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Commissioning, characterising and applying HARPS3 to search for low-mass, long-period exoplanets
Lead Supervisor: Didier Queloz, Cavendish Astrophysics
Co-supervisor: Clark Baker, Cavendish Astrophysics

Brief summary
The measurement of the radial-velocity signal of an Earth-twin is by no means easy. The semi-amplitude of the radial-velocity signal induced by Earth orbiting around our Sun is ~9cm/s (~speed of a baby crawling). This signal is then buried in noise from the stellar-activity of the star; on the order of several m/s. As such, it is of utmost importance to have a stable and precise instrument (HARPS3) that is accurately characterised.

The student’s goal is, as a part of a team, understand the instrument and measurement processes sufficiently that the instrument can be characterised at the ~cm/s level.

Importance of the area of research concerned
An Earth-twin exoplanet is yet to be discovered and is of great scientific interest. A catalogue of discovered Earth-twins will not only allow us to better understand our own planet (and place in the universe) but also provide a major stepping stone in the search for life in the Universe.

The cutting edge, third generation of the highly successful High-Accuracy Radial-velocity Planet Searcher: HARPS3 is currently being assembled at Cambridge and will be commissioned on the Isaac Newton Telescope in La Palma in late 2024. 

HARPS3 will engage in a, world-leading, intensive study for Earth-like planets orbiting around Sun-like stars, measuring the radial-velocity of ~30 Sun-like stars ‘nightly’ over the period of a decade in order to be sensitive to the signal of an Earth-like planet orbiting around these stars.

What the student will actually do?
HARPS3 will be assembled and commissioned in La Palma at the end of 2024, coinciding with the start of the student’s PhD. This will provide the student an unrivalled opportunity to learn about highly-stabilised, high-resolution spectrographs by being involved in the commissioning team of HARPS3.

During the commissioning, the student will contribute to the assembly of HARPS3, followed by verification activities; where the instrument and its subsystems are tested to ensure they are performing correctly.

With the instrument assembled and operating, the student will engage in a project to characterise the radial-velocity measurement and instrument-performances of HARPS3, including looking at correlation between a suite of environmental-sensors and the measurements of HARPS3. A key step in ensuring our instrument is ready to search for Earth-twins.

With the understanding gained by these works, the student will look to apply for time on HARPS3 to engage in the radial-velocity follow-up of transiting exoplanets.

Thompson, Samantha J., Didier Queloz, Isabelle Baraffe, Martyn Brake, Andrey Dolgopolov, Martin Fisher, Michel Fleury, et al. ‘HARPS3 for a Roboticized Isaac Newton Telescope’. In Proc. SPIE, 9908:99086F. International Society for Optics and Photonics, 2016.

Requirements as to the educational background of candidates that would be suitable for the project
This project will require a degree in Physics or related discipline. It would suit a student with a background in optics, instrumentation and/or data analysis; with skills in Python.

You can find out about applying for this project on the Leverhulme Centre for Life in the Universe widening participation PhD Studentships page.