Seminars and Colloquia at ESO Santiago

Over the past two decades, we have sketched the broad outline of exoplanet demographics. The frontier of the next decade hinges on our ability to understand the formation history of these exoplanets through their compositions, masses, and birth environments. There is a community-wide interest in studying planet formation via measuring their elemental abundances (e.g., carbon-to-oxygen ratio; C/O), given that different formation processes yield distinct relative compositions between planets and their parent stars.

In this talk, I will introduce an ongoing spectroscopic program designed to measure elemental abundances across a large ensemble of directly imaged exoplanets, benchmark brown dwarfs, and their host stars. I will spotlight a remarkable planetary system (AF Lep A+b) to illustrate our analysis approaches. Our spectroscopic analysis of planets leverages (1) a novel retrieval framework that we developed to robustly characterize cloudy self-luminous atmospheres, and (2) a Bayesian forward-modeling framework enhanced by machine learning techniques and Gaussian processes. By applying these methods to the benchmark brown dwarfs within our sample, we have been quantifying the systematic errors inherent in state-of-the-art model atmospheres, enabling reliable atmospheric characterization for gas-giant planets. Looking ahead, the wealth of forthcoming data from large sky surveys such as LSST and Gaia DR4 will substantially expand the targets of our program, illuminating the diversity of outcomes in the realm of planet formation.

This is part 3 of the 3-part series "Improving interferometric imaging fidelity through self-calibration"

To study Earth as an exoplanet, we observe its spatially integrated visible reflected spectrum via the dark side of the Moon (Earthshine). This approach enables us to examine Earth from different phase angles as the Sun-Earth-Moon geometry changes. Employing the full-3D Monte Carlo radiative transfer code MYSTIC, we generate synthetic spectra and phase curves of Earth as an exoplanet in intensity and polarisation. Our simulations incorporate realistic 3D atmospheres, patchy clouds, and 2D planetary surfaces. By comparing these simulations with Earthshine observations, we assess our sensitivityto detect liquid water on the surface of the planet via ocean glint and liquid water clouds. Comparing spectroscopy and spectropolarimetry, we propose a newstrategy for assessing the habitability on Earth-like exoplanets in the future.

Observations of Supernova progenitors are rare, obscuring what kind of star leads to what type of SN. In this talk, I present a new diagnostic for determining the mass at explosion (M_preSN) of Stripped progenitors (Types IIb, Ib and Ic), which is based on the strength of [N II] 6548, 6583 λλ emission in the nebular phase. In my talk, I will walk you through how this diagnostic is first obtained for model SN spectra, spectra which have been simulated using the SUMO code for five SN progenitor models with different masses at six different epochs. Then, I will compare these results with a sample of observed SESNe to be able to provide progenitor mass estimates for them. Finally, I will put these results in the context of the different SN types present in the sample. 

I will summarize recent advances in understanding star formation across the local galaxy population. These advances are enabled by state-of-the-art observations with ALMA, VLT/MUSE, HST, and JWST, which resolve nearby galaxies into fundamental units of star formation (molecular clouds, HII regions, and star clusters). We find that molecular clouds, which set the initial/boundary condition of star formation, are strongly coupled to the large-scale properties of their host galaxy. Once star formation takes place, feedback from young stars quickly disperses the natal cloud, resulting in an overall low star formation efficiency. While this process is violent and highly non-equilibrium on 10-100 pc scales, star formation in massive disk galaxies appears self-regulated when averaging over kpc-scale regions -- supernova feedback counteracts turbulence cascade and cooling losses in the long run and keep the interstellar gas in a quasi-equilibrium state. I will also highlight some latest results from long-baseline ALMA observations in Cycle 8 and 9. Combining them with match-resolution HST and JWST data, we can probe star cluster formation and intricate gas structures down to <10 pc scales, thereby bridging the gap between Galactic and extragalactic studies.

During its mission, Euclid will observe tens of thousands of dwarf galaxies in the Local Universe with fantastic depth and spatial resolution. Such a dataset enables us to identify globular clusters (GCs) around these dwarf galaxies and gain unprecedented insight into their formation and evolution. In this talk, I present my ongoing work on investigating the capabilities of Euclid VIS/NISP images for identifying and characterization of GCs around galaxies and dwarf galaxies within the Local Volume. This has been possible given Euclid's Early-Release Observations (EROs) of several nearby targets. In this talk, I describe the methodology and the developed data-analysis pipeline for identifying GCs in the data of wide astronomical surveys like Euclid. At the end, I present my findings (preliminary results) and discuss our plans within the Euclid consortium science working groups for studying Dwarf Galaxies and their GCs. 

With the completion of ALMA, we now have unparalleled spatial resolution at submm wavelengths, enabling detailed kinematic studies of z > 4 galaxies for the first time. In this presentation, I will show kinematic models of four galaxies at z ~ 4.5, with some of the most spatially resolved observations in [CII] using ALMA. Our findings indicate that each of these galaxies features a regularly rotating disc, and their gas velocity dispersions are significantly lower than predicted by current cosmological hydrodynamical simulations. By decomposing the rotation curves into the different mass components, we derive properties of both the dark matter halo and baryons within the inner 3 to 5 kpc. Additionally, by analysing the velocity dispersion in the discs, we find that the gas turbulence is likely driven by the intense stellar feedback, without the need for other mechanisms. Furthermore, we contextualise these galaxies within the baryonic Tully-Fisher relation, exploring potential evolutionary links to local elliptical galaxies. Our findings show that cold discs can form earlier than previously thought and suggest that stellar feedback is at play to control the gas turbulence.

This is part 2 of the 3-part series "Improving interferometric imaging fidelity through self-calibration".

Narrowband surveys allow us to collect large, uniform samples of Lyman Alpha emitting galaxies (LAEs) at specific redshifts, giving us the ability to use LAEs to probe large scale structure and the temporal evolution of galaxy properties. The One-hundred-deg^2 DECam Imaging in Narrowbands (ODIN) utilizes three custom-made narrowband filters on the Dark Energy Camera (DECam) to discover LAEs at three equally spaced periods in cosmic history. In this work, we introduce an improved method for Lya equivalent width estimations. Using this method, we discover >10,000 LAE candidates over redshifts 2.4, 3.1, and 4.5 in the COSMOS field. A combination of narrow-band excess and galaxy colors allows us to identify [OII] and [OIII] emitters at lower redshift and to remove them from the LAE samples. We find that [OII] emitters are a minimal contaminant in our LAE sample, but that green pea-like [O III] emitters are an important contaminant for our redshift 4.5 sample. Additionally, we present scaled median stacked SEDs of each galaxy sample, revealing the overall success of our selection methods. In the future, these selections will be applied to all seven of ODIN’s fields, yielding one of the largest LAE samples to date and enabling key studies in galaxy formation, galaxy evolution, and cosmology.

It is well established that massive galaxies host massive black holes
(MBHs) in their centers. Lower-mass galaxies frequently host nuclear
star clusters (NSCs) and there exists a transition region where both an
NSC and MBH are present. However, the total number of galaxies with
detected NSCs and MBHs is much smaller than expected from occupation
fraction statistics, which is problematic if we want to better
understand their co-evolution. In this talk I will introduce NSCs and
their connection to MBHs at high-, medium-, and low-redshift. Then I
will detail our approach of finding MBHs in NSCs with eROSITA, an
all-sky survey mission in the X-ray regime. Combined with the
literature, the data reveal that MBHs in NSCs frequently exist but are
difficult to detect because of both instrumental limitations and low
accretion signatures of the MBHs.

This is part 1 of the 3-part series "Improving interferometric imaging fidelity through self-calibration".

The heart of the Milky Way is our nearest galactic nucleus and the only one where it is possible to resolve individual stars down to milli-parsec scales. Therefore, it is a unique template for understanding other galactic nuclei and their role in galaxy formation and evolution. The Galactic centre is also the most prolific star-forming environment in our Galaxy when averaged over volume, making it a perfect laboratory to understand star formation under extreme conditions, similar to those in starburst or high-redshift galaxies. However, high crowding and extinction hinder its study, and even its morphology and kinematics are not yet entirely clear. The recent publication of new photometric and proper motion catalogues has allowed us to gain new insights into its properties. In this talk, I will describe our recent results on its stellar population, formation scenario, and morphology.

Mass loss in evolved massive stars is still an open question that has impact on a wide variety of fields, since the stellar evolution theories to the chemical enrichment of the ISM. Constraining the mass-loss rates in each evolved phase is crucial to understand and predict their destiny as a SN or the resulting compact object. Although some evolved phases are well understood, the mass loss of RSGs is still very uncertain. Episodic mass loss events are thought to play a role on them but is not established yet whether it can be the dominant mechanism. In this talk, we present the perfect target to study the episodic mass loss in RSGs in a sub-solar metallicity environment. [W60] B90, with a luminosity close to the revised Humphreys-Davidson limit, is one of the most luminous RSGs in the Large Magellanic Cloud. It exhibits relevant photometric variability as it has increased its brightness by 1 magnitude within the last year. By monitoring spectroscopically the star, we have found changes in both the extinction and the temperature indicating a certain degree of instability. Moreover, we have detected shocked material surrounding the star in the direction of the proper motion, suggesting the possibility of it being the first extragalactic RSG with a bow shock and the 4th case known in total. All these characteristics are shared with the well-known Betelgeuse, the most studied RSG so far which fascinated the world a couple of years ago during its dimming.

High-energy gamma-ray astrophysics focuses on the study of the most extreme accelerators in the Universe. An example of these accelerators are gamma-ray binaries. These systems are composed of a massive O or Be-type star and a compact object, emitting gamma rays up to multi-TeV energies. Because only a handful of them are known and some of their properties are not fully understood, the discovery of new gamma-ray binaries may help to answer many open questions through population studies, though it may eventually open new ones. Given that the known gamma-ray binaries containing O-type stars are runaways, we search for runaway stars within catalogs of massive stars using Gaia DR3 astrometric data. We present here the current status of our project, with tens of new runaway O and Be stars identified, together with multi-wavelength information. The search for non-thermal emission using multi-wavelength data, together with radial velocity studies to confirm their binary nature, will help us build a list of potential gamma-ray binaries. The future Cherenkov Telescope Array (CTA) will play a crucial role in unveiling their nature as gamma-ray sources, thus allowing to enlarge the population for future studies.

Enhanced isotope ratios (in particular ¹³C/¹²C and ¹⁸O/¹⁶O) have been proposed as an indication of a top-heavy IMF in distant star forming galaxies (Romano et al 2017). However, the possibility has not been ruled out that the same effect can be produced by a very young starburst. Until the advent of ALMA the ability to probe and analyse multiple Super Star Cluster (SSC) regions, in a single galaxy was unfeasible. Now, however the high resolution achievable by ALMA allows us to probe the varying behaviour of these isotope ratios at parsecs scale in nearby starburst galaxies. This study made use of data from the ALMA Comprehensive High-resolution Extragalactic Molecular Inventory (ALCHEMI) Large Programme. ALCHEMI  is a wide ranging spectral scan of the Central Molecular Zone of the nearby starburst galaxy NGC253 covering bands 3 to 7. With the use of multiple transitions of CO, HCN and HCO+ and their C, N and O isotopologues we have put to the test the capability of these isotope ratios to trace the age of SSCs.  We accomplished this by taking a number of regions containing star clusters with ages determined through stellar population modelling and comparing them to the column density abundance ratios obtained via radiative transfer Large Velocity Gradient (LVG) modelling. In this talk I will present whether we found a relation between isotope ratio and cluster age, and whether this supports the theory that ages drive the isotopic abundance ratios.

Ultra-hot Jupiters are essential in advancing exoplanet observation techniques, with their significant transmission depths and bright emission spectra enabling even modest telescopes to detect subtle signals. KELT-9b is a prime example, featuring a high equilibrium temperature of 4000 K and a luminous host star (7.6 V mag), which provides a strong signal for sophisticated observational methods. Our research is divided into two main areas. Firstly, we analysed archival data from transit observations of KELT-9b using the HARPS-N and CARMENES spectrographs, applying alias regression to enhance sensitivity and discover new atomic and ionised species in the planet’s atmosphere. Our second area of focus involved the Wendelstein 2m telescope, equipped with the FOCES spectrograph. A comparative analysis was conducted with a single transit observation using the HARPS-N spectrograph, followed by an exploration of the Wendelstein telescope's capabilities. We found that the Wendelstein telescope can achieve detections comparable to the HARPS-N spectrograph, provided it combines multiple transits. These efforts highlight the untapped potential of the cross-correlation method in analyzing exoplanet atmospheres, a potential greatly facilitated by KELT-9b's accessible spectrum. This research underscores the importance of continued observation of ultra-hot Jupiters, which serve as key platforms for pioneering new techniques applicable to more challenging observational targets.

Metals trace the full evolution of the Universe: from primordial Helium and Lithium in the big-bang nucleosynthesis to all heavier elements produced in stars and explosive events. Determining their relative abundances in different environments, and across cosmic time, reveals the underlying star formation history and gas exchange processes. Recent progress in instrumentation and modelling now permits using metal production and distribution to test our ideas of galaxy evolution at many different hierarchical scales: from stellar clusters to clusters of galaxies. The hierarchical build up of present-day structures at different redshifts can also be followed, which go in parallel with the build-up of stellar and metal mass. These processes are interwoven: during most of cosmic history metal production happens at stellar scales, but metal distribution is effective on spatial scales covering several orders of magnitude. Therefore simulations require exceptional computational power, and tracing metals across cosmic time needs an equivalent investment in observational facilities. In 2013 we held a meeting at the Observatoire de Paris to review the state of the art in all these different research areas.

The alpha-elements are the proof of the chemical enrichment delay due to Supernovae type-II. 

When compared with iron, they can be used as cosmic clocks for placing constraints on both stellar nucleosynthesis and galaxy's formation history.

Sulfur is the outcast alpha-element. Indeed, its analysis is often skipped in favor of the other alpha-elements, which are less complicated to measure. 

The challenges in question are the weakness of optical sulfur lines, the contamination due to telluric lines, and the deviation from local-thermodynamical

equilibrium of near-infrared sulfur lines.

For these reasons, so far, the behavior of sulfur has been mainly investigated in Galactic stellar atmospheres and a few globular clusters.

Among the alpha-elements, sulfur is the proxy for high-redshift systems. Its volatile nature allows to directly compare sulfur abundances measured in local

stars and gaseous phase in the far Universe, as extragalactic HII regions and Damped Ly-alpha systems (DLA).

This kind of studies are relevant for the understanding of galaxy's formation and the evolution, since DLA are the progenitors of dwarf galaxies (i.e. the Milky Way building blocks).

However, the Sculptor dwarf spheroidal galaxy is the only extragalactic system for which sulfur abundances has been measured from stellar atmospheres.

This talk aims to show up new outcomes concerning the behavior of sulfur in the Milky Way major components. 

The results for 74 bulge stars, 21/30 thick/thin-disk stars and 24 halo stars observed with FLAMES/UVES@VLT (Paranal, Chile) will be presented.

Exploiting sulfur as tracer of the chemical evolution of our Galaxy, clues on the Milky Way's formation and a reliable dataset to compare local and distant systems will be provided.

The evolution of galaxies is shaped by external forces as much as by the interplay of internal mechanisms. We will start by looking at the deep scars left by the tidal interactions of the Small Magellanic Cloud (SMC), a dwarf satellite of the Milky Way (MW), with its larger sibling, and how the SMC still suvives. We will then move to the centre of our own galaxy to see how the correct modeling of all the substructures is vital in conducting accurate studies of the MW bulge region.

Planetary rotation and atmospheric features, such as giant storms and hurricanes, give rise to variability in exoplanet atmospheres as they rotate in and out of view. By monitoring this variability, we can construct maps that detail their physical appearance. Ground-based observatories have the resolution and photon collecting power to reach the high contrasts and small inner working angles needed to monitor these faint companions over their rotation timescales. But, bright host stars and a lack of reference stars accessible to the typically narrow field of view of ground-based coronagraphic imagers makes this difficult. Here, I present a new approach with results from our differential spectrophotometric monitoring campaign of a young, widely-separated substellar companion using NALES/LBT, an integral field spectrograph (R=40) in combination with a vector Apodising Phase Plate (vAPP) coronagraph. Unlike focal-plane coronagraphs, the vAPP is insensitive to telescope vibrations, reaching deep speckle suppression and provides an unsaturated PSF of the star as a reference to remove variations due to Earth’s atmosphere. By adopting techniques traditionally used for exoplanet transmission spectroscopy, we create light curves of the companion directly to search for inhomogeneities in its atmosphere. I will show the ~4-5% differential precision we already achieve with just one night of monitoring and an analysis of the astrophysical features we find in the light curve. Through this method, we can achieve high-precision differential spectrophotometry for directly imaged exoplanets inaccessible to space-based telescopes. This work is a path-finder for further studies with VLT ERIS and exoplanet mapping with ELT/METIS.

Exoplanets are a diverse population reflecting the range in possible outcomes of the planet formation process. Yet there are also patterns in the demographics of exoplanets with certain types of planets and planetary systems being much more common than others.

In this talk I will paint a consistent picture of exoplanet demographics consisting of two main planet populations: hot super-Earths and cold Jupiters. These exoplanet populations are constrained by transit, radial velocity, direct imaging, and micro-lensing surveys. I will place these results in the context of the solar system, showing that it is neither an extreme outlier nor a typical system.

While some stars have both hot super-earths and cold giant planets, other stars have only one or the other, highlighting the variety of planetary systems architectures. The demographics of these planetary systems is still in its infancy, but provides new ways of understanding how planets form and why the solar system -- with cold giant planets but lacking close-in super-earths -- looks the way that it does.

Stellar spectra contain thousands of lines, used to search for exoplanets and to infer physical properties.  While current spectrometers reach resolutions around 200,000, that is not sufficient to show all spectral signatures.  Synthetic spectra from time-variable 3D stellar model atmospheres can be computed at hyper-high resolutions (R=1,000,000), then revealing subtle details in convective wavelength shifts and in the temporal jittering of apparent radial velocity.  The latter effect limits discoveries of low-mass exoplanets but appears possible to understand and calibrate.  If the full physical signal is understood at hyper-high resolution, one can deduce what spectral fidelity will be required to trace it already with current instruments, or to evaluate what will be desired from later-generation spectrometers for the ELT, perhaps also with detectors in a post-CCD era.

In this talk I will report on interferometric observations of the so-called "J1030" field centered around the z = 6.3 SDSS Quasar J1030+0524, carried out with ALMA and JVLA. This field hosts a LSS assembling around a powerful HzRG at z = 1.7 that shows evidence of positive AGN feedback in heating the surrounding ICM and promoting star-formation in multiple galaxies at hundreds kpc distances. I report the detection of gas-rich members of the LSS, show that the LSS is going to evolve into a local massive cluster and that the HzRG is the proto-BCG. I will show signatures of the proto-BCG's interaction with the surrounding ICM, strengthening the positive AGN feedback scenario. From the JVLA observations of the "J1030" field we extracted one of the deepest extra-galactic radio surveys to date (~12.5 uJy at 5 sigma). Exploiting the synergy with the X-ray deep survey (~500 ks) we investigated the relation of the X-ray/radio emission of a X-ray-selected sample, unveiling that the radio emission is powered by different processes (star-formation and AGN). AGN-driven sample is mostly composed by RQ objects that display a significant X-ray/radio correlation, possibly indicating the presence of jet-induced feedback in RQ AGN.

The Large Magellanic Cloud (LMC) is a unique laboratory for extragalactic studies of star formation owing to its proximity (~50 kpc) and nearly face-on orientation. Since 2019, using the APEX telescope, we have been surveying the LMC in the CO(3–2) line unveiling the detailed distribution of the molecular gas in the LMC disk. So far, 13.9 sq. deg. of the disk have been covered at a spatial resolution of 5 pc. In this talk, I will introduce the survey as well as present one of the first projects based on its data – analysis of feedback fingerprints in the clouds of the active star-forming region 30 Doradus. Namely, we find that compared with the rest of the observed molecular clouds in the LMC disk, the ones of 30 Doradus show the highest areal number density; they are spatially more clustered, move faster with respect to each other and feature larger linewidths. We interpret our results as signatures of gas dispersal and fragmentation due to high-energy large-scale feedback.

The study of planet formation and circumstellar discs is experiencing a golden age in which observational and theoretical efforts are accelerating rapidly. The observatories of Chile are at the forefront of the field, with their unprecedented imaging and spectroscopic capabilities. Simultaneously, cutting edge modelling and simulation techniques have ensured that theoretical investigations continue to push at the edge our knowledge of the environment of young stellar systems in which new worlds are born.

Deadline to register abstracts is September 5th

The Epoch of Reionisation (EoR) describes one of the major phase changes in the
Universe, in which it went from being neutral to being transparent to ionising radiation
around z~5-6. Understanding the sources responsible for this transition is one of the major
outstanding problems in observational astronomy. In this talk I will present my recent work
regarding the ionising photon production efficiency of galaxies, xi_ion. We use NIRCam
deep imaging from the JADES collaboration, to construct a sample of 677 galaxies at z~4-
9, for which we can estimate xi_ion. By combining observational methods and SED-fitting,
we are able to shed light on the type of galaxies responsible for ionising the Universe. We
find that low mass galaxies with bursty star formation are likely the main sources driving
the EoR, and place our results in the context of the cosmic budget of ionising photons.

GRAVITY and MATISSE have produced a wealth of observations of NGC1068 which
allowed for single-waveband image reconstructions to be produced from 2-12 microns.
From these images, morphological information was inferred from the brightness
distributions and, by aligning the images, temperature profiles were extracted to produce
information about the dust composition. However, it is difficult to infer the true multi-
wavelength geometry from individual band images because the absolute position of each
image is unknown and therefore the image alignment (and resulting SEDs) are based on
assumptions. Indeed, there have been multiple published interpretations of the central
morphology at different wavelengths. In this talk, I will present our attempt to
simultaneously model the observations of NGC1068 provided GRAVITY and MATISSE
over the entire wavelength range. We use a polychromatic model with a geometry based
on the disk+wind interpretation of the unified model of AGN to test if this morphology can
simultaneously explain every band. Furthermore, our images in each wavelength are not
independent so a model based alignment between images can be made from which
temperature distributions and dust composition can be inferred.

September 2021 I started my PhD at ESO Chile. In this presentation, I will show my work of the past two years involving HARPS and NIRPS. This includes our recent discoveries of long-period gas giants through the ongoing 20-year HARPS radial velocity survey of extrasolar planets, the successful installation of NIRPS onto the 3.6m telescope at La Silla, the characterization of this high-resolution nIR spectrograph, and the future prospects of the ongoing surveys for gas giant planets around low-mass stars.

The chemical abundances of gas-giant exoplanet atmospheres hold clues to the formation and evolution pathways that sculpt the exoplanet population. Novel advancements in atmospheric retrieval methods for ground-based high-resolution cross-correlation spectroscopy have enabled the measurement of atmospheric C/O and metallicity of gas giant exoplanets at precisions comparable to that of solar system gas giants. To date, only a handful of gas-giant exoplanets have had their atmospheric chemical abundances constrained via this route. One of them is the particularly puzzling non-transiting hot-Jupiter tau Bootis b. SPIRou emission spectroscopy observations of the planet in the 0.9 to 2.5-micron range indicate an atmosphere depleted in water and a high C/O and high metallicity, which is at odds with the standard core-accretion model of planet formation. On the other hand, recent observations using CARMENES in the 0.9 to 1.7 micron detected an atmosphere with solar abundance water. To investigate these seemingly contradictory results, we revisit the archival K band VLT/CRIRES observations of the secondary eclipse of tau Bootis b. I will present results from new analyses of these archival data using PCA-based systematics detrending coupled with Bayesian atmospheric retrieval framework for high-resolution spectroscopy. Through these results, I will demonstrate the importance of accounting for 3D and viewing geometry effects in increasingly sensitive observations of exoplanet atmospheres for accurate measurement of their abundances.

The Large and Small Magellanic Clouds provide the closest example of a galactic
“three-body train wreck” in the local Universe. In fact, several stellar substructures, based on
photometry and/or proper motions, have been uncovered in the outskirts of the Clouds,
evidence of past interactions between the two dwarfs, and disturbances due to the Milky Way
tidal field. Mira variables are long-period pulsating red giant stars, bright enough to trace the
Magellanic outskirts with precise Gaia eDR3 proper motions. In this talk, I will present a
COSMOS spectroscopic campaign to derive radial velocities for tens of Mira stars in the
Magellanic periphery. On-sky position, distances from period-luminosity relations, and 3D
velocities were used to elucidate the origin of these tracers and their observables. Using a suite
of dynamical models for the past interactions of the Clouds, a recent (~1 Gyr old) disk crossing
of the SMC, largely disturbing the east side of the LMC, successfully reproduces the observed
properties of the Mira-like stars. The implications of our findings, in the context of the previous
detections of stellar overdensities around the Clouds, will be discussed.

The circumgalactic medium (CGM) is a complex multiphase environment surrounding galaxies that is key to understanding galaxy evolution as it provides the gas to fuel star formation, and it is where galactic feedback and gas recycling happens. At high redshift, massive galaxies or active galactic nuclei are surrounded by Ly-α emission extended up to 500 kpc. These giants are believed to trace the cold and ionized gas of the CGM. The present work aims to understand the properties of Ly- α nebula around quasars that have proximate and very dense Ly- α absorption systems known as proximate damped Ly- α systems (PDLA). By studying these systems, we have the unique opportunity to test the current theories about the powering mechanisms and try to understand what role the PDLA system has in these environments. For example, are they related to the nebula or to neighboring galaxies? To achieve our goals, we used MUSE instrument observation taken with the Very Large Telescope over three different high redshift quasars with PDLA absorption systems. We detected three different Ly- α nebulae, all showing different morphologies and kinematic features. 

Ultra-cool M-dwarfs are challenging for radial velocity (RV) searches of exoplanets due to their faintness and stellar activity, and thus almost no planets have been detected in this regime so far. With our survey, we obtain high-precision RV measurements of ten ultra-cool (Teff < 2800K) M-dwarfs using the uniquely suited high-resolution spectrograph HPF at the 10m HET telescope. Our high-precision RV measurements allow us to search for rocky exoplanets in the habitable zones of those stars. Additionally, we investigate the relationship between RV jitter, magnetic field strength, and stellar rotation in preparation for our survey. In my talk, I introduce the survey and display the RV precision reached in our observations of ultra-cool M-dwarfs so far.

Small Solar System bodies are among the oldest remnants of the building blocks that led to the formation of the planets. As they experienced little geological evolution since their formation, they are valuable tracers of the early time of the Solar System. Studying their physical properties is  thus essential. Recently, an important high-angular resolution imaging survey of large main belt asteroids with the VLT/SPHERE (Vernazza et al. 2021) provided shape models of these bodies with an unprecedented accuracy. The adaptive-optics images show that most asteroids with diameters larger than 100 km present irregular shapes with significant topographic features. Hence the main question is: what forces are responsible for sustaining the observed topography? To answer that, we have to explore more complex structural models by considering layered internal structures and solid elastic-plastic materials with cohesive and shear strength in addition to a weak gravity. After an overview of the small body population, a more specific and detailed study of (2) Pallas asteroid will be presented. Between December 2022 and March 2023 (ESO Program ID 110.23P6.001; PI: M. Marsset), new observations under an equator-on orientation have been conducted to complement previous observations oriented pole-on. Now that its external shape is better constrained, we attempt to determine if its surface is relaxed. Additionally, we assess the error on models coming from SPHERE imaging by comparing them with models from the Dawn mission for Ceres and Vesta.

Magnetic fields influence a large range of processes in and around stars. For this reason it is important to classify the magnetic fields on stars of a wide range of masses and evolutionary stages. In this talk we will go through how stellar magnetic fields are obtained using high resolution spectroscopy by studying the influence magnetic fields on spectral line shapes in both polarised and non-polarised spectra. These results can also be used to understand how stars affect both themselves and their circumstellar environment. I will also talk about the CRIRES instrument, a spectropolarimeter at the VLT, that is a powerful instrument to study activity on cool stars.

With the purpose of unveiling the optical counterpart of the first Black Hole Transient (BHT) ever detected, a 12 sq. degree field of view was surveyed with DECam around the estimated position of Cen X-2.  BHT are known to harvour a stellar black hole, making them the perfect field for hunting for this kind of objects. BHT show very little X-ray emission while they are in quiescences. When they go into outburst, they may outshine the brightest X-ray sources in the sky. Nevertheless, it is more efficient to look for the optical counterpart than waiting for new outbursts to come. This 12 sq. degree survey displayed initially more than 10**7 objects, were only a few hundred of them were known to be variable stars . Nevertheless, it was expected that thousands of variable stars would be found in the whole field. This project reviews the whole process that has been done to reduce the 10**7 initial objects to 10**4  confirmed variable stars. A brief analysis into statistical techniques to distinguish the variable stars from the rest followed by a light curve morphology study accompanied with color analysis to determine the nature of the object. Finally, the study concludes with the discovery of a dozen pulsant objects and a candidate list of objects to be the historical XRT Cen X-2

Bars are prominent features observed in most disc galaxies, having a crucial role in the secular evolution of their hosts. Indeed, they redistribute material within the galaxies, while rotating around the centre at a given bar rotation rate.
When formed in an isolated galaxy, a bar is expected to be born as fast rotating. During its evolution, the bar can be slowed through the exchange of angular momentum with the other components and/or when an efficient dynamical friction is exerted by the dark matter (DM) halo. In this case, the bar tends to rotate slowly, while the bar radius and strength increase. On the other hand, extremely fast rotating bars are unstable. Measuring the bar rotation rate becomes desirable both to investigate the secular evolution of barred galaxies and to test whether the measured DM distribution matches the prediction of LCDM cosmological simulations. 
The only model-independent way to recover the bar rotation rate is the Tremaine-Weinberg (TW) method: most of the analysed bars are compatible with the fast regime, while a non-negligible fraction are unstable, rotating extremely fast. I will explore the open questions related to the bar rotation rate derived with the TW method by
1. testing the reliability of the TW measurements which led to extremely fast rotating bars
2. pushing further the quest of slow bars applying the TW method to a sample of dwarf barred galaxies, the best candidates to host slowly-rotating bars, since they are commonly thought to host a massive and centrally-concentrated DM halo.

High-resolution spectra provide a unique window into the composition and dynamics of exoplanet atmospheres. I have developed an end-to-end data reduction pipeline for the MEASURE data set, observed with the NIR ARIES spectrograph on the MMT. This data set contains a diverse set of exoplanets with a wide range of periods, equilibrium temperatures and masses. One of our targets, the Ultra Hot Jupiter WASP-33 b, I report the first detection of CO emission lines, implying an inverted atmospheric structure. Moreover, by incorporating a Bayesian framework with 1D PHOENIX and 3D GCM atmospheric models, I show via Cross-Correlation-to-log-Likelihood mapping that the spectra are consistent with an eastward hot spot. I present characterisation of other targets in our survey, as well as archival observations from instruments such as CRIRES. Finally, I will present preliminary results on how winds/spatially varying abundances may affect accurate abundance measurements.

Hypervelocity Stars (HVSs) are flying away from the Galaxy with a velocity larger than the local escape velocity.  Among the models that explain their extreme velocities, the most accepted and successful is the Hills (1988) mechanism, in which a Supermassive Black Hole (SMBH) disrupts a binary stellar system, ejecting one component as an HVS. So far, just a few HVSs have been identified in the Galactic halo and none in the Galactic bulge. Under the assumption that HVSs originate from the Galactic centre, their expected density should be higher in the region of the Galactic bulge.

In this talk, I will present results from our ongoing search for HVSs in the Galactic bulge, combining optical -Gaia DR3- and infrared data -VVV/VIRAC2-, where we have identified afew promising HVS candidates that we will follow up spectroscopically to confirm their nature and to constrain the ejection rate and the slope of the mass function in the Galactic centre.

Our search for HVSs is restricted to red clump stars, which places these stars within the Galactic bulge. Our study aims to constrain properties of binary stars in the Galactic centre and their recent interactions with the SMBH. Moreover, we investigate possible systematics in Gaia DR3 proper motion measurements in the crowded Galactic bulge regions through a careful comparison of the HST, Gaia DR3 and VVV/VIRAC2 proper motion catalogues.

I would like to take this opportunity to present the first data release of VELOCE, a project dedicated
to measuring high-precision radial velocities (RVs) of Galactic classical Cepheids. In my presentation, I
will discuss the insights provided by the VELOCE data regarding the pulsational variability of
Cepheids. This data release offers a unique opportunity to compare and evaluate the RV precision
and accuracy of other literature datasets, as well as Gaia RVs.

Additionally, as part of the VELOCE project, I will present our analysis of single-lined spectroscopic
binaries (SB1s). By utilising the VELOCE RV data, we have been able to discover new SB1s and to
verify those already documented in the literature. Depending on the sampling and coverage of the
data, we have employed various methods to investigate the binary nature of different systems within
our sample. During my talk, I will discuss some intriguing SB1 Cepheid systems and provide an
up-to-date overview of the orbital parameters for the SB1 Cepheids.

Young clusters and star forming regions are home to a large number of substellar objects with masses below the hydrogen-burning limit at ~0.075 MSun. Their populations have been studied extensively in nearby star-forming regions (d < 400 pc), where we consistently find that 2-5 young brown dwarfs are born for every 10 newborn stars. However, brown dwarf formation theories predict that high gas or stellar densities, as well as the presence of massive OB stars, may stimulate the formation of brown dwarfs with respect to stars. It is thus imperative to extend the study of the population of brown dwarfs to massive young clusters, which are characterised by significantly different star-forming environments than those found in our immediate vicinity. In this contribution I will present our deep spectroscopic study of massive cluster NGC 2244 using VLT/KMOS as well as our deep NIR imaging using VLT/HAWK-I of the entire massive cluster RCW 38. In NGC 2244 we find that brown dwarfs are preferentially closer to the OB stars of the cluster than stars, which could potentially be the first ever evidence of OB stars affecting the formation of brown dwarfs. I will also report the most complete substellar initial mass function in the two clusters, along with the first bona-fide free-floating brown dwarfs beyond 1 kpc, providing an ideal dataset for comparison with nearby star forming regions.

Dusty Star-Forming Galaxies (DSFGs) exhibit some of the most starbursting events across Cosmic time at z>1, yet the process in which their molecular gas budgets are converted into stellar mass is still physically unconstrained. Sub-mm color surveys conducted with the all-sky coverage of the Planck telescope revealed some of the brightest DSFGs ever observed. The most extreme cases exhibited fields that were highly magnified due to gravitational lensing, offering a powerful opportunity to study these systems in greater detail. ALMA follow-up has revealed one rare example of a DSFG over-density (protocluster) being strongly lensed by a foreground cluster. Combining with HST, Gemini, and MUSE observations we can constrain and construct a lens model to be able to characterize their intrinsic, de-lensed properties. We aim to understand the potential environmental effects on the evolution of these starbursting galaxies and what that implies for the assembly of large-scale structures. Modeling the CO line and dust Spectral Energy Distributions (SEDs) enables us to estimate molecular gas budgets and SF to find evidence of enhanced SF efficiency in these dense protocluster environments.

In recent years, high-angular resolution observations have revealed the tiniest details of circumstellar discs. Such circumstellar discscomposed of gas and dust are found at different evolutionary stages of stars. I will focus on a class of evolved stellar systems that are surrounded by stable, dusty circumbinary discs, namely post-asymptotic giant branch (post-AGB) binary systems. These discs show remarkable, but unexpected, similarities with planet-forming discs around young stars. Studying these discs enables us to constrain processes for planet formation in a peculiar parameter space (short disc lifetime, high stellar luminosity, different disc formation mechanism). With recent observing campaigns with ESO’s current VLTI instruments, PIONIER, GRAVITY, and MATISSE, we gain insight in the physical processes in the inner regions of the circumbinary discs. In this talk, I will show recent observational and modelling results, providing strong implications of the disc structure which allows us to further quantify the analogy between protoplanetary discs and the circumbinary discs around evolved systems.

This talk will present the new CCAT Observatory which is planned to be installed in Chile in 2024. I will discuss the status of the observatory and its instrumentation and I will outline the science program planned with this new survey observatory, including the mode and rules for the participation by the Chilean community.

Recent observational successes are providing a new impetus to the study of binaries containing stellar-mass black holes.  I will start with a review of the current understanding massive binary evolution leading to the formation of black-hole binaries.  I will then focus on a few outstanding issues in interpreting observations and propose pathways to improving our understanding of some challenging aspects binary evolution.

Star formation is one of the main research areas in Astrophysics. Stars form by gravitational collapse of dense cores in molecular clouds. To understand the origin of stellar masses, multiple systems, and outflows, it is necessary to understand the formation and evolution of dense cores. To date, several hypotheses have described their gravitational collapse. Deriving the dynamical model that fits both the observed dust and the gas emission from such cores is therefore of great importance. The aim of this project is to simulate the molecular gas emission as predicted by three different theories of gravitational collapse: quasi-equilibrium Bonnor-Ebert sphere, singular isothermal sphere, and Larson-Penston flow using radiative transfer modeling (i.e., RATRAN). We will further investigate the spatial distribution of cold gas as it would be seen by the most powerful (sub)-mm interferometric and single-dish observatories (e.g., ALMA, APEX) and what it means for prestellar core chemistry. Additionally, in later stages of star formation after the collapse of dense cores, protostars are born and embedded in dusty envelopes. We explore the characteristic protostellar bipolar outflows traced by distinct CO lines to characterise the morphology of the same.

ALMA, despite being the most powerful (sub-)mm observatory in the world, has its own limits. When a PI requests a given image sensitivity, ALMA's capability to reach that requirement will depend on different parameters. Being an interferometer, phase noise can be one to drastically limit that combine with the brightness of the target. In the ALMA Proposer's Guide, it is mentioned that ALMA can nominally reach peak continuum flux to map rms ratios (aka, imaging dynamic range, IDR) between 50 to 100. However, this only refers to the standard phase referencing and, even then, these values are considered conservative. In this work, we have used calibration data (bandpass and phase calibrators) within ALMA data from cycle 3 to 7 to have a more realistic assessment of the IDRs obtained by ALMA. The data was pushed to their limits adopting self-calibration (reaching IDRs up to ~40'000). This presentation covers my work with Bill Dent and Hugo Messias during the 3-month visit to ESO/ALMA made possible with SSDF funds. I will go through the results, the different conclusions of this work, and cover one time-based non-standard way of doing self-calibration that you may use to further increase the IDR compared to the standard 6s-based solutions.

Star formation takes place inside dense and cold clouds composed mainly 
of molecular gas. Its study in galaxies is currently of great interest 
since we still do not understand the detailed physical mechanisms that 
drive the formation of stars. With the aim of improving our 
understanding of the star formation process in galaxies, in this 
colloquium I will present observations of a sample of galaxies 
characterised by their high infrared luminosities (LIRGs). We began by 
studying the nearby Seyfert 2 barred galaxy NGC1068 and then focused on 
a sample of 16 local LIRGs that feature different morphologies. 
Throughout this work we have studied each galaxy using interferometric 
observations at high angular resolution. In addition, we have 
complemented these observations with images of the Pa-alpha line 
emission in the near infrared. Our work focuses mainly on the study of 
the star formation relations. To carry out this study, we have performed 
the necessary observations and analysis to obtain the physical 
quantities with which we determine the gas properties and the rate of 
recent star formation.  We analyse the SF relations at several spatial 
scales and after that we study an alternative prescription that 
correlates the star formation efficiency with the boundedness of the 
gas. This prescription shows the importance of the dynamical environment 
of the gas when it comes to forming stars. The results obtained suggest 
that galactic dynamics plays an important role in the efficiency of 
converting the gas into stars. To conclude, I will comment on the study 
that is being carried out based on the results obtained in this work and 
the next steps that would have to be taken to continue deepening our 
knowledge in this field.

TBC

The search for dormant black holes received a lot of attention lately. One way to identify these is to look for binary stars with a mass ratio larger than unity, but where the companion is not visible. This can, however, be rather misleading as shown in several recent works. In this talk, I will present the discovery of another such example. Based on photometry and high-resolution spectroscopy, we found a binary system on a circular orbit with an orbital period of 34.5 days. The system consists of an evolved F-type star almost filling its Roche lobe and a B-type star.
We further investigated the history of the system using MESA models. The system belongs to the Algol class of binaries, having undergone a period of rapid non-conservative mass transfer and recently reversed its mass ratio while significantly widening its orbit. Furthermore, the system shows the peculiar behavior of the helium I lines that display line profile variations and asymmetries on various timescales and also emission component in Balmer lines. In the future, the system will likely become a detached stripped star binary similar to the LB-1 and HR 6819 systems.

Being the interface between the intergalactic medium and the central galaxy, the circumgalactic medium, or CGM, plays a fundamental role in the formation and evolution of galaxies and holds the key to understanding how galaxies acquire, process and expel their gas. The cool (T~10^4 K) phase of this medium has been extensively observed in the last decades, generally in absorption, using the lines in the spectra of background quasars that lie in the projected proximity of the foreground galaxies. However, given that these observations usually have only one quasar sightline per galaxy, understanding the structure and the dynamics of the cool CGM is to date extremely challenging. In this talk, I will focus on two particular surveys that have recently detected the cool circumgalactic gas in a spatially extended way: i) a set of arctomographic data, where the background sources are not point-like quasars, but giant gravitational arcs, which have been observed with MUSE to analyze the MgII absorption lines originated by the gaseous halos of foreground galaxies; ii) the data of the AMIGA Project, where the cool CGM of the Andromeda galaxy has been detected in absorption along more than 40 quasar sightlines, observed with the COS spectrograph, spanning the whole galactic halo. I will show how, by comparing these unique types of data with different empirical and theoretical models of the cool CGM, we have been able to make strong conclusions on the structure, the dynamics and the origin of this medium. If time allows, I will show how I have been using the results obtained from the comparison of data and models to develop high-resolution hydrodynamical simulations, which are crucial to infer the fate of the cool gas and its connection with the central galaxy.

We present a photometric variability survey of 12 young T-type and 6 young L-type planetary-mass objects with masses <= 20 M_J and ages <= 200 Myr using SOFI at NTT in the Js and Ks bands. The variability of L and T brown dwarfs reflects their inhomogeneous atmospheric structures as they are usually fast rotators. Atmospheric models reveal that surface gravity is crucial for shaping the atmospheric structures of ultracool objects. Preceding variability surveys suggest some correlation between surface gravity and variability occurrence rate as young low-gravity L-type objects have an enhanced variability rate compared to their field counterparts. Thanks to a recent detection of dozens of young T-type planetary-mass objects, we are able to conduct a variability survey of these objects for the first time and investigate the effect of surface gravity on the variability of L- and T-type objects in a large sample size. Five new variables and two variable candidates were detected. Combining previous variability surveys of field and young L- and T-type objects, we find that young objects are more likely to be variable than field objects. The variability occurrence rate of young T-type objects is more than twice the rate of field T-type dwarfs and the results of L-type objects are consistent with the previous study. Both field and young samples have higher variability rates at the L/T transition than outside the L/T transition. This work provides insights into the effect of surface gravity on the variability of L and T dwarfs, contributing to our understanding of the atmospheric structures of ultracool objects such as giant exoplanets.

To date, precise astrometric measurements have lead to the discovery of only two exoplanets. These modest statistics could soon be significantly brushed up by the astrometry-based non-single-star catalogue contained in the third data release of Gaia. Being a rich source of potentially sub-stellar companions to nearby stars, it can be used to identify promising candidates that lend themselves to follow-up observations by precision-astrometry instruments. Here, we present preliminary results of our study into using Gaia to first predict the position of as yet unknown sub-stellar companions before viable targets are then confirmed via direct detection by GRAVITY. Furthermore, we introduce a method of combining astrometry data collected by Gaia and GRAVITY. The employed MCMC approach manages to significantly constrain the orbital solutions of five brown dwarf candidates and nail down their absolute dynamical masses. Further characterisation of the object can be achieved by fitting atmospheric forward-models to the companions' K-band spectra taken by GRAVITY at R~500. While brown dwarfs offer an ideal testing ground to develop these methods today, in the near future they can and will be used to detect and characterise new exoplanets by means of optical interferometry.

Recent advancements in ground-based high-resolution spectrographs have propelled ground-based astronomy to the forefront of exoplanet detection and characterisation. However, the resultant transmission and emission spectra of exoplanetary atmospheres are inevitably contaminated by telluric absorption lines due to the light's transmission through the Earth's atmosphere above the observatory. Retrieving accurate atmospheric parameters relies on proper modelling and removal of this telluric contamination whilst preserving the faint underlying exoplanet signal. There exists many methods to model telluric contamination, whether directly modelling the Earth's transmission spectrum via radiative transfer modelling, or using linear basis models to fit the time-invariant features of a spectrum, and removing these models from the observations. We plan to compare these methods, in order to optimise the retrieval of exoplanetary atmospheric parameters from time-series transmission spectra.

Globular clusters (GCs) have long held promise to provide powerful insights into how galaxies form and evolve. Unfortunately, the challenges of dating of GCs in distant galaxies has prevented us to unlock their potential to trace galaxy assembly. Here I show how we have overcome the longstanding problem in the determination of ages of extragalactic GCs using models with flexible properties of horizontal branch stars. Then I will how the improved dating method has allowed us to reconstruct the properties of the progenitor of the most recent accretion event in Andromeda. These results have opened the door for galactic archeology studies in the local volume.

(Sub-)mm observations of the sky have transformed our understanding of the origin of chemical complexity, the birth of stars and planetary systems, the evolution of galaxies across cosmic times, and the large-scale architecture of the Universe. The current generation of 10-meter-class single-dish telescopes has given a glimpse of the potential for discovery, while interferometers have presented a high resolution view into the finer details of known targets or in small-area deep fields. However, significant advances in our understanding of such cold and dense structures are now hampered by the limited sensitivity and angular resolution of our (sub-)mm view of the Universe at larger scales. The design study for the Atacama Large Aperture Submillimeter Telescope (AtLAST, https://www.atlast.uio.no) is developing a concept for a new, single-dish (sub)-mm telescope, with a 50-meter diameter and hosting multiple instruments with field-of-view of 1-2 degrees. These specifications, combined, are unprecedented in the field of (sub-)mm astronomy, and will make AtLAST the fastest, most sensitive, and highest resolution mapping machine of the (sub-)mm sky. Besides the structural design of such next-generation telescope, the study is also addressing the selection of the optimal site, the power supply through renewable energy, the science goals, and the governance and operational model for the new facility. The EU project, which started in 2021 and will be completed in 2024, will deliver a full feasibility study that considers the technical, operational, environmental, and scientific challenges of building and operating AtLAST.

We are building a novel near-IR and visible MKID (Microwave Kinetic Inductance Detector) - based instrument called SPIAKID for Spectro-Photometric Imaging for Astronomy with Kinetic Inductance Detectors, which can be deployed on the ESO 3.58 m NTT telescope. It will be dedicated to primarily observe and study ultra faint dwarf (UFD) galaxies in the Local Group. SPIAKID will use ~ 130 x 130 pixel TiN-based MKID arrays that we will be arranged in a mosaic of 4 arrays, operating in 400-1600 nm wavelength range cooled down in a 100mK dilution cryostat. Here, we will give an overview of the instrument design by focusing on detector, optical and readout electronics configurations that are being implemented.

The tidal tails of stellar clusters are an important tool for studying the clusters’ birth conditions, their evolution, coupling, and interaction with the Galactic potential, and to understand how field stars populate the Milky Way. Thanks to Gaia, much progress has been accomplished in finding tails of open clusters. We will show here that the physical size of such tidal tails is larger than previously thought. Their identification requires combining the sophisticated analysis of the Gaia catalogue using machine learning techniques to the use of N-body simulations and the convergent point method. We will highlight recent results about the tails of the Hyades and of NGC 752, which extend over several hundreds of parsecs.

From detecting the atmospheres of faraway planets to identifying the earliest galaxies beyond the epoch of reionization, JWST is transforming our view of the Universe. In this talk I will report on the first results from an Early Release Science (ERS) program focusing on the AGN-starburst connection in nearby luminous infrared galaxies. Near and mid-infrared imaging and IFU spectroscopy at the highest spatial and spectral resolutions with NIRCam, NIRSpec and MIRI reveal previously unknown young, massive star clusters in galaxy mergers, uncover the nature of power sources at the core of galactic nuclei, and characterize the effect of heating mechanisms on their surrounding interstellar medium.

To understand the early phases of galaxy formation, metal-poor stars in the local universe play a special role, allowing to trace both how galactic assembly proceeds, and the conditions in which early star formation proceed. Metal-poor stars in our Galaxy and its satellites are fossils of these past processes and have therefore been the subject of intense dedicated searches and surveys since decades. Here I shall review some of the recent results that the « Pristine » narrow-band photometric survey at CFHT, has enabled, aided by the transformational information brought by the Gaia astrometric and spectro-photometric information. Beyond the identification of very metal-poor stars (and their ongoing follow-up with UVES@VLT), I will present results ranging from enravelling a very primordial disc in the Milky-Way to characterizing very pristine streams of stars in the galactic halo. Finally, I will outline the plans to characterise further these extreme and very metal-poor stars with the new WEAVE multi-object facility that should start its science surveys in 2023.

Active Galactic Nuclei are strong sources of X-ray radiation powered by the accretion of gas onto the central Supermassive Black Holes. The observed Eddington luminosity of most AGN is considered as an upper limit to the total luminosity that can be radiated by a compact object in a situation of radiation-pressure equilibrium. Even if the observed bolometric luminosity of most AGN is smaller than the Eddington value, a super-Eddington accretion is thought to be possible. I will present our recent work on the first systematic broad-band X-rays study of a sample of 8 super-Eddington AGN with Eddington ratios ranging from ~1 to ~ 460. In this work we analysed the X-ray broad-band emission spectra of these targets founding that they show a steep primary continuum slope, as expected for sources accreting in the super Eddington regime, mostly dominated by relativistic reflection. They also show the presence of a relativistic broadened iron Kα line and a statistically significant correlation between the photon-index of the primary power-law and the Eddington ratio. Moreover, we found that in super-Eddington AGN, as for lower Eddington ratio AGN, the X-ray corona is controlled by pair production and annihilation.

In this talk, I will present some of the results of an analysis of 114 galaxies observed by the AMUSING survey that hosted core-collapse supernovae (CCSNe) detected or discovered by the ASAS-SN survey. This is the largest analysis to date of CCSN host galaxies observed by the MUSE instrument at the VLT. We used stellar population synthesis and spectral fitting techniques to derive physical parameters of all HII regions detected within each galaxy, such as the star formation rate (SFR), Hα equivalent width (EW), and metallicity. We found that SNe Ibc occur in environments with higher values of SFR, Hα EW, and oxygen abundance than SNe II and IIn/Ibn. The distributions of SNe II and IIn are very similar, indicating that these events explode in similar environments. Between the SNe Ibc, SNe Ic higher median values of SFR, Hα EW, and oxygen abundance than SNe Ib. SNe IIb are related to environments with similar values of SFR and Hα EW to SNe Ib, and similar oxygen abundance values to SNe Ic. We also show that the luminosity of SNe Ibc correlates with the oxygen abundance at their environments, suggesting an intrinsic relation between metallicity and 56Ni produced in these events.

Asymptotic Giant Branch stars are a late-stage for stars with initial mass ranging from 0.5 to 8 solar mass. During this evolutionary phase, the star loses most of its mass through stellar wind and eventually evolves into a planetary nebula. Such nebulae are known to have very peculiar shapes, one of the most accepted explanations is the presence of a close-by companion. But due to the dynamic of the star, only a few binaries involving an AGB component have been detected so far, and the population of binary AGBs and binary planetary nebulae do not match. In this talk, I will present our hunt for a binary companion around the AGB star V Hydrae. We compare images obtained in the infrared with VLTI/MATISSE with orbital analysis obtained from radial velocity monitoring and astrometric proper motion.

The baryon cycle in galaxy halos is the result of an interplay between AGN/stellar outflows and inflows from the intergalactic medium. Observational constraints on the gas properties provide a clue for cosmological simulations and shed light on feedback mechanisms. Due to the complex multiphase nature of the gas, understanding feedback processes requires a comprehensive study of the gas in the hot ionized as well as warm and cold neutral phases. Unfortunately, in contrast with cold and ionized gas, estimation of the temperature of the warm phase is a difficult task. This can be overcome using the analysis of absorption lines imprinted onto quasar spectra.  We present such measurements of the warm neutral gas temperature, based on the state-of-the-art VLT/UVES observations. We show that the warm neutral gas exhibits a huge variety of estimated temperatures, which in some cases even exceed the canonical Galactic value.

The Dispersed Matter Planet Project targets bright FGK dwarf stars within 100 pc with signs of circumstellar absorption in archive spectra. The absorption is caused by mass loss from close-in planet(s). Using a carefully selected sample of candidate systems showing absorption signatures, we are conducting high cadence radial velocity surveys to search for planets with short periods. Our targets, with magnitudes of V < 10, are good candidates for follow-up characterisation studies.

The planets we are identifying are in diverse systems and include close orbiting gas giants, low-mass multiplanet systems and planets in binaries. I will present the first systems we have published based on HARPS data from the 3.6m telescope. I will also discuss two new systems that we have identified with observations at other precision radial velocity facilities. All our targets with 60 or more RV epochs have yielded candidate planet detections, indicating the effectiveness of our target pre-selection procedure. I will briefly discuss our latest observations from La Silla, which confirm the presence of planets or planetary systems around many of our candidate host stars.

Massive stars are important metal factories which provide energy and chemical feedback to their surroundings. However, stellar evolution models currently contain large theoretical uncertainties for physical mechanisms at work in the deep interiors of early-type stars. The uncertainties associated with interior rotation, chemical mixing and angular momentum transport propagate throughout their evolution making it difficult to accurately determine their masses and ages. However, asteroseismology allows one to break model degeneracies, uniquely probe stellar interiors, and constrain largely-uncalibrated physical processes. In this talk, I provide an introduction of asteroseismology for the non-expert, and discuss some of the recent constraints on interior rotation, mixing and magnetic fields from forward asteroseismic modelling of early-type stars based on space-based photometry, high-resolution spectroscopy and spectropolarimetry.

For the last two decades, much of the work of high-contrast imaging of exoplanets has been focused on detecting these planets, with characterization being a secondary goal. It is only with the current suite of instrumentation that we are able to characterize the atmospheres of these young, gas giants in detail, though there are many avenues being explored. Using the VLTI/GRAVITY, we can obtain high precision of exoplanets at small angular separations. High spectral resolution instruments such as CRIRES+ unlock the ability to measure isotopic abundances, and finally, JWST is opening the door to broad wavelength spectral measurements at exquisite precision. In this talk, I will present the current ongoing efforts and challenges in understanding the atmospheres of these objects, together with preliminary results for the benchmark system HR 8799 using a combination of VLTI/GRAVITY and other high-contrast imaging instruments.

Omega Centauri is the most massive globular cluster of the Milky Way and believed to be the nucleus of an accreted dwarf galaxy. We want to contribute to understanding its formation history by creating a deep high-precision proper motion catalogue for the core of the cluster based on archival HST data and a dedicated HST program. Using those data, we will also create a six filter photometric catalogue which will allow us to disentangle its multiple stellar populations. Our catalogue will contain more than a million stars - more than 2 orders of magnitude larger than the Gaia sample in this region of the cluster.
In combination with MUSE spectra for more than 100 000 stars (another project in our group), this will enable several interesting science cases such as studies of the dynamics of different stellar populations or the search for high proper motion stars which could reveal an IMBH.

Quasars are widely used in astrophysics to probe various environments, ranging from large-scale studies of clustering and the intergalactic medium to galactic-scale studies of the interstellar and circumgalactic media. Moreover, quasars are intriguing objects on their own and many aspects of quasar evolution and the multitude of observational phenomena are still not fully understood. One main limitation to quasar studies in general is the pre-selection for spectroscopic observations. The largest spectroscopic quasar samples to date have been selected based primarily on optical colors with inhomogeneous inclusion of multi-wavelength data to increase purity. Such identifications may lead to potential biases in the derived quasar demographic and can have severe consequences for foreground absorption studies. In this talk, I will highlight our efforts to obtain the first color-independent quasar sample by selecting candidate quasars purely based on astrometry from Gaia. This method allows us to select a sample of optically bright quasars with no further assumptions on the spectral shape. The talk will focus on the implications for studies of foreground absorption systems.

Binary interactions play a crucial role in the evolution of massive stars. Yet, the complex interaction physics and the outcome of the interactions remain poorly understood. We want to remedy this situation by searching for systems that underwent binary interactions already, so called binary interaction products, in intermediate-age (20-100 Myr) clusters in the Magellanic Clouds. Characterizing their occurrence and physical properties provides stringent tests for stellar evolution theory, with far-reaching implications for our understanding of massive-star evolution and stellar feedback.

In my talk, I will focus on the massive star population of the ~40-Myr old SMC cluster NGC 330 in the Small Magellanic Cloud, which contains more than 250 O- and B-type stars. I will present multi-epoch MUSE observations obtained in Wide-Field mode that allow to investigate the multiplicity fraction, the occurrence of classical Be stars, and the physical properties of the brightest stars, in particular their rotational velocities. I will discuss observational constraints on post-interaction products and compare the derived effective temperatures, luminosities, and rotation rates with findings for clusters at different ages and metallicities.

Cataclysmic variables are a unique laboratory to test the current evolution scenarios of compact binaries. They are numerous and relatively bright, but still hold many secrets. In this talk, I will illustrate how important the determination of reliable stellar masses in these systems is for our understanding of their nature and evolution, and will present a variety of awkward behaviour still unexplained.