Homepage of John Southworth (John Taylor)

I am a Lecturer in Astrophysics working in the Astrophysics Group at Keele University, UK. My primary research areas are the study of transiting extrasolar planets and eclipsing binary stars, although I retain a strong interest in asteroseismology, cataclysmic variables and post-common-envelope binaries. Brief descriptions of these research areas are given below. My main aim is to measure the properties of stars and planets as accurately as possible.

The links below give access to various resources, including scientific papers, published data, and computer codes useful for studying binary stars and extrasolar planets. I maintain catalogues of the known transiting planets and well-studied eclipsing binaries. I can be contacted at .

My research

Extrasolar planets are currently a big subject in astrophysics, as we struggle to understand where our own Solar System came from, where is it going, and how many others there are which might support life. I work on transiting extrasolar planets: ones which periodically pass in front of their parent stars as seen from Earth. From observations of these planets we can precisely determine their masses and radii, and so understand the properties of planetary systems in general. A lot of my observations are done with telescopes deliberately driven out of focus, which makes things more interesting.

Detached eclipsing binaries are vital to our basic understanding of stars, and thus galaxies and the Universe, because they are pretty much the only ones for which we can accurately measure such fundamental properties as their mass and radius. Understanding the real-life properties of stars allows us to model them and investigate their structure and evolution. My work on eclipsing binaries is mainly directed towards ones containing high-mass, low-mass, or peculiar stars, and ones which are members of star clusters.

Cataclysmic variables are a particular type of interacting binary system where a white dwarf (the extremely dense core of what used to be an evolved star) is gradually devouring a low-mass companion star. This results in an accretion disc and lots of nasty and poorly-understood physical phenomena. My work concentrates on measuring the properties (mainly orbital periods) of homogeneous samples of these objects, which can then be used to constrain theories about how they form and evolve. The physics of accretion is needed to study some of the most violent phenomena in the Universe, such as quasars, supernovae and black holes.

Post-common-envelope binary systems form from a wide binary in which the more massive star puffs up to become a giant, engulfing its companion. Most of the giant star is ejected, forming a planetary nebula which then disperses, leaving behind the core of the giant and its companion in a close orbit. Many post-common-envelope binaries will become cataclysmic variables, so offer the opportunity to study binary evolution processes without the difficulties caused by the accretion discs which produce much of the overall light in cataclysmic variables.

Asteroseismology holds a lot of promise for improving our understanding of stellar physics. Many stars pulsate, for different reasons, and these pulsations can be used to probe not only their surfaces but also their interiors. This is practically our only way of seeing inside stars, but requires extensive and continuous observations of specific objects. The era of large-scale asteroseismology has now begun, with several space missions (CoRoT, Kepler, MOST) obtaining long and uninterrupted measurements of the brightnesses of thousands of stars. In particular, I aim to study pulsations in eclipsing binaries, in order to combine the advantages of the two approaches.

Last modified: 2022/02/23           John Southworth   (Keele University, UK)