Atmospheres of alien worlds: preparing for the next generation observations of exoplanet atmospheres

Type of project: observational astrophysics


An extra-solar planet, or exoplanet, is simply a planet that is not in our Solar System. The first detection of an exoplanet around a “Sun-like” star was in 1995, and since then thousands of exoplanets have been detected in our Galaxy. Exoplanets have even been discovered in the so called “habitable-zone”, a region around a star where liquid water can exist on a planet's surface, considered one of the main requirements for life.

The next step in our understanding of exoplanets is to obtain more detailed observations of their atmospheres. This gives us insight into their compositions, temperature structures, formation, and even weather patterns. Such measurements have so far been obtained for hot, giant planets, and using next generation facilities such as the James Webb Space Telescope and the European Extremely Large Telscope, these techniques are expected to be extended to rocky exoplanets, with the long-term goal of searching for signs of life in the atmosphere.


Transmission and emission spectroscopy are the most commonly-used probes of exoplanet atmospheres. By observing wavelength-dependent variations in the transit and eclipse signals as a planet orbits its host star, we can search for absorption and emission features from the planet's atmosphere.

These signals are tiny in comparison to the glare of the host star, and therefore are extremely challenging to disentangle from the stellar light. There are two main methods for doing this. The first, and most common, is to measure extremely precise time-series photometry of the star-planet system, and the resulting light curves can be used to temporally separate light from the star and planet. The second method is to exploit the high velocity (and the resulting doppler shift) of the exoplanet relative to its host star. Using high-resolution spectroscopy we can separate the light from objects moving at different velocities, and therefore recover the exoplanet's spectrum.

These techniques will be capable of detecting the atmospheres of rocky planets using next generation telescopes such as JWST and the E-ELT. This PhD project will explore the use of one or both methods using state-of-the-art statistical techniques and observations from world-leading 8-m class telescopes. It will be well timed to exploit new facilities such as the CRIRES-plus instrument expected to return to ESO's VLT in late 2017/early 2018, and the James Webb Space Telescope (launching 2018).


The student will develop skills that are highly valued in the astrophysics community and in industry. This will include image processing and data reduction, advanced signal processing using Bayesian techniques, and an understanding of atmospheric physics. In particular, the student will be ideally placed to exploit future facilities such as ESO's European-Extremely Large Telescope, and ESA's James Webb Space Telescope.

More info

For more information on this project, please contact Neale Gibson.

public/phds2017/2017_gibson.txt · Last modified: 2016/12/09 22:32 by Stuart Sim

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