Profile

I am a computational astrophysicist working in the field of Exoplanets – and I can link my research to Star Wars and Doctor Who (read on to find out)! That is, I use computers and my knowledge of physics to try and understand more about planets that orbit around other stars. Working with exoplanets is unbelievably cool because it touches on many questions, one of the most important being; is there life out there in the rest of the universe? I bet you already know that we’ve discovered hundreds of exoplanets in recent years. Many of these have been found using a telescope you might have heard of named Kepler. We know these planets exist, but we don’t know a lot about how they formed. So my work essentially boils down to…

How do you build a planet?

We can’t really see planets forming with telescopes so we have to use computer simulations to try and create them based on our understanding of the science. We think that planets form from gas and dust that are mixed together in a big disk which surround a young star. Dust starts sticking together into small grains, and these grains stick together into larger rocks. These rocks collide with each other and sometimes merge into bigger and bigger rocks… until they get big enough to become a planet like Earth or Mars. If they get really big, then they start pulling the gas onto themselves and turn into a gas planet like Jupiter!

I use computer codes to generate big disks full of rocks… sometimes as many as over a million. You then evolve the disk under the forces you think they will experience such as gravity and friction. The problem here is that each rock (which we call a planetesimal) feels not only the star it orbits, but also every other planetesimal. So if you have a million rocks, you have to do around a million calculations to work out the force acting on just one rock. Then you need to do that for each of your other million rocks… Eugh! That’s one trillion calculations to do – and that’s just gravity – and just one moment in time!

Luckily, I get to use some of the most powerful computers on the planet to do these calculations for me…quickly. The job requires knowledge of programming to make sure the code does what you want, followed by analysing the data from millions of planetesimals. After thousands of years you can ask; did I form a planet?

To finish, more precisely I work on the formation of a type of planet called a circumbinary planet. We only know of less than 10 of these so far in the whole galaxy – and they are special because they are planets that orbit around binary stars (two stars). The planet Tatooine in Star Wars and Gallifrey (home of the time lords) in Doctor Who are both circumbinary planets – and you can see they have two sunsets. It’s much harder to make planets around binary stars because they introduce some crazy gravitational forces that make planetesimals explode on impact… rather than merge together and grow like we need.

Generally speaking, as a computational astrophysicist, I spend most of my day working closely with computers. Aside from numerous coffee breaks and science-based chats with my colleagues, I’ll spend the day writing computer code and scripts, analysing data and producing fancy graphs to communicate my results to other people.