Description du sujet de thèse

Title: The Atmospheric Composition of the Ice Giants Uranus and Neptune.

The ice giants Uranus and Neptune have only been visited once by the Voyager 2 spacecraft over 30 years ago. They represent the least-explored category of planet in our Solar System, and furthermore, a large fraction of the confirmed exoplanets is from a similar class of planet, i.e., made out of a hydrogen and helium envelope but richer in heavier elements than Jupiter and Saturn. The exploration of Uranus is now identified by the American National Research Council (NRC) as the top scientific priority for the next decade.

The PhD-thesis work proposed is to understand and model the abundance profiles of the main volatile species in Uranus and Neptune using numerical simulations to (i) prepare the future exploration of these worlds with an orbiting spacecraft, and (ii) reinforce the scientific expertise of our team in characterizing the outer planets. The abundance distributions of key chemical species across the planet provide information about the planet's deep chemical inventory, therefore bringing constraints on the planet formation scenario. Such model predictions are necessary to interpret in-situ measurements performed by entry probes (e.g., Mousis et al., 2020). Additionally, these distributions contain the signature of the planet transport processes, and are important to understand how the planet interact with its local environment.

The numerical simulation tool to be used and to be further-expanded is a 2D-photochemical model developed to model Jupiter and Saturn (Hue et al., 2015, 2018), and already adapted to model Uranus and Neptune. Such tool will allow:
• predicting the abundances of key species as a function of altitude and latitude in order to infer the planet's deep elemental abundances (e.g., Mousis et al., 2018; Cavalié et al., 2020),
• modeling the seasonal stratospheric composition of the ice giants, in order to provide constraints on the dynamical processes occurring throughout the atmosphere, when compared with available ground- and space-based observations (e.g., Moses et al. 2018).
• deriving key constraints on the formation scenarios of the ice giants to compare with our current knowledge of the outer solar system composition.

Bibliography:
• Cavalié, T, et al., The Deep Composition of Uranus and Neptune from In Situ Exploration and Thermochemical Modeling., SSR 216(4):58, May 2020
• Hue, V., et al. 2D photochemical modeling of Saturn's stratosphere. Part I: Seasonal variation of atmospheric composition without meridional transport., Icarus 257:163–184, September 2015.
• Hue, V., et al. Photochemistry, mixing and transport in Jupiter's stratosphere constrained by Cassini., Icarus 307:106–123, June 2018.
• Moses, J. I., et al. Seasonal stratospheric photochemistry on Uranus and Neptune., Icarus 307:124–145, June 2018.
• Mousis, O., et al., Scientific rationale for Uranus and Neptune in situ explorations., SSR 155:12–40, June 2018.

Contexte de travail

We offer:
• An active and inspiring research environment, a vibrant PhD community and many ways to connect with peers from home and abroad on a social and professional level.
• A broad range of interdisciplinary training possibilities and school activities, such as leadership skill trainings, workshops, seminars, mobility and summer schools.

Contraintes et risques

This job includes several national and international trips (Europe, USA, Japan) to attend workshops and conferences.

Informations complémentaires

Application documents:
• Cover Letter (2 pages maximum)
• Academic CV, including references
• List of publications, teaching evaluations (if available)
• Degree certificate(s) with academic transcript
Please send the whole file to: vincent.hue@lam.fr

Job Description:
• Participation in research and teaching
• Participation in publications / academic articles / presentations
• Potential supervision of students
• Involvement in the organization of meetings, conferences, symposiums
• Involvement in the department administration as well as in teaching and research administration

Potential candidates must have the following attributes:
• Master's Degree or equivalent in Astronomy/Astrophysics/Fundamental Physics or Computer Science
• A very strong background in programming with Fortran
• A good background in programming with Python, IDL or similar programming languages
• Able to effectively write and speak English

The following experience will be highly regarded:
• Involvement in public outreach and science community engagement activities
• Presentation experience at international conferences
• Ability to speak French
• Experience with data processing