Seminars and Colloquia at ESO Santiago

High-resolution observations with ALMA have revealed that concentric rings and gaps are common features in protoplanetary disks. A favored mechanism for creating these substructures is planet-disk interactions, in which growing planets open gaps in the disk, and particles become trapped at the pressure maxima that form at the corresponding gap edges. Since the particle density in these pressure bumps can become very high, they are likely sites for planetesimal formation via the streaming instability. I have studied the formation and fate of such planetesimals formed at planetary gap edges, and found that this process can have a dramatic impact on the evolution of solids in protoplanetary disks, and therefore also on how the disks appear in observations. I will present results from 1D hydrodynamical simulations and N-body simulations, as well as preliminary results from 3D hydrodynamical simulations.

Modern galaxy simulations routinely reach parsec resolution, thereby unlocking a more self-consistent treatment of the internal structure of GMCs while accounting for the galactic-scale gas flows. This has led to significant theoretical progress, particularly concerning the cycle between star formation and feedback, the multi-phase ISM, and galactic wind driving. The latest improvement is the advent of star-by-star models, enabling simulations including individual stars. My model INFERNO incorporates stellar feedback, chemical enrichment, and the natal velocities of individual stars in hydrodynamical simulations of entire galaxies. This alleviates many of the restrictions imposed by the traditional approach, e.g., when and where stars inject feedback. Furthermore, INFERNO incorporates a state-of-the-art chemical yield model with on-the-fly enrichment calculations for the majority of elements in the periodic table.

In my talk, I will present results from simulations of dwarf galaxies in cosmological environments where all observable stars are treated with star-by-star calculations throughout a Hubble time. I will focus on predictions for observations of faint galaxies in the Local Universe and how the chemical signatures of these galaxies can help constrain our models.

B[e] stars are massive, hot B-spectral type stars embedded within a dense dust circumstellar envelope. As a result, their continuous spectrum shows a strong infrared excess, forbidden and permitted optical emission lines. Because they constitute a vast and heterogeneous class of objects in terms of stellar evolution, from new born stars (Herbigs Ae/Be) to evolved stars (supergiants), B[e] stars are not yet very well understood despite a long history of observations (half of them still unclassified). For instance, recent observations indicate that supergiants showing B[e] characteristics can host circumstellar rings. So far, the main scenarios to explain the detection of a large amount of gas and dust, geometrically distributed in discs around the latter, are either due to decretion mechanisms, driven by radiative pressure, rotation, pulsation or mass transfer due to binary interaction. As the structure and dynamics of these discs are still unclear, the analysis of our high angular resolution observation campaigns conducted over 17 B[e] stars with the VLTI/MATISSE instrument between 2018 and 2021 will improve the general understanding over the mechanisms that drive phases of enhanced mass loss and mass ejections, responsible for the shaping of the circumstellar material of B[e] stars. Following the approval of a new observation proposal with VLTI/MATISSE, submitted during the ESO P112 call, the coverage of the interferometric aperture plane - commonly refered as the (u,v)-plane coverage - for eight stars of the survey has been enhanced, enabling an in-depth image reconstructions for those. The focus of this presentation will therefore lie on the multi-component geometric modelling and image reconstruction on the mid-infrared data of the supergiant A[e] star l Puppis, one of the targets of our current MATISSE B[e] survey. The results presented have been partially obtained through the ESO Early-Career Scientific Visitor Programme at ESO Santiago, Chile, during a collaborative period spanning two months with Claudia Paladini and Julien Drevon. Implications with regard to previous results obtained with the first generation interferometric instruments VLTI/MIDI and AMBER will also be explored.

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MOONS is a 0.8–1.8-μm multi-object spectrometer designed to work at the Nasmyth focus of the VLT’s UT1. It will have 944 fibres patrolling a field 25 arcminutes in diameter. MOONS can be used with a spectroscopic resolving power R ~ 4000 spanning the full near-infrared wavelength range, or with R ~ 9000 in the I band and R ~ 18 000 in the H band. MOONS has two main sub-components, the rotating front end (which is at the focal plane and houses the fibre positioners, the acquisition system and the metrology system for the fibres) and the cryogenic spectrographs, which will be on the telescope’s Nasmyth platform. MOONS is now fully assembled at the UK-ATC, Edinburgh. PAE is expected this summer and it will arrive at Paranal by the end of the year. This talk will cover the science drivers behind the instrument and its current status.

Studies of micrometeorites in mid-Ordovician limestones and Earth’s impact craters show that our planet witnessed a massive infall of ordinary L chondrite material ~466 million years ago that it believed to be at the origin of the first major mass extinction event (Schmitz et al. 2019). The breakup of a large asteroid in the main belt is the likely cause of this massive infall. In modern times, material originating from this breakup still dominates meteorite falls (~37% of all falls). I will present spectroscopic observations and dynamical evidence that we have identified the only plausible source of this catastrophic event and of the most abundant class of meteorites falling on Earth today.

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