Institute for Astronomy

Exoplanet PhD projects

Research projects on offer in our Exoplanet research group:

Characterising small exoplanets

Ken Rice

There is still uncertainty about the origin of the radius gap in the exoplanet distribution.  Exoplanets tend to have radii below ~1.5 Earth radii and are rocky, or have radii above ~2 Earth radii and retain a substantial volatile envelope/atmosphere.   This may be indicative of their primordial compositions, but may also be a consequence of the population being sculpted by photo-evaporation; highly-irradiated exoplanets could lose their atmospheres.  Hence, the population of small exoplanets may be the stripped cores of planets that were once larger. It's important to understand this if we are to try and infer the frequency of true Earth-analogues.

One way to address this is to characterise as many small exoplanets as possible.  The Institute for Astronomy is part of the HARPS-N consortium. HARPS-N is a high-accuracy spectrometer on the Telescopio Nazionale Galileo (TNG) telescope on La Palma, Spain.  It is used to follow-up, and characterise, exoplanets first detected by NASA's Kepler mission, the K2 mission (which followed-on from the Kepler mission) and TESS, NASA's recently launched Transiting Exoplanet Survey Satellite.  The project will involve helping to analyse the HARPS-N data and also to develop techniques for analysing the population of small exoplanets so as to infer their origin. It will also involve collaborating within the HARPS-N team, and potentially undertaking some of the telescope observations.