We invite applications from outstanding and highly motivated students for the Warwick Prize Scholarships in Astrophysics. The successful applicant will work with Prof. Peter Wheatley within the Astronomy and Astrophysics group in the Department of Physics at the University of Warwick.
In this project you will use data from ground-based and space telescopes to explore the atmospheres of transiting exoplanets. This includes the composition of the atmosphere, the formation of climate and weather systems including winds and clouds, and the evaporation of atmospheres irradiated by X-rays from the parent star.
We can probe the 3D structure and composition of planetary atmospheres using the technique of transmission spectroscopy, where opacity sources in the planetary atmosphere are detected in high-precision spectra taken during a transit of the planet across the face of its parent star. This can reveal the presence of specific atoms and molecules in the planetary atmosphere, as well as clouds and photochemical hazes. With transmission spectroscopy at high spectral resolution we can also detect Doppler shifts due to winds in the planetary atmosphere, and begin to map global climate systems.
Recently discovered exoplanets around bright stars, together with new more powerful instruments such as ESPRESSO and the James Webb Space Telescope (JWST), provide exciting new opportunities to map the 3D structure of exoplanet atmospheres. This goal builds on our own pioneering work spatially resolving the winds on an exoplanet for the first time (see this paper and press release). A main goal of this PhD project will be to map the climate systems of hot, giant planets, thereby testing 3D models of global circulation.
The same transmission spectroscopy techniques can be used to map the 3D structure of gas escaping from planetary atmospheres. We have directly detected the evaporation of some exoplanet atmospheres using transmission spectroscopy (e.g. this paper and press release) and it has become clear that the observed population of close-in exoplanets is severely influenced by the evaporation of their atmospheres. In particular, we see very few planets of Neptune-size close-in to their parent stars, a region that has become known as the Neptune desert. Further out, we also see a deficit of planets between the size of Earth and Neptune, known as the evaporation valley. A further goal of this project will be to apply the same technique of transmission spectroscopy to trace the mass loss of planetary atmospheres using the Doppler shift of an infrared helium line and possibly X-ray absorption.
The cause of atmospheric evaporation is hotly debated, with some scientists suggesting this is due to heating by X-rays emitted from the parent star, and other researchers arguing that the main source of energy comes from the core of the planet. We can test these ideas by directly measuring the X-ray emission of exoplanet host stars, and relating the X-ray irradiation of the planetary atmosphere to its measured and inferred mass loss. We will do this using ESA's XMM-Newton space telescope and NASA's Chandra mission. A further goal of this project is to model the resulting mass loss over the lifetime of the exoplanets in order to assess whether X-ray driven evaporation is sufficient to explain the Neptune desert and the evaporation valley. In particular, we will focus on planetary systems where some planets have been evaporated down to their bare core, while others retain at least some of their atmosphere. These systems provide the most sensitive tests of atmospheric evaporation mechanisms.
Warwick is an internationally recognised centre of research excellence. Our group takes leading roles in many major ground and space-based projects, including the Gravitational-wave Optical Transient Observer (GOTO), Next Generation Transit Survey (NGTS), PLAnetary Transits and Oscillations of stars (PLATO) telescope, Sloan Digital Sky Survey (SDSS), WHT Enhanced Area Velocity Explorer (WEAVE) spectrograph, 4-metre Multi-Object Spectrograph Telescope (4MOST), Dark Energy Spectroscopic Instrument (DESI), and CHaracterising ExOPlanet Satellite (CHEOPS).
The Astronomy & Astrophysics group is part of the Physics Department at Warwick; both the department and the university hold Athena SWAN Silver awards, a national initiative to promote gender equality for all staff and students. The Physics Department is also a Juno Champion, which is an award from the Institute of Physics to recognise our efforts to address the under-representation of women in university physics and to encourage better practice for all. The Astronomy & Astrophysics group also hosts monthly equitea forums to break down barriers faced by all under-represented groups in science.
More details on PhD positions with the Astronomy and Astrophysics group at Warwick are available here.
Start Date: October 2024
Funding Duration: 3.5-4.0 years
Applications due by: 9 January 2024
You must have or expect a First or Upper second class MSci, MPhys or equivalent degree in Physics or a closely related discipline. Holders of BSc honours degrees are eligible but successful BSc applicants typically have substantial additional research experience. International equivalents are detailed here.
For students whose first language is not English, we normally require a score of 6.5 in IELTS or equivalent. If your previous degree was taught in an English-speaking country this requirement may be waived. See this page.
The award is available to home and international applicants.
How To Apply
You must apply through the University’s online application system and follow the instructions. Use course code P-F3P0, and see our Frequently Asked Questions. Make sure to state an interest in the Astronomy and Astrophysics group. Please state ‘Warwick Prize Scholarships’ as the funding option. We encourage applicants to express interest in more than one available PhD project.
The project will provide a full UK-standard annual tax-free stipend of £19,370, rising with inflation, plus allocations for travel and computing.