Habilitation à Diriger les Recherches - Miguel Montarges

Value of the Information & Strength of the Argument

The presentation provides a comprehensive overview of the state of the art in studying cool evolved stars, with a strong emphasis on observational techniques and recent results. The argumentation is solid, based on peer-reviewed publications and direct comparisons between observations and simulations. The speaker clearly explains the challenges and limitations of current models, such as the difficulty in reproducing the observed small-scale convective cells in simulations, which may be key to understanding mass loss. The value lies in the synthesis of multiple observational methods and the identification of open questions that guide future research.

Scientific Rigor, Source Quality, Title Accuracy

The scientific rigor is high, with references to published papers and ongoing collaborations. The sources cited are primarily the speaker’s own work and that of his collaborators, which is appropriate for a habilitation defense. The title accurately reflects the content, as it is a formal presentation of the candidate’s research and future directions. No public comments were provided, so no analysis of audience reception is included.

The title accurately reflects the content: a habilitation defense presenting the candidate's research and future plans.

8/10

The presentation is based on peer-reviewed research, including interferometric observations and simulations, with clear methodology and references to published work. The speaker is an established researcher in the field.

Markers derived by PSI from the transcript: the creator did not define chapters.

• 00:00Introduction by the jury president, outlining the procedure for the defense.
• 02:00Miguel Montargès begins his presentation, introducing the field of cool evolved stars.
• 10:00Discussion of the HR diagram and the evolution of stars towards the red giant and red supergiant phases.
• 20:00Presentation of interferometric observations of Betelgeuse, including the detection of a bright spot and evidence for rotation.
• 30:00Discussion of the role of convection in triggering mass loss, with observations of Antares showing small-scale convective cells.
• 40:00Introduction of the use of polarimetry to monitor stellar surfaces over time, with examples from CE Tauri and Betelgeuse.
• 50:00Presentation of the occultation of Betelgeuse by asteroid Leona in December 2023, and the ongoing analysis to reconstruct an image.
• 1:00:00Discussion of the potential companion of Betelgeuse and its implications for the star's rotation and evolution.
• 1:10:00Presentation of preliminary work with the GRAVITY instrument to map the velocity field above the photosphere.
• 1:20:00Discussion of using neural networks for image reconstruction from interferometric data, avoiding prior biases.

• Montargès et al. 2016 (PIONIER observations of Betelgeuse) — Cited as the source of the 2016 result on the bright spot on Betelgeuse.
• Montargès et al. 2017 (Antares observations) — Cited as the source of the 2017 observations of Antares with PIONIER.
• Montargès et al. 2018 (Betelgeuse rotation) — Cited as the source of the detection of rotation in Betelgeuse.
• Goldberg et al. 2024 (Betelgeuse companion hypothesis) — Cited as the source of the hypothesis that Betelgeuse's long-term variations are due to a companion.
• Gemini Observatory press release (2025) — Mentioned as the source of the announcement of a possible companion detection.

• Montargès et al. 2016 (PIONIER observations of Betelgeuse) — Supports the claim of a bright spot on Betelgeuse.
• Montargès et al. 2017 (Antares observations) — Supports the claim of small-scale convective cells on Antares.
• Montargès et al. 2018 (Betelgeuse rotation) — Supports the claim of rotation in Betelgeuse.

• Goldberg et al. 2024 (Betelgeuse companion hypothesis) — The speaker notes that the detection of a companion is only at 1.5 sigma, which is weak, and there is debate about whether the observed variation is due to a companion or convective patterns.