Manon Diez
I am currently pursuing a PhD in Astrophysics at LUPM (Laboratoire Univers et Particules de Montpellier) in France, where I started in October 2024. My research focuses on studying the magnetic activity of cool stars. In parallel, I teach at the University of Montpellier and engage in science outreach. I aim to inspire young people, especially young women, to pursue careers in science, as women are often underrepresented in scientific fields.
EDUCATION 🎓
- PhD Student: Stellar Astrophysics (AS), 10/2024 – present
Université de Montpellier – LUPM (Laboratoire Univers et Particules de Montpellier), Montpellier, France
Funding: Doctoral School (I2S)- Master’s Degree (M2): Astrophysics, Space Sciences and Planetology,
09/2023 – 06/2024
Université Paul Sabatier (Toulouse III), Toulouse, France
Relevant coursework: Compact objects, interstellar medium, and cosmology- Master’s Degree (M1): Universe Sciences and Space Technologies,
09/2022 – 06/2023
Université Paul Sabatier (Toulouse III), Toulouse, France
- Bachelor’s Degree (L3): Physics,
09/2020 – 06/2022
Université Paul Sabatier (Toulouse III), Toulouse, France
Relevant coursework: Nanophysics, astrophysics, and advanced analytical methods in physics- Preparatory Program for French Grandes Écoles (CUPGE): Mathematics and Physics,
09/2016 – 06/2020
Université Paul Sabatier (Toulouse III), Toulouse, France- French Baccalauréat (Scientific – SVT option, Physics-Chemistry specialization)
09/2013 – 06/2016
Lycée Jean Vilar, Villeneuve-lès-Avignon, France
RESEARCH ✨
Artist's view, credit: M. Weiss/CfA
Over the past two decades, our understanding of stellar evolution and planetary systems has advanced tremendously, thanks to space missions like CoRoT, Kepler, and TESS. These missions have made it possible to measure stellar brightness with unprecedented precision, leading to the discovery of thousands of exoplanets and the rise of asteroseismology, a technique that reveals the internal structure of stars. In parallel, stellar spectropolarimetry has emerged as a powerful method to observe stellar magnetic fields, which are still not fully understood but play a key role in shaping stellar activity and the environments of orbiting planets.My research fits into this context and focuses on the magnetism of cool stars. These stars host large-scale magnetic fields that evolve over time,sometimes cyclically, and strongly influence both surface phenomena (spots, flares…) and the surrounding planetary environment.To study this magnetic activity, I follow a multi-technique approach, combining two main types of observations:• On one hand, photometric data from space missions like TESS, which allow us to track changes in brightness and determine stellar rotation periods and spot-related variability;• On the other hand, spectropolarimetric data collected at the Canada-France-Hawaii Telescope (CFHT) using ESPaDOnS and SPIRou, and at the Télescope Bernard Lyot (TBL) with Neo-Narval.These observations allow me to reconstruct the geometry of the surface magnetic field using Zeeman-Doppler Imaging (ZDI), a technique that maps the different components of the field based on polarization signatures in the stellar spectra.Since 2024, I have been involved in a long-term monitoring program targeting a sample of FGKM stars located in the PLATO South and North Field. The PLATO mission, set to launch in late 2026, aims to discover and characterize planetary systems around Sun-like stars, while also providing continuous high-precision photometric data ideal for studying stellar magnetic activity (I am a member of the PLATO Mission Consortium). The stars I focus on were selected for their strong magnetic signatures, well-constrained stellar parameters, and overall relevance to PLATO’s scientific goals.My thesis aims to follow the temporal evolution of their magnetic fields over several years, and to link this information with photometric indicators (rotation, spots, flares…) already observed and those that PLATO will continue to monitor. More broadly, my goal is to improve our understanding of magnetic cycles in cool stars, their diversity, and their impact on the stellar and planetary environments.
OBSERVING EXPERIENCE 🔭
ESPaDOnS (CFHT: Canada-France-Hawaii Telescope) :- coPI of Multi-instrumental magnetic survey of PLATO LOPN1 solar-type targets in semester 2026A- coPI of Multi-instrumental magnetic survey of PLATO LOPS2 solar-type targets in semester 2024B and 2025B
NeoNarval (TBL: Télescope Bernard Lyot) :- coPI Long-term monitoring of the large-scale magnetic field of M dwarfs 2025B, 2026A- coPI BCool monitoring program: magnetic cycles of solar-type stars 2025A, 2025B, 2026A- coPI Multi-technique monitoring of the magnetic cycles of cool stars in the PLATO Northern field in semester 2024B, 2025A, 2026A
SPIRou (CFHT: Canada-France-Hawaii Telescope) :- coPI of Unveiling the magnetic cycles of M dwarfs : reconciling magnetic and activity cycles in semester 2026A- PI of Unveiling the magnetic cycles of M dwarfs with multi-technique monitoring (LOPS2) in semester 2025B- coPI of Unveiling the magnetic cycles of M dwarfs with multi-technique monitoring (LOPS2) in semester 2024B
HARPSpol (ESO: European Southern Observatory) :- coPI of 2nd Mapping the PLATO-HARPSpol Activity & MagnEtism Survey (PHAME-MAP^2) in semester P117- coPI of Mapping the PLATO-HARPSpol Activity & MagnEtism Survey (PHAME-MAP) in semester P116- coPI of The PLATO-HARPSpol Activity & MagnEtism follow-UP (PHAME-UP) in semester P115- coPI of The PLATO-HARPSpol Activity & Magnetism Exploration (PHAME) Survey in semester P114
PUBLICATIONS , POSTERS & TALKS 📄
• PUBLICATIONS :Magnetic geometry of M dwarfs in the southern PLATO field : Diez et al, 2026 — A&AMagnetic cycles of cool stars : Manon Diez, Julien Morin, Pascal Petit. — SF2A 2025 Proceedings• POSTERS :Magnetic cycles of cool stars in the PLATO fields : Manon Diez, Julien Morin, Pascal Petit.→ Canada-France-Hawaii Telescope 14th Users' Meeting, 26 - 28 May 2025, Lac-à-l'Eau-Claire, Canada. (in person)
→ European Astronomical Society Annual Meeting 23 - 27 June 2025, Cork, Ireland. (online)
→ PLATO ESP2025 – Planets throughout the Habitable Zone, 23-25 June 2025, Marseille, France. (in person)Magnetic cycles of cool stars : Manon Diez, Julien Morin, Pascal Petit.→ Semaine de l'Astrophysique Française (SF2A) , 1 - 4 July 2025, Toulouse, France. (in person)• TALKS :→ Magnetism of M dwarfs in the PLATO Field. Presentation at Leiden University to the stellar team, January 2026, Leiden, Netherlands (internal / collaboration visit)→ Magnetic geometry of M dwarfs in the PLATO fields. Presentation at PS2E Team Workshop (Institut de Recherche en Astrophysique et Planétologie, IRAP), January 2026, Germ, France (internal / team seminar)
TEACHING & SCIENCE COMMUNICATION 📐
Teaching- Université de Montpellier – FranceL1 PCSI (Physics, Chemistry, and Engineering Sciences), Semester 2 (2025/2026)
• Laboratory Instructor (Travaux Pratiques)L2 ManipLab, Semester 2 (2024/2026)
• Interviewed by second-year physics students as part of a course project, regarding my Master’s thesisL1 Approches Physiques du Vivant, Semester 1 (2024/2025)
• Tutorial Instructor (Travaux Dirigés)Supervision- Université de Montpellier – France
Semester 2 (2024/2025)
• Co-supervisor of a Master 1 student during a research internship
Project: "Relations between rotation and magnetic fields in M dwarf stars"
Science Communication- Université de Montpellier – France
(April 16, 2026)
• "Journée Sciences pour Toutes et pour Tous"
• A hands-on workshop to observe the Sun and its eruptions using instruments similar to those used by astronomers
• Introduce students to scientific careers and help them explore their future options- Lycée professionnel Léonard de Vinci – Montpellier, France
(April 7–8, 2026)
• Spectroscopy workshop organized as part of the Eclipse 2026 project (University of Montpellier) and IRES (Institut de Recherche pour l’Enseignement des Sciences)
• Introduction to spectroscopy for high school students through hands-on experiments
• Introductory presentation on the applications of spectroscopy in astrophysics- Lycées Narbonne, Sérignan et Montpellier – France
(2024/2026)
• Spectroscopy workshops supervised by IRES ( Institut de Recherche pour l’Enseignement des Sciences)
• Introduction to spectroscopy for high school students through hands-on experiments
• Gave an introductory presentation on the applications of spectroscopy in astrophysics- Lycée Peytavin de Mende – France
(October 9, 2025)
• Panel discussion: "Sciences and Women"
• Shared my doctoral journey and research with high school students
• Engaged in an interactive exchange on breaking stereotypes in scientific careers
• Contributed to workshops encouraging young women to pursue scientific and technical studies
• Event organized as part of the VEST (Vers les Études Scientifiques et Techniques) initiative, led by UM- Lycée Champollion de Lattes – France
(March 7, 2025)
• Invited talk: "Women in Science"
• Shared my academic journey and discussed the invisibilization of women in science
• Led a short interactive workshop on how to develop a scientific mindset