Seminars and Colloquia at ESO Santiago

Heavy-element abundances in ionized nebulae are fundamental to understanding how galaxies chemically evolve. Yet for more than 80 years, abundances derived from collisionally excited lines and recombination lines have systematically disagreed, giving rise to the long-standing “abundance discrepancy (AD) problem.” In this talk, I will present spatially resolved observations of the Lagoon Nebula with the SDSS-V Local Volume Mapper, mapping its temperature structure, chemical abundances, and the AD across the nebula. I will show that the AD closely follows electron temperature fluctuation in the ionized gas, and present a new method to quantify these fluctuations and reconcile the two abundance measurements.

The short lifespans of massive OB stars tightly link their spatial distribution to the Galaxy's star-forming regions. In the ongoing revolution brought by Gaia's sub-milliarcsecond astrometry, our view of the Milky Way and its history is changing at rates never seen before. We are starting to realise the convoluted intricacies of the solar neighbourhood in the young stellar component, while witnessing previously well established stellar structures being called into question. Here I will present the most comprehensive 3D map of the ~3 kpc solar neighbourhood, using an updated version of the Alma Luminous Star catalogue (the ALS III) of young massive stars, now including some ~20.400 objects, integrating new data from the Galactic O-star Catalogue (GOSC) and the Galactic Wolf Rayet Catalogue. Since Gaia DR3 we have been working on improving the astrometric and photometric calibrations of the data, while developing a Bayesian framework for reliable distance estimation. These improved standards allow us to trace the spiral arm structure in our vicinity, uncovering the Cepheus spur (with evidence for a possible corrugation pattern in the Galactic disk), extending the Sagittarius spur, and giving a new overarching interpretation about the nature of Gould's Belt. I will also give an overview of recent advances in the field of Galactic cartography including dust maps, young clusters, Hα maps, and core-collapse supernova histories that bring us an accurate 3D view of photoionization and stellar feedback across the local Milky Way.

Star formation proceeds in magnetized clouds, in which a combination of gas dynamics, dust evolution and angular momentum transport results in new stellar objects and their protoplanetary disks. In this talk, I will show how one can use facilities such as ALMA and NOEMA to get an all-around view on dust, gas, and magnetism evolution during the collapse phase. I study two protostars in the Perseus region, B1b-North and B1b-South. About 5,000 au apart from each other, these objects show both similarities and differences in the aspects mentioned above. Did these new stars form in the same way? Is their future bound to be the same? Or are they non-identical twins?

Rings are among the most highly anticipated discoveries in exoplanetary science. Rings and circumplanetary disks far larger than Saturn's have been proposed to explain a handful of long, deep and complex stellar eclipses, most famously J1407b, but each candidate admits competing explanations. In this talk I approach the problem of discovery and characterisation of these objects. First, I test whether an eclipsing disk system is really the best explanation for the periodic, deep and asymmetric eclipse of NOI 105872, weighing it against alternatives using the host star's properties and the structure of its light curve. Second, I present high-resolution GHOST spectroscopy of ASASSN-21js, a B-type star in the middle of a multi-year dimming event attributed to a transiting ring system. I separate photospheric, circumstellar and interstellar absorption across several epochs and look for spectral signatures of the occulting material, which also tells us what the host star actually is. Finally, I describe a systematic search for new exoring candidates in long-baseline ATLAS and SuperWASP photometry. The detection algorithm flags extended, multi-night dimming events and slow long-term fading, and I compare how well the two surveys can find such events. Together, these results show how hard it is to confirm a single exoring, and give a first step towards estimating how common these systems really are.

TBD

The discovery and characterization of young planets embedded in protoplanetary disks is fundamental for understanding planet formation mechanisms and timescales. We present a survey of 7 stars observed with Keck/NIRC2, hosting disks with substructures potentially indicative of embedded protoplanets. Our aim is to assess whether these embedded planets can be directly detected. We confirm the planetary candidate around Elias 2-24 at a separation of 394 ± 31 mas (54.9 ± 4.3 au) and a position angle of 298.8 ± 3.2°, located within the narrow gap of the disk. The source is detected also in a subsequent 2020 Keck observation, and proper motion tests confirm that it is bound to the host star. Comparing the derived photometry with 1 Myr isochrones, we infer a mass between 1.9 and 4.0 Jupiter masses for Elias 2-24 b, without considering accretion. Since Elias 2-24 (age ≲ 1 Myr) is significantly younger than other systems with directly imaged planets, the confirmation of Elias 2-24 b, the youngest planet detected so far, has important implications for planet formation timescales, demonstrating that giant planets can form through core accretion at separations of ~50 au within only ∼ 1 Myr, supporting the idea that such planets are responsible for the gaps observed in large and bright disks at these young ages. We also derived 5σ detection limits for all the systems in our sample, reaching sensitivities down to 1-11 Jupiter masses at separations ≳0.25".

To be announced

To be announced

To be announced

To be announced

To Be Announced

tbd

To Be Announced

To Be Announced

Accurately balancing gas reservoirs, star formation, and feedback across cosmic time remains a central challenge for galaxy formation models. In this talk, I will present a comparison of three state-of-the-art cosmological simulations: Magneticum, IllustrisTNG, and SIMBA, with recent observational constraints from MaNGA, eROSITA, and Sunyaev-Zel'dovich measurements. While reproducing the observed hot gas content of dark matter halos requires strong AGN feedback, such models often overquench star formation in galaxies. Conversely, weaker feedback better reproduces galaxy populations but systematically overpredicts the hot gas content of massive halos. I will discuss how these results reveal fundamental shortcomings in current AGN feedback prescriptions, suggesting that the challenge lies not only in the amount of energy injected but also in its timing, location, and coupling to the surrounding gas. These findings provide important guidance for the development of the next generation of galaxy formation models.

To be announced

Core-collapse supernovae are very energetic explosions that have a significant impact in the interstellar medium within galaxies. However, it is not well understood how progenitors of core-collapse supernovae form, evolve, and explode. In this talk, I plan to constrain the core-collapse supernova progenitor properties studying their star formation efficiency (or molecular gas depletion time) environments. In summary, it is found that interacting massive binaries occur in regions of intense, efficient star formation rather than simply higher gas content.

The past decade of observations of directly imaged companions has signaled a revolution in exoplanet spectroscopy. The objects observed to date reveal an extraordinary diversity of atmospheres, spanning a wide range of ages, temperatures, metallicities, and cloud properties. In this talk, I will present various results obtained with the numerical frameworks I am developing to model these complex exoplanetary spectra: ForMoSA and Optex. Using ForMoSA, I will discuss key atmospheric retrieval findings on benchmark targets (e.g., AF Lep b, beta Pic b, VHS 1256 b) alongside statistical studies of field brown dwarf spectral libraries. Specifically, I will address how these results help us piece together the broader picture of planet formation and evolution, particularly in contrast to stellar formation mechanisms and how formation pathways impact observable spectral features. Finally, I will conclude by outlining future prospects for the ELT era, highlighting end-to-end simulation work for MICADO's Long-Slit Spectroscopy (LSS) mode and its potential to further uncover the atmospheric properties of directly imaged exoplanets.

To be announced

To be announced

To be announced

To be announced

To be announced

To be announced

To be announced

To be announced