Exoplanet characterisation with interferometry and Exeter's BIFROST instrument
Supervisor: Professor Stefan Kraus
The Exeter instrumentation group is building the BIFROST instrument for ESO’s Very Large Telescope Interferometer (VLTI) to enable imaging & spectroscopy of exoplanets at smaller separations than possible so far. We would like to recruit a highly motivated PhD student to work on a combined instrumentation + observational project that will include testing & commissioning the BIFROST exoplanet spectroscopy mode and using existing interferometric instruments for exoplanet science.
BIFROST is built as a visitor instrument for the Very Large Telescope Interferometer (VLTI) in Chile. The VLTI array consists of four 8.2m telescopes and four 1.8m telescopes that can be combined interferometrically to achieve extreme angular resolution and high contrast. BIFROST is designed to achieve very deep contrasts by combining the star-light suppression from adaptive optics with star-light suppression from interferometry. This technique has recently been used with the GRAVITY instrument to derive spectra of more than a dozen exoplanets, where it demonstrated 100x higher signal-to-noise than possible with conventional imaging techniques. BIFROST will be able to employ this method at shorter wavelengths (down to 1 micrometre), providing access to additional molecular tracers, such as the O2 absorption bands. These tracers are highly complementary to the K-band probed by GRAVITY and provide further constraints for atmospheric retrieval.
You will work with our engineering team on assembling & optimising the BIFROST exoplanet spectroscopy mode and integrate it in our operational software framework. We anticipate installing the instrument at the observatory in the middle of the project, providing opportunities to participate in the commissioning in Chile and to obtain first on-sky data.
In parallel, you will use existing interferometric instruments to device new methods for exoplanet detection and characterisation. The latest interferometric instruments combine extreme astrometric precision with high spectral resolution, which should allow us to separate atmospheric spectral features from Hot Jupiter planets from those of their host star. This could result in the first emission spectra and phase curves for Hot Jupiters. For this work, we will use the MIRC-X instrument at the CHARA array, which currently undergoes various upgrades that will make it the supreme instrument for applying this method.
You will oversee collecting & analysing science data with this new method and interpret the derived orbits and exoplanet spectra. For atmosphere retrieval we will work closely with theory experts at Exeter and abroad.
You will join our diverse, dynamic, and rapidly growing group and work closely with our international partners in the US and Australia. While the project is most suitable for candidates who want to focus on experimental astrophysics, there is some flexibility for adjusting the balance between engineering & science exploitation based on your interests and skills.
For more information contact Professor Stefan Kraus