LIRA

The French DraMS-GC subsystem for the Dragonfly mission has successfully passed the mechanical and thermal qualification phase

Raphael PERALTA — 2026-04-03T11:26:35Z

NASA's Dragonfly mission, dedicated to exploring Titan and studying its potentially prebiotic chemistry, has reached a crucial milestone with the qualification of the flight models for the DraMS-GC instrument. Developed under the leadership of LATMOS, with a major contribution from LIRA, this state-of-the-art instrument will enable in situ analysis of the molecular composition of Titan's surface by 2034. By combining gas chromatography and mass spectrometry, DraMS-GC will play a key role in identifying complex organic compounds and characterising the conditions necessary for habitability in unique environments such as those of icy moons. This achievement is the result of several years of work by LIRA's engineering and research teams, who were involved in the design, manufacture and qualification of the instrument.

DragonFly: a dragonfly on Titan searching for potential clues to prebiotic chemistry

Figure 1: Exploded view of the Dragonfly drone, showing in red the location of the DraMS instrument, a gas chromatograph coupled with a mass spectrometer designed to study Titan's complex chemistry.

Credit: NASA/Johns Hopkins APL

The Dragonfly mission is a NASA mission led by the Applied Physics Laboratory (APL) at Johns Hopkins University. Scheduled for launch in 2028 and arrival in 2034, its aim is to study the atmosphere and surface of Titan, Saturn's largest moon.

Following on from the European Huygens lander, which arrived over twenty years ago, Dragonfly is a rotorcraft capable of flying a few hundred metres above Titan's surface. It will thus be able to explore different geological environments, hundreds of kilometres apart, in search of evidence of prebiotic chemistry – that is, chemical interactions between complex organic compounds that may have existed before the emergence of life as we know it on Earth.

During its mission, scheduled to last more than three years, Dragonfly will explore the region from the equatorial dunes to the Selk impact crater, which is around 70 km wide, where liquid water, mixed with organic matter, has likely persisted for hundreds, or even thousands, of years. At these exceptional sites, it will collect surface material samples to analyse their molecular composition using the DraMS (Dragonfly Mass Spectrometer and Gas Chromatograph) instrument. The samples will be vaporised and then analysed in detail using a gas chromatograph coupled with a mass spectrometer (see Figure 1). These analyses will enable the study of the evolution of the building blocks of prebiotic chemistry across the different types of terrain encountered (ranging from arid dunes to the Selk impact crater, which may have once contained liquid water).

The French contribution at the heart of Dragonfly's instrumentation

Figure 2: The two subsystems of the DraMS-GC instrument, developed in France with the involvement of LIRA, currently undergoing qualification in mechanical and thermal environments.

On the left, the He Supply system mounted on a vibration test bench for mechanical testing. On the right, the Integrated-GC system housed in a chamber simulating the pressure and temperature conditions on Titan.

Credit: LATMOS

France is involved in the Dragonfly mission through the development of DraMS-GC, the gas chromatography component of the DraMS instrument. Funded by CNES, this instrument is being developed under the leadership of LATMOS (Laboratory of Atmospheric Sciences and Space Observations), in collaboration with LIRA. More specifically, LIRA was responsible for the mechanical and thermal design of the instrument, the manufacture of the various models, including the flight models intended for Titan, as well as the conduct of the qualification campaigns.

DraMS-GC consists of two subsystems. The first, called He Supply (see Figure 2.a), transports the vaporised samples in gaseous form using helium, which acts as a neutral carrier gas. These samples are then conveyed to the second subsystem, the Integrated-GC (see Figure 2.b), which is responsible for trapping and then separating the various constituents of the gaseous mixtures obtained after pyrolysis or treatment with a chemical agent. The latter facilitates, in particular, the detection of complex molecules, including chiral molecules, within the chromatography columns. The compounds thus separated can then be analysed by the mass spectrometer, the second part of the DraMS instrument, in order to determine their composition.

Validation in mechanical and thermal environments for DraMS-GC

Figure 3: The LIRA team, involved in the mechanical and thermal design, manufacture and integration of the DraMS-GC instrument.

Credit: LIRA

In collaboration with teams from LATMOS and the Integration and Test Platform at the Versailles Saint-Quentin-en-Yvelines Observatory, and under the supervision of LIRA, the DraMS-GC flight models have just been successfully qualified in mechanical and thermal environments.

This qualification is based on a series of mechanical and thermal tests designed to replicate the conditions to which the instrument will be subjected during its mission. The mechanical tests are carried out using vibration test rigs (see Figure 2.a), in order to simulate the vibrations associated with rocket launch and the operation of Dragonfly. The thermal tests, meanwhile, are conducted in chambers capable of reproducing the pressure and temperature conditions prevailing on Titan, which the instrument will have to withstand during its exploration (see Figure 2.b).

Now that this key milestone has been reached, the next phase involves delivering DraMS-GC to NASA's Goddard Space Flight Center (GSFC). The He Supply subsystem has already been shipped to the United States. As for the Integrated-GC, having just completed a bakeout phase (a degassing process lasting around ten days at +60 °C) at LIRA, following its scientific testing campaign at LATMOS, it will be delivered to GSFC in April for environmental functional testing.

These developments crown six years of work by LIRA's technical and engineering teams (see Figure 3), notably the GEFL (LIRA's Research and Manufacturing Group), responsible for the design, manufacture and qualification of the instrument, SPIN (Project and Instrumentation Support), responsible for project support and quality activities, and MESPAL (Test Facilities, Clean Rooms, AIT/AIV), involved in bake-out operations as well as IT and administrative support. These are the result of a long and rigorous process, punctuated by numerous reviews validating the various stages of a space instrumentation project.

Contacts:

Napoleon Nguyen Tuong, LIRA Technical Manager at DraMS-GC ;
Sandrine Vinatier, LIRA Scientific Lead at DraMS-GC.

Delivery of the MICADO adaptive optics bench

Raphael PERALTA — 2026-03-21T16:17:39Z

An impressive lifting operation took place on 16 March at the Meudon site, marking a major milestone in the development of MICADO, the future flagship instrument of the European Extremely Large Telescope (ELT) in Chile. Combining a special transport operation, precision crane work and the mobilisation of numerous teams, this extraordinary delivery illustrates the scale of the technical challenges facing the astronomy of the future.

An extraordinary operation in Meudon

Figure 1: Delivery by crane on 16 March 2026 of the crate, weighing over a tonne, containing the adaptive optics bench for MICADO, the first-light instrument for the ESO's (European Southern Observatory) Extremely Large Telescope (ELT).

Credit: Raphaël de Assis Peralta (LIRA - Observatoire de Paris-PSL)

On 16 March, the Communs site in Meudon was the scene of a spectacular logistical operation: the crane-assisted delivery of the MICADO adaptive optics bench (see Figure 1). Having arrived on site that morning via a special heavy-goods convoy, the crate containing the equipment — weighing 1.3 tonnes on its own — required meticulous planning.

Manufactured in Germany by CarbonVision, this carbon-fibre bench, designed by LIRA, boasts impressive dimensions: over 2.5 metres in diameter, nearly 1.5 metres in height and weighing around half a tonne. Added to this is a specialised 750 kg pallet truck. The entire assembly, packed in a custom-made crate measuring 3.8 × 3.3 × 2.5 metres and weighing a total of around 3 tonnes, meets the requirements for future transport to Chile.

On the day, a 60-tonne mobile crane was brought in to lift the container off the lorry, swing it over the Communs buildings, and set it down in the inner courtyard, opposite the UNIDIA reception hall. The operation continued with an even more delicate manoeuvre: using the crane to turn the carriage and bench upright, placing them on rolling supports, moving them to the overhead crane in the integration hall, and finally turning the carriage and bench back to a horizontal position.

This manoeuvre involved numerous teams: scientists and engineers from LIRA and UNIDIA, logistics and safety services from the Paris Observatory-PSL and LIRA, as well as the communications teams from LIRA and the CNRS. ULISSE, the CNRS unit specialising in the transport of scientific instruments, provided its expertise for the design of the crate and the organisation of the transport. GT Logistics handled the transport and coordinated the handling operations, whilst MS Levage carried out the handling itself.

MICADO, the ELT's first-light instrument

Figure 2: The ELT and the MICADO instrument.

On the left, the ELT under construction in Chile. On the right, a view of the MICADO instrument on the ELT's Nasmyth platform.

Credit: ESO/consortium MICADO

MICADO (Multi-Adaptive Optics Imaging Camera for Deep Observations) is the first-light imager for the Extremely Large Telescope (ELT), a giant 39-metre telescope (see Figure 2) currently under construction in Chile by the European Southern Observatory (ESO). Its first scientific observations are scheduled for around 2030.

This state-of-the-art instrument will enable major advances in astrophysics, particularly in the study of the formation of the first galaxies and the detection of exoplanets in the habitable zone of their host stars. To achieve these objectives, MICADO will operate in the near-infrared (0.8–2.4 μm), like the JWST, whilst offering angular resolution up to six times higher at equivalent sensitivity.

To reach the diffraction limit of the ELT and thus fully exploit the potential of the 39-metre telescope, MICADO relies on adaptive optics systems capable of correcting atmospheric disturbances in real time. Among these, the SCAO (Single Conjugate Adaptive Optics) mode, which uses a natural star to analyse atmospheric turbulence, is being developed within the MICADO consortium under the leadership of LIRA, with contributions from several French laboratories.

The MICADO SCAO bench

Figure 3: The MICADO SCAO module's carbon-fibre opto-mechanical bench, installed in the integration room at Les Communs de Meudon, where it will be integrated and tested until 2028.

Credit: MICADO Consortium

The bench delivered to Meudon is designed to support the various opto-mechanical subsystems of MICADO's SCAO: its wavefront analyser, its calibration system and its dichroic mirror, which reflects visible light from the telescope towards the SCAO's wavefront analyser whilst transmitting infrared light to the scientific camera.

This bench is a complex assembly of epoxy carbon fibre and aluminium honeycomb. It comprises baffles, a segmented cover, support and stiffening columns, and, most importantly, a multitude of inserts. These are metal parts passing through the bench and serving as fixing points for the various opto-mechanical elements of the SCAO.

The bench's specifications presented a real challenge for CarbonVision: the absolute positioning of the optical elements is guaranteed to within a tenth of a millimetre on the bench's surface, and the flatness of the bench's top and bottom surfaces is 5 hundredths of a millimetre per metre!

The bench will remain in Meudon until 2028, where the teams will carry out the system's integration and testing phases, before it is transferred to Germany for the final assembly of the MICADO instrument. This key stage forms part of a major French contribution to the project, particularly in the areas of adaptive optics and high-contrast imaging dedicated to the study of exoplanets.

Several laboratories are involved in these developments — LIRA, UNIDIA, LMA, LCF, Theta — alongside the technical division and the EFISOFT unit of INSU, demonstrating France's expertise in cutting-edge scientific instrumentation.

Supported by funding from the Île-de-France Region's DIM ORIGINES, the F-CELT project under the Investments for the Future Programme, the CNRS/INSU, the Paris Observatory – PSL and the European Southern Observatory (ESO), the MICADO project is at the heart of the major research infrastructures that will shape 21st-century astronomy.

Contact : Yann Clénet (yann.clenet@obspm.fr)

For more information:

Thesis defence by Garance BRAS on Thursday 19 March 2026

Raphael PERALTA — 2026-03-17T17:00:08Z

Garance BRAS's thesis defence will take place on Thursday 19 March 2026 at 2 pm in the Evry Schatzman lecture theatre in Meudon. The thesis will be defended in English, with visual aids in English.

It can be followed live on the LIRA YouTube channel

Title of the thesis

Optimised modelling of pulsating stars for the extragalactic distance scale.

Composition of the jury

Yveline Lebreton (LIRA): Chair;
Katrien Kolenberg (KU Leuven): rapporteur;
Denis Mourard (OCA): rapporteur
Louise Breuval (STScI): examiner;
Grzegroz Pietrzyński (CAMK): examiner;
Antoine Mérand (ESO): invited member;
Nicolas Nardetto (OCA): invited member;
Pierre Kervella (LIRA): supervisor

Abstract

Pulsating variable stars, particularly Cepheids and RR Lyrae stars, are powerful tools for determining distances. Period-luminosity relations allow us to deduce their intrinsic luminosity, which is then compared to their apparent magnitude. In addition, the parallax-of-pulsation method uses the trigonometric relationship between the radius variation and the angular diameter variation to determine the distance. This latter technique involves a parameter, the projection factor, which converts the observed radial velocity to the photospheric pulsation velocity. This parameter, which is entirely degenerate with distance, shows significant statistical variations, preventing us from using parallax-of-pulsation on a large scale. A more detailed understanding of pulsation is required in order to determine the origin of this dispersion.
In this thesis, I first study the projection factor of RR Lyrae stars, using the SPIPS code and new radial velocity measurements, in order to compare it with Cepheids. I show that the value and dispersion of the projection factor for RR Lyrae stars are quite similar to what has been observed for Cepheids and that the different methods of measuring radial velocities have little impact on this dispersion, provided that homogeneous data are considered. I also present my work on the variation of the centre-to-limb darkening coefficient during pulsation, a key ingredient of the projection factor, using interferometric observations of the Cepheid η Aql.
Secondly, I develop generic light curves for Cepheids using SPIPS multi-band models. These templates make it possible to predict the shape of the light curve for a given pulsation period in a large variety of photometric bands. They are particularly effective for modelling light curves based on rare or imprecise observations, as is the case with extragalactic Cepheids.

The great adventure of interferometry

Raphael PERALTA — 2026-03-01T19:06:57Z

Born in the 19th century from the intuition of a French physicist, interferometry has become one of the most powerful techniques in modern astronomy. From the initial theoretical idea to giant observatories such as the VLT, we look back on an extraordinary scientific and human adventure, recounted in a video by Eitan Péchevis, an optical research engineer at LIRA.

How did astronomers manage to probe the Universe with ever greater precision, to the point of building the largest telescopes in the world? To answer this question, we must go back to the mid-19th century. At that time, a French physicist, Hippolyte Fizeau, laid the foundations for a technique that would revolutionise astronomical observation: interferometry. The principle consists of combining the light collected by several instruments in order to increase their resolving power, as if they formed a single, immense telescope. It was a bold idea for its time, requiring more than a century of theoretical and technological development to reach full maturity.

This scientific epic — in which the Paris Observatory played a major role — is made up of groundbreaking insights, technical innovations and international collaborations. From the first idea sketched on paper to modern instruments capable of revealing the most subtle details of stars and galaxies, Eitan Péchevis, an optical research engineer at LIRA, explains in a video how scientific perseverance transformed a visionary intuition into a major tool of contemporary astronomy.

Credit: Labeyrie Sphere, located on the Meudon campus of the Paris Observatory.

Built in the early 1970s, this small stone prototype enabled Antoine Labeyrie to demonstrate the usefulness of optical interferometry in astronomy. Thanks to his work, Labeyrie paved the way for a new observation technique, now used by the world's largest telescope, the VLT, in the Atacama Desert.

Credit: Eitan Péchevis

LIRA mobilised to promote scientific careers among young people

Raphael PERALTA — 2026-02-23T11:54:21Z

To mark International Day of Women and Girls in Science, celebrated on 11 February, members of LIRA rallied together through several initiatives designed to encourage young girls to consider careers in science. Here is a look back at these initiatives.

A scientific immersion for secondary school girls at the Paris Observatory

In spring 2025, Franck Razafimaharo, a physics and computer science teacher at Saint-Exupéry High School in Bourg-Saint-Maurice (Savoie), contacted the Paris Observatory to organise a school trip mainly for the girls in his classes. His goal was to show that science — and digital science in particular — is not just for boys.

For a week, 33 female and 3 male students in their final two years of secondary school visited several laboratories in the Paris region: the Curie Institute, the Institute of Natural Substances Chemistry, the Paris Institute of Nanosciences and the Paris Observatory.

At the Meudon site, the students followed the path of the solar system, observed the sun through a spectroheliograph and took part in a round table discussion with women scientists and engineers.

Five speakers shared their career paths and experiences: Yaye Awa Ba (LUX), Pernelle Bernardi (LIRA), Isabelle Bualé (LIRA), Cécile Hamy (DIO) and Florence Henry (LIRA). The rich and direct exchanges prompted many questions from the students.

The visit was so successful that a new edition is already planned for next year.

Raising awareness from an early age

On 11 February, Thibaut Paumard and Elsa Huby visited Marie Curie Primary School in Villepreux. The programme included a workshop on gender stereotypes and a presentation aimed at showing that science in general — and astronomy in particular — is open to everyone.
They drew on resources provided by the Femmes & Sciences association.

A third intervention to come

A third initiative, led by François Dulieu, is planned for the third quarter, thus extending LIRA's commitment to equality and the promotion of scientific careers.

FIRST's photonic lantern has just successfully completed the commissioning phase.

Raphael PERALTA — 2026-02-02T18:00:02Z

The beginning of February 2026 is a significant date for the research conducted at LIRA, since the dawn of the 21st century. The FIRST-PL (PL for Photonic Lantern) instrument, installed on the Subaru telescope at the Mauna Kea Observatory in Hawaii, has just successfully completed its commissioning phase. This means that it has now been validated by the Subaru telescope committee and is therefore available to researchers. As of 2 February 2026, researchers can submit observation programmes to use telescope time. This is the very first photonic lantern to be made available to astronomers. New prospects for high angular resolution observations are opening up in the visible wavelength range.

The culmination of an idea initially proposed by Guy Perrin, astronomer at LIRA and member of the French Academy of Sciences, the photonic lantern is the result of a quarter of a century of research and technical improvements involving researchers, post-docs and PhD students at the laboratory. Among them, without being exhaustive: Sylvestre Lacour (2007), Elsa Huby (2013), Kevin Barjot (2023), Manon Lallement (2024), Jehanne Sarrazin (thesis in progress) ... No doubt others will follow!

On 22 October 2025, a publication in The Astrophysical Journal Letters highlighted this excellent research based on international collaborations. We invite you to step back in time and experience this exciting adventure by visiting the FIRST project page. From its first draft to the still unfathomable possibilities opened up by the photonic lantern, fibre optic imaging will hold no more secrets for you.

Image of the optical bench, with the schematic lantern connected to the spectrograph

Path of light from the Subaru telescope, passing through the photonic lantern to reach the spectrograph.

Credit: Vievard et al. 2024

LIRA celebrates its first anniversary

Raphael PERALTA — 2026-01-13T12:34:07Z

In 2026, the Laboratory for Instrumentation and Research in Astrophysics (LIRA) will celebrate its first year since its official creation on 1 January 2025: a major milestone for this laboratory of excellence in astrophysics and instrumentation.

The result of a merger between the LESIA, LERMA and GEPI teams, LIRA brings together nearly 300 researchers, engineers, post-docs and doctoral students around key themes – from solar-planetary systems to galaxies, planetary atmospheres to exoplanets – while developing cutting-edge scientific instruments for use on the ground and in space. Through international collaboration and instrumental innovation, LIRA pushes the boundaries of knowledge, contributes to the training of new generations of scientists and participates in ambitious observation and analysis projects, thus fulfilling its mission of scientific excellence.

Le LIRA fête son premier anniversaire

Credit: Raphaël Peralta

The Sun shines on LIRA in a new documentary by LeBlob media

Raphael PERALTA — 2026-01-06T17:56:27Z

LIRA is featured in a documentary produced by LeBlob, the media outlet of the Cité des Sciences et de l'Industrie and the Palais de la Découverte, directed by science journalist Sébastien Avila.

The documentary explores the study of the Sun through the Parker Solar Probe and Solar Orbiter space missions, in which LIRA is heavily involved. These probes enable analysis of the solar magnetic field and a better understanding of its role in the mechanisms of solar activity.

The film features several members of LIRA who are heavily involved in these missions: Milan Maksimovic, Director of LIRA, Nicole Vilmer, Emeritus Research Director, Xavier Bonnin, Research Engineer, and Isabelle Bualé, Assistant Engineer. Part of the filming took place at the Paris Observatory, on the Meudon site.

Link to the documentary: Brushing past the Sun to unlock its secrets: the feat of the Parker Solar Probe and Solar Orbiter

First image of a planet so close to binary stars

Raphael PERALTA — 2025-12-19T19:24:36Z

With the latest Avatar film, set on Pandora, a moon of the gas planet Polyphemus located in the Alpha Centauri star system, the closest multiple star system to us, now in cinemas, it is legitimate to wonder whether such worlds can really exist... The answer is yes! Recently, a research team, including scientists from the Paris Observatory – LIRA, announced the discovery of a new exoplanet orbiting a double star system. Named HD 143811 b, this giant planet was detected by direct imaging using the SPHERE instrument on the Very Large Telescope (VLT) and the GPI instrument on the Gemini South telescope. Becoming the seventh circumbinary planet ever imaged, HD 143811 b stands out for its proximity to its host system and for being the least massive known in this category.

The rarity of circumbinary planets

Tatooine, the planet with two stars, imagined by George Lucas in Star Wars.

Credit: Star Wars/Disney

Understanding how planets form sheds light on the birth of our solar system and our own origins. Unlike the Sun, the only star in the solar system, most stars are born in pairs or groups in multiple systems. It is therefore crucial to estimate the effect of this binary nature on planetary formation, known as circumbinary formation.

However, detections of planets in these systems — sometimes referred to as Tatooine-type planets in reference to Star Wars — remain exceptionally rare. Today, we know of nearly 800 binary systems hosting exoplanets. A recent study conducted by Philippe Thébault, a researcher at LIRA, shows that the presence of a second star disrupts planetary formation, even when the two stars are very far apart — sometimes at distances several hundred times greater than that between the Earth and the Sun. In fact, only 22% of stars with planets have a stellar companion, while 46% of stars in our Galaxy are part of a binary system.

Among this set of known binary systems, only six planets have been detected by direct imaging, i.e. observed directly on images. This is far too limited a sample, even though this technique provides crucial information about the physical properties of planets and a more solid understanding of their formation mechanisms, compared to those at work around single stars.

A planet hidden in archives

The SPHERE instrument, in which LIRA is heavily involved, is fitted to one of the four giant telescopes of the Very Large Telescope (VLT) in Chile, which has revealed exoplanets through direct imaging.

Credit: Claude DELHAYE/ESO/CNRS Photothèque

As part of the ERC COBREX project, which aims to systematically reanalyse thousands of archival observations using advanced tools that significantly improve planet detection, the team of scientists identified several candidates that had escaped initial analyses of data from the Gemini Planet Imager (GPI) instrument on the Gemini South telescope. One of them orbited HD 143811, a young binary system, approximately 15 million years old, located 137 parsecs away in the Scorpius-Centaurus association, within the closest star nursery to us.

Observed in 2016 and 2019 with GPI, this candidate appeared to accompany the stars in their movement, but its weak signal in 2019 left some doubt. A new observation with the VLT's SPHERE instrument in July 2025 settled the matter: the companion was shining exactly where expected for an orbiting planet. Thanks to this effort, the team confirmed the existence of HD 143811 b, a planet orbiting two binary stars. It thus becomes the seventh circumbinary planet to be imaged and joins the very select group of around 50 planets directly photographed over the last 20 years.

This discovery was also independently corroborated by an American team, which simultaneously detected the planet using data from the Keck telescope (Jones et al., 2025), further strengthening the robustness of the result.

HD 143811 b, the circumbinary planet with particularly interesting properties

Time-lapse video of the exoplanet HD 143811 b orbiting its two stars.

This timelapse, interpolated by computer from two observations made by the GPI and SPHERE (VLT) instruments over a period of nine years. A complete orbit of the planet around its two stars takes approximately 320 Earth years, slightly longer than Pluto's orbit around the Sun. In order to make the planet visible, astronomers masked the light from the stars in the centre using coronography. Two star-shaped icons indicate their position.

Credit: Jason Wang (Northwestern)/Nathalie Jones (Northwestern)/Vito Squicciarini(LIRA - Paris Observatory - PSL / Exeter)

HD 143811 b differs from the six other circumbinary planets imaged to date. It is the closest to its system, at only 60 astronomical units, a distance more comparable to that observed in our Solar System, whereas other planets of this type are generally located several hundred astronomical units away. It is also the least massive in this category.

Nine years of observations have shown that it orbits its two stars in approximately 320 years on a nearly circular trajectory, seen almost face-on from Earth. Analysis of its light has revealed a surface temperature of 1000 Kelvin, corresponding to a gas planet 6.1 times more massive than Jupiter, but only 40% larger. The planet still appears hot and inflated, like all gas giants in their youth.

Next observations

Black and white image of the four lasers pointed towards the observation target of ESO's Very Large Telescope Interferometer (VLTI) with the GRAVITY+ instrument.

Credit: ESO

In the coming months, this team plans to use the GRAVITY+ instruments on the VLT and the MIRI coronagraph on the James Webb Space Telescope, two instruments with significant LIRA contributions, to refine its orbit and characterise its atmospheric composition in detail. This discovery also illustrates the potential of reanalysing archives with modern algorithms. The precise characterisation of this new circumbinary planet and comparison with other young planets will be crucial to understanding the formation mechanisms of these fascinating worlds.

Contacts: Johan Mazoyer & Anne-Marie Lagrange

Find out more:

CNRS press release
Northwester press release
ERC COBREX
Article by the European team: V. Squicciarini et al., "GPI+SPHERE detection of a 6.1MJup circumbinary planet around HD 143811", Astronomy & Astrophysics, septembre 2025
Article by the American team: Jones et al 2025

Thesis defense by Lucie DEGOTT on Thursday, January 8, 2026

Raphael PERALTA — 2025-12-19T10:15:41Z

Lucie DEGOTT's thesis defense will take place on Thursday, January 8, 2026, at 2:00 p.m. at the Institute of Space Astrophysics (IAS), in room 123.

It can be watched live on the IAS YouTube channel.

Thesis title

Stellar magnetism in the era of high-precision photometric space missions Abstract

Composition of the jury

Chairwoman: Nabila Aghanim
Rapporteurs: Nadège Meunier, Pascal Petit
Examiners: Laurène Jouve, Magali Deleuil
Thesis supervisors: Frédéric Baudin, Réza Samadi
Invited: Barbara Perri, Charly Pinçon

Abstract

The spots that appear on the surface of stars are not mere dust, but excellent tracers of stellar magnetism, whose functioning remains poorly understood and whose diversity is unexplained. Yet stellar magnetic fields have a direct impact on the habitability of planets, particularly our own, Earth. One way to study this magnetism is to decode the variations in starlight that are induced by these spots.

However, this method is subject to significant degeneration, as a single light curve contains a large amount of information. This thesis therefore consisted of developing a new method to circumvent these limitations, while establishing the first links between photometry and 3D simulations in order to better understand the expression of magnetism through these spots. This work also aims to open up new perspectives for analysis for the PLATO mission scheduled for 2026.