About myself

I'm an astronomer at ESO, where I started in late 2014 as an ESO Fellow. Before that I was a Postdoctoral Research Fellow at the University of Toronto with Marten van Kerkwijk.
I finished my thesis, titled "Type Ia Supernovae: Progenitors and explosions", in 2011 with Brian Schmidt at the Australian National University.

Research overview

My research focuses on stars before, during and after explosion (exploding stars are known as supernovae). My two particular topics in this field are the search for surviving companions in ancient supernova remnants and synthesizing and fitting spectra of supernovae. I also have an interest in the nuclear star cluster of our own Milky Way. Tuan Do and I are trying to understand the origin of this dense and massive cluster. Finally, I am working with the Science Data Group at ESO to think about novell ways to extract measurements from raw data. In particular, I am developing a method to use all available information using a statistical framework when extracting spectra from X-Shooter data. All of this research is tied together with an interest in numerical methods, machine learning and the idea of open software as well as open collaboration.


The history of the Universe begins with the Big Bang and thus the creation of large quantities of the primordial building blocks of our cosmos: hydrogen and helium. It continues with the creation of the first stars – gravitationally bound gas spheres that become dense and hot enough for nuclear fusion, transforming the primordial hydrogen via helium to carbon and oxygen for lower mass stars and to iron for the most massive ones. Supernovae return these elements to the interstellar medium – and provide the extreme conditions required to make many of the heavier ones such as iron or silicon. Since the elements beyond helium are crucial to the formation of rocky planets such as the Earth – and for life as we know it – understanding supernovae thus is an integral part of understanding how our Universe came to be the one we observe today.
Supernovae have been seen by humankind throughout the ages, with famous examples recorded in 1572 by Tycho, and in 1604 by Kepler, but only the last century had seen the necessary technological and scientific advances to start understanding these most energetic events. There are two basic classes of supernovae, those with hydrogen and those without: Those with hydrogen were designated Type II and those without Type I.
Today we understand that the collapse of massive stars (ten times more massive than the sun) powers the Type II supernova. It now also seems obvious that these supernovae would show hydrogen as it is the the most abundant element in the Universe and thus stars.
The lack of hydrogen in Type I supernovae is a bit of a mystery. In addition, this class of supernovae splits itself into two further subclasses named Type Ia and Type Ibc. My research focuses on Type Ia supernovae that are characterized by showing silicon.

The mysteries surrounding Type Ia supernovae

Why would certain types of exploding stars not exhibit the

Supernova spectral synthesis with TARDIS

Supernova spectral synthesis with TARDIS