Dr Steven Parsons

STFC Ernest Rutherford Fellow

Contact Details

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Astronomy and Astrophysics Group


I am a Leverhulme Early Career Fellow in the astronomy group at the University of Sheffield. I earned my MPhys in Physics with Astrophysics at the University of Kent in 2008, followed by a PhD at the University of Warwick under the supervision of Prof. Tom Marsh. After receiving my PhD in 2012 I moved to the Universidad de Valparaiso in Chile. Following a 1 year ESO/Comite Mixto Post Doc I was awarded a 3 year FONDECYT Post Doctoral fellowship at Valparaiso. When this finished in 2016 I moved to the University of Sheffield as part of a 1 year Post Doc with Prof. Vik Dhillon, before starting my Leverhulme Fellowship in May 2017.


My research involves the study of white dwarfs, the incredibly dense burnt out embers of former stars. White dwarfs have masses similar to the Sun, but are only the size of the Earth. Many are found in binary systems with other stars or white dwarfs, a few of which are aligned with the Earth such that one star passes in front of the other, causing regular eclipses. I use a range of telescopes from around the world to search for and study these eclipsing binaries in order to better understand the structure and composition of white dwarfs as well as the evolution and fate of these binaries.

There is a theoretical upper limit to the mass of a white dwarf, known as the Chandrasekhar mass. If a white dwarf gains mass (e.g. from a binary companion) and reaches this limit it will blow up in an explosion known as a Type Ia supernova, visible from across the Universe. These supernovae are extremely useful to cosmologists since their distances can be reliably measured, leading to the discovery of the accelerating expansion of the Universe and the existence of dark energy. However, how the white dwarf gains the mass, and the nature of its binary companion are not well known. I search for the progenitors of type Ia supernovae in our own Galaxy to better understand how they are created and whether or not the existence of multiple formation channels could ultimately limit their use as distance indicators.


Journal articles