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UCSC Model Links JWST Steam Detections to the Interiors of Sub‑Neptune Worlds

The new framework ties atmospheric spectra to extreme water physics to steer upcoming observations.

Overview

  • UC Santa Cruz researchers led by Artem Aguichine published the model on July 24 in The Astrophysical Journal with Natalie Batalha and Jonathan Fortney.
  • The model integrates laboratory data on water under extreme pressure and temperature, including supercritical phases and potential superionic ice.
  • It tracks how sub‑Neptunes evolve over millions to billions of years rather than relying on static interior snapshots.
  • JWST has detected steam in the atmospheres of multiple sub‑Neptunes, with GJ 9827 d cited as an example that is considered inhospitable.
  • Ongoing JWST observations and ESA’s upcoming PLATO mission are expected to test and refine the model’s predictions.