Exoplanet PhD projects

Research projects on offer in our Exoplanet research group.

Detecting and Characterising Giant Planets with JWST Direct Imaging

Prof Beth Biller

Direct imaging will be a vital method to characterize a wide range of exoplanets in the next decades, and may eventually determine whether “habitable zone” planets are truly habitable. Deep characterization of giant exoplanet atmospheres now is necessary to develop the expertise for similar studies of Earth-like exoplanets in future decades. The James Webb Space Telescope (JWST) represents a paradigm shift for this field, enabling imaging and spectroscopy of these objects (Teff = 500-2000 K) for the first time ever at λ > 5 μm.  This project will leverage the transformative capabilities of JWST to directly image and characterize the atmospheres of lower mass, cooler exoplanets (<1 MJup, <500 K).  In Cycles 2 and 3, the JWST sub-Jupiters survey (GO 4050, GO 5835, SURVEY 6005) has collected imaging data for 170 nearby, young stars, to search for sub-Jupiter mass companions down to Saturn masses. The student recruited for this project will join the JWST sub-Jupiters survey team, and will focus on applying machine-learning methods to improve achieved contrast and hence, minimum detectable exoplanet mass, from this survey data.

Machine Learning Laser Guide Star Adaptive Optics Imaging

Dr Trent Dupuy

Traditional direct imaging techniques for exoplanet detection rely on the host star to serve as the guide star for the adaptive optics (AO) system. Brown dwarfs are typically much too faint for such techniques, so an artificial, laser guide star (LGS) must be used instead. This project will analyse thousands of Keck LGS AO images of the coldest objects in the sky, taken over the past two decades. While these data have proven useful in the past for binary surveys and orbit monitoring, their full potential has never been unlocked, due to the time-variable and irregular correction delivered by LGS AO. Robustly quantifiable detection limits on even fainter objects orbiting these faint brown dwarfs will require the development of machine learning techniques to fully leverage the information content of the images. Keck LGS AO can potentially reach much closer separations than even JWST, thanks to its 10-m diameter mirror, as compared to 6.5-m for JWST. Therefore, this project has the potential to out-perform all other existing surveys for close companions to brown dwarfs.

Exploring the demographics of brown dwarfs and giant exoplanets

Dr Clémence Fontanive, Dr Trent Dupuy, Prof Beth Biller

The direct imaging method has uncovered a remarkable diversity of substellar objects, from gas giant exoplanets around stars to rogue planetary-mass brown dwarfs. These discoveries have transformed, but also challenged, our understanding of the formation and evolutionary processes that shape both stellar populations and planetary systems. This PhD project focuses on developing a statistical framework for population-level studies of substellar objects. The student will work with archival and new survey observations from facilities such as HST, JWST, and VLT to investigate the demographics of giant exoplanets and brown dwarfs across a wide range of system configurations — including free-floating objects, substellar binaries, and wide-orbit companions to stars. The methodology centres on direct imaging, with scope to incorporate complementary techniques such as astrometry and radial velocity depending on the candidate’s interests. Core goals include measuring occurrence rates and probing environmental dependencies in physical properties, atmospheric characteristics, and orbital architectures, to uncover the diversity and origins of extra-solar worlds

Modelling atmospheric chemistry and dynamics on a Venus-like exoplanet

Prof Paul Palmer, Prof Ken Rice, and Dr Alistair Glasse

There are striking similarities between Earth and Venus. They are nearly the same size and density, yet one evolved to support life and the other evolved into an inhospitable planet that is the hottest in our Solar System. There are many fundamental gaps in our understanding of Venus, but this PhD will focus on the evolution of its atmospheric composition. We will use recent discoveries of Venus-like exoplanets, e.g., Gliese 12 b discovered in 2024, to provide important insights into how Venus evolved into its current form. 

In this project, we will use a planetary climate model to describe plausible environmental conditions on a Venus-like exoplanet, nominally Gliese 12 b. Gliese 12 b is similar in size to Venus and is orbiting an M-type star with a period of 12.8 days. Despite the proximity of the planet to its host star, it receives a similar amount of radiation to Venus. Our initial chemical network will be informed by established Venusian atmospheric chemistry networks that include gas-phase and heterogenous chemistry, accounting for refinements as they become available. We will use a range of initial environmental conditions, informed by literature, to explore how they influence the evolution of atmospheric chemistry and dynamics, including the theoretical existence and sustainability of atmospheric habitable zones. 

To understand how the atmosphere of a Venus-like exoplanet would be observed, we will use an instrument simulator for the Mid-infrared ELT Imager and Spectrograph (METIS), one of the first instruments planned for the Extremely Large Telescope (ELT) at the European Southern Observatory. 

The UK Astronomy Technology Centre in Edinburgh is leading the design and build of the METIS LM-band spectrometer (LMS), which covers the wavelength range 2.7-5.5 microns. The LMS will combine the ELT’s unprecedented spatial resolution with very high spectral resolution and high contrast coronagraphic imaging, to open up a new parameter space ideal for the investigation of the atmospheric properties of exoplanets.  The coronagraph will provide contrasts of ~100,000 at angular separations six times smaller than JWST, while the high dispersion will enhance molecular species detection using the systematic spectral shift due to the planet’s orbital velocity. 

Requirements

The successful candidate will have a degree in the physical sciences and most likely physics, chemistry, or applied mathematics. This is a computational and data analysis project: no prior computing experience is necessary, but some knowledge of coding would be useful (e.g., Python, FORTRAN).

References

Gliese 12 b: 

https://academic.oup.com/mnras/article/531/1/1276/7679807

https://iopscience.iop.org/article/10.3847/2041-8213/ad3642

Venus photochemistry and clouds: 

https://www.sciencedirect.com/science/article/pii/S0019103523000246?via%3Dihub

METIS: 

https://arxiv.org/pdf/2103.11208  

Modelling stellar flares and their influence on biosignatures in the atmospheres of habitable worlds

Dr Sarah Rugheimer

For the first time in history, humanity has the technological capability to probe the atmospheres of terrestrial exoplanets and search for biosignatures. The research will focus on disentangling true biosignatures from false positives by studying the interplay between atmospheric escape, stellar activity, and photochemistry. In particular, the project will explore how flares from active M dwarf stars, such as those hosting the TRAPPIST and Proxima Centauri systems, alter planetary atmospheres and impact the likelihood of detecting life. By coupling atmospheric escape processes with chemical and dynamical models, this work aims to build new frameworks for interpreting upcoming exoplanet observations and assessing planetary habitability.

With the arrival of transformative observatories such as JWST, ELT, and ARIEL, we are entering an unprecedented era for exoplanet characterization. This PhD project will use advanced atmospheric modelling to contextualize early data on terrestrial worlds, while also helping to define observing strategies for horizon concepts such as the Large Interferometer for Exoplanets (LIFE) and NASA’s Habitable Worlds Observatory (HWO). By advancing theoretical forward models and incorporating the time-dependent influence of stellar flares, the project will provide essential tools to distinguish genuine biosignatures from abiotic imposters. The ultimate goal is to help establish whether the first atmospheric detections of terrestrial exoplanets point to a second origin of life in the Universe.

Background of a successful applicant: A strong coding background is required. A student will need to be able to modify and update large complex codes of tens of thousands of lines written in Fortran and Python. A demonstrated skill in independence in technical writing is also useful, but not required. 

Under the Astrobiology projects, see also:

• Investigating the desiccation limits to life on Earth and elsewhere - Prof Charles Cockell

Under the Astronomical Instrumentation projects, see also:

• High Contrast Wavefront Control for Ground and Space-Based Telescopes - Dr Charlotte Bond (UK ATC), Dr Trent Dupuy, and Prof Beth Biller