Special Session SS37  3 July 2024

Interferometric imaging of the inner few AU of circumstellar environments

Aims and scope

Interferometry at optical wavelengths is undergoing a transformation, where visibility modelling is increasingly complemented with model-independent aperture synthesis imaging. This is driven by three factors: First, optimised operational model, where ESO and other observatories collects data in a fashion optimised for imaging. Second, a new generation of interferometric beam combiners at the CHARA array that combine for the first time 6 telescopes spread up to 330 metres apart, increasing both the imaging efficiency and angular resolution of the reconstructed images. And, third, image reconstruction algorithms with new capabilities, such as chromatic, machine-learning supported, or spectral line imaging, are increasingly available also for non-experts.

One area that is particularly impacted by these new capabilities, is the study of circumstellar discs, from the early to the late stages of stellar evolution. Optical interferometric images are now routinely obtained from protoplanetary discs, where they teach us about the disc physics near the dust sublimation rim, and start to reveal also temporal variability on time scales of days. This enables intriguing new insights on planet formation near the dead zone that is associated with the inner dust rim, and allows searching for signposts of planets that might already be present. Mass-loss processes, e.g. in the form of decretion discs, winds or jets, are studied with spectral line imaging around objects over a wide range of evolutionary stages. Intriguing results are also obtained for post-AGB stars, where the images indicate that these discs are also governed by dust sublimation physics and highlight the potential of these discs to facilitate planet formation around evolved stars.

The aim of this session is to hear about the latest results on high-angular resolution imaging of circumstellar environments, to discuss with theory experts the implications on our understanding of disc physics, disc evolution, and planet formation, and to explore similarities between the discs found around stars at different evolutionary stages. Furthermore, we would like to explore new potential observing campaigns that could focus on studying local variations in dust mineralogy with mid-infrared interferometric imaging and constraining the disc kinematics through spectral line imaging. Finally, we intent to give non-experts an overview about available instruments and tools, and upcoming new opportunities.


  • Astrophysical results obtain with long-baseline (VLTI, CHARA, etc) and single-aperture interferometry (JWST, SPHERE, etc), and related theory, modelling and interpretation efforts
  • Observing campaigns on studying circumstellar environments across evolutionary stages, from pre-main-sequence to late stages of stellar evolution
  • Image reconstruction approaches across different communities, e.g. optical interferometry, EHT, ALMA
  • Novel algorithms, e.g. for polychromatic, machine learning-supported, or spectral line imaging

Invited speakers

To be announced soon

Scientific organisers

  • Fabien Baron (Georgia State University, USA)
  • Rebeca Garcia Lopez (University College Dublin, Ireland)
  • Stefan Kraus (University of Exeter, UK; chair)
  • Foteini Lykou (Konkoly Observatory, Hungary)
  • John Monnier (University of Michigan, USA)
  • Claudia Paladini (ESO, Chile)


Stefan Kraus (s.kraus @ exeter.ac.uk)

Updated on Thu Jan 25 13:38:14 CET 2024