Breaking the stellar activity barrier to determining robust masses of small exoplanets, Astronomy – PhD (Funded)

Project Description:

Recent observations from Kepler, Gaia, TESS and other exoplanet surveys show that planets orbiting other stars are ubiquitous, especially small ones (Neptune- to Earth-size). Confirming these planets and determining their masses via radial-velocity (RV) follow-up is an essential step to identifying the planets most amenable to atmospheric characterisation with JWST. The main obstacle to determining reliable planet masses is the intrinsic magnetic variability of the host stars, which drowns out the planets’ RV signals. The Sun is the only star whose surface we can image directly and at high resolution. It is therefore a unique benchmark to explore the physical phenomena responsible for intrinsic stellar RV variability.

In this PhD Project, the student will use a variety of solar observations to develop models of intrinsic RV variations. They will identify and study velocity flows and small-scale magnetic features seen in spatially resolved observations of the Sun, notably from the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory (SDO/HMI). This will allow them to develop models of intrinsic RV variations, which they will test against observations of the Sun seen as a distant, point-like star with the High-Accuracy Radial-velocity Planet Searcher in the Northern hemisphere (HARPS-N). The student will apply their models to other stars to determine robust planet masses by participating in the HARPS-N RV follow-up of TESS planet candidates. They will have opportunities to work with international collaborators in the United States and Europe.

All qualified applicants are encouraged to apply and will receive consideration without regard to race, religion, colour, national origin, age, sex, sexual orientation, disability status, or any other characteristic protected by applicable law. To learn more about the Astrophysics Group’s commitment and support of equity and inclusion, please see: https://emps.exeter.ac.uk/physics-astronomy/inclusivity/.

For more details on this project, please contact Dr Raphaëlle Haywood ([Email Address Removed])