Tidal flows in extrasolar planets and stars

Supervisor(s)

Contact Dr Adrian Barker to discuss this project further informally.

Project description

Since 1995 astronomers have discovered and partially characterised several thousand extrasolar planets. Many of these planets have masses similar to Jupiter’s, and orbit their host stars in only a few Earth days -- a fascinating class of planets that we refer to as hot Jupiters. Since these planets orbit their stars very closely, gravitational tidal interactions between the planet and star can determine the orbits of these planets, and the spins (axial rotations) of the planet and its host star. A familiar example of tides, much closer to home, is the interaction between the Earth and the Moon, which results in a gradual lengthening of both the day and month.

This means that the Earth is gradually spinning down (by a few milliseconds per century) as the Moon is receding from the Earth (at a rate of a few centimetres per year). Evidence for the influence of gravitational tides in extrasolar planetary systems is most clearly seen in the orbits of the closest planets. Tides can change the shape of the orbit: how circular or elliptical (eccentric) it is. Indeed, the closest planets, that orbit their stars in less than 10 Earth days, preferentially have circular orbits, while those that orbit their stars more distantly tend to have eccentric orbits. This is thought to primarily result from the dissipation of tidal flows inside these planets. These (and related) observations motivate theoretical work to understand tidal flows inside planets and stars, to determine and elucidate the mechanisms by which they may dissipate.

This requires understanding the fluid dynamics and magnetohydrodynamics of tidal flows inside planets and stars, including the effects of rotation, stratification, convection and magnetic fields. This project will investigate some of these effects using a combination of computer simulations and theoretical (analytical) calculations, with the aim to understand tidal flows in stars and in the fluid layers of planets. The ultimate goal of this research is to explain astrophysical observations and make predictions to be tested by future observations. The group in Leeds is one of the leading groups in the field of Astrophysical and Geophysical Fluid Dynamics (https://agfd.leeds.ac.uk), and is actively engaged in research on a wide range of topics including planetary and extrasolar planetary dynamics (the geodynamo, planetary dynamos, tidal interactions between planets and stars, planet formation), solar and stellar dynamics (solar and stellar dynamos, hydrodynamic and magnetohydrodynamic instabilities, turbulence), as well as galactic and extragalactic dynamics on the largest scales. Although this project does not have dedicated funding, all successful applicants without funding will be considered for both STFC funding, and for a fully-funded scholarship in an open competition across the entire School of Maths.

Entry requirements

Applications are invited from candidates with or expecting a minimum of a UK upper second class honours degree (2:1), and/ or a Master's degree in a relevant subject such as (but not limited to) mathematics.

If English is not your first language, you must provide evidence that you meet the University's minimum English Language requirements.

How to apply

Formal applications for research degree study should be made online through the university's website. Please state clearly in the research information section that the PhD you wish to be considered for is the ‘Tidal flows in extrasolar planets and stars’ as well as Dr Adrian Barker as your proposed supervisor.

We welcome scholarship applications from all suitably-qualified candidates, but UK black and minority ethnic (BME) researchers are currently under-represented in our Postgraduate Research community, and we would therefore particularly encourage applications from UK BME candidates.  All scholarships will be awarded on the basis of merit.