Speaker: Dr. Romain Allart (Université de Montréal in Québec, Canada)

Title: From space precision to ground-based resolved line profiles: Probing exoplanet atmospheric composition and escape

Abstract: Astronomy is in a transformative era. Flagship facilities such as JWST
and the forthcoming ELT are delivering unprecedented constraints in our
characterization of astronomical objects. At the same time, an expanding
suite of ground-based instruments on small telescopes enables
population-scale surveys. Exoplanet science is no exception, with
promising breakthroughs in planetary demographics, atmospheric
characterization, and even the search for Earth-like worlds and
biosignatures. Atmospheric observations provide direct access to a
planet’s composition, dynamics, and mass loss—essential clues to its
origins and evolution. In this talk, I will demonstrate how space-based
precision and resolved line profiles from ground-based spectrographs can
yield a coherent picture of exoplanet atmospheric composition and
escape. JWST now provides transformative constraints on chemistry and
thermal structure, and can even map the extent and morphology of helium
outflows. In parallel, high-resolution spectroscopy from instruments
such as NIRPS detects individual atomic and molecular lines, measures
their Doppler signatures, and constrains species identification,
dynamics, relative abundances, and mass loss rate. By placing
composition and escape of giant planets side by side, I will illustrate
how these complementary instruments reveal the physical processes
shaping atmospheric diversity and how they can constrain their formation
and evolution. I will conclude by showing how this multi-technique
framework and the NIRPS consortium atmospheric program pave the way for
the ELT era, where unprecedented collecting power and spectral
resolution will enable a unified approach to probing atmospheric
chemistry, structure, and escape.

Note: Romain will be visiting AIP for two days (Nov 24th & 25th)

• Date:
  Nov. 24, 2025, 11 a.m. – noon
  
  
• Location:

  AIP; Kirch building, Conference room

  
  
• Contact:
  Jean-Michel Désert
  jmdesert@aip.de