University of Exeter funding: Breaking stellar activity barrier

Breaking the stellar activity barrier to determining robust masses of small exoplanets, Astronomy – PhD (Funded) Ref: 3838

About the award

Supervisors

Lead Supervisor

Dr Raphaëlle D. Haywood, Department of Physics and Astronomy, University of Exeter.

Additional Supervisor:

Professor Tim Naylor, Department of Physics and Astronomy, University of Exeter.

 

The University of Exeter’s College of Engineering, Mathematics and Physical Sciences is inviting applications for a fully-funded PhD studentship to commence in September 2020 or as soon as possible thereafter. For eligible students the studentship will cover UK/EU/International tuition fees plus an annual tax-free stipend of at least £15,009 for 3.5 years full-time, or pro rata for part-time study.  The student would be based in the Astrophysics Group in the College of Engineering, Mathematics and Physical Sciences at the Streatham Campus in Exeter, Devon, UK.

Location: Department of Physics and Astronomy, Streatham Campus, Devon, Exeter, UK

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 (rhaywood@cfa.harvard.edu)

Figure 1 The height of a planets atmosphere depends strongly on the planets surface gravity which is set by the planets mass Robust mass determinations are therefore crucial to selecting the planets most amenable to atmospheric characterisation with JWST Artist impression NASAJPLCaltech

Figure 1: The height of a planet’s atmosphere depends strongly on the planet’s surface gravity, which is set by the planet’s mass. Robust mass determinations are therefore crucial to selecting the planets most amenable to atmospheric characterisation with JWST. Artist impression: NASA-JPL/Caltech.

 

Figure 2 The intrinsic magnetic variability of stars is the main obstacle to characterising the small planets orbiting them Artist impression by M Garlick

Figure 2: The intrinsic magnetic variability of stars is the main obstacle to characterising the small planets orbiting them. Artist impression by M. Garlick.

 

Figure 3: The student will use observations of the Sun’s surface to build models of radial-velocity variations for other stars. Shown here: SDO/HMI continuum.

Entry requirements

Applicants for this studentship must have obtained, or be about to obtain, a First or Upper Second Class UK Honours degree, or the equivalent qualifications gained outside the UK, in an appropriate area of science or technology. 

If English is not your first language you will need to have achieved at least 6.0 in IELTS and no less than 6.0 in any section by the start of the project.  Alternative tests may be acceptable (see http://www.exeter.ac.uk/postgraduate/apply/english/).

How to apply

In the application process you will be asked to upload several documents. 

  • CV
  • Letter of application (outlining your academic interests, prior research experience and reasons for wishing to undertake the project).
  • Transcript(s) giving full details of subjects studied and grades/marks obtained (this should be an interim transcript if you are still studying)
  • Two references from referees familiar with your academic work. If your referees prefer, they can email the reference direct to stemm-pgr-admissions@exeter.ac.uk quoting the studentship reference number 3838.
  • If you are not a national of a majority English-speaking country you will need to submit evidence of your proficiency in English.

The closing date for applications is midnight on 27 January 2020.  Interviews will be held on the University of Exeter Streatham Campus (dates to be confirmed).

If you have any general enquiries about the application process please email stemm-pgr-admissions@exeter.ac.uk or phone +44 (0)1392 722730 or +44 (0)1392 725150.  Project-specific queries should be directed to Dr Raphaëlle Haywood (rhaywood@cfa.harvard.edu).

Summary

Application deadline:27th January 2020
Value:£15,009
Duration of award:per year
Contact: STEMM PGR Admissions stemm-pgr-admissions@exeter.ac.uk