Circumbinary disks are found in a variety of astrophysical scenarios, from binary star formation to supermassive black holes. The interaction and accretion from a disk can influence the orbit of the binary, either leading to circularization, or exciting the eccentricity, widening the orbit or shrinking it and facilitating mergers. I will talk about how these effects come into play and what kind of observational signatures can they leave on a population of binaries.

Quasars are known for their intrinsic variability, which is stochastic at a range of timescales. Studying these objects in very large samples helps to improve the statistics and to have a systematic study of the time scales of variability, probing the relationship with the physical mechanisms driving these changes. With the upcoming large-time domain photometric surveys, we expect to discover at least a few millions of new AGN. However, detection and estimating their redshifts from photometric data presents an active research problem, and the large number of sources makes spectroscopic follow-up impossible. I will present ongoing research results on redshift estimation for these sources, taking advantage of cosmological time dilation coupled to intrinsic variability. We used MCMC iterations, effectively modeling the optical light curves of AGN by constraining the structure function and obtaining their redshift priors. I will present a validation of this method, conducted using a well-sampled light curve from the Zwicky Transient Facility (ZTF), as a proof of concept for our approach, which demonstrates that the obtained redshift priors align very well with spectroscopically determined redshift values.

Incredible images of astrophysical objects in printed materials and in digital form are used by professional astronomers for research and by the general public for outreach and educational purposes. However, professional astronomers and the general public alike are blind to nearly all astronomical phenomena without technological and computational aids to produce the images that we are now used to ?seeing?.

Challenging the idea that we should always use visualisations of astronomical data (i.e., graphs or images), there has been an emerging research interest over the past decade in converting astronomical data and phenomena into sound ("sonification"). Motivation for this includes the potential to enhance scientific discovery within complex datasets, by utilising the inherent multi-dimensionality of sound and the ability of our hearing to filter signals from noise. Other motivations include creating engaging multi-sensory resources, for education and public engagement, and making astronomy more accessible to people who are blind or have low vision, promoting their participation in science and related careers.

I will review the current status of the field of sonification in astronomy, and describe potential benefits of sound in the context of research, outreach, and education. I will also discuss current limitations and challenges of the approaches taken and suggest future directions to help realise the full potential of sound-based techniques when applied within the astronomy community.

Star formation occurs in the densest parts of molecular clouds, which can be studied via molecular line emission, typically rotational transitions observed at radio wavelengths. These molecular lines provide a wealth of information about the physical condition of the interstellar medium, including the gas density, temperature and dynamics. In this blackboard presentation, I will present how turbulent models of star formation describe the density structure of molecular clouds. Based on these models, I will discuss how the properties of molecular clouds affect molecular line emission and the star formation rate. I will conclude by comparing the model predictions with observations and show that density-sensitive line ratios are powerful tracers of molecular cloud density.

Galaxy clusters are an important cosmological probe, tracing both the growth of structures and the expansion history of the Universe. The population of distant (z>1) clusters remains poorly known, due to the limited sensitivity of present telescopes. In X-rays, the ATHENA mission is a promising observatory to detect large numbers of these early massive objects. During this informal discussion, I will introduce cluster number counts cosmology, present the capacities of ATHENA regarding high-z cluster detection, and discuss how it could help cosmology in the 2030s.

I will discuss an HR diagram and chi2 map from a multi-data analysis of a triple star. One of the components is very offset from a normal position. This is either related to its log g value or to its mass. However, both values are well constrained by observations. I would welcome your comments and ideas.

Since 2018, ESO Supernova has been presenting to the public how science and cutting-edge engineering can help unravel the secrets of the Universe. An education programme is running that attracts almost 6000 children (K-12)every year. Despite being in Garching, we welcomed educators and teachers from almost all member states so far. The interest in support in education is increasing in Chile as well because of ESO’s presence there. A visit of ESO’s education coordinator to Santiago and most of the telescope sites was intended to find out, how parts of the education programme can be made accessible to the Chilean community, what the local needs are and how the ESO Department of Communication in Vitacura can be supported to establish some of the programmes developed at ESO Supernova. This talk will give an overview of this visit and the discussions with local education institutions. It’ll encourage further discussions on how the Chilean community can benefit from ESO’s work in education.

Massive binaries are relatively rare systems in our universe and our understanding of the physics governing their evolution remains limited. Mass transfer events within these binaries can induce significant alterations in their structure, potentially resulting in the formation of close binary black holes or neutron stars. These binaries, in turn, are sources of observable gravitational waves. Alternatively, mass transfer events can hypothetically give rise to esoteric objects such as Thorne-Zytkow objects and Quasi stars, which are hybrid stars consisting of either a neutron star or black hole at the core of a non-degenerate star. This talk offers an overview of the various pathways through which massive binaries can transform and explores key determinants of their evolutionary outcomes, including radial expansion and the role of convection within stellar envelopes.

Strong large-scale magnetic fields play a crucial role in powering the central engine of high-energy astrophysical sources, which invariably require a central accreting compact object as main ingredient.

However, whether we consider the formation of a proto‐neutron star during the gravitational collapse of a massive star or the accretion disk around a supermassive black hole, it is still not well understood how such fields can be amplified to the point where they can extract rotational energy from the accreting compact object and launch the powerful outflows that we can observe.

Numerical models are an invaluable tool to study the complex dynamics of these astrophysical systems, but despite the enormous increase in computational power currently available, the large separation between all the relevant scales (e.g. plasma kinetic scale, compact object's size, jet and emission site) represents a hard challenge that astrophysical simulations still need to face.

In this informal discussion I will present some recent results on large-scale magnetic field amplification and dissipation in accreting compact objects, from their "infancy" (i.e. the proto-neutron star phase after the gravitational collapse of a massive star) to the case of black hole-accretion disk systems and relativistic jets.

I will highlight similarities and differences between these different sources, and present some of the msot recent analytical and numerical tools currently employed to address the impact of magnetic fields on the dynamics of compact objects.

What do the Pleiades have to do with a school of sardines? How can habitat exist in a computer?

These kind of conundra arise when a passionate zoologist talks to passionate astrophysicists and their very bizarre discussions get transformed and catalyzed by the expert and talented digital hand of an illustrator.

Under the premise of Baba Dioum "In the end we will conserve only what we love, we will love only what we understand, and we will understand only what we are taught", a few years ago, a group of five women embarked in a project in Valparaiso to make the general public get to know and fall in love with pairs of "astro" and "marine" "beasts". With a wink to the great "Bestiario del Reyno de Chile" illustrated book, and another one to the "memory game", the project translated in a beautifully illustrated book with key and curious facts about the wonderful "creatures" that "populate" the media above and below the coastal horizon.

In this informal talk I will present a bit of the process of this book and its inspiring illustrations.

The chronicle to be relayed may appear unbelievable but was carefully researched.  The story was written by brilliant scientists and violent potentates over two centuries and across large parts of Europe and North America.  It consists of several strands that will be woven from threads as seemingly incoherent as the following examples:

• a penniless child that bought a glass-polishing machine from money given to him after he had been rescued from a collapsed house;
• an Italian Jesuit and observatory director, who was curious about the composition of stars and discovered the circumstellar matter surrounding the object of the talk;
• effects that WWII had on the sociology of science;
• one of the last mysteries of naked-eye astronomy;
• observations made amidst exploding bombs;
• the second most important astronomy family dynasty;
• a ‘law’ that is still valid after nearly a century but already in the year following its proclamation was dramatically violated by the prototype of the stars it had been established for;
• a second unlawful star that led a whole field of research into a temporary dead end;
• a daring interpretation of decades-old observations that is still wanting a physical basis;
• astronomers who had to flee their home countries to escape from military and political threats;
• long series of careful measurements by passionate to desperate observers, who did not understand what they were seeing but refrained from adding undue speculations;
• restrictions that a very persuasive but merely empirical ‘law’ can impose on scientific thinking;
• an astronomer who rose from a peon in the streets of a megapolis in an Asian country to president of the IAU;
• the technology that enabled a science-driven entrepreneur to build a first extremely large telescope;
• efforts supported by an American lawyer to obtain a copy of an 80-year-old PhD thesis from a library in London;
• a famous female astronomer, who suffered many times from gender discrimination but called another female astronomer a man;
• a subtle mistake in the description of observations that let an ingenious ansatz fall short of the full explanation;
• a refractor that broke two observers’ legs;
• an observatory that was founded because an imperialist wanted to have accurate maps of the territories he had conquered;
• some of the last observations made at an observatory later looted by an occupation army.

The red thread onto which all these beads will be stringed is provided by a naked-eye star that has showcased itself on a dynamically evolving pedestal sculptured by physicists, chemists, glass cutters, opticians, spectroscopists, astronomers, inventors, etc.  The story started and found its current end in the Munich area. 

(It seems that the above information does not [yet] enable ChatGPT to identify the star.)

Understanding the physical and chemical properties of the interstellar medium (ISM) and circumgalactic medium (CGM) of nearby and distant galaxies is crucial to understanding galaxy evolution. We describe our studies of the gas in star-forming galaxiesat redshifts 0.02<z<0.14, based on HST COS, SDSS, and GBT spectroscopy of background quasars located within impact parameters of 1-7 kpc from the galaxies, and in galaxies at redshifts 0.2 < z < 1.4 based on HST imaging and VLT MUSE integral field spectroscopy.Combining our sample with the literature, we find the H I column density to be anticorrelated with impact parameter and stellar mass. We also find that the SFR correlates well with the stellar mass, consistent with the star formation main sequence (SFMS), althoughsome galaxies associated with DLAs/sub-DLAs lie below the SFMS, suggesting longer-than-typical gas-depletion timescales. Additionally, we find that the absorption and emission metallicities correlate with 𝑀∗ and sSFR, implying metal-poor absorbers arise ingalaxies with low past star formation and faster current gas consumption rates.

I will discuss ways that we can support LGBT people in academic science. LGBT drop out of science careers at greater rates than non-LGBT and experience higher rates of dissatisfaction. I will discuss the national support organisation QueersInScience, of which I am among the founding board members, for LGBT researchers. The group organizes events to highlight LGBT researchers, provides a networking support, and has recently begun LGBT awareness training that is tailored for life in academia.

The detection of several X-ray-quiescent black-hole (BH) binaries via single-lined spectroscopy has been recently reported for the first time. Here we present the implications on natal kick during BH formation for the most massive source of this population: VFTS 243. With a BH mass of 9.1 ± 1.0 Msun, an eccentricity of e = 0.017 ± 0.012, and no apparent X-ray-emitting accretion disk, the BH of VFTS 243 is a strong candidate for the complete collapse scenario. This scenario suggests stellar collapse without an explosion and therefore mass ejecta exclusively lost via neutrino emission. We explore the natal kicks of VFTS 243 and find that the current orbital configuration is consistent with the complete collapse scenario. I present the preliminary results of this exploration and the implications to neutrino natal kicks and asymmetries during BH formation.

In my first postdoc year in the US, I published a paper in Science on the discovery of water plumes on Jupiter’s moon Europa. The paper and the results had large impact in the field and in the community and even possibly affected the decisionfor NASA’s Europa Clipper mission. This certainly helped my career but it also was a burden at times and defined the perception of myself by the community more than I wanted. I will tell the story about the discovery and my role in it.

The Intracluster Medium (ICM) of galaxy cluster is a hot, X-ray emitting gas in the plasma state. Turbulence driven by AGNs jets and cluster mergers is an attractive heating source to counteract its intense radiative cooling. In this discussion, I will present a mechanism in which large scale turbulence can directly heat the plasma at small scales, bypassing the turbulent cascade via a process called magnetic pumping. I will describe its theoretical basis, provide a plot of our numerical simulations and discuss the implications for the heating of the ICM.

Andromeda galaxy (M31) is the closest spiral galaxy to our own Milky Way. Due to its proximity, it is a galaxy that has been observed in detail, including chemistry, kinematics and stellar populations from the centralregions to its halo, over a field of view of nearly 100 degrees squares. The observed number density map of its extended halo (PAndAS) present some archetypal signatures of accretion events. Apart from this, there are also data from its stellar disc and innerhalo fields that are indicative of a major merger event in its recent past. 

In this Informal Discussion, I will present the main observational data we have for M31, and try to highlight especially those that point to the direction of a major merger (mass ratio ~1:4) event that created thedisc of M31, as well as the spatial distribution of the observed substructures in its inner halo. I will present the main features of an N-body, hydrodynamical simulated model of a major merger paradigm for the formation of M31 and briefly talk about my currentwork on comparing the predictions of this model with data from M31's disc, inner halo and its faint substructures.

A significant fraction of all stars forms in binary or higher-order systems. Stellar multiplicity is even more ubiquitous for massive stars: almost all O-stars have at least one companion, and many of them transfer mass to a companion over their lifetimes. Those interactions shape the feedback from massive stars. Most stars also form within clustered environments, where binary systems are formed, modified, or destroyed through gravitational dynamics. It is therefore crucial to account for the interplay between binaries and the larger-scale cluster environment to paint a complete picture of star cluster formation.

In this informal discussion, I will present key results from simulations of star cluster formation with hydrodynamics, stellar dynamics and feedback, and sub-grid star and binary formation. I will also discuss ongoing work on the implementation of feedback from massive interacting binaries in those simulations. I will conclude by highlighting what kind of observational results would be helpful to the design of our feedback model.

Nuclear star clusters (NSCs) are dense, massive star clusters found in the centres of at least 70% of all galaxies. NSCs are known to co-exist with central black holes (BHs), our own Milky Way being the most prominent example, and are known to follow the same scaling relations with host galaxy properties, suggesting a connected evolution. However, unlike BHs, NSCs still contain records of their formation and evolution imprinted in their stellar populations. Generally, two main scenarios are discussed for NSC formation that are ultimately linked to the evolution of galaxies and their star cluster systems: NSCs might form in-situ from gas at the galactic centre, a process that is linked to galactic star formation and dependent on the availability of gas. Alternatively, NSCs might form from the (dissipationless) accretion of globular clusters that spiral inwards due to dynamical friction. Most likely, a mixture of both pathways is realized in nature.

In this informal discussion, I will discuss how MUSE data can be used to disentangle the dominant NSC formation channel in individual galaxies and will present a clear dependence of the dominant NSC formation channel from globular cluster-accretion being the dominant channel in dwarf galaxies to in-situ formation forming massive NSCs in massive galaxies.

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.

What is the relationship between astronomy and colonialism? This question has been discussed extensively within parts of the astronomical community after indigenous demonstrators blocked the construction of the Thirty Meter Telescope on Hawai'i in 2014. In this informal discussion, I will approach the question with the help of material that I found while doing research for a popular science book about black holes. In particular, I will show previously unpublished material from the archive of Karl Schwarzschild that elucidates the surprising link between black hole science and colonialism.

We know by now that many stars live their lives in binary or higher-order multiple systems. Many of those systems are close enough to interact during their lifetimes, leading to a diversity of different pathways for the future evolution. Nevertheless, the outcome of such interaction and the nature of post-interaction systems remains fairly unconstrained.

In the informal discussion, I want to explain how we can use young and massive star clusters to spot a variety of binary interaction products, not only blue stragglers that are most likely the most prominent members of their class. I will use one particular example cluster, NGC 330, and compare observational findings to theoretical predictions (on the blackboard, of course).

Our success in understanding the baryon cycle of galaxies largely relies on our ability to constrain the physical conditions of their interstellar medium (ISM), out of which the next generation of stars can form. Far-infrared fine-structure lines provide us with a powerful toolset to infer such conditions, both in nearby galaxies and at high-z. These lines are reasonably bright, mostly thin, and not affected by dust obscuration, except in the most extreme cases. With them we can characterize the ionized and neutral gas phases of the ISM, constraining some of their key properties such as the average intensity of the radiation field (G), the density of the gas (nH), and its temperature (Tkin). Photo-dissociation region (PDR) models tell us that the ISM conditions in nearby dusty, star-forming galaxies vary significantly from source to source, for instance changing by orders of magnitude in G/nH. In this talk I will present an array of physical interpretations we can attach to some of the observed correlations seen between emission lines, and as a function of luminosity and luminosity surface density; but since this is an informal discussion, I will also try to highlight some aspects or details of these correlations that I think currently don't have an answer or lack a robust physical interpretation. Hopefully this will trigger minds to help us better understand the reason(s) why we see some of the trends we see in the nearby Universe and apply this knowledge to better interpret galaxies in the distant One.

Rest-frame optical emission lines provide a wealth of information about the physics of gas and stars in star-forming galaxies.

For instance, the position of galaxies onto the classical diagnostic diagrams like the “BPT diagrams” are widely used to discriminate between different spectral ionising sources, or to infer the chemical and excitation properties of the ISM.

However, although variations in emission line ratios can be theoretically reproduced by the interplay of many different parameters, it is often difficult to break the degeneracy and disentangle their true relative contribution.

I will present an approach that leverages Machine Learning techniques to identify which physical parameters are the most intrinsically responsible for the observed position of galaxies in different diagnostic diagrams, highlighting strengths and weaknesses, and discussing perspectives in the study of the redshift evolution of galaxy properties from current and future large observational surveys.

Observations imply that only 5% of the total energy of the universe is in the form of baryonic matter. The remaining 95% is dark matter (e.g. undiscovered particles) and dark energy (e.g. the cosmological constant, a new scalar field of nature). Ongoing and future research is expected to either reveal the nature of the dark sector or revise our fundamental theories. Astronomical observations probe temporal, spatial and energy scales unavailable in terrestrial experiments and are therefore better suited for this purpose. New, advanced astronomical instrumentation is being built to perform unique tests of fundamental physics, complementary to those made using supernovae, the large scale structure, the Cosmic Microwave Background, and gravitational lensing.

I will present how high precision quasar absorption spectroscopy can be used:

(1) to probe new physics by searching for variations in the fundamental constants of physics, and 

(2) to directly measure the temporal redshift evolution (redshift drift) of objects in the Hubble flow.

The two projects are also science goals of the Extremely Large Telescope and its ANDES instrument in particular.

Astronomy has a bright future in the coming decades with (1) state-of-the-art telescopes such as the James Webb Space Telescope and the Extremely Large Telescopes leading to unprecedented in-depth characterization and (2) the multiplication of small ground-based instruments and space missions unlocking large-scale surveys. The field of exoplanets is no exception with intended groundbreaking results on their demography, formation, evolution, chemistry, and potential detections of Earth-like planets and biosignatures. By analyzing the atmosphere of exoplanets, we can determine their chemistry, dynamics, and climate delivering knowledge on the evolution and formation of exoplanets. At high spectral resolution, planetary lines are resolved, which provides more details on the atmospheric structure and their profile informs us on their dynamic (wind patterns, atmospheric escape, …). I will discuss the homogeneous study of the upper atmosphere of 11 exoplanets observed with SPIRou through the near-infrared helium triplet. Finally, I will outline the NIRPS spectrograph (operations starting April 1st) and the objectives of its consortium as well as their 725 nights of guaranteed time observations.

The Pre-Main-Sequence stellar evolution is shaped by the mass accretion process. In recent years, we discovered the variable nature of the mass accretion process on embedded young star objects (YSOs). High-amplitude irregular accretion bursts were observed across all wavelengths on timescales from months to decades, which are triggered by various instabilities throughout the accretion disc. On the other hand, periodic accretion bursts were discovered among a group of embedded YSOs, which might be consequences of dynamical perturbations in young binary or star-planet systems. In the first part of the talk, I will present our latest search results on long-term eruptive YSOs from the decade-long near-IR VVV survey, including 15 new FUor-type objects. In the second part, I will briefly present our latest publication on periodic outbursting YSO candidates that provides indirect evidence of early planet/companion formation.

Climate change is one of the biggest threat modern generations have to face. To ensure a liveable future, urgent measures should be taken. One of the best ways to obtain such quick change in our society is by informing citizens, to engage them, and try to reach the social tipping point as fast as possible.

I will introduce the PLEES index. This index is based on Maslow's hierarchy of needs and is projected under different climate change scenarios, to quantify the psychological, social, and economical impact of climate change in the world.

This index is a visual tool, easily distributable in social medias, aiming to inform people about climate change, targeting wealthier European countries, with financial and political means to generate a positive change, showing that their life comfort is at risk.

Our working group in Vienna believe that popularising the idea of social tipping point is a good way to show that big changes can happen very fast if citizens act together.