Seminars and Colloquia at ESO Garching and on the campus

Relativistic cosmic-rays created by stellar and black hole feedback may play an important role in many aspects of structure formation. Cosmic-rays can drive outflows from galaxies and groups, and heat diffuse gas in the circumgalactic and intergalactic medium.  In this talk I will describe some of the possible impacts of cosmic-rays on galaxy formation, observational probes of their impact, and the theoretical uncertainities in our understanding of the role of cosmic rays in structure formation.

Polarimetry of Tidal Disruption Events

(TDEs) provides an invaluable diagnostic for the

geometry and physical mechanisms driving the

accretion flow, potentially distinguishing between

competing emission models. Recent observations

have revealed that even non-jetted TDEs can be

highly polarized (e.g. AT2020mot), raising

fundamental questions about emission mechanisms

during the early stages of accretion. While stellar

stream shocks offer an attractive interpretation, it is

not yet clear whether this is a common underlying

mechanism.I will present results from the Black hOle

Optical polarization TimE-domain Survey

(BOOTES): the first systematic optical polarization

survey of TDEs using the Nordic Optical Telescope,

the Calar Alto 2.2m telescope, the Skinakas

Observatory 1.3m telescope and the Very Large

Telescope. We find a variety of polarization

behaviors across our sample. Combined with

contemporaneous multi-wavelength data, these

trends constrain the geometry and dynamics of the

disrupted debris and the nascent accretion flow. In

particular, we report time-variable polarization

degree and position angle -an effect not previouslyadelerickerby@yahoo.com.au

reported in TDEs- pointing to more dynamic and

anisotropic systems than commonly assumed, as

well as the possible emergence of jets. Our results

showcase how polarimetric monitoring opens a new

window on the mechanisms powering supermassive-

black-hole accretion and on the earliest stages of

accretion-disk formation, and they provide testable

predictions to distinguish shock-powered and

reprocessing-dominated models.

Paul Goldsmith, Shengzhe Wang, Xin Wang, Raphael Skalidis, Gary Fuller, Di Li, Chao-Wei Tsai, Lile Wang, and Donghui Quan

One of the many aspects of interstellar medium (ISM) physics that has remained elusive is turbulence.  A significant fraction of the ISM energy resides in the chaotic (turbulent), superthermal motions of the gas, which play a key role in supporting molecular clouds against gravitational collapse and thus have a major influence on the rate of star formation.The origin and dissipation of this energy on small scales remains poorly understood.  Models of turbulent dissipation regions (TDRs) in the diffuse ISM include intermittent bursts of energy loss that can heat gas to temperatures exceeding 1000 K.  These TDRs  consist largely of warm H₂ molecules, which can be observed through rovibrational transitions at infrared and far-infrared wavelengths.  The emission integrated over larger scales from such regions was observed in regions around the boundary of the Taurus molecular cloud using Spitzer by Goldsmith et al. (2010).  We have used JWST/MIRI to observe two regions in the boundary of Taurus in the 17.04 𝝁m S(1) transition of ortho H₂, and very clearly detected small-scale structure on scales  1” – 2.5” (140 – 350 AU), limited in part by signal to noise ratio considerations (Goldsmith et al. 2025 ApJL).  The column density in the J = 3 level is typically 1.6e17 cm^-2.  This is reasonably well-determined, but the total H₂ column density uncertainty is large because the 28 mm S(0) line, the lowest transition of para H₂, could not be observed with JWST/MIRI.  

We will discuss the implications of these observations in the context of different models of excited H₂ emission based on dissipative vortices and shocks.  We will present constraints on the physical conditions based on limited observations of the S(2) 12.28 𝝁m line with JWST, and the connection with observations of widespread presence of CH⁺ molecular ions in the diffuse interstellar medium which require a high temperature ( ³ 1000K for formation).  The next steps will be to image this emission over larger areas to obtain better statistics on the characteristics of the emitting regions.  This will be carried out in a recently-selected JWST Cycle 5 proposal that will observe four additional sources. 

White dwarfs are at the core of several research areas in modern astrophysics: one of the dominant low-frequency gravitational wave signals that LISA will detect originates from the galactic population of short-period white dwarf binaries; white dwarf binaries are also the progenitors of thermonuclear supernovae (the cosmic beacons that led to the discovery of dark energy); and white dwarfs are also excellent laboratories to study accretion physics. I will give an overview of our observational census of the extremely varied population of white dwarf binaries, and of our theoretical understanding of their evolution.

At the center of virtually all galaxies lies a supermassive black hole (SMBH) with a typical mass of ~0.5% of its host galaxy. Recently, JWST has discovered over-massive BHs (OMBH) at high redshift with M_BH/M_* ~10%, which have been interpreted as remnants from the rapid accretion of recently born SMBHs. However, the processes that can lead to OMBHs are poorly understood. In order to do so, we searched for OMBHs AGN at low redshift within the eROSITA Final Equatorial Depth Survey (eFEDS), covering ~140 deg². Eight OMBHs have been identified, providing the opportunity to study systems in rapid growth in the local Universe.

In eFEDS, deep and high-resolution images from HSC are available, in addition to X-ray fluxes from eROSITA and high S/N optical spectra from SDSS. These ancillary data are used to study the structural and environmental signatures, to discriminate between different formation scenarios, and to link local OMBHs to the extreme systems observed at high redshift. In my talk, I will present the results of morphological and environmental analyses aimed at understanding how these properties relate to the evolution of the host galaxies.

V1125 Sgr is a rare multiperiodic RR Lyrae star exhibiting unusual pulsational properties that place it among a small and poorly understood subclass of RR Lyrae variables. Recent high-resolution spectroscopic analysis reveals that V1125 Sgr is extremely metal-rich and chemically associated with the low-\alpha population of the Milky Way disk, while its pulsational behavior challenges current stellar pulsation models. These properties make V1125 Sgr a unique object that may help resolve the current conundrum surrounding metal-rich RR Lyrae stars and their origin. In this talk, I will present the pulsational, kinematical, and chemical properties of V1125 Sgr and discuss its implications for RR Lyrae evolution and the formation history of the Milky Way thin disk.

Stellar systems are the product of the collapse of dense cores within interstellar molecular clouds. It is therefore important to study dense cores, as the initial conditions for star and planet formation are to be found there, including all the ingredients participating in the spectacular chemical and physical evolution from interstellar clouds to planets such as our Earth. In this context, it is still unclear the extent to which the environmental properties play a role in setting the initial conditions. I will present a comparative study of two dense cores located within the Corona Australis molecular cloud, which reside in two regions that are very distinct in terms of environmental conditions. I will focus on the deuteration levels of key molecular tracers, which are sensitive probes of the physical conditions in the earliest stages of star formation, particularly gas density and temperature.

Luminous high-redshift quasars provide a unique laboratory to investigate the coevolution of supermassive black holes and their host galaxies during the early stages of galaxy assembly. In these systems, AGN feedback is expected to significantly affect the physical and chemical state of the interstellar medium (ISM), potentially regulating the cold molecular gas reservoir that fuels both star formation and SMBH accretion. Interpreting the observed molecular gas properties, therefore requires physically motivated models capable of linking the cold gas excitation to the underlying gas heating mechanisms.

In this talk, I will present a novel analysis of the CO spectral line energy distributions (CO SLEDs) of luminous high-redshift quasars based on a recent model that combines the internal density structure of giant molecular clouds with stellar heating in photon-dominated regions (PDRs) and AGN-driven heating in X-ray dominated regions (XDRs). Applying this methodology to quasars observed in multiple CO transitions allows us to quantify the contribution of AGN radiative feedback to the high-J CO excitation, while simultaneously deriving robust constraints on the CO-to-H2 conversion factor. For the best-sampled CO SLEDs, the inferred molecular gas masses can be constrained with uncertainties below 15%. These results demonstrate the importance of physically motivated CO SLED modeling to accurately constrain the molecular gas content and feedback processes in massive galaxies in the early Universe.

Less than 30 years ago, we did not know whether planets exist outside our solar system. Fast forward to 2026, astronomers have discovered well over 7000 planets orbiting other stars similar to our Sun, including some that may have the right conditions to host life. As we learned that the formation of planets seems to go hand-in-hand with the birth of stars, we begin to wonder:

• What happens to planetary systems when their host stars run out of fuel, and turn into Earth-sized white dwarfs?
• Are those systems, if they exist, detectable?
• What will happen to our solar system, and to the Earth?
• And what are the possible implications for life?

I will discuss the final fate of planetary systems, the observational fingerprints of planets and their debris orbiting white dwarfs, and how studying these exotic systems help us to improve our general understanding of the formation of planets.

Spirals are iconic features of galaxies, and yet conventional theoretical models for how they emerge and evolve only partially capture their observed traits and their connections to their host disks.  Recent JWST observations of beautiful, regular spiral patterns at redshifts z~2 and beyond underscore the need to resolve these theoretical shortcomings.  I will present a new picture of spiral patterns as short-lived density waves, analytically bridging the gap between the conventional long-lived density wave picture and the model of spirals as transient material patterns.  This new view forces a wholesale revisioning of how spirals influence their host galaxies: rather than merely reflecting conditions in the underlying disk, collectively excited spirals actively shape it, producing widespread changes in galaxy structure through dynamical heating and changes in angular momentum.  I will describe how these widespread changes are the very ingredients that give rise to global spiral patterns and naturally lead to stellar bulge growth, radial gas inflows and an overall structural compaction over cosmic time.  The picture of global, collective spiral excitation also has implications for the kinematics and the rich structure of gas disks, as revealed by JWST/MIRI imaging of nearby galaxies. These structures suggest a simple unified model in which radial gas flows appear alongside dynamical heating, and the latter acts as an important source of turbulent motion to offset dissipation.

Despite the key role of the large-scale matter distribution in the Universe in regulating hierarchical structure formation, its impact on the baryonic physics that shape star formation and chemical enrichment histories of galaxies is still not fully understood. In this work, we assess the effect of local and large-scale environmental metrics on stellar population properties and star formation timescales derived from rest-frame optical absorption spectra and photometry of massive LEGA-C galaxies at 0.6<z<1. We report that overdensity derived from reconstructed density field is the main environmental metric driving the stellar population properties of massive galaxies (M_star>10^10 Msun) at intermediate redshifts. We observe that galaxies of a given stellar mass in overdense regions are older and form earlier on and over shorter time-scales than the ones in underdense regions. What’s more interesting, these trends remain after accounting for the galaxies’ hierarchy within groups and clusters and their position in the large-scale cosmic web. Our results suggest that the initial conditions of the matter density field have a profound effect on the quenching and star formation histories of galaxies, leaving an imprint into observed galaxy stellar populations and scaling relations that are already in place at intermediate redshifts.

The Extremely Large Telescope (ELT) is set to transform ground-based astronomy in the 2030s. Yet the scientific return of even the largest telescope ultimately depends on the capabilities of its instruments. The ANDES spectrograph will serve as the ELT’s high-resolution spectrograph, operating across optical and near-infrared wavelengths. Its science goals span some of the most compelling questions in modern astrophysics: detecting biosignatures in the atmospheres of rocky exoplanets, uncovering the chemical fingerprints of the first generation of stars, and testing the stability of Nature’s fundamental constants.

How do such ambitious objectives translate into a working instrument? This informal discussion will explore how cutting-edge astronomical instruments are conceived, designed, and built, and the role ESO plays in bringing them to life.

Measurements of the extragalactic background light in the 1990s revealed that nearly half of all starlight in the Universe is absorbed by dust and re-radiated into the far-infrared. In the decades since, we have come to understand the importance of this dust-obscured mode of star formation, which has dominated the volume-averaged star formation rate density over the unobscured mode for the past 12 billion years. The submillimeter-bright population of dusty star-forming galaxies (DSFGs) contributes substantially, with prodigious assembly of stellar mass at rates of 100-1000+ Msun per year. With telescopes like ALMA and JWST, we can resolve their internal structure for the first time. A large fraction of these extreme objects are well-described as isolated rotating disks that replenish gas continuously from the surrounding circumgalactic medium, suggesting that many are simply the highest-mass end of the star-forming main sequence of galaxies. Their ability to sustain intense, efficient star formation is reshaping our conception of how stellar feedback regulates galaxy growth in the early Universe. I will discuss in particular how gravitational lensing is a key tool for zooming in on critical ~100 pc scale regions. Finally, in the latter part of my talk, I will introduce SN-ECHOES, an upcoming JWST Cycle 5 program designed to search for lensed supernovae in DSFGs and their nearby companions with multi-epoch NIRCam imaging. This program has the potential to discover new candidate supernovae for inferring the Hubble constant, H0, through a technique known as time-delay cosmography, but it will also provide a valuable opportunity to better understand the Mpc-scale environments of extreme DSFGs.

All stars with initial masses below ~10Msun will end their lives as white dwarfs: Earth-sized stellar embers sustained against a gravitational collapse by electron degeneracy pressure. I will: 

• give an overview on the stellar evolution leading to the formation of white dwarfs, with special attention to the outcomes of stars with masses near the boundary to core-collapse supernovae; 
• show how measuring the masses and radii of white dwarfs allows a quantitative test of their internal structure;
• discuss the complex physics encountered in white dwarf envelopes atmospheres which can have effective temperatures in the range of ~3000 to 100,000K;
• illustrate how volume-complete samples including white dwarfs and main-sequence stars can provide constraints on the local star formation history; 
• and show how white dwarfs can serve as cosmic laboratories for fundamental physics at conditions unattainable on Earth, e.g. the behaviour of atoms in magnetic fields of up to 1000 MG.

Binary black holes (BHBs) hold the promise of
"multi-messenger astrophysics": their detections in both gravitational
waves (GWs) and electromagnetic (EM) observations will help reveal
their astrophysical origin and yield novel probes of cosmology,
fundamental physics, and accretion physics.  This is true for massive
BHBs expected to be discovered by the future GW satellite LISA and by
pulsar-timing arrays, and for stellar-mass BHBs already detected by
ground-based detectors.  I will describe how circumbinary gas may
produce characteristic EM signatures for both massive and stellar-mass
BHBs, based on analytic models and hydrodynamical simulations and
discuss some binary candidates identified in optical surveys.

Mergers and interactions are important events in galaxy evolution, and have been shown to enhance star formation rates, decrease metallicities, and disrupt kinematics. Observations in the local universe and galaxy simulations across cosmic time suggest that mergers can also increase turbulence. However, observational studies of interaction-driven turbulence at z > 1 are limited, as kinematic measurements of interactions have been inhibited by beam smearing.

In this talk I will present a systematic observational study quantifying the impact of interactions on galaxy turbulence at cosmic noon (z ~ 1-3). We leverage a spatially non-parametric kinematic deconvolution code to account for beam smearing and apply it to integral field spectroscopic observations of ionised gas from the KMOS3D survey. We compare deconvolved velocity dispersions of interacting galaxies to mass- and lookback-time-matched isolated galaxies. Despite finding increased star formation in interacting galaxies, we find no increase in galaxy-scale velocity dispersions.

Our findings put constraints on the level of interaction-driven turbulence at cosmic noon. I will also discuss our results on the relative increase in SFR of interacting pairs in the context of other merger samples across cosmic time.

The depletion time of cold gas reservoirs in galaxies suggests that ongoing accretion is required to sustain star formation. However, direct detections of gas inflows have remained notoriously challenging. In this talk, I will present the detection of more than 50,000 Na I D down-the-barrel absorbers in galaxies at z < 0.6 from the Dark Energy Spectroscopic Instrument (DESI) Data Release 2. I will discuss evidence for multiple pathways of accretion found in more than 10,000 galaxies, including radial inflows, gas recycling via fountains and mergers. I will then examine the stellar and morphological properties of galaxies hosting inflows and outflows. Finally, I will discuss the derivation of mass inflow and outflow rates from these measurements to understand whether ongoing accretion can sustain the star formation rate of galaxies at low redshift.

Star clusters are the fundamental building blocks of Galaxies. The most young an massive ones host a high concentration of massive stars which, through their powerful stellar winds and eventual supernova explosions, inject enormous amounts of mechanical energy into the surrounding medium. This violent injection of power creates the ideal conditions for efficient particle acceleration, transforming these clusters into Galactic cosmic-ray factories. In recent years, gamma-rays observations have confirmed this high-energy side in many star clusters, with some even reaching the PeV (10^15 eV) regime, challenging our understanding of particle acceleration mechanisms. In this talk, I will review the implications of cosmic ray production in young star cluster: from how this shapes the gamma-ray and neutrino sky, to how sub-GeV particles can provide a significant source of ionization in the surrounding interstellar medium and nearby molecular clouds, influencing the chemical and dynamical evolution of the very sites where the next generation of stars is born. A full understanding of young star clusters as high-energy sources requires a multi-scale and interdisciplinary approach, spanning from stellar evolution, to feedback processes, down to a deep comprehension of the Galactic population and its properties. In turn, high-energy observations potentially provide a powerful and complementary window on these systems, probing recent supernova activity and the ionization state of their environments, making the high-energy perspective a key tool in the broader astrophysical picture, and one that will be further advanced by the next generation of gamma-ray observatories such as the Cherenkov Telescope Array Observatory.

Since the revolutionary discovery of gravitational wave (GW) emission from a binary black hole merger in 2015, the remarkable GW detectors LIGO, Virgo and KAGRA have detected at least 220 compact object mergers. These events are transforming modern astronomy and physics. In particular, the first, and to date the only, binary neutron star merger, dubbed GW170817, was observed in both gravitational and electromagnetic radiation, thus opening up a new era in multi-messenger astrophysics. The multi-messenger characterisation of such an event has enabled major advances into diverse fields of modern physics from gravity, high-energy astrophysics, nuclear physics, to cosmology. In this talk, I will discuss our work in strong-field gravity astrophysics and how combining observations, theory and experiment have been key in making progress in this field. I will present the challenges and the opportunities that have emerged in multi-messenger astrophysics, particularly in the past decade, and what the future holds in this new era.

When we have an unobscured view of the accretion disc, which peaks in the UV, QSOs display very blue UV–optical colours. However, there exists an important population of QSOs, obscured by dust, which are typically uncharacterised by optical spectroscopic surveys. These dusty QSOs could represent an important short-lived transitional phase in the evolution of galaxies (a “blow-out” phase).  Utilising data from DESI we can now, for the first time, explore a statistically significant sample of these reddened QSOs. Combining DESI spectra with radio data from the LoTSS DR2, we find a striking positive relationship between the amount of dust extinction and the radio detection fraction in DESI QSOs. This demonstrates an intrinsic connection between opacity and the production of radio emission in QSOs which may be due to outflow-driven shocks.  Exploring the radio morphologies and spectral slopes, we find that dusty QSOs typically have compact (small-scale) radio morphologies over 144 MHz, 1.4 GHz, and 3 GHz, which show an excess of steep-spectrum emission (α ≈ −1) not seen in normal blue QSOs or dusty QSOs with extended low-frequency radio emission. The strength of this excess steep-slope radio emission increases with increasing dust extinction, along with an overall increase in the radio-detection fraction. The majority of the dustiest QSOs with steep slopes have radio luminosities consistent with the prediction from a wind-shock model.  These results support a picture in which compact, dusty QSOs are undergoing a blow-out phase, where an AGN-driven wind and/or compact jet interacts with a dusty ISM, causing shocks, leading to steep spectral slopes and enhanced radio detection rates.

Spectroscopic surveys have been providing invaluable data in the field of Galactic archaeology and nucleosynthesis. While we are about to witness another revolution in the field with the start of 4MOST this year, we have already started to think about the next generations of spectroscopic survey facilities. In this talk, I will introduce the concept of the wide-field spectroscopic telescope (WST), which is planned for 2040s. I will discuss the need for equipping the WST with a higher spectral resolution spectrograph than the current generation of surveys, and how it can open new windows to study the origin of the elements and stellar populations in the Milky Way. 

PLATO is the ESA's M3 mission optimized for the identification and characterization of Earth-like planets orbiting within the habitable zone of Sun-like stars, i.e., true Earth analogues. The mission development has already been completed and after finishing the late tests at ESTEC it should be shipped after the Summer to Kourou, for a launch planned for January 2027. 
In this talk I will summarize the performance of PLATO, the kind of data it will provide and the characteristics of the different data releases. A call for open time proposals during the first 2 years of operations was released last April 7th, and will remain open until May 21st. I will present how to prepare proposals for open time, the capabilities and limitations, and will provide some guidelines about the Proposal Handling tools at ESA.  

MeerKAT telescope has improved our understanding of various aspects of our radio universe ranging from stars, supernova remnant, pulsars, radio galaxies, Galaxy Clusters, and cosmology. In this talk, I will highlight some of the recent results from MeerKAT with particular focus on the South African Radio Astronomy Observatory (SARAO) MeerKAT Galactic Plane Survey (SMGPS) as it relates to star formation, and the influence of cluster environment to the evolution of radio galaxies as described below.

Intra-Cluster Magnetic field play a key role in the evolution of the cluster member galaxies. MRC 0600-399 is the second brightest member galaxy of the merging galaxy cluster Abell 3376 (redshift 0.0461). Elongated X-ray emission in the east–west direction shows a comet-like structure that reaches the megaparsec scale. MRC 0600-399 shows a 90-degree bend at the contact discontinuity, and the collimated jets extend over 100 kiloparsecs from the point of the bend. I will show the results of the polarization observations of MRC 0600-399 with MeerKAT to explore the properties of the magnetic fields of the galaxy.

Dust and cold interstellar medium (ISM) play crucial role in galaxy evolution. In particular, dust removal processes are tightly connected to quenching star formation (SF). For a deeper understanding of the large-scale interrelation between dust availability and physical properties, we worked with around 18 000 early-type galaxies (ETGs). Combining multi-wavelength spectral energy distribution modeling with Herschel-based dust classification, we obtained a great laboratory to study SF quenching, dust depletion and their influence on physical properties of ETGs. During the talk I will mention some of the results that we obtained in this field.

The large amount and diversity of documentation available for users of the European Southern Observatory (ESO) — including Phase 1, Phase 2, and Phase 3 guidelines, instrument manuals, data-reduction pipeline documentation, and archive interfaces — makes it increasingly challenging for the astronomical community to efficiently find relevant information. To address this, we have developed ESOFinder, an in-house chatbot powered by Large Language Models (LLMs) and Retrieval-Augmented Generation (RAG). ESOFinder integrates public information from instrument manuals, phase 1/2/3 documentation, data reduction pipeline manuals, the ESO Knowledge Base, and key web resources to provide concise, context-aware, and reference-linked answers to user queries about proposal/observation preparation, data retrieval, and data processing. Built on open-source European LLMs (Mistral AI models), ESOFinder ensures data privacy, transparency, and complete control over the knowledge base. Its multi-step architecture allows verification of retrieved documents and generated answers, reducing the risk of hallucinations and improving the reliability of responses compared to generic tools like ChatGPT or Gemini. The current version of ESOFinder is being tested internally at ESO/DMO to evaluate its performance, assess its integration with internal workflows, and identify limitations in coverage and accuracy. These tests will guide further improvements, including the incorporation of additional documentation, and enhanced retrieval strategies. Ultimately, ESOFinder aims to become an interface for users to navigate ESO’s complex observing documentation ecosystem and to support both staff and community astronomers in their daily tasks. In this talk, I will introduce ESOFinder, describe its design—including the RAG pipeline and answer-generation strategy—and present the quality assessment of the tool based on feedback collected from ESO staff. I will finalize with a tutorial on how to use the tool so ESO staff, students, and fellows can help us test it.

Classical Cepheids are fundamental calibrators of the cosmic distance scale and powerful tracers of stellar populations. In this talk, I present a new grid of nonlinear, convective pulsation models computed with the Stellingwerf hydrodynamical code.

The models are computed by simultaneously varying the mass–luminosity relation and the efficiency of superadiabatic convection, enabling a systematic exploration of key physical uncertainties. In the Gaia passbands, they provide the first homogeneous theoretical atlas of light curves, together with new metallicity-dependent Period–Luminosity–Color and Period–Wesenheitrelations. When applied to Galactic Cepheids with measured metallicities, these relations allow the derivation of theoretical parallaxes that can be directly compared with Gaia astrometry, offering an independent assessment of the Gaia parallax zero-point in view of Gaia DR4.

The same framework is extended to the near-infrared by transforming bolometric light curves into the JWST and Roman photometric systems. I will briefly present the first theoretical Period–Luminosity–Color and Period–Wesenheit relations in these bands, currently in preparation, along with initial predictions for the distance scale and a comparison with recent results based on JWST Cepheid samples from the literature.

By combining pulsation models with updated BaSTI evolutionary tracks, new metallicity-dependent Period–Age and Period–Age–Color relations are also derived in both Gaia and JWST passbands, enabling precise age estimates for Galactic Cepheids and providing new constraints on the recent star-formation history of nearby galaxies.

These results define a unified theoretical framework bridging Gaia, JWST, and Roman observations, providing essential tools for next-generation high-precision measurements of the Hubble constant and for the study of stellar populations in the Local Universe. Implications for ongoing efforts within the SPECTRUM project will also be briefly discussed.

The Galactic Center (GC) offers a unique opportunity to study the complex interstellar medium and star formation in a galactic nucleus with high resolution.
In the circumnuclear disk (CND) near SgrA*, using MeerKAT 1.3 GHz continuum and ALMA H40α data from ACES at ~0.2 pc resolution, we separate thermal and nonthermal emission, finding a thermal fraction of ~13%. The equipartition magnetic fields correlate with JCMT CO (J = 3→2) observations data in this region, indicating a pressure balance between magnetic fields, cosmic rays, and molecular gas. While ionized gas and magnetic fields persist, molecular gas density drops within R≤2pc, likely due to feedback from Sgr A*. We find that nonthermal pressure from turbulence balances magnetic and cosmic-ray pressures, exceeding thermal pressure by two orders of magnitude. The environment is characterized by a low thermal-to-magnetic energy ratio, supersonic plasma with an Alfvén Mach number of ≃ 4. A subcritical mass-to-magnetic flux ratio suggests that magnetic fields stabilize the CND against gravitational collapse.
Further from Sgr A*, we are studying the extended ionized gas in Sgr B1, a specific HII region in the GC, to investigate gas kinematics and star-formation feedback.

Axions and other Weakly Interacting Sub-eV Particles (WISPs) are compelling candidates for physics beyond the Standard Model, offering solutions to the strong-CP problem and viable dark matter components. Astrophysical X-ray observations provide a powerful and complementary approach to searching for these particles through their conversion into photons in large-scale magnetic fields.Using data from NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR), we pursue multiple strategies for axion detection. We search for axion–photon conversion in the Sun’s atmospheric magnetic field during the 2020 solar minimum, and for axion production via the nuclear M1 transition of 57Fe in the cores of nearby supergiant stars such as Betelgeuse. In addition, NuSTAR observations of Betelgeuse, following the work of Gianotti et al., probe axion production through the Primakoff process and axion–electron interactions, providing sensitivity to axion–photon, axion–nucleon, and axion–electron couplings. These studies yield the most stringent astrophysical constraints to date, improving previous solar and stellar limits by up to 1–1.5 orders of magnitude. Looking ahead, wide-field X-ray surveys such as eROSITA, with improved effective area and a complementary energy range, offer strong potential to further extend astrophysical axion searches across a broad range of masses and couplings. Together with laboratory experiments such as CAST and the forthcoming IAXO, these results underscore the growing role of X-ray astronomy in probing axions, WISPs, and the dark sector.

Hydra I cluster hosts a large population of Ultra Diffuse Galaxies, which

are defined by their low central surface brightness(μg,0 ≥ 24 mag/arcsec2)

and large effective radii (Re ≥ 1.5kpc). The combination of photometry from

OmegaCAM@VST and VIRCAM@VISTA with integral-field spectroscopy from

MUSE@VLT allowed a detailed study of Globular Cluster (GCs) in the Hydra

I UDGs. In this presentation I will outline the photometric, morphometric and spec-

troscopic criteria for selection of GCs, the analysis of their physical properties

and use to trace the dark matter content and structure of UDGs. We found

that Hydra I UDGs can be divided into two groups: one that is GC-poor, and

the other containing brigth and potentially numerous GCs. Exploiting the es-

tablished relation between GC number and host halo mass we derived the dark

matter content of the UDGs. An independent probe of the dark matter was ob-

tained from the deep H-band observations. The GC counts and stellar masses

indicate that these low-surface brightness galaxies are dark matter dominated

with dynamical to stellar mass ratios of ∼10-1000.

Advances in global magnetohydrodynamic (MHD) simulations have greatly promoted our understanding of astrophysical discs. Applications include compact X-ray binaries, discs in active galactic nuclei and entire galaxies, as well as outlining conditions for planet-formation in circumstellar discs. Depending on the overall degree of ionisation, several independent processes have been identified that may govern the transport of angular momentum. With few exceptions, magnetic fields are found to play the pivotal role in torquing the flow. One major goal in the field is to derive simplified long-term evolution models (e.g., for the disc surface density as a function of radius), and from those derive synthetic populations for comparison with the results found in big ALMA surveys. In the context of planet-formation theories, such models also serve as

the backdrop for planet-population-synthesis codes – governing the growth as well as orbital migration of the evolving planets, and discerning in-situ from ex-situ formation pathways. Irrespective of whether the plasma flow inside the disc remains laminar or becomes turbulent, the evolutionary processes are generally found to depend sensitively on the overall amplitude of the large-scale magnetic flux. This mandates to follow the magnetic flux evolution in tandem, either via non-ideal plasma effects, or –in the case of fully ionized discs– by means of a suitable mean-field description. Finally, we place these developments in the broader context of disc winds, mass loss, and observational diagnostics – highlighting how thermally driven and magnetically mediated outflows emerge from joint MHD and radiative-chemical modelling efforts and suggesting pathways toward directly linking theory to high-resolution disc observations.

The diffuse stellar component of galaxy clusters known as intracluster light (ICL) has been proposed as an observable tracer of the cluster’s dark matter (DM) halo. Investigating the orbital properties of the intracluster stars is essential for understanding how they are linked to the underlying DM distribution and, consequently, assessing the reliability of the ICL as a DM tracer. In this talk, I will describe how the orbital properties of the intracluster stars differ from both the DM and galaxy population, and how this translates into observable quantities. I will then present the emerging theoretical picture of the important factors driving this relationship between the ICL and DM halo.

Accretion disks in quasars cannot be directly resolved in most systems, so indirect methods are needed to study their structure. One of these methods is chromatic microlensing in gravitationally lensed quasars, where stars in the lens galaxy produce different magnifications for emission regions of different size. This effect can be detected by comparing the flux ratios of the continuum and the emission line cores between the lensed images, with the emission line cores defining the baseline for no microlensing and the wavelength dependence of the continuum flux ratios constrains the size of the accretion disk. Then, we can use simulations to estimate both the disk size and the temperature profile.

In this talk, I will present a spectroscopic analysis of four lensed quasars observed with VLT/X-shooter and FORS2. We detect chromatic microlensing in all four systems and use it to estimate the accretion disk size and the slope of the temperature profile. We find accretion disk sizes larger than those expected from the standard thin-disk model, while the inferred temperature profiles are in better agreement with the thin-disk prediction than in many previous microlensing estimates. I will also discuss the differences among the systems and their implications for the interpretation of single-epoch microlensing measurements.

Detections of simple and complex organic molecules (COMs) in the interstellar and circumstellar medium are noteworthy because of their potential as building blocks of more complex, biologically relevant species. Widely detected across all evolutionary stages of star and planet formation, detections of COMs in protoplanetary disks are of particular interest, as part of this material will be incorporated into forming planetary systems, with significant implications for habitability prospects. However, their detection is hampered by the cold conditions that sequester organic material—especially O-rich species—into the ice mantles on dust grains. Consequently, catching O-bearing COMs in the gas-phase of protoplanetary disks is particularly challenging, unless exceptionally warm conditions sublimate material inherited from earlier evolutionary stages. Still, in cold protoplanetary disks, exposure to stellar UV radiation from the central pre–main sequence star may promote not only their release into the gas-phase but also further in situ chemical complexity. To test this, we need to identify and characterize chemical tracers sensitive to these processes—that is, species whose gas-phase presence is favored by UV irradiation. In this talk, we will discuss how this can be addressed from an observational perspective by exploiting the unprecedented capabilities of ALMA, including the study of chemistry in other UV-irradiated environments and ongoing efforts across multiple Large Programs focused on protoplanetary disk chemistry, such as DECO, DiskStrat, and CHEER.

Ionization within protoplanetary disks is a fundamental driver of complex chemistry, especially in the formation of the complex organic molecules.  The ionization rate in the upper layer of disks has only recently been inferred indirectly via chemical modelling of spatially resolved (≳50au) Atacama Large Millimeter/submillimeter Array (ALMA) line observations of the exotic molecules N2H+ and HCO+ for a small number of disks. Furthermore, spatially unresolved JWST/MIRI spectroscopic observations of TW Hya’s inner disk ≲1au) were able to detect HCO+ and CH3+ lines in its inner regions. Their abundances are very sensitive to the ionization rates from the different sources.  They show that current ionization prescription by disk structure models under-evaluates the ionization in DM Tau inner regions (r < 100 au).  We found that stellar energetic particles could be a significant source of ionization, both at the altitude where the lines were observed and within the midplane up to 30 AU from the star. 

Early high-energy emission provides a direct window into the physics of relativistic jets, the properties of the central engine, and the underlying radiation mechanisms. This is particularly important in the era of multi-messenger astronomy with gravitational waves, as binary neutron star mergers are possible progenitors of short gamma-ray bursts (GRBs). 

In the first part of my talk, I will present a systematic study of the early X-ray emission of merger-driven GRB candidates. Using 20 years of data from the Neil Gehrels Swift Observatory, we performed a time-resolved spectral analysis of their bright steep decay phase, covering the 0.3-150 keV energy band. We adopted both a physical synchrotron model and an empirical smoothly broken power-law model, allowing us to track the evolution of the spectral peak energy and bolometric flux during the steep decay. We find a tight correlation between rest-frame peak energy and isotropic luminosity, providing new insight into the intrinsic properties of short GRBs. We also assess the detectability of these sources with wide-field X-ray cameras such as Einstein Probe.

In the second part of my talk, I will discuss GRB 250702B, detected by Fermi Gamma-ray Burst Monitor and followed up by Swift and the Nuclear Spectroscopic Telescope Array. Its gamma-ray emission lasted over three hours, making it the longest MeV transient ever observed, and was followed by a rapidly decaying soft X-ray counterpart over the subsequent ten days. We performed a time-resolved spectral analysis of both the gamma-ray and X-ray emission. The extreme duration, spectral properties, X-ray evolution, and energetics suggest the emission originates from a relativistic jet launched during the tidal disruption of a star by a compact object.

The tidal breakup of binary stars by a massive black hole (MBH), known as the Hills mechanism, occurs when a binary approaches sufficiently close to the MBH. This well-known process produces a hyper-velocity star that escapes the galaxy and a captured star that is tightly bound to the black hole on a highly eccentric orbit.

In this talk, I explore what happens both before and after the Hills breakup. Prior to disruption, perturbations from the MBH over numerous pericenter passages can excite the inner binary orbit to high eccentricities, triggering strong tidal interactions between the two stars. We find that a significant fraction of initially wide binaries are driven into close configurations through tidal interactions in the chaotic regime, and subsequently undergo Hills breakup as close binaries.

After the breakup, the long-term evolution of the captured stars can produce a variety of nuclear transients. These include repeating partial tidal disruption events (TDEs) on timescales of years or longer and quasi-periodic eruptions (QPEs) with periods ranging from hours to months. We further show that collisions between Hills-captured stars and accretion disks formed by unrelated TDEs can efficiently circularize their orbits, providing a natural pathway for producing the shortest-period (sub-day) QPEs.

Artificial Intelligence (AI) has changed our way of assessing, processing, and distributing information, and Large Language Models (LLMs) like Chat GPT, Gemini, Claude and others could be seen as a replacement of intellectual performance previously only available through human intelligence. In the scientific community, many of us have been using AI and LLMs to accelerate their scientific productivity. However, it is unclear whether LLMs are actually needed to do high-quality science or simply yield higher productivity without substantially extending knowledge? This informal discussion was triggered by a discussion I had with Jason at the ESO guest house in Chile in January. I would like to discuss whether science actually profits from LLMs or if these tools rather undermine novel, quality research by design.

By harnessing the unique capabilities afforded by optical interferometry, VLTI/GRAVITY+ has recently become a powerful new tool for the direct detection and characterisation of exoplanets. Its extreme astrometric precision allows us to accurately constrain orbital geometries and dynamical masses just as its direct K-band spectra permit peering into the atmospheres of these objects. On top of this, its unmatched inner working angle enables exoplanet detections at separations of a few AU from the stellar hosts, a parameter space currently inaccessible to classical imaging instruments. Combined with the plethora of astrometric data contained in Gaia DR4, we will soon be able to efficiently build a population-level sample of benchmark exoplanets with direct mass measurements on orbits comparable to those found in our own Solar System. Besides building an extensive target sample for future follow-up with ELT/METIS, exploiting the profound synergies between Gaia DR4 and GRAVITY+ in a concerted large-scale follow-up effort will shed light on long-standing questions as to the giant planet occurrence rate around the water ice line, preferred formation channels, the validity of initial entropy models, and cloud properties around the L-T transition. In this talk, we make the case for focussing these endeavours in a coordinated and collaborative ESO Large Programme.

We explore the formation history of the Milky Way using RR Lyrae variable stars (RRLs) as fossil tracers of ancient stellar populations. The investigation focuses specifically on the Oosterhoff dichotomy, a phenomenon characterized by the separation of RRLs into two distinct groups in the Bailey diagram. The primary objective of this research is to confirm whether this dichotomy is an intrinsic feature of the Galaxy or if it was "imported" through merging events with dwarf galaxies, such as Gaia-Enceladus and Sagittarius. To test this hypothesis, chemo-dynamic classifications from existing literature were applied, analyzing their distribution in the integrals of motion space to distinguish between in situ and accreted populations. A new Period-Wesenheit-Metallicity (PWZ) relation was derived to ensure the accuracy of the distances required for the dynamical analysis. The adopted methodology relies on a robust statistical approach based on: the use of photometric parallaxes combined with Gaia astrometric data, a Bayesian MCMC (Markov Chain Monte Carlo) algorithm for parameter inference. Preliminary results indicate that the PWZ relation coefficients are consistent with current literature. Future work will involve a detailed characterization of the pulsational properties (including Fourier parameters) for each identified dynamical component, aiming to reconstruct the early evolutionary stages of our Galaxy with greater precision.

For decades, the standard paradigm has held that internal photoevaporation efficiently carves clean, empty gas cavities in protoplanetary discs, directly producing the transition discs we observe. By self-consistently coupling the evolving disc structure with photoevaporative flows in 2D radiation-hydrodynamical simulations, we revealed a very different dynamical reality. Once a density depression begins to form, the local mass-loss rate sharply drops, effectively choking off the wind. Simultaneously, viscous inflow and radial surface flows partially refill the gap. The result is not a clean cavity, but a persistent, shallow gas depression. Nevertheless, a pressure maxima forms at the outer edge of the gas depression acting as a dust trap, creating the observational illusion of a cleared transition disc. Finally, we provide a new, dynamic 1D mass-loss prescription that captures this stalling behavior, offering an updated tool for planet population synthesis models.

We have known for decades that magnetic fields and relativistic particles (cosmic rays) can play a key role in some astrophysical environments. But it has only recently become possible to model these directly including other key physics (like radiative cooling, self-gravity, star formation, etc.) in models of galaxies and super-massive black hole growth and “feedback.” Moreover those simulations have historically been limited to a very narrow dynamic range of scales being probed. I’ll discuss how a combination of new physics and new numerical methods has led to breakthroughs that now allow us to simulate problems like supermassive black hole growth, star and galaxy formation with truly unprecedented dynamic range reaching from the horizon to the intergalactic medium. These have revealed some major surprises. In particular, non-thermal physics may be vastly more important on both the smallest and largest scales, compared to previous assumptions. I’ll show how these simulations predict qualitatively new forms of strongly-magnetized accretion disks around supermassive black holes, that can resolve many decades-old observational puzzles and make new unique observational predictions. At the same time, the feedback from supernovae and black holes could be, on the largest (circum and intergalactic medium) scales dominated by cosmic rays. I’ll show how recent new observations of X-rays and the Sunyaev-Zeldovich effect, in particular, appear to be indicating that most of the pressure on these scales is not — as assumed in almost all models for decades — primarily thermal, but appears to be coming from cosmic rays. And I’ll show how new observations can probe this further over a range of galaxy mass scales.

Despite the century-long study of star-forming regions, we still do not have a clear observational picture of how star clusters actually assemble:
Is there a switch between hierarchical and monolithic formation? 
When do young stars decouple from their parent gas clouds? 
Current formation theories rely heavily on simulations, which often offer contrasting predictions. But with new data from multi-epoch surveys, we can finally push the boundaries of observational science and address the questions from a data-driven viewpoint.
I will briefly introduce these open questions and why they matter, and then discuss how multi-epoch NIR surveys like VISIONS, combined with new machine-learning tools, are letting us measure the motions of deeply embedded young stars and even the ISM itself. I will show what these measurements are telling us about cluster formation and how this will improve in the era of JWST, Roman, and Vera Rubin.

The interpretation of stellar surface images, fundamental parameters, stellar variability, and the detection and characterization of hosted planets requires realistic simulations of stellar convection. Regarding exoplanetary atmospheres, a time-dependent representation of the background stellar disk using 3D radiative-hydrodynamical (RHD) simulations is a natural and necessary step toward a better understanding of stellar properties and enabling a detailed and quantitative analysis of the atmospheric signatures of hosted planets. 3D RHD simulations have been, and will continue to be, crucial for studying the properties and dynamics of evolved stars as well. I will present how these simulations and their observables extend across the M-type domain of the Hertzsprung–Russell diagram.

We used ALMA for what it was built for: opening up new science by observing in the high frequency Band 10 (and 9). Specifically, we targeted the [OI] 63µm fine structure line in a sample of 12 gravitationally lensed dusty star-forming galaxies at 4.2<z<5.8. This line was expected to be as bright as the [CII] and [OIII]88µm lines, but we found it to be almost 100x fainter. Such extreme line ratios can only be explained by very strong self-absorption by foreground material within the galaxies, as also predicted in new hydrodynamical simulations. We only detect several narrow, spatially localized  [OI] 63µm emission “escape channels” preferentially detected in regions with weak or absent dust continuum emission. Intriguingly, in a few cases, the [OI] 63µm is detected in absorption against a bright continuum, reaching levels below the local CMB temperature. This suggests the presence of low-excitation, low-density gas along the line of sight. We argue that the very high [OI] 63µm optical depth is the dominant effect causing this strong absorption, limiting the diagnostic power of this line to trace regions of massive start formation in high-redshift DSFGs.

Unraveling the planet formation process and the origin of the diversity of planetary systems require a comprehensive understanding of the planet-forming disks surrounding young stars. ALMA’s unprecedented spatial resolution and sensitivity have enabled a detailed examination of the physical and chemical structures of planet-forming disks (at ~10 au scale). The detections of gaps and rings in numerous disks have transformed our understanding of disk evolution and planet formation. I will first provide a summary on the detection and characterization of disk substructures, and discuss the exciting avenue of young planet search as guided by these disk features. While ALMA excels in probing the bulk disk property, the very innermost disk (within 1-3 au), remains elusive to its capabilities, which can now be well studied with JWST. In the second half of the talk, I will touch upon our expanding view of the inner disk chemistry, especially the interplay with substructures at large disk radii and for disks around very low-mass stars. By leveraging the capabilities of ALMA and JWST, we aim at establishing a global view of disk evolution, laying the groundwork for the development of a robust predictive model of planet formation.  

Bio: Feng Long is an Assistant Professor at the Kavli Institute for Astronomy and Astrophysics of Peking University. After receiving her PhD from Peking University in 2019, she spent three years as an SMA Postdoc Fellow at the Center for Astrophysics | Harvard & Smithsonian. From 2022 to 2025, she worked at the University of Arizona as a NASA Sagan Fellow. Her research uses advanced facilities like ALMA and JWST to study protoplanetary disk evolution and planet formation. 

Asymptotic Giant Branch (AGB) stars play a key role in galaxy evolution 

by producing dust and enriching the ISM. Moreover, during their 

thermally pulsing (TP-AGB) phase, they can contribute up to 50% of the 

integrated NIR light in galaxies with stellar ages between 0.2 and 2 

Gyr. Accurately modeling the TP-AGB phase is therefore essential for 

reliable SED-based estimates of stellar ages, masses, metallicities, 

dust attenuation, and photometric redshifts. This will become even more 

relevant for galaxy evolution studies using upcoming deep, wide-area 

surveys such as Euclid and LSST. However, the TP-AGB phase is 

notoriously difficult to model, leading to uncertain lifetimes and NIR 

luminosities, and previous small-sample studies reported contradictory 

results. We address this remaining uncertainty using ultra-deep 

JWST-NIRspec spectra of a sample of 10 z~0.7 quiescent galaxies, 

combined with a systematic analysis of a much larger quiescent galaxy 

sample based on LEGA-C spectra and COSMOS-Web photometry. In this talk, 

I will present our measurements of the TP-AGB contribution to the NIR as 

a function of stellar age and metallicity and discuss the implications 

for galaxy evolution.

When governments decide whether to invest in long-term international research infrastructures such as ESO, what factors shape their decisions? Is scientific excellence sufficient? What additional returns do Member States expect?
As part of my role, I report regularly to ESO’s Member States on the national impact and benefits of membership. While scientific leadership and discovery remain integral, they represent only part of the value proposition that governments evaluate.
I will speak on the broader framework within which governments assess participation in large-scale astronomy organisations. How expectations have evolved, the role of science diplomacy in decision making, and the role of astronomers in the long-term organisational sustainability for ESO.

Outflows driven by the propagation of radio jets in galaxies used to be so rare that they were thought of as oddities. Thanks to ALMA, instruments on the VLT, and JWST, jet-driven outflows are now routinely detected in the local and distant Universe. They are even used to indicate the passage of jets they have outlived, which can no longer be detected at radio wavelengths. The molecular gas in such outflows is heated, excited, and often dispersed, becoming optically thin. Yet, very dense cores are also found within the flow. I will summarize findings on the properties of the gas in jet-induced molecular outflows, and I will address how we can link them to ongoing star formation changes. For this purpose, I will present a stability analysis for entrained clouds, performed with the aid of data from all the above-mentioned facilities and excitation/radiative transfer codes that provide the multi-phase gas pressure.

Over the past decade, observations of protoplanetary disks have revealed numerous substructures in their dust distributions at both (sub)millimeter and near-infrared (NIR) wavelengths. These features provide a blueprint for the wide range of physical properties and orbital architectures observed in exoplanetary systems. Although the origins of these disk substructures remain uncertain, their multiplicity reflects the underlying gas dynamics, as dust grains are coupled to gas motion. By examining the motion of gas within these disks, we can investigate the physical processes that govern disk evolution and planet formation. In this talk, I will present an overview of recent and upcoming science results from the exoALMA Large Program, a sub-millimeter planet-hunting campaign that employs molecular line observations to uncover the complex gas kinematics of protoplanetary disks.

The recently launched XRISM (JAXA/NASA/ESA) observatory has provided long-awaited high-resolution spectra of extended X-ray sources, including clusters of galaxies. These spectra enable direct measurements of gas kinematics in the intracluster medium (ICM). I will present XRISM results from observations of well-known bright galaxy clusters and discuss their implications for the physics of AGN feedback, ICM turbulence, cluster mergers and their assembly history, and cluster mass measurements for cosmology. Finally, I will compare these measurements with cosmological simulations, highlighting both what they reproduce and remaining challenges.

The SDSS-V Local Volume Mapper is a novel integral field spectrograph with an extremely wide field of view. It is currently conducting a survey of a large fraction of the Southern Milky Way plane and the Magellanic Clouds.
In this talk I will present the results of Early Science observations which target the massive globular cluster Omega Centauri.
Due to its brightness and large extent in the sky, this cluster provides a perfect benchmarking target for extragalactic stellar population studies. At the same time the wide LVM field of view allows study of the poorly constrained kinematics in the outer region of the cluster, providing a missing piece for dynamical modelling efforts.

From the integrated light we successfully measure the rotation curve of the cluster out to a radius of three half-light radii, significantly extending the range of our previous kinematic investigations based on resolved measurements with VLT MUSE. We can also recover the age and the metallicity of the cluster and provide detailed comparisons between different single stellar population models.

Thanks to the Hubble Space Telescope, combined with major ground-based facilities and gravitational lensing (“cosmic telescopes”), we have entered an era in which stellar clusters can be identified at cosmological distances. The James Webb Space Telescope (JWST) is now transforming this field -- and, more broadly, our view of the early Universe. With its exceptional sensitivity and angular resolution at infrared wavelengths, JWST, when coupled to strong gravitational lensing, can isolate individual star clusters even within the first half 0.5 Gyr of cosmic history. This lensing-enhanced spatial contrast enables the identification of candidate progenitors of present-day globular clusters and places them in the context of key questions, from the sources of ionizing photons during reionization to the emergence of extremely metal-poor (possibly near-pristine) star formation, and the possible connection to black-hole seeds. Looking ahead, ground-based facilities in the 2030s equipped with extreme adaptive optics (AO) -- most notably the ELT -- will consolidate these studies and push to even finer physical scales. The synergy between space and ground-based facilities will thus open an unprecedented window on the earliest stellar systems, connecting parsec-scale star formation to the assembly of galaxies and black holes in the reionization era.

Red supergiant stars (RSG) are experiencing significant mass loss. It ultimately determines their late evolution into a type II supernova leading to a remnant that can be a neutron star or a black hole. Therefore, understanding the mass loss properties is key to predicting their final fate. Optical interferometry has previously shown that the surface of RSGs present prominent convective features. Further away from the photosphere, several direct images of RSG have revealed large clumps of dust in their surroundings, providing clear evidence of inhomogeneous mass loss. However, current radiative-hydrodynamics simulations of RSG fail to explain how such an amount of material leaves the star, although they do predict the strong convective activity. Antares, the closest RSG, is the ideal laboratory to better investigate the mass-loss phenomenon, its triggering mechanisms, and the processes by which material escapes from the star. Using a multi-epoch VLTI/GRAVITY dataset, we aim to link the convection on the star’s photosphere to the material in the upper molecular layers, and ultimately unveil the physical mechanism that triggers mass loss.

I will present an overview of the instrumentation development program and strategic R&D interests of the Herzberg Astronomy and Astrophysics Research Center, part of the National Research Council of Canada. Active major facility class instrumentation development includes real time control systems for the ELT's ANDES and MORFEO  instruments, next generation correlators for ALMA and the SKA mid telescopes, opto-mechanical systems for the Gemini Infrared Multi-Object Spectrograph (GIRMOS) and the second generation of the Gemini Planet Imager (GPI2), as well as low noise amplifiers for SKA mid and CCAT. I discuss the related R&D program and technology development roadmaps, including but not limited to adaptive optics, high contrast imaging and detectors. Finally, I discuss the evolving Canadian astronomical landscape and highlight future opportunities.

Understanding how atmospheres move is key to understanding the inner workings of planets - how their material is distributed and the subsequent implications on their formation and potential to host life. In our own Solar System, the observable fingerprints of winds in spectra are easily accessible and have provided substantial input into the composition and formation of our gas giants. Until recently, however, directly measuring winds in exoplanet atmospheres remained out of reach.

In this talk, I will present recent results that use ESPRESSO in 4-UT mode to directly probe atmospheric winds on close-in exoplanets. By resolving individual atomic absorption lines during planetary transit, we can detect Doppler shifts caused by day-to-night flows and global circulation patterns at different depths in these distant worlds. These measurements provide the first direct three dimensional constraints on wind speeds and directions in exoplanet atmospheres.

I will outline the observational technique, discuss what these wind measurements tell us about atmospheric dynamics and energy transport under extreme irradiation, and highlight how such observations are opening a new window on comparative planetology beyond the Solar System — just in time for the ELT era.

James Webb Space Telescope (JWST) has opened a new window into the early universe, enabling sensitive, high-resolution images of the near-infrared sky and spectroscopy of faint, distant sources. The JWST Advanced Deep Extragalactic Survey (JADES) is a collaboration of the NIRCam and NIRSpec GTO teams pooling over 750 hours of JWST time to conduct an ambitious study of galaxy evolution in the Great Observatories Origins Deep Survey GOODS-South and GOODS-North fields. I will discuss exciting results from JADES observations about discoveries in the distant (z>12!) universe that provide new insight into the process of early galaxy formation and cosmic reionization. We discuss how our new constraints on star formation and galaxy growth at the very earliest times are rewriting the story of how the first galaxies form and evolve.

One of the most surprising results coming out of the first years of science operations with JWST is the unexpectedly high abundance of actively accreting black holes in the early Universe. Compared to the local population, many of these early black holes appear to differ in various aspects, such as their relation to their host galaxies or their multi-wavelength properties. These observational findings challenge our understanding of the past evolution of present-day supermassive black holes, and provide new ways to constrain theoretical models of black hole formation and growth. I will give an overview of recent observational results on massive black holes in the first few billion years, driven by the unprecedented capabilities of JWST to explore cosmic dawn, and with a focus on results from the GTO and GO NIRSpec-IFS surveys GA-NIFS and BlackTHUNDER.

Combining telescopes (or antenna) has been a staple of observatory design and operations. The technique, known as interferometry, is rooted in the nature of the light we are seeking to observe: because of light’s wave nature, interferometry provides high angular resolution without having to build prohibitively large collecting areas. Our own Very Large Telescope Interferometer (VLTI) is one of the very few interferometers operating in the optical regime, and arguably the most ambitious one with the largest telescopes, most advanced adaptive optics and laser guide stars.

The recent first light of the 4 UTs with laser guide stars is an opportunity to retell the story of VLTI, which started in the late 1970’s with extraordinary scientific vision and perceptive technical foresight. What kind of observations are carried out by VLTI? how unique are its contributions? What will the recent upgrade (GRAVITY+) yield? After introducing a brief history of the VLTI (and the VLT), I will showcase the recent and prospective astrophysical results of this unique facility.

An Informal Discussion showcasing the analysis of Chen et al. 2025, “Who Uses Whose Telescopes? Analyzing the Knowledge Geography and Research Dominance of Global Astronomical Facilities”, sparked curiosity about the initiatives ESO has supported in Chile (its hosting country) regarding scientific and technological advancement. Since 1995, ESO has committed to supporting the development of astronomy in Chile, in the form of direct funding for research, education and training. We will show the main legal basis of the involvement of ESO in the development of astronomy in Chile, based on the “Acuerdo” for the construction of telescopes and its further modifications. Then, we will discuss the variety of astronomy initiatives supported by ESO, with an emphasis on the projects financed by the “Comite Mixto ESO-Chile", including its regional call, and the participation of Chilean students and postdocs in ESO programs.

Distinct sets of elements are produced from different nucleosynthesis processes in galaxies that occur in core-collapse supernovae (CCSNe), Type-Ia supernovae (SNe Ia), asymptotic-giant-branch stars (AGBs), and various other enrichment sources. I will discuss both supernova and AGB enrichment in galaxies, as probed from integrated deep emission-line spectra of star-forming galaxies (SFGs) with direct elemental abundances. Galactic chemical enrichment from SNe has historically been constrained by alpha-enrichment ([α/Fe]) and metallicity ([Fe/H]) measurements from deep absorption-line spectra of individual stars in the Milky Way (MW) and some local group dwarf galaxies (and a handful of massive ellipticals with deep integrated absorption-line spectra out to z~2). The vast majority of galaxies in the universe are SFGs, with their fraction increasing with increasing redshift. We have recently shown that for SFGs (having deep integrated spectra with temperature sensitive auroral lines, enabling direct abundance determination), the oxygen-to-argon abundance ratio, log(O/Ar), vs Ar abundance, 12+log(Ar/H), is analogous to [α/Fe] vs [Fe/H] for stars. At low-z (z<0.3) with SDSS observations of ~800 SFGs, we show that galaxy chemical enrichment history is driven primarily by the interplay of CCSNe and SNe Ia, with their impact varying with galaxy mass. With a smaller sample of 11 SFGs at high-z (z~1.3-7.7) with JWST/NIRSPEC and Keck/MOSFIRE, we show that MW-like CCSNe and SNe Ia dominated enrichment processes occur at least out to z~4, beyond which rapid but intermittent star-formation may be at play. On the other hand, AGB nucleosynthesis is probed in SFGs from relative abundances of N & O. NIRSPEC@JWST observations revealed a handful of SFGs at high-z with high N/O abundance ratio at low O/H, dubbed extreme N-emitters. Some attribute this to extreme enrichment mechanisms active only in the early universe. However, we found high N/O at low O/H for a sample of 19 low-z (z<0.5) SFGs (a five-fold increase compared to earlier) using DESI DR1 spectra. The enhanced N/O values can be explained using galactic chemical evolution (GCE) models having long-lived N-enhancement from AGBs, coupled with strong outflows.

I will discuss the results from my recent research that explores multi-phase gas reservoirs in extreme environments during the epoch of peak cosmic star formation (z ~ 2-4). Using multiwavelength observations, we reveal how massive gas structures fuel intense star formation in overdense regions while being shaped by energetic feedback processes. Our work demonstrates that both high-resolution interferometry and wide-field observations are essential for understanding the complete picture of gas as protoclusters begin to take shape.

High-resolution data resolve compact cores with extraordinary star formation rates and reveal narrow metal-enriched filaments tracing galactic outflows extending 60+ kpc from their hosts. Meanwhile, single-dish observations recover a significant excess of gas than interferometric maps alone, revealing extended low-surface-brightness reservoirs that could represent a proto-intracluster medium. Together, these findings reveal complex gas ecosystems in the early universe where intense star formation, AGN activity, and powerful feedback coexist, driving the assembly of the most massive cosmic structures.

Understanding the role of magnetic fields in the formation of planetary systems has been a long-standing goal of astronomy. Although magnetic fields are widely believed to be a critical ingredient in planet formation, direct observational constraints during the protoplanetary disk phase remain limited. In this talk, I will review previous efforts to detect magnetic fields threading protoplanetary disks and discuss the key limitations of these approaches. I will then present a new observational technique that we have recently developed, which enables a more robust detection of disk magnetic fields. Finally, I will place these results in the broader context of Solar System constraints and outline how forthcoming observations and planned upgrades to ALMA will further advance this field.

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.

Faint blazars are often difficult to identify, as their recognition typically requires cross-matching positional counterparts across radio, optical, and X-ray catalogs. To support high-energy studies for the Cherenkov Telescope Array Observatory (CTAO), we adopted an alternative approach. Starting from the Fermi-LAT 4FGL-DR4 catalog (5,062 γ-ray sources at galactic latitude |b| > 10°), we searched for blazar counterparts using Firmamento*, a web-based platform developed within the Open Universe initiative of UNOOSA. Firmamento integrates multi-frequency data and high-level analysis tools for spectral energy distribution (SED) studies.
By combining automated algorithms with visual inspection and validation by experts, high-school, and undergraduate students — given the large size of the sample — we discovered 421 new blazar associations, reducing the fraction of unassociated Fermi-LAT sources from 25% to 17%. The resulting catalog, 1FLAT, has been published in the Astrophysical Journal Supplement Series.
This talk presents both the scientific results and the educational framework behind this collaborative effort.

 

* https://firmamento.nyuad.nyu.edu/data_access