The Hebrew University of Jerusalem

We invite applications for a postdoctoral research fellow to work on exoplanetary atmospheres, with a particular emphasis on hydrogen-rich and other low mean molecular-weight (low-μ) atmospheres. We welcome candidates interested in theoretical, numerical, and observational aspects of atmospheres that differ substantially from modern Earth, e.g., sub-Neptunes or Gas Giants.

Potential research topics include, but are not limited to:

• The climate and convective regimes of hydrogen-dominated atmospheres and other low-μ compositions.
• Moist and runaway greenhouse processes in hydrogen-rich environments like Hycean worlds.
• Coupling between convection and large-scale circulation in low-μ atmospheres.
• Radiative transfer, spectra, and observational diagnostics for hydrogen-rich exoplanets.

The position will involve running and analyzing numerical experiments using a suite of models, including 1-D atmospheric column models, 3-D global climate models (GCMs), and convection-resolving models.

Preferred Qualifications:

• A PhD in planetary science, astrophysics, atmospheric science, climate science, earth science, or a closely related discipline.
• Experience with one or more of the following: GCMs, cloud-resolving models, 1-D column models, radiative transfer modeling for exoplanets.
• Demonstrated familiarity with atmospheric physics relevant to hydrogen-rich or non-Earth-like compositions (e.g., different thermodynamics, opacities, condensation physics).
• Strong quantitative skills and experience analyzing large datasets using Python, Matlab, Julia, R, or similar tools.
• Good programming ability and experience with high-performance computing.

The postdoctoral fellow will be based in the research groups of Prof. Guy Dagan and Dr. Nathan Steiger at the Hebrew University of Jerusalem. The initial start date is flexible, beginning anytime from January 2026 onward. The appointment is for one year with the possibility of renewal for additional years depending on performance. We support and encourage flexible working hours and remote work.

We value diversity of background and thought; applicants from underrepresented groups, non-traditional career paths, and those with a wide range of experiences are encouraged to apply.

To apply, please email Nathan Steiger (nathan.steiger@mail.huji.ac.il) a single PDF containing: a cover letter describing your research interests and relevant experience, a CV, and the names and contact details of at least three references. Review of applications will begin on December 31, 2025 and continue until the position is filled. For questions about the position, contact Nathan Steiger (nathan.steiger@mail.huji.ac.il) or Guy Dagan (guy.dagan@mail.huji.ac.il).

Further information about our research groups:
https://njsteiger.github.io
https://guydagan.huji.ac.il

The Hebrew University of Jerusalem is Israel’s leading research university. The Institute of Earth Sciences is located on the Safra Campus in central Jerusalem, a city with a pleasant Mediterranean climate, extensive historical sites, and a thriving scientific and technology community.