Institute for Astronomy

Exoplanet PhD projects

Research projects on offer in our Exoplanet research group:

Orbital Architectures of Planet-Hosting Multiple-Star Systems

Trent Dupuy

Video: Orbital Architectures of Planet-Hosting Multiple-Star Systems
Orbital Architectures of Planet-Hosting Multiple-Star Systems

The vast majority of small exoplanets orbiting close to single stars, such as those found by transit and RV surveys, offer few clues as to their origins. A notable exception has been multi-planet systems, because of the dynamical information available. Likewise, planets orbiting stars with additional stellar bodies provide special tests of planet formation theory. This project will explore the influence that stellar companions have on planetary systems by examining the orbits of multiple-star systems from the Kepler exoplanet survey. This work will focus on the ultra-precise astrometry measured by the Gaia spacecraft to measure the orbital motion of wide binaries. Analysis of a large sample of binaries will answer questions like whether certain orbital eccentricities or perhaps alignment between stellar and planetary planes provide more favorable environments for planet formation and survival. In addition to the data from space missions, there will be opportunities to participate in ground-based observing to monitor the orbits of tighter binaries with laser guide star adaptive optics using the Keck Telescope in Hawaii. (Observing will most likely be done remotely from Edinburgh.)

This project can be funded either as a normal UK PhD, or through the new Edinburgh-Leiden joint studentship scheme, where the student would spend 1-2 years of their PhD in Leiden, working under the joint supervision of Matt Kenworthy.

Detecting and Characterising Giant Planets with Direct Imaging

Beth Biller

Video: Detecting and Characterising Giant Planets with Direct Imaging
Detecting and Characterising Giant Planets with Direct Imaging

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>5μm.  This project will leverage the transformative capabilities of ERIS, a new mid-IR imager for the VLT, and JWST.  There are three potential directions to be explored with this project:

  1. The full spectral energy distributions of giant exoplanet atmospheres: Professor Biller is co-PI of the JWST Early Release Science programme 1386, which will, for the first time, directly image exoplanets at λ = 5 – 15 μm.  The ERS data is expected 6 months after launch in October 2021.
  2. Weather maps of exoplanets: Variability monitoring probes the 3-d time-resolved structure of exoplanet atmospheres. JWST and ERIS will enable variability searches at λ >2 μm and for exoplanet companions >0.5" from their stars.
  3. Confirmation of exoplanet candidates with novel spectral detection techniques: multi-band imaging using carefully selected narrow-band filters can immediately confirm exoplanet candidates.  We plan a high-contrast survey with ERIS' gvAPP coronagraph, to search star-forming regions for young exoplanet companions.

 

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.