Seminars and Colloquia at ESO Santiago

In this lecture, I will discuss the physical properties of active galactic nuclei (AGN), focusing in particular on some of the most extreme objects recently discovered by the James Webb Space Telescope. I will describe how their main physical properties are measured, the challenges involved in interpreting these measurements, and the possible connection between highly accreting AGN in the early and local Universe. Finally, I will briefly discuss the role of ESO facilities, with particular emphasis on GRAVITY and its potential to probe the structure and dynamics of the broad-line region in these systems.

There has been growing evidence that Type Ia supernovae (SNe Ia) arise from various progenitor channels and explosion mechanisms. One such reason for this is the growing number of peculiar groups of SNe Ia that differ from cosmologically useful (normal) SNe Ia in photometric and spectroscopic properties. Here I look at 02es-like SNe Ia which are under-luminous at peak with a light curve width too broad for its luminosity. They show similarities to other under-luminous SNe Ia in their spectral features except a large range in their photospheric velocities. When observed early enough they have shown early UV flux excess, and [O I] in their late time nebular spectra. Considering these combined properties and more, literature suggests the violent merger of two white dwarfs is a strong contender for the progenitor for the 02es-like class. Using 1D radiative-transfer code TARDIS, we synthesise the spectra for this scenario for three violent merger models with differing initial white dwarf masses, with strong considerations made to line of sight effects that have shown to significantly impact observables in the model. TARDIS was used to investigate a large parameter space generating 36,000 synthetic spectra for which we developed methods to then compare to 02es-like SNe Ia observations. We found that the diversity within the sample arises from line of sight effects, and that the models explain the spectral evolution of the 02es-like observations particularly well.

SN 2023ixf and SN 2024ggi are among the best-observed Type II supernovae discovered to date, with multi-wavelength observations starting only hours after explosion. Their exceptional early coverage has provided new insight into the final stages of red supergiant evolution and the physical conditions immediately surrounding the progenitor stars. In this talk, I will summarize the main results obtained for both events and discuss their implications for pre-supernova mass loss and explosion properties. I will focus on the nebular phase of both events, where late-time spectra probe the inner ejecta and provide constraints on nucleosynthesis, explosion geometry, progenitor mass, and mass loss history. Finally, we place these results in the broader context of Type II supernova diversity and discuss how future high-cadence and multi-wavelength surveys will help clarify the role of circumstellar interaction in the final evolution of massive stars.

Long-baseline optical interferometry provides access to the spatial scales of stellar surfaces and their immediate circumstellar environments, but its sparse and incomplete Fourier-plane coverage makes image reconstruction an intrinsically ill-posed problem. Regularized reconstruction combines the information contained in the interferometric observables with prior assumptions on the image, allowing physically plausible solutions to be recovered. In this presentation, I introduce the principles of interferometric image reconstruction, from the likelihood and Bayesian framework to commonly used regularization functions such as quadratic smoothness, total variation, and hyperbolic regularization. I also discuss the choice of the regularization strength and the L-curve method. Finally, I present PYRA/MYTHRA, a user-friendly and reproducible framework that I designed during my ESO fellowship to facilitate interferometric image reconstruction and its application to the study of stellar surfaces and circumstellar environments.

Compact multi-planet systems can provide important insights into planetary formation and dynamical evolution. Of particular interest are systems with orbital period ratios close to mean-motion resonances, as these configurations may retain signatures of their dynamical history and can give rise to enhanced transit timing variations (TTVs), providing additional constraints on planetary properties.
In this talk, I will revisit several planetary systems with period ratios close to mean-motion resonances. By analysing transit photometry, searching for TTVs, and performing N-body simulations, I will investigate their dynamical properties and test whether apparently resonant architectures correspond to dynamically resonant behaviour. I will also discuss how resonant configurations may provide clues to the possible locations of additional planets. Together, these systems illustrate how resonances can be used as a valuable tool for probing and interpreting compact planetary systems, while also highlighting the caution required when inferring dynamical resonance from period ratios alone.

The elusive cosmological redshift drift — predicted by General Relativity as a direct and model-independent signature of the Universe's accelerated expansion — remains one of the most ambitious goals in observational cosmology. In this work, we take the first steps toward detecting this effect using the Lyman-α forest of bright quasars as tracers of the expanding Universe. Focusing on the most luminous quasar in the southern sky, J052915.80−435152.0, we present results from three high-resolution, high signal-to-noise spectral epochs obtained with ESO's ESPRESSO instrument over a two-year baseline. By comparing the positions of the Lyman-α absorption features across epochs, we constrain the cosmological acceleration at the level of 3.6 m/s/yr, currently the tightest high-redshift constraint to date. We also investigate the dominant observational systematics — including wavelength calibration stability and precision — that will ultimately limit the detection of the cosmological signal, expected to be of order 0.5 cm/s/yr in a ΛCDM Universe. Finally, we show that a joint long-term VLT/ESPRESSO + ELT/ANDES programme targeting the seven super-bright quasars identified by the QUBRICS survey could achieve a significant detection of the redshift drift by the 2080s.

For decades, RR Lyrae stars have been the bedrock of Galactic archaeology, serving as definitive tracers of the oldest and most metal-poor components of the Universe. According to the classical canon, these core-helium-burning pulsators are strictly old (>10 Gyr). However, this long-standing paradigm is now being tested. A mounting body of kinematic, spectroscopic, and photometric data suggests the existence of a 'forbidden' population of RR Lyrae stars: those that are both surprisingly young and metal-rich. In this seminar, I will examine the growing tension between stellar evolution theory and current observations, and discuss how this shift fundamentally changes our understanding of the Milky Way’s assembly history.

Benchmark stars are essential for testing theoretical models, vetting parameter pipelines from spectroscopic surveys, building empirical relations, and developing data-driven analysis tools. At their most powerful, such empirical relations or data-driven models are capable of providing parameters for large samples of stars in a manner largely independent of theoretical spectral or evolutionary models. For this to be effective though, our benchmark libraries must be clean, representative, homogeneous, and up-to-date—which is decidedly not the case for main sequence K/M dwarfs. Here I lay out a set of best practices for benchmarking cool dwarfs as model-independently as possible, with particular emphasis on homogenised and expanded Teff , 𝑅★, [Fe/H], and [X/Fe] scales and relations. I update pre-Gaia photometric Teff − (𝐵𝑃 − 𝑅𝑃) − [Fe/H] and 𝑅★ − 𝑀_𝐾s − [Fe/H] relations, now with broader [Fe/H] coverage, Gaia parallaxes, and lower contamination from unresolved binaries and young stars. Using our self-consistent benchmark scales, I train a 6 label (Teff , log g, [Fe/H], [Ti/Fe], [Mg/Fe], [Ca/Fe]) data-driven Cannon model with low-to-medium resolution optical spectra of 111 Southern Hemisphere cool dwarf benchmarks. This model demonstrates recovery of Fe, Ti, Mg, and Ca abundances to ±0.05 − 0.11 dex precision, and I leverage it as a bridge between observations and theory to probe the sensitivity of optical wavelengths to stellar parameters. I close by discussing outstanding challenges and opportunities for benchmarking K/M dwarfs, all with the goal of eventually unlocking their chemistry for Galactic archaeology and exoplanet demographic studies.

I will present my ERC advanced grant project, StarDance. This is based on the knowledge gaps in the study of star clusters, such as the existence of multiple stellar populations in globular clusters, with different chemistry, and of exotic stellar populations, that are thought to be byproducts of stellar interaction. Given the mounting problems faced by the most favored scenarios to explain multiple populations, it is now time to revisit the foundations of our current thinking. New results show that: (i) the peculiarities in the chemistry of multiple populations are not limited to the oldest globular clusters; (ii) they can be transient in the evolution of individual cluster stars; and most importantly (iii) binary interactions and fast stellar rotation cannot be neglected in the study of star clusters and do have the capability to produce the observed chemistry. The ERC StarDance hypothesis assumes that multiple stellar populations and non-canonical stellar populations (extreme horizontal branch stars and hot sub-dwarfs; extended main sequence turn-offs; red stragglers and sub-subgiants; lithium-rich stars; and blue stragglers) are caused by the interplay between stellar rotation and binary interactions, that are greatly enhanced in the special environment of star cluster, with spectacular results. I will also briefly describe the ERC funding scheme. 

Warm gas giants are valuable targets for understanding how planetary systems form and evolve, as their transits and radial velocities provide key clues about structure and dynamics. In this talk, I will present part of my PhD work on the detection and characterisation of these planets, using transit photometry, radial velocities, and transit timing variations.
I will focus on TOI-4504, where we detected transits from a planet that was not transiting a few years ago and has since begun transiting due to dynamical interactions in the system. This enabled a much better characterisation of the system. I will also discuss five planetary systems with close-in gas giants and long-period companions identified through extended radial velocity monitoring. Together, these systems expand the sample of giant planet architectures and help place warm gas giants in a broader dynamical context.

Instrumental polarization has long been a concern in optical interferometry, as different optical paths affect the incoming light differently, potentially reducing fringe contrast. But what if we went a step further by characterizing the polarization introduced by the VLTI telescopes and offering a polarimetric observing mode to the community? 

Such a mode would combine the high spatial resolution of the VLTI instruments with accurate polarimetric capabilities, enabling the study of dusty environments. To achieve this, I will present the development and calibration of a model designed to retrieve the intrinsic polarization state of the incoming light, by correcting for instrumental effects. This model is intended to be applied to the observed visibilities of on-sky data, providing access to the polarized signal information.

A large fraction of the material that accretes onto the supermassive black hole in an active galactic nucleus (AGN) on parsec scales does not fall into the black hole, but is instead launched outwards by radiation-driven outflows, primarily in the form of ionised gas. However, accurately determining the strength and structure of these outflows remains a challenge, and many open questions regarding AGN outflows still remain.

In this talk I will present the results of my 3-month internship at ESO, of which the aim has been to characterise the ionised outflows of the Seyfert Type II AGN in the Circinus galaxy. Being one of the AGNs closest to us, it is a great laboratory for improving our understanding of their physics. Using long-slit spectroscopic data of the [S IV] 10.51 μm and [Ne II] 12.81 μm coronal lines from VLT/VISIR, we created a pseudo-IFU and used it to measure emission line properties along the slits, most importantly the velocities. We then fitted a model consisting of a biconical outflow and a rotating disk to these velocities to determine the orientation and geometry of the ionised outflows of the Circinus AGN. I will lay down the results of both steps of this procedure, discuss how these results compare to the literature and lay down the next steps in improving our understanding of AGN outflows.

The innermost regions (< 1 au) of protoplanetary disks are sites of complex processes and peak dust densities, where rocky planets such as those detected via transits are formed. Stellar irradiation is intense enough to sublimate dust grains, creating an inner rim identified by hot dust emission. Due to the tiny angular scales involved (< 10 milliarcseconds), only optical long-baseline interferometry has been able to resolve these regions. Large surveys with PIONIER, GRAVITY, and MATISSE at the VLTI are providing measurements of inner rim radii, widths, and fluxes, as well as constraints on azimuthal asymmetries and radial gaps on a hundred of Herbig and T Tauri stars. In order to link these measurements to the physical nature of the dust, we are creating a grid of self-consistent radiative transfer models on a large range of stellar luminosities, grain sizes and grain compositions. After introducing the history of this topic, I will present comparisons of predictions from these models to measurements from large VLTI surveys, and discuss the constraints it provides on the dust composition. I will also discuss how these models can hint at the presence of compact dusty structures (such as vortices) in interferometric data.

 The remarkable diversity of exoplanets originates in the protoplanetary disks that surround young stars during their first few million years. Recent years have seen considerable advances in our understanding of the structure and composition of these disks, driven by instruments like ALMA, VLT/SPHERE and the JWST. Yet, these instruments cannot resolve the innermost regions of protoplanetary disks, a gap that near- and mid-infrared interferometry at the ESO/VLTI (Paranal, Chile) is uniquely positioned to fill.

MATISSE is an imaging spectro-interferometer at the VLTI, that combines the light of four telescopes. It operates in the L, M and N (3 to 12 µm) bands and offers a range of spectral resolutions. When combined with observations from the VLTI/PIONIER and VLTI/GRAVITY instruments, it provides access to measurements spanning 1.6 to 12 µm, and probing spatial scales from approximately 0.1 to several tens of au, corresponding to the regions where most planets, particularly the rocky ones, are supposed to form.

In this talk, we present high-resolution observations of the inner disk of the TTauri “dipper” star RY Lup, obtained with the VLTI instruments MATISSE, GRAVITY, and PIONIER. This system exhibits several intriguing features that currently lack a consistent interpretation. These include a misalignment between the inner and outer disks (Bohn et al. 2022, GRAVITY and ALMA data), a ~3.75 day optical variability (up to ~3 mag) possibly caused by a warped inner disk modulating the stellar flux along the line of sight, and the presence of a candidate companion recently proposed by Vioque et al. (2026) using GAIA data. Here, we use the “oimodeler" tool to fit the VLTI observations spanning 1.6 to 12 µm, in order to derive unprecedented constraints on the disk structure while assessing the potential presence of companions.

In this Python Coffee, I will introduce CIGALE (Code Investigating GALaxy Emission), an open-source, Python-based spectral energy distribution (SED) fitting code. CIGALE is designed to infer galaxy properties from measured multi-band photometry by statistically comparing modelled SEDs with the observed fluxes, using modules that describe emission from stars, gas, dust, and active galactic nuclei. Through a Bayesian statistical framework, CIGALE derives physical parameters such as star formation rate, stellar mass, dust luminosity, and attenuation. I will teach you how to set up and configure CIGALE from scratch and how to construct physically motivated SED models. I will cover the workflow step by step, including initializing a configuration file, generating parameter grids, and running the full analysis. By the end of the workshop, you will be able to run CIGALE and measure the physical properties of your own galaxies from multi-band photometry.

Every galaxy is embedded in a vast halo of diffuse gas known as the circumgalactic medium (CGM). This atmosphere serves as the interface between galaxies and their environment, regulating galaxy evolution. Because the CGM is extremely diffuse, it is most readily detected in absorption against bright background sources, typically quasars. However, quasars are rare and provide only a single pencil-beam sightline through a galaxy halo. By combining the angular extent of bright gravitational arcs with integral-field spectroscopy, we obtain many contiguous, quasi-independent sightlines through individual halos, enabling direct mapping of the geometry, kinematics, and structure of the CGM. In this talk, I will introduce the principles of gravitational-arc tomography, highlight recent observational results, and discuss our ongoing work and future prospects.

Brown dwarfs occupy the mass regime between planets and stars. In systems containing both a star and a substellar companion (be it a brown dwarf or an exoplanet), a third object orbiting the companion can be called an exosatellite. Exoplanet satellites can be easily described as exomoons, but it is not clear if satellites of brown dwarf companions can be called the same, as the term lacks a formal definition. Despite more than 6,000 exoplanets being discovered, no exomoon has ever been confidently detected. Although there are candidates, they lack confirmation and remain controversial. In this work, we present evidence of an exosatellite orbiting the directly imaged brown dwarf companion CD-35 2722 B. Applying radial velocity analysis, the same technique used to discover the first exoplanet around a Solar-type star, to VLT/CRIRES+ spectra of this brown dwarf, we find what appears to be the periodic signal of at least one orbiting satellite. This is the first time, to our knowledge, this technique has produced evidence of satellites around a companion brown dwarf. Our best-fitting model includes a satellite with a minimum mass of about 0.9 Jupiter masses and a period of around 170 days. Although it is uncertain whether this exosatellite will fulfil the presently undefined criteria for qualifying as an exomoon, it is a marked step towards that first uncontroversial detection, as advancing technology will allow the same method to be applied to less massive targets.

The Galactic Centre hosts the Milky Way’s nuclear stellar disc and nuclear star cluster, providing a unique opportunity to study the physical processes that shape galactic nuclei at the level of individual stars. However, the extreme crowding and extinction towards the central regions have historically limited spectroscopic investigations. The VVVX-GalCen ESO Public Survey is a 140-night KMOS/VLT programme designed to obtain homogeneous spectroscopy for more than 40,000 stars across the Galactic Centre and inner Galaxy. The survey will deliver radial velocities, metallicities, and chemical abundances for an unprecedented stellar sample, enabling detailed studies of the structure, kinematics, stellar populations, and formation history of the nuclear stellar disc and its connection with the Galactic bar. I will present an overview of the survey, its scientific goals, and the first results from the pilot observations, highlighting the potential of VVVX-GalCen to transform our understanding of the formation and evolution of the Milky Way’s central regions.

We report the discovery and characterization of two new transiting giant planets orbiting TIC184397998 and TIC279514271, whose transit events were detected in the light curves of the Transiting Exoplanet Survey Satellite (TESS) space mission. By combining TESS light curves with ground-based photometric and spectroscopic follow-up observations, we confirm the planetary nature of the observed transits and radial velocity variations through a joint global fitting analysis. These newly discovered systems provide valuable observational constraints on the origins and evolution of giant planets. This work was carried out as part of the Warm gIaNts with TESS (WINE) collaboration, a survey dedicated to identifying, confirming and characterizing warm Jupiters using TESS data together with photometric and spectroscopic follow-up observations from ground-based facilities, with the main goal of building a warm Jupiter database to constrain theories of planetary formation and evolution.

 In SDSS-V’s Milky Way Mapper, more than 1.17 million cool stars (Teff<~4,000 K) have been observed with the APOGEE and 425,000 cool stars with the BOSS spectrographs, with similarly high numbers in other spectroscopic surveys. This vast dataset opens the door to constrain their stellar parameters, dwarfs and giants alike, but there are several outstanding issues in modeling and fitting their spectra. These issues stem from the stars’ large, convective cells, the dominance of molecules in the stellar opacity, and uncertain constraints on their radii. In this talk, I will discuss some of the issues preventing accurate analysis of the cool giants and dwarfs and how myself and others within SDSS have worked to solve them. For the giants, we are working to measure interferometric diameters of nearby stars to constrain the temperature scale in the upper red giants. For the dwarfs, the issues are primarily in constraining accurate metallicities and abundances, for which we are performing high-resolution spectroscopic follow up and developing new tools to synthesize model spectra. This work is composed largely of open source tools and will facilitate more accurate parameters for the coolest stars within SDSS-V as well as other large surveys.

The intracluster light (ICL) offers a uniquely luminous probe of galaxy cluster halo shape and orientation, but its extremely low surface brightness has historically made robust cluster-scale morphological measurements challenging. In this talk, I will present ICL ellipticity and position-angle measurements from Euclid’s Quick Release (Q1) for nearly 200 clusters at 0.1 ≤ z ≤ 0.8, selected from the eROSITA All-Sky Survey and the Dark Energy Survey. We quantify ICL morphology across five bands (VIS, Y, J, H, and coadded YJH), finding consistent shape parameters across filters, with the H band tracing the ICL to the largest cluster-centric radii. The ellipticity distribution peaks at e ≃ 0.5, in close agreement with halo ellipticities from strong and weak lensing, supporting the view that the ICL traces the cluster's large-scale structure. Radially, BCG-dominated cores are relatively round (e ≃ 0.2), while the diffuse component becomes progressively more elongated, reaching e ≃ 0.5 by 0.1R₂₀₀ (~100 kpc). By stacking clusters in redshift bins, we extend surface-brightness constraints to ~0.8 R₂₀₀ and ellipticity measurements to ~0.4R₂₀₀ (350–400 kpc), where we observe an ellipticity plateau beyond ~0.1R₂₀₀ with no detectable redshift evolution, challenging theoretical expectations.

To bridge observations and theory, we compare to Hydrangea simulations using two complementary ICL definitions: (i) a theoretical “unbound” ICL+BCG component, and (ii) fully forward-modelled mock observations that include subhaloes and realistic backgrounds. The unbound ICL is systematically rounder, while the forward-modelled distribution matches the observed distribution well—highlighting that forward-modelling is essential for direct comparisons when observational processing and measurement extraction are imperfect. Overall, our methodology provides a benchmark for testing hydrodynamical simulations and forthcoming Euclid data releases will enable substantially tighter statistical constraints.

During May, our group spent 2 weeks visiting remote schools in the Aysén region, in Chilean Patagonia. Our aim was to reach a historically underdeveloped area of the country, and meet students in their own communities and territory. After the visits, we will tutor their teachers, and follow-up with the schools during one year, so the project can have long-lasting effects in their communities.
By bringing astronomy-focused activities we hope to spark interest in STEM careers, and by using a gender and neurodivergent perspective we aim to broaden their sense of what's possible, and reinforce that science is for everyone.

iSpec is a tool designed for the treatment and analysis of stellar spectra. It facilitates a wide range of spectroscopic tasks, including continuum normalization, resolution degradation, radial velocity correction, atmospheric parameter determination, and chemical abundance analysis.

In addition, iSpec enables the determination of stellar atmospheric parameters for F, G, K, and M-type stars. These parameters can be derived using two complementary approaches: the synthetic spectral-fitting technique and the equivalent-width method.

The software integrates MARCS and ATLAS model atmospheres and supports several widely used radiative transfer codes, including SPECTRUM, Turbospectrum, SME, MOOG, and Synthe/WIDTH9.

In this Python Coffee, I will give a practical introduction to iSpec using a solar spectrum as an example. I will show how to use its graphical interface to perform basic steps such as continuum normalization, radial velocity correction, stellar parameter estimation, and chemical abundance determination. The goal is to provide a first overview of the tool and its main capabilities for stellar spectroscopy .

I will then place NGC 1427A in the context of a broader MUSE sample of Fornax dwarfs spanning H I detections, CO detections, and gas-poor systems. Our goal is to characterize the physical pathways by which infalling dwarfs are transformed inside clusters, by connecting multi-phase gas content with resolved stellar populations, ionised-gas properties, star formation, and kinematics.

Stellar UV radiation plays a key role in shaping the physico-chemical structure of molecular gas and thus directly impacts star formation. Typical examples are photodissociation regions (PDRs), which are the edges of molecular clouds exposed to the radiation from massive stars. As the name suggests, large molecules in these regions were usually expected to be photodissociated by interactions with FUV photons. However, recent evidence suggests that the formation of complex organic molecules (COMs) can even be favored in these harsh environments, but exactly how is not entirely clear yet. In this presentation, I will review some recent work in one of the most representative PDRs: the UV-illuminated edge of the Horsehead nebula. We moderately resolved, for the first time, the emission of COMs in this region by combining ALMA and IRAM 30m single-dish observations, providing observational support to some chemical pathways initially suggested by laboratory experiments and theoretical predictions. Although chemical modeling is needed to confirm the efficiency of the proposed pathways, the mere presence of COMs favored by UV radiation under cold temperatures can have important implications for other environments, such as protoplanetary disks.

Service mode scheduling at ALMA requires integrating many competing demands at once. Selecting the wrong observations can lead to incomplete science goals, hours of wasted observing time, and failure to satisfy executive balance goals. Dynamic scheduling algorithms (DSAs) can help the observatory complete more high-priority science goals while respecting environmental conditions and executive balance constraints. However, the existing DSA has not been able to meet all of these demands without human supervision, and ALMA does not have tools to clearly visualize the trade-offs of different scheduling decisions.

We develop a new dynamic scheduling algorithm that incorporates executive balance constraints, and improves graded completion metrics relative to the currently-deployed DSA. Our approach integrates historical climate data and real-time weather forecasts to improve faithfulness to executive balance targets while also increasing completion rates for high-priority science goals. We build a framework for historical back-testing that captures the most important components in service mode scheduling on the 12m array, including maintenance shifts, downtime events, weather, array configuration, and antenna availability. We demonstrate a dashboard that visualizes executive balance and project/scheduling block completion metrics on historical simulations, allowing ALMA to reason about trade-offs between these metrics. On Cycle 10 data, our proposed algorithm satisfies all executive balance targets within 0.1% tolerance, while the current DSA violates targets by 2-7%. The proposed algorithm also completes an additional 34 grade-A and 60 grade-B SBs and an additional 4 grade-A and 2 grade-B projects relative to the current DSA.

Cosmological models predict the existence of dual supermassive black holes (SMBHs) in-spiraling toward the centers of merging galaxies. During these phases, dual active galactic nuclei (AGN) at kpc and sub-kpc separations represent a key stage in galaxy evolution, where SMBH growth, galaxy interactions, and AGN feedback are expected to be tightly coupled.

Dual AGN are predicted to be common at z > 0.5, yet only a small number of systems has been robustly confirmed so far, primarily due to the observational challenges. In this talk, I will show how the recently developed Gaia Multi-Peak (GMP) method has enabled the selection of a large sample of candidate dual AGN at sub-arcsecond separations, providing an efficient way to uncover the population of dual AGN beyond the local Universe. I will then discuss the follow-up strategy required to confirm their nature and to distinguish true dual AGN from gravitationally lensed systems or chance superpositions with a foreground star, using high-resolution imaging and spatially resolved spectroscopy.

Finally, I will show initial results on the physical properties of dual systems, including masses, luminosities, separation distribution, and redshift evolution.

In this talk, I will present the main results of my one-year internship, which focused on characterising wind conditions at two locations on the Chajnantor plateau using on-site measurements. By comparing wind patterns at different heights, we can highlight how local atmospheric conditions vary across the plateau and discuss their relevance not only for the design and construction of a 50-m telescope, but also for its long-term operation and performance.

The environment surrounding binary stars is dynamically complicated, making planet formation and survival challenging. Nevertheless, planets are known to exist in binary systems, either orbiting a single star of the binary, circumstellar planets, or orbiting both stars, circumbinary planets. Circumbinary exoplanets have proven the most difficult to detect, with only 19 currently known orbiting main-sequence binaries. To date, just three circumbinary planets have been discovered using radial velocities, all as part of the BEBOP (Binaries Escorted By Orbiting Planets) survey, a project focused on detecting circumbinary planets with radial velocities. In this talk, on behalf of the BEBOP consortium, I will present the fourth such discovery, BEBOP-5b. HARPS radial velocity measurements collected over three years reveal a 0.9 M_Jup circumbinary planet following a 85 day period. The planet orbits an unusual binary system within the BEBOP sample, consisting of a fairly evolved 1.7 M_⊙ primary and a 0.13 M_⊙ full convective M-dwarf secondary still on the Main Sequence. Additionally, the radial velocity data contains a long-term drift suggestive of a second, longer-period companion in this system. BEBOP-5b expands the parameter space where circumbinary planets are known to exist and, for the first time, probes the circumbinary planet population as stars evolve off the Main Sequence. 

Streamers, elongated gaseous structures that range from a few hundred to over 10,000 au, have emerged as a novel mechanism of material supply to protostellar and protoplanetary disks. Thanks to advanced millimeter/submillimeter interferometers like ALMA and NOEMA, we now know that streamers are frequently found around protostars, rather than isolated occurrences. However, their effects on disk composition are only recently being studied in detail. In this talk, I will present detections of sulfur dioxide (SO₂, a known shock tracer) toward the Class I source Per-emb 50, which are located between the streamer detected for this source and its disk. The SO₂ emission consists of several velocity components, tracing part of the disk kinematics as well as the inner envelope, but its emission peaks are offset from the position of the protostar. After analyzing the velocity profile in comparison with the expected infalling envelope, we conclude that the streamer is shocking the inner envelope region before reaching the disk.

I present a simple, Python-based method to enhance faint, time-dependent signals in astronomical data. The idea is straightforward, when a source moves or varies across a detector, its signal in a single pixel follows a predictable time profile set by the PSF, cadence, and the source behavior. We can use this to our advantage.

For moving objects, this pixel light curve is approximately Gaussian as the source passes through. By convolving each pixel time series with a matched Gaussian kernel and taking the maximum response, we can build a single combined image where faint signals are enhanced and noise is suppressed.

Although developed for detecting Solar System objects, the method is general. With small adaptations, it can be applied to other time-domain problems, such as transient detection, variability studies, or high-contrast imaging. It offers a simple and computationally efficient way to extract low-SNR signals from noisy datasets.

Intensity interferometry connects optical telescopes electronically by software.  The error budget is shifted from optical phase stability to the time domain, where a noise of, say, 1 ns corresponds to 30 cm light-travel distance, making the method insensitive to atmospheric seeing or telescopic imperfections, and thus enabling long baselines.  Also Cherenkov telescopes can be used, as currently done at VERITAS, H.E.S.S. and MAGIC + CTAO North on La Palma (especially during bright-Moon time, when gamma-ray observations are constrained).  The numerous forthcoming telescopes of CTAO in the Paranal/Armazones area should enable interferometry across a few square km, where any pair or triplet of telescopes can be electronically connected, reaching optical resolutions comparable to the EHT in radio.  Detector developments and telescopes with tighter specifications hold the promise to reach fainter targets, eventually realizing a fully electronic optical array for two-dimensional imaging with baselines of 10 km or more.

Planets form in discs around young intermediate-mass stars (Herbig stars) within the first 10 Myr. These protoplanetary discs have been studied extensively, and can be classified into 2 groups, depending on their geometry: flared with a gap (group I) or flat/self-shadowed and continuous (group II) . Within group I, we can still distinguish between objects with a warm inner dust disc and those without. In this talk, I will present a study of the properties of Herbig stars, concentrating on the influence of the presence of a warm inner disc. In particular, I will discuss the stellar metallicity. In a second part, I will present recent findings about the evolution of the accretion rate in intermediate-mass stars, that appears to increase with age. 

I will present the status and summarise the science case of the QUVIK mission. QUVIK will be an ultraviolet (UV) space observatory on a 200 kg small satellite with a moderately fast repointing capability and a near-real-time alert communication system. It is a Czech-led mission realised through ESA as a 3rd-party project, with significant international participation. The mission will provide imaging in the NUV ( 260-360 nm) and FUV ( 150-200 nm) bands, with the latter provided by the Italian community (ASI and INAF). The mission will fill an important wavelength gap in our observing capabilities at the beginning of the next decade, providing key follow-up capabilities for transients detected by gravitational wave observatories and future wide-field multi-wavelength surveys. The mission will target sources of interest identified by
the upcoming ULTRASAT satellite in complementary near- and far-UV bands. Between observations of transient sources, the satellite will observe other targets of interest to the scientific community, such as stars, stellar systems, and galactic nuclei. The mission will also provide open time to the worldwide astronomical community and a public archive.

Planets and stars form from the same proto-stellar material. Hence the stellar refractory elemental abundances are assumed to be strongly linked to rocky planet interiors. This is also found for the refractory elemental abundances of the Sun and Earth. For exoplanets, this compositional link has been recently suggested and explored in small demographic studies. However, the sample of rocky planets around metal-poor stars is limited. This makes it challenging to find and validate potentially vital chemical trends. We present a novel machine learning approach to identify planet hosting stars of interest to fill in the lack of well-characterised small planets around metal-poor stars. 

We present newly characterised systems containing Ultra-Short Period Super-Earths and Sub-Neptunes around compositionally-diverse stars. These planetary systems were observed with photometry and radial velocity allowing us to measure their radius and masses precisely. We modelled their interior structures for which we further developed tools to link stellar abundances to the core and mantle mass fractions of the planet. These give insights into the elemental abundance ratios of the planets.  Hence, we directly study the connection between the planet and host star abundances. These new discoveries significantly add to the sample of rocky planets around thick disk stars and will be followed by further detections and characterisations from our machine learning algorithm. 

Young Massive Clusters (YMCs) are key sources of mechanical, radiative and chemical feedback to their host galaxies, and present an exciting nexus of stellar and high-energy astrophysics. YMCs such as Westerlund 1 have a collective wind driven primarily by their powerful Wolf-Rayet stars, which transports enriched material and momentum outwards in a quasi-spherical outflow. As this outflow expands, it can ablate Cool Supergiants (CSGs) in wind-wind interactions, which mass-loads and further enriches the outflow. In this talk, I will bridge the scales from simulations of individual winds of massive stars to simulations of YMC outflows. I will address how a YMC outflow changes with stellar metallicity and evolves over Myr timescales using new pySTARBURST99 population synthesis models, accounting for deceleration from mass-loading. I will also show 3D hydrodynamic models of interactions between cluster outflows and individual CSGs, which offer unique opportunities to measure uncertain RSG mass-loss rates and place observational constraints on turbulent radiative mixing processes. I will also present simulations of cluster outflows with individually resolved stellar wind sources, and detail how the intense radiation fields in YMCs modify the properties of core collapse supernova remnants via photoionization. 

We know Type Ia supernovae well enough to use them to measure the expansion of the universe — but we still don't know what actually explodes, or how. JWST is changing the game, delivering exquisite infrared spectra that hold clues to the physics of the explosion itself – if we know what to look for. 

In this talk, I will present first comparisons between JWST observations of SNe Ia and synthetic late-time spectra computed with the NLTE radiative-transfer code CMFGEN. Stable nickel is a powerful fingerprint of the white dwarf's mass at the moment of explosion: its abundance is sensitive to the progenitor's core density, making it a key lever for distinguishing between explosion models. These diagnostics offer a path toward using late-time JWST spectroscopy to place direct constraints on SN Ia progenitor masses and disentangle the contributions of competing explosion channels. 

The detection of an Earth 2.0 via the radial velocity (RV) method requires a 10 cm/s stability over several years. However, current state-of-the-art instruments are not there yet, with best-delivered results as low as 30–50 cm/s of RV jitter on a few M dwarfs (ESPRESSO). A key obstacle to long-term stability comes from wavelength calibration, as spectrographs broadly rely on hollow-cathode lamps (HCL) that exhibit a ~30-50 cm/s intrinsic jitter due to uncertainties on line positions, sparse wavelength coverage, and lamp aging. In the last ~10 years, astronomical Laser Frequency Combs (LFCs) came to light to overcome HCL limitations, with a theoretical long-term stability of few cm/s over decades. However, current on-spectrograph LFCs performances are still sub-optimal and demand a more thorough characterization before scientific use. On this line, we analyzed the benchmark LFC system on HARPS@3.6m in La Silla, proudly started and operated by ESO since 2015, and with available high-cadence solar observations since 2018 (HELIOS). Once confirmed that the LFC spectrum is intrinsically stable over long periods of time, we moved to the assessment of LFC-based wavelength solutions and tested them on real solar data. We find that instrumental effects—such as component aging or overall flux and background variations—induce irregular wavelength shifts on the detector not observed with HCL calibrations. We thus developed an optimized method for LFC-based wavelength solutions, including background subtraction and accurate line fitting, to mitigate the spurious m/s-level offsets that we otherwise see in LFC-calibrated solar RVs, when not accounting for all effects. In this talk, I will first introduce the HARPS-LFC system and his performances over the years; I will then present in detail the key elements and interplays to consider when computing LFC-based WS for extreme-precision RV data, showing the improvements brought by the optimized calibration strategy developed for the HARPS LFC as a result of this project. 

The James Clerk Maxwell Telescope (JCMT) has been monitoring eight nearby low-mass star-forming regions in the Gould Belt at submillimetre wavelengths for more than eight years to search for and quantify the time dependent brightness variability of the resident deeply embedded protostars. Secular variability is common among these protostars; greater than 25% of the sample show measurable long-term brightness changes and 10% show burst behaviour lasting months to years. We interpret this secular variability as reflecting changes in the mass accretion rate from the disk to the protostar, as predicted by theoretical models of (proto)stellar assembly. For a subset of our sample we have contemporaneous mid-IR light-curves which allow additional constraints on the conditions responsible for the brightness variations, confirming that the submillimetre variability is driven by changes in the dust temperature profile of the envelope. Furthermore, we have combined, for one source, single dish and interferometric sub-mm monitoring, which has allowed us to unambiguously recover a time lag in the variability at larger angular scales and use the results to confirm the envelope structure surrounding the embedded protostar.

fist - FITS Inspection Streamlined Tool

The most commonly used FITS display tools, such as RTD or DS9 are now more than 25 years old. They are extremely powerful but can at times lack flexibility, specially in what comes scripting and interfacing. I created ´fist´ as a simple browser-based FITS interface, programmed completely on python. The package already includes the most commonly used features and allows for including additional instruments or tools.

exoptima: an observability and radial precision interface for observing Exoplanets  

´exoptima´ is a web-based interface that computes observability for a given object, and evaluates this observability not only for a specific date but also over the whole year. It also estimates radial velocity precision for a given instrument/telescope using a simple scaling from the ESPRESSO ETC values. The tool can be a valuable aid at planning Exoplanet RV observations.

The ESPRESSO spectrograph, mounted on the VLT, was designed to achieve a long-term radial velocity (RV) precision of 10 cm/s, enabling the detection of Earth-mass planets within the habitable zones (HZ) of their host stars.

I present results from the instrument’s Guaranteed Time Observations campaign on three low-activity G, K, and M stars. We characterize the precision achievable from the timescales of minutes and dominated by pulsations, to timescales of years as required for HZ planet detection. To achieve this, we employ different RV calculation methods and activity indicators, assessing the limiting factors of both instrumental precision and stellar RV stability. Using a comprehensive analysis, we reach a RV floor level of 40 cm/s over a timescale of several years.

Interestingly, the ESPRESSO data shows no evidence for several previously announced planetary signals; we discuss the population of planets that, while not directly observed, remain consistent with ESPRESSO data. 

Finally, I explore the stellar physical phenomena that can be studied to further improve RV precision and enhance our planet detection capabilities. This is key for the future precise RV campaigns as enabled by ESPRESSO and similar instruments.

Many exoplanets have been found, but still no Earth-like planet in a one-year orbit around a solar-type star. Limitations no longer stem from observations but from the physical variability of the host star, which greatly exceeds the radial-velocity modulation by an Earth-like planet.  Current observational efforts are to find planets around our Sun, monitoring the Sun-as-a-star with extreme precision radial-velocity spectrometers.  Theoretical hydrodynamic simulations produce time-variable solar spectral atlases, where radial-velocity jittering is followed in different spectral features.  A step toward exoEarth detection will be to identify dissimilar spectral lines (strong or weak, neutral or ionized, high or low excitation, etc.) with disparate responses to stellar activity, to disentangle wavelength shifts induced by exoplanets from those originating in stellar atmospheres.

tbd

How are the extended and low-surface brightness halos of early-type galaxies built up, and which role does their environment play in their evolution? Studying their halos provides essential insights into their accretion history as accretion and merging events leave behind long-lasting signatures. These accretion events also release stars into the intra-group light (IGL), whose assembly is closely linked with the morphological transformation of galaxies in groups and clusters.

In the first part of my talk, I will present our work charactering the haloes and surrounding IGL of nearby massive early-type galaxies in groups and clusters with planetary nebulae as discrete kinematic tracers in synergy with deep and wide-field imaging, resolved stellar population studies, and integral-field spectroscopy. In the second part of my talk, I will address the discovery space for simultaneously studying planetary nebulae and stellar populations with integral-field spectrographs such as MUSE at the VLT and SITELLE at the CFHT. I will present our pilot papers on planetary nebulae in early- and late-type galaxies and contrast our observational results with predictions from state-of-the-art simulations of post-asymptotic giant branch stellar evolution.

Classical Wolf-Rayet (WR) stars represent the final evolutionary stage of the most massive stars and are immediate progenitors of stellar-mass black holes. They are hot, stripped, often core-He burning stars that have strong, optically thick winds. Their formation has long been a topic of debate, with two popular channels being self-stripping through strong stellar winds or stripping by a companion. The multiplicity properties of WR stars can provide important insights into their formation as well as their eventual fate. In this talk, I will present a VLTI/GRAVITY survey searching for wide companions in these stars that are often inaccessible with spectroscopy. The strong capabilities of GRAVITY combined with the strong stellar winds of WR stars also led to serendipitous discoveries deserving their own investigation. I will briefly discuss these new exciting science cases and how we can advance them.

REBOUND is an N-body simulation python (and C++) package which is easy to use and includes lots of useful tools and features. We will go through a few examples of how to apply REBOUND to a diverse array of problems, from exomoon studies, to multiple star systems, to galaxies (kind of).

Extreme day-night temperature contrasts in hot Jupiters drive strong winds that control their climate by transporting heat and material, yet the mechanisms that regulate wind speeds remain poorly understood. High resolution spectroscopy is sensitive to the line-of-sight velocity of the atmosphere and can hence provide key observational constraints on wind speeds. Recently, CRIRES+ observations of WASP-127 b have revealed the first direct evidence of an equatorial super-rotating jet, and allowed a precise measurement of the jet speed. This detection stands in contrast with observations of the similarly irradiated planet HD 209458 b, where CRIRES+ showed no sign of a jet-like circulation. This change in behavior, together with the precise wind speed measurements, provides a unique opportunity to both quantitatively and qualitatively test the dynamical predictions of general circulation models (GCMs). Here, we present a comprehensive modeling study of these two planets, and discuss potential origins of the different circulation patterns. We further discuss the data processing techniques used to extract the Doppler signature of atmospheric circulation from high resolution spectra, and show how common telluric removal methods significantly bias the retrieved signal. We propose a new, PCA-based method to overcome these biases, which will be particularly useful for future ELT observations.

The majority of the elements in the periodic table are produced inside the cores of stars via different nucleosynthesis channels. The elements are released in the interstellar medium at the end of the stellar evolution, enriching the material from which new stars and planets are formed. Therefore, it is pivotal to derive precise and accurate chemical abundances of stars. In this lecture, I will give you an overview of the most commonly used spectroscopic techniques to infer the stellar properties (parameters and abundances), focussing on their pros and cons. Finally, I will discuss how we can use the stellar abundances to study the exoplanets and Galactic properties.

AB Aurigae is a class II young stellar object (YSO) located at a distance of 156 pc. With several candidate protoplanets identified or predicted within its very extended structure with multiple spiral arms, some of which having been attributed to late infall, it is a complex and interesting disk. In this talk, I present a newly detected candidate protoplanet first observed in near-infrared, which we now look at using ALMA line emission data from 12CO, 13CO and C18O. I will then discuss some masking techniques we will use to make a deeper search into our region of interest. Finally, I show and discuss the detection of well-defined regions of emission around the coordinates of the detected candidate, as well as velocity kinks in all of our tracers.

Cool dwarfs (Teff < 4700 K) are the most abundant stars in the Milky Way and preserve a primarily stable surface composition over their lifetimes.  As such, these stars can provide critical insights into Galactic chemical structure and evolution, with cool subdwarfs specifically tracing the oldest stellar populations.  On smaller star-planet scales, the chemical composition of cool-dwarf planet hosts offers fundamental constraints on planet formation pathways and bulk planetary composition. Despite their importance, the spectroscopic analysis of cool dwarfs remains challenging. Their low effective temperatures produce spectra dominated by dense and blended molecular absorption bands, resulting in a long-standing lack of accurate and homogeneous chemical abundance measurements for these stars. In this talk, I first review our previous work on the fundamental properties of a large sample (~3800) of M dwarfs and M subdwarfs based on low-resolution spectroscopy and discuss their role in probing the chemical enrichment history of the Milky Way. I then introduce AutoSpecFit, an automated, line-by-line spectral fitting pipeline for high-resolution spectroscopy, paired with AutoSpecNorm, a complementary code designed to achieve robust and consistent spectral normalization. Our technique allows for reliable abundance measurements of up to 15 key elements in cool dwarfs, including the main planet-building elements, i.e., C, O, Mg, Al, Si, Ca, and Fe.  As illustrative applications, I demonstrate results from high-resolution (R=45,000), NIR IGRINS spectra of cool-dwarf planet hosts, including stars having planets targeted by JWST programs, and highlight our exploration of star–planet compositional links for different types of planets. I also show results from a high-resolution (R=31,500) optical ARCES spectrum of a bright halo M subdwarf, presenting the applicability of the method at low metallicities. The advent of future facilities such as the Extremely Large Telescope will enable high-resolution, high-signal-to-noise-ratio spectroscopy of faint and distant cool dwarfs, extending these studies to currently inaccessible stellar populations. The methodology presented here opens a new vista for exploring Galactic archaeology as well as exoplanet formation and composition using future high-resolution surveys.

Low-mass galaxy groups are the most common environments for galaxies and serve as a key bridge between cosmological structure formation and galaxy evolution. Yet, their hot gas and baryonic content remain poorly characterized, largely due to their low surface brightness in X-rays. In this talk, I will show how spectral stacking of eROSITA data offers a powerful method to uncover the X-ray properties of galaxy groups and clusters identified through large spectroscopic surveys, including SDSS, GAMA, and DESI. Focusing on eRASS1 results, I will present stacked X-ray measurements for these systems and compare them with mock observations based on hydrodynamical simulations such as Magneticum and IllustrisTNG. This technique allows us to trace the intra-group medium from massive clusters down to group scales comparable to the Local Group, extending and validating key X-ray scaling relations into the low-mass regime. These results open new pathways to connecting observations and theory across the full mass spectrum of cosmic structures

Quasar studies with Herschel/SPIRE often report host luminosities ranging from 10^{12} to 10^{14} solar luminosities, suggestive of star formation rates (SFRs) of up to several thousand solar masses per year. However, due to the limited spatial resolution of SPIRE, it is uncertain whether the far-infrared (FIR) emission originates from the quasar itself, nearby sources, or unrelated sources within the SPIRE beam. High-resolution observations at wavelengths close to the SPIRE coverage are needed to pinpoint the true source of the FIR emission. In this talk, I will discuss the unambiguous identification of ALMA Band 7 counterparts of a statistical sample of 152 FIR-bright SDSS quasars and subsequent multiplicity rates among these systems. The multiplicities will be discussed as a function of redshift, IR properties and "balnicity". I will also report on the serendipitous detection of intermediate CO transitions. Preliminary results on the SEDs of these objects and the calibrated SFRs will also be shown.

Galaxy clusters exhibit Mpc-scale diffuse radio emission that is associated with the microphysics of the intracluster medium (ICM) and with radio galaxies. However, many questions remain open regarding the origin of this diffuse radio emission. In this talk, I will discuss the role of AGN bursts, merger shocks, and particle acceleration mechanisms, such as diffusive shock acceleration (DSA) and turbulent re-acceleration, in explaining radio observations. I will present results from MHD simulations of binary galaxy cluster mergers that include a jet model injecting a bi-directional, cosmic-ray (CR)–loaded jet at the center of the main cluster. I will discuss the role of sloshing, turbulence, and shocks in redistributing CRs from central AGN throughout galaxy clusters. Finally, if time allows, I will present preliminary results based on simulations and LOFAR radio observations of the cluster MACS J0018.5+1626, highlighting the power of combining multi-wavelength analyses with simulations of individual systems to better constrain the underlying merger and ICM physics.

For the 11th International Day of Women and Girls in Science, we celebrate women and girls in Science, Technology, Engineering, and Mathematics (STEM) fields. One initiative for this edition focuses on women in the optical/infrared interferometric community, with participation from around the world. Community participation was sought by sending around an announcement of the initiative. Subsequent questionnaires were sent to interested participants. In this talk, I will present the results, giving visibility to the women working in the optical/infrared interferometric scientific community. I will illustrate the current participation of women in the field, and present the community insights on the current challenges and the way ahead. I will open the floor for discussion in and outside this specific scientific community, seeking similarities, differences, and perceptions on how to move forward to normalise women participation in astronomy.

NASA has invited the ADS team to further expand to other Earth and space science disciplines. Thus, SciX was born as a new service built on top of ADS infrastructure and databases. By serving a broader range of disciplines, SciX will also foster cross-disciplinary discovery. In this informal discussion, I will provide an overview of the current situation, ADS’ way forward, and present SciX. Particular emphasis will be put on how researchers can use SciX effectively with minimal changes to their established workflows.

Reflected light observations will soon open a new frontier in the characterization of nearby rocky exoplanets. ESO facilities, starting with VLT/RISTRETTO and soon ELT/ANDES and ELT/PCS, will enable spectroscopy and possibly polarimetry of non-transiting planets such as Proxima b as spatially unresolved worlds. Reflected light encodes key atmospheric and surface properties, including potential habitability tracers like liquid water and surface heterogeneity. We observe Earth as an exoplanet using Earthshine—sunlight reflected by Earth onto the darker portion of the visible Moon—capturing our planet as a single pixel. Using 3D radiative transfer models with realistic clouds, surface albedo, and ocean reflectance, we test the detectability of signatures such as ocean glint and the primary rainbow, which probe surface liquid water and cloud microphysics. This work establishes Earthshine as a benchmark for interpreting future reflected-light observations of nearby rocky exoplanets.

Studying the chemical composition of the warm gas surrounding embedded solar-type protostars is one of the areas for which the Atacama Large Millimeter/submillimeter Array (ALMA) is particularly well suited. Since Cycle 9, the ALMA Large Program “Complex Organic Molecules in Protostars with ALMA Spectral Surveys (COMPASS)” carried out an observing campaign of a sample of 11 protostellar regions to investigate the chemical impact of their environments and evolutionary stages. This JAO talk will be a mix of technical and scientific, providing an overview of the experience of proposing, preparing, and executing the observations and subsequent data analysis for a Large Program. We recently submitted the first series of scientific papers by the COMPASS collaboration, addressing topics of spatial distribution of complex organic species and their relative abundances, variations among oxygen- and nitrogen-bearing species, methanol and its isotopic fractionation, methyl cyanide isotopologues, a class I methanol maser transition and its association with acetaldehyde. Based on our experience, I’ll summarize the benefits and challenges of unbiased spectral surveys, as well as opportunities in the era of ALMA’s Wideband Sensitivity Upgrade.

Environmental interactions in the densest regions of the cosmic web are a major driver of accelerated galaxy evolution. It is widely accepted that the cold gas reservoirs of cluster galaxies, which fuel star formation and regulate how galaxies evolve, are the components most strongly affected by environmental processes. Ram pressure stripping is one of the most prominent mechanisms driving galaxy evolution in clusters and is often manifested by asymmetric, tailed atomic gas disks. Recent MeerKAT H I observations revealed that this process is acting on a population of starburst galaxies in the Hydra I cluster (de la Casa et al. 2025). This raises the question: is RPS removing gas while simultaneously accelerating its conversion into stars, thus increasing even more the quenching rate of cluster galaxies?

In this talk, I will present a detailed study of the cold gas content of four extremely ram pressure stripped galaxies in the core of the Hydra I cluster that nonetheless exhibit relatively high star formation rates. I will show how their molecular gas distributions, traced by CO(1–0) emission observed with ALMA, as well as the molecular-to-atomic gas fractions, reveal an evolutionary path shaped by RPS. Finally, I will discuss how the stage of ram pressure stripping can be linked to a galaxy’s orbital history and how it can be traced in projected phase space.

Japanese-South American Supernovae (J-SAS) 2026 three-day mini workshop.

The chemical composition of ionized gas is a key tracer of galaxy evolution, but measuring it presents significant challenges. In this lecture, I will introduce the principal tracers of chemical abundances in ionized gas, discuss the main methods used to estimate them, and outline their advantages and limitations. Finally, I will highlight the main sources of uncertainty in abundance measurements and their impact on our understanding of galactic evolution.

A thousand hours of XMM observation time have been allocated to the FornaX Heritage project, making it the largest program since the launch of XMM.

Observations of the Euclid Fornax deep field began in 2024 and will be completed in 2027. The program will achieve unrivalled sensitivity over 10 square degrees in the X-ray, optical, and infrared domains, making the dataset and expected scientific results unique. A few hundred clusters as well as a few thousand AGN will be detected. Around 50 scientists are participating in the project.

During this seminar, we will discuss the scientific motivations of the FornaX project as well as the many challenges related to data reduction and scientific analysis. We will describe the work organization within the collaboration, its implementation in the Euclid consortium structure, and the possibility of involving external scientists.

Numerous follow-up programs will be undertaken to enhance the XMM catalogue of clusters and AGNs (spectroscopic campaigns, detailed studies of particular objects, etc.). Ideas and contributions of ESO scientists will be greatly appreciated!

Website of the FornaX project: https://fornax.cosmostat.org/

This talk will present an overview of the Yebes Radio Astronomy Observatory, located in the municipality of Yebes (Guadalajara, Spain). Its main facilities will be described, along with a review of the most relevant technical and scientific developments carried out at the observatory. In addition, a summary of the results obtained from radio frequency interference (RFI) measurements performed at the OSF and AOS in the 72–90 GHz frequency range during a research stay at the ALMA Observatory will be presented.

The Magnetic activity of cool stars is connected to the stellar age. The activity-rotation relations combined with Gyrochronology give us the big picture of the evolution of cool star activity. However, how similar could co-eval Gyr old stars of the same metallicity and similar mass be in terms of magnetic activity? Little is understood about this intrinsic scatter of activity in cool stars. It is, however, an essential piece of information required to understand the variability in the stellar environment over giga-years of stellar evolution. Including having implications on the evapouration of exoplanetary atmospheres. In my talk, We investigate this scatter using a statistically relevant sample of wide binaries. I show how the co-eval nature of wide binaries can be exploited to find this intrinsic scatter in the activity of cool stars. I additionally present how future works could use this scatter to constrain the activity-age relationship of Gyr old cool stars.

I will present recent ALMA molecular-line studies of nearby star-forming galaxies from the PHANGS survey, with a focus on the dense molecular gas that is most closely linked to active star formation. I will begin with a brief overview of the PHANGS project, which aims to understand the baryon life cycle in galaxies on the scales of individual molecular clouds by combining observations across the electromagnetic spectrum from state-of-the-art facilities such as HST, JWST, VLT, and ALMA. I will then highlight my work within the PHANGS collaboration that extends beyond the low–critical density CO lines observed by the PHANGS–ALMA survey (Leroy et al. 2021). In particular, the ACA Large-sample Mapping of Nearby galaxies in Dense gas (ALMOND) survey (Neumann et al. 2023a, 2025) targets dense molecular gas traced by high–critical density transitions such as HCN(1–0), HCO⁺(1–0), and CS(2–1), which are more directly connected to the local star formation rate in galaxies. Together with additional ALMA pilot studies (Neumann et al. 2024, and work in preparation), these observations demonstrate ALMA’s unique capability to map dense gas tracers across the nearby galaxy population. These data provide new insights into key questions of galaxy evolution and star formation: Is there a universal star formation law? How efficiently is dense molecular gas converted into stars? How do the physical conditions of the gas regulate star formation, and how are these processes influenced by galactic environment and external conditions?

Galaxy clusters constitute a key cosmological probe as their properties are sensitive both to the geometry of the universe and to the growth of cosmic structures. We will review the various cosmological tests involving clusters. We shall then focus on the cosmological forward-modelling of the X-ray properties of the cluster population, which allows bypassing the direct computation of individual cluster masses. Finally, we shall present recent developments using artificial intelligence, allowing for cosmological simulation-based inference; the method relies on purely observable (cosmology-independent) quantities and avoids any use of (cosmology-dependent) mass-observable relations.

The James Webb Space Telescope (JWST) is the most complex and sensitive space observatory ever deployed, combining revolutionary engineering with unprecedented scientific capability. With its segmented 6.5-meter primary mirror and suite of infrared instruments, JWST enables observations of the Universe with extraordinary sensitivity and angular resolution. In this talk, I will discuss the key technical innovations that underpin JWST’s performance, as well as the challenges and excitement of on-orbit commissioning. I will also address some of the operational and technical obstacles encountered during the first years of science operations. Finally, I will highlight a selection of scientific results and demonstrate how JWST’s engineering design directly enables these new discoveries.

Clusters are the largest gravitationally bound entities in the universe and are located at the nodes of the cosmic web. Paradoxically, in these objects, whose mass ranges between 1E13 and 1E16 Mo, the mass of galaxies is negligible. But the interactions between intra-cluster gas and galaxies make clusters very interesting physics laboratories. We will discuss the different methods used to detect galaxy clusters across the electromagnetic spectrum, focusing on the role of the X-ray band in both detection and physics of their evolution.

We will also review the current challenges associated with numerical simulations of clusters.