accretion rates.