I am an assistant professor in computational and theoretical astrophysics
at the Institute of Gravitational Wave Astronomy at the University of Birmingham.
I'm interested in the formation and evolution of stellar systems, such as binaries and triples.
How do they evolve? And how do they end their lives? What are the properties of the
energetic and transient phenomena they produce - both in electromagnetic and in
gravitational wave radiation?


Contact details

s.toonen [at] bham.ac.uk
My previous email (toonen [at] uva.nl) is deactivated

Physics West office 237
Birmingham B15 2TT
Edgbaston, United Kingdom


Recent highlights


Check out our webtool!

In Toonen et al. 2020 we introduce a webtool to estimate the dynamical impact of the tertiary star onto the inner binary in a hierarchical triple. Using the webtool, one can make a figure like the one above to assess the different dynamical regimes of three-body dynamics for your own favorite triple! The webtool is based on a python notebook.
Have you discovered a new triple? Plug it in the webtool!

And if you're browsing anyway, check out our Facebook group on triple evolution and dynamics too!


Roadmap for triple evolution

Many stars do not live alone, but instead have one or more stellar companions. Observations show that these binaries, triples and higher-order multiples are common. Whereas the evolution of single stars and binaries have been studied extensively, the same is not true for the evolution of stellar triples. To fill this gap in our general understanding of stellar lives, we aim to systematically explore the long-term evolution of triples and to map out the most common evolutionary pathways that triples go through. We quantitatively study how triples evolve, which processes are most relevant, and how this differs from binary evolution.

fault in our stars

The fault in our stars

I am super proud to announce the paper of my former MSc student Karel Temmink on stellar mergers. Karel showed that looks can be deceiving; many merger remnants may be hiding amongst single white dwarfs. This may cause a problem when using white dwarfs as a tool to measure stellar ages and constrain Galactic structure and evolution.