Seminars and Colloquia at ESO Santiago

NGC 253 is the one of the brightest molecular emitters outside the Galaxy and therefore the more suited candidate for deep molecular surveys. Despite of being observed at every wavelengths for decades, ALMA keeps unveiling new details on its central molecular zone. I will summarize the current status of the ALCHEMI project which is an ALMA large program consisting of an unbiased line survey from ALMA bands 3, 4, 5, 6, and 7 (85-370 GHz). Covering the whole central molecular zone of this starburst galaxy, this project is the most ambitious study of the molecular content and distribution in an extragalactic object. This presentation will briefly present the first results on the low resolution data from the 7m compact array which already shows an unprecedented molecular richness. More importantly, some preliminary results with the highest resolution data towards the brightest giant molecular cloud complex will be presented. These observations increase significantly the number of molecular species detected towards the extragalactic interstellar medium, and more importantly these data finally get us in the realm of complex organic molecules at Mpc distances.

The ALMA Large Program ATOMIUM1 is the first observational campaign of a large sample of oxygen-rich Asymptotic Giant Branch (AGB) stellar winds at high angular resolution and sensitivity. ATOMIUM exploits the unique ability of ALMA to study the many oxides and hydroxides which are the precursors of dust in oxygen-rich winds. The goals of the ATOMIUM program are: (1) to establish the dominant physical and chemical processes in the winds of oxygen-rich evolved stars over a range of stellar masses, pulsation behaviours, mass-loss rates, and evolutionary phases; (2) to unravel the phase transition from gas-phase to dust species; (3) to pinpoint the chemical pathways; (4) to map the morphological structure; (5) to study the interplay between dynamical and chemical phenomena; (6) to elucidate the role of (un)correlated density structures on the overall wind structure; and (7) to understand the chemistry of dust precursors and dust formation. A more general aim of the ATOMIUM project is to build a strong foundation to better understand astrochemical processes in a range of research fields including novae, supernovae, exoplanets, protoplanetary nebulae, and interstellar shocks.

In this talk, we present one of the early successes of ATOMIUM which was published in Science in September 2020. Planetary nebulae (PNe) are well-known to reveal a wide range of morphologies. Bipolarity is the main characteristic, but jets and tori are also detected. Several contending theories of the evolution from a (roughly) spherically symmetric Asymptotic Giant Branch (AGB) stellar wind to a very non-spherical PN have emerged. Here, we present the first observational proof that (sub)stellar binary activity – including the effects of planets, brown dwarfs, and low-mass stellar companions - is the dominant shaping mechanism of AGB stellar winds, and their successors the PNe. We show that low mass-loss rate oxygen-rich AGB winds are more readily prone to complex structural deformations owing to their slow wind acceleration, whereas a binary-induced spiral structure is more prevalent in other classes of AGB stellar winds. These results resolve several previously unexplained phenomena — including the absence of detached shells around oxygen-rich AGB stars and disks around carbon-rich PNe — and have critical implications for the formation of type Ia supernovae. Our results also imply that the effects of planets around evolved stars are more easily detected in early-type oxygen-rich AGB stars.

1 ATOMIUM refers to the ALMA Cycle 6 Large Project in Band 6, ALMA Tracing the Origins of Molecules formIng dUst in oxygen-rich M-type star

Cold gas and cosmic dust are the fuel of star formation. ALPINE is an ALMA Large Programme which has built the first statistically representative sample of star-forming galaxies at z>4 by targeting emission from singly ionized carbon [CII] at 158 μm, which traces both emission from star-forming regions and molecular hydrogen gas clouds, and the thermal continuum from dust at the end of the epoch of reionisation (4.4 < z < 5.9). Observations by the ALPINE team have revealed that a significant fraction of the star formation at this epoch is already hidden by dust clouds. ALPINE observations have also shown how unruly these young galaxies were by finding a large fraction of disturbed morphologies and ubiquitous gas outflows.

The circumgalactic medium (CGM) is the gas surrounding Galaxies outside their disk. The CGM is important to understand galaxy evolution. Many observations have been made using QSO beams however spatial information is lacking and this has hindered 3D models of the CGM. In this work i will be presenting a 3D spatial and kinematic model for the rotating disk-like CGM. The model is based on a radial profile of individual clouds with a velocity, inclination, etc. Model parameters are constrained  using IFU data from the arc-tomography survey. These tomographic data use giant gravitational arcs as background sources addressing so the problem of spatial information. Preliminary results using chi-square minimization show a good match of the model with the data.

The site of both the slow and rapid neutron capture processes are poorly understood, and can be constrained by obtaining the abundances for the neutron capture elements in various galactic environments. As the spectral lines of these elements are very weak, in order to see them it is necessary to get a very high signal to noise spectrum, in this case, achieved through stacking. The goal for this internship was to create a stacked spectrum of HST/COS spectra to quantify the chemical composition of the Milky Way as seen from a quasar sightline, and assess the feasibility of detecting neutron capture species in quasar sightlines passing through other galaxies. During this presentation I will talk about how we approached this problem, and share some preliminary results.

With the aim of characterizing the role played by magnetic fields in the formation of young protostars, several recent studies have revealed unprecedented features toward high angular resolution ALMA dust polarization observations of Class 0 protostellar cores. Especially, the dust polarization has been found to be enhanced along the cavity walls of bipolar outflows, which are subject to high irradiation from the reprocessed radiation field emanating from the central protostar. In addition, highly polarized dust thermal emission has been detected in region most likely linked with the infalling envelope, in the form of filamentary structure being potential magnetized accretion streamer. These observations allow us to investigate the physical processes involved in the Radiative Alignment Torques (RATs) acting on dust grains from the core to disk scales. Notably, we propose that the polarized emission we see at millimeter wavelengths along the irradiated cavity walls can be reconciled with the expectations of RAT theory if the aligned grains present in these cavities have grown larger than what is typically expected in young protostellar cores. To approach an estimation of the efficiency of dust alignment in protostars, we gathered all the available ALMA dust polarization observations of Class 0 protostars, to perform a statistical analysis examining the trend between the dispersion of polarization position angles S, and the fractional polarization P_frac. We report a significant correlation between S and P_frac, whose power-law index differs significantly from the one observed by Planck in star-forming clouds. The grain alignment efficiency, is surprisingly constant across three orders of magnitude in envelope column density. Synthetic observations of non-ideal magneto-hydrodynamic simulations of protostellar cores implementing RATs, show that the ALMA values of grain alignment efficiency lie among those predicted by a perfect alignment of grains, and are significantly higher than the ones obtained with RATs. Ultimately, our results suggest dust alignment mechanism(s) are efficient at producing polarized dust emission in the local conditions typical of Class 0 protostars. The grain alignment efficiency found in these objects seems to be higher than the efficiency produced by the standard RAT alignment of paramagnetic grains. Further study will be needed to understand how more efficient grain alignment via, e.g., different irradiation conditions, dust grain characteristics, or additional grain alignment mechanisms can reproduce the observations.

In this talk I will present three new planetary systems we have detected from our precision radial-velocity analyses, two of which were candidate planets announced by TESS and confirmed through HARPS follow-up.   The third planetary systems was found as part of our planet search program using the PFS, and subsequently appeared as a single transit in TESS observations.  With masses between 20-40 Me and radii 3.5-4.5 Re, these planets can all be classed as exo-Neptunes.  I will discuss the detection of these worlds and the characterisation of their physical structures, with a particular focus on the first Ultra Hot Neptune, LTT9779b.  I will then finish by looking at the follow-up studies we are currently engaged in and what we aim to learn about the population of Neptune planets.

Giant radio galaxies (GRG) are thought to represent one of the oldest structures in the Universe, since the size of their radio jets/lobes, larger than 0.7 Mpc, implies that they lived about 10^8 yr. A look at hard X-rays with INTEGRAL/Swift seems to favor the selection of GRG with restarted activity in their nuclei. I will speak about a sample of GRG selected at these energies, and take a deeper look into two of the GRG using multiwavelength data. These are PBC J2333.9-2343, a radio galaxy that changed the direction of the jet and became a blazar, and Mark 1498, that seems to be an aftermath of a merging event that reinitiated its nuclear activity.

Despite being extensively studied, Betelgeuse still holds many mysteries.  

The famous red supergiant recently experienced an unusual dimming in the visible.

A number of publications propose different interpretations of this phenomenon and some of these revisit fundamental characteristics of the star.

After presenting a review of high-angular resolution diagnostics, I will provide an overview of current understandings regarding Betelgeuse's variability. 

Understanding geometry of the material in the broad line region (BLR) can shed light on the physics in the proximity of active galactic nuclei (AGN). Three BLR properties, the cloud velocity distribution, their distance from the central supermassive black hole (BH) and the virial factor f, are directly involved in BH mass (Mbh) determination. Systematics about the BLR dynamics are encoded in the virial factor f, that is a scale factor upon which all the virial Mbh estimates are rooted, and affects up to ∼2-3 the Mbh uncertainties. The f-factor has been directly determined on a small sample of local broad-line AGN, allowing the community to infer a correlation between f and line-of-sight inclination. However, little is known about the BLR and f-factor in obscured AGN. Understanding whether biases arise in MBH estimation with increasing obscuration is possible only by studying an obscuration unbiased (hard) X-ray selected AGN statistical sample in the rest-frame near-infrared (0.8–2.5 micron). The rest-frame near-infrared penetrates deeper into the BLR than the rest-frame optical band. We here present a detailed analysis of 65 local BAT-selected Seyfert (Sy) galaxies observed at Magellan/FIRE. Adding these to the near-infrared BAT AGN spectroscopic survey (BASS) database (mostly observed with the ESO VLT/Xsh), we study a total of 314 unique near-infrared spectra with ancillary spectral data in optical and X-ray. This is the largest statistical sample of local AGN with rest-frame near-infrared spectra. These observations allow us to 1) construct a statistical sample of AGN to assess the presence of correlations between f and AGN properties, 2) build a more complete and less biased sample of AGN, by considering also Sy 1.8-1.9-2 with broad lines in the near-infrared, and 3) verify systematics in BLR characterisation (broad-line FWHM and luminosity and hence Mbh) as a function of X-ray obscuration and dust extinction.

Young giant planets and brown dwarf companions emit near-infrared radiation that can be linearly polarized up to several percent. This polarization can reveal the presence of an (unresolved) circumsubstellar accretion disk, rotation-induced oblateness of the atmosphere, or an inhomogeneous distribution of atmospheric dust clouds. In this talk I will present the results of our near-infrared linear polarization measurements of more than 20 known directly-image exoplanets and brown dwarf companions using SPHERE-IRDIS at the VLT. We have detected for the first time the polarization from three substellar companions and one low-mass stellar companion, which we interpret to be caused by accretion disks around the companions. I will discuss these results in terms of the system architectures and the companions formation, and outline the implications of our non-detections.

The interaction between a supermassive black hole (SMBH) and the surrounding material is of primary importance in astrophysics. The detection of the molecular 2-pc circumnuclear disk (CND) immediately around the Milky Way SMBH, SgrA*, resembles the "molecular torus" in AGNs, provides an unique opportunity to study SMBH accretion at sub-parsec scales. However, the CND is transient if its gas density is under the tidal threshold of SgrA*/nuclear star clusters, thus depleting the source of fuel. In our new CS line maps, we find several dense gas streamers appear to carry gas directly toward the nuclear region and might be captured by the central potential. These streamers show a signature of “infalling” motion with progressively higher velocities as the gas approaches the CND and finally end up co-rotating with the CND. Furthermore, utilizing the JCMT 850 um polarization data, we also find that the magnetic field appears dynamically significant toward the CND and also onwards to the inward ionized flows.  Our results might suggest a possible mechanism of gas feeding to the CND. I will also talk about the observed morphology, kinematics of gas, and effects of magnetic fields in the GC. I will present our newest ALMA CS line maps in this region. As the nearest observable Galactic nucleus, this feeding process may have implications for understanding the processes in extragalactic nuclei.

 High-precision brightness measurements for stars with space telescopes have made it possible to detect very low amplitude brightness variations in the stellar surface and hence provided us the study of the stellar interior physics via nonracial oscillations, ‘ Asteroseismology'. We know that the fraction of multiple systems in main sequence populations (e.g. from solar-type to high mass) varies from ~ 44% to ≥60%. When studying the pulsation of A/F-type intermediate-mass stars that are residing in the binary systems, not only we have access to an independent additional tool to derive the stellar fundamental parameters but also we can detect the pulsations modes that provide a perfect laboratory to check the influence of binarity (e.g., eccentricity, tidal effects, mass transfer, chemical peculiarities and the presence of a third body, etc.) on stellar structure, stellar evolution, and the excited oscillation modes. Moreover, Ignoring the multiplicity of stars leads us to a wrong history of the stellar evolution. Considering the spectroscopic methods (i.e. model-dependent and extinction considerations ) for driving the stellar distances, astronomers need to know, finally, if they can rely on the massive astrometric observations from Large surveys like Gaia in the case of binary stars. I will try to address some interesting results for both pulsation and distance measurements in binary stars. 

Although more than 30 years have passed since their discovery, narrow-line Seyfert 1 galaxies (NLS1s) still present challenges for unified models of active galactic nuclei (AGN). Their physical properties are ambiguous, and their role in galaxy evolution remains poorly understood. In this seminar we will outline their most relevant characteristics, and present the two current main hypotheses about their physical nature, with particular attention to their broad-line region geometry. We will discuss the radio properties of NLS1s, presenting some very recent puzzling results obtained with the Metsähovi Radio Telescope and the Very Large Array. Finally we will present our host galaxy survey carried out with the New Technology Telescope, showing how it can impact our understanding of this interesting class of AGN.

Quasar sightlines through intervening material provide insights into the evolution of gaseous reservoirs within and surrounding galaxies across cosmic time. With the advent of high resolution spectrographs on 8m class telescopes, quasar absorption line systems are excellent probes of the chemical evolution of neutral gas, providing an orthogonal approach to detailed stellar abundances in the Local Group. In this talk I will present recent work focussing on using both damped and sub-damped Lyman alpha systems to study the chemical enrichment of the Universe from the XQ-100 survey between redshifts 2 and 4. I will highlight what these quasar absorbers can tell us about enrichment of both the interstellar and circumgalactic media based on detailed chemical abundance measurements.

Herbig Ae/Be stars are high-mass Pre-Main Sequence objects which are key to understanding the formation mechanisms of high-mass stars and the evolution of their protoplanetary discs. Historically, the study of the general properties of these objects has been hampered by the lack of a well-defined, homogeneous sample, and because few and mostly serendipitously discovered sources were known. Applying Machine Learning techniques to Gaia DR2 data we have constructed a large and homogeneous catalogue of Pre-Main Sequence stars with, at least, 1361 new Herbig Ae/Be candidates. Classical techniques are not efficient for identifying these objects mainly because of their similarity with classical Be stars, with which they share many characteristics. By focusing on disentangling these two types of objects, our algorithm has also identified 693 new classical Be stars. 

This catalogue of new high-mass Pre-Main Sequence stars increases the number of known objects of the class by an order of magnitude. In this talk, I discuss the methodology used and the general properties of the new sources. Furthermore, I present the results of independent spectroscopic observations of 100 of these newly discovered Herbig Ae/Be stars.

For a new and homogeneous photometric catalogue of dwarf galaxies in the Fornax cluster, we calculate the expected tidal radii for those dwarf galaxies in the galaxy cluster potential, for both MOND and LCDM cosmology. Combining this with estimates of tidal disruption times from galaxy harassment in each cosmology, we define a tidal susceptibility parameter for each dwarf in both MOND and LCDM. In general, tidal susceptibility in MOND is significantly larger than in LCDM. We then contrast the expected levels of tidal susceptibility of the dwarfs in MOND and LCDM with their visually observed levels of morphological disturbance. We discuss our findings and point out the next steps in this ongoing investigation.

PS: for some more background on MOND and LCDM, please check the recent ESO duologue

https://www.eso.org/sci/meetings/2020/Cosmic-Duologues/duologue1.html

A bright star catalog object (HR 6819, V=5.5, d~300pc) was recently identified as hierarchical triple system, where a Be star (a rapibly rotating B star with mass-loss through a disk) is in wide orbit around a close binary consisting of a B star and a stellar mass black hole (Rivinius et al 2020). I will review the story of that discovery, including the evidence for a black hole rather than any other type ofcompanion, as well as age and distance. HR6819 will be discussed in light of recent results concerning this and several other Be and Black hole multiple systems. The presence of line emission poses unique challenges to obtain the radial velocity curve, and has to be taken with greatest care. Finally, potential implications and further work will be indicated.

The ESPRESSO spectrograph was built with the declared goal of detecting Earth-mass planets orbiting inside the habitable zone of G, K, and M stars. The Guaranteed Time Observations awarded by the ESPRESSO Consortium are in part commited to this goal. In this talk I present a brief summary of the work conducted until now by the working group dedicated to the blind search for planets through radial velocity. I will also present our first work, the independent confirmation of planet Proxima b.

First edition of the PSO Training for Newcomers

High angular resolution images of protoplanetary disks are revolutionising the field of disk evolution, and implying important constraints on planet formation models. Even though there are strong observational biases in the sample of spatially resolved disks hosting structures, at least some of them show indirect evidence of massive (sub-)stellar companions perturbing their density and kinematics. I will discuss some recent results trying to fill the gap between the exquisite quality of recent datasets and current theoretical models, focusing in particularly in the planet/companion hypothesis. Finally, I will show how the PDS70 system with its two recently detected planets can be used as a testbed for models including migration, dust trapping, and circumplanetary disk physics.

ALMA proposals preparation workshop

ALMA proposals preparation workshop

Discovery of only handful of exoplanets required to establish a correlation between giant planet occurrence and metallicity of their host stars. More than 20 years have already passed from that discovery, however, many questions are still under lively debate: What is the origin of that relation? what is the exact functional form of the giant planet – metallicity relation (in the metal-poor regime)?, does such a relation exist for terrestrial planets? All these question are very important for our understanding of the formation and evolution of (exo)planets of different types around different types of stars and will be the subject of my talk. Besides making a comprehensive review about the role of metallicity on the formation of exoplanets, I will present my latest results related to formation of super-massive planets. Contrary to the previous claims, I will show that there is no breakpoint planetary mass at about 4Mjup above and below which planet formation channels are different. However, I will argue that planets of the same  (high) mass can be formed through different channels depending on the (disk) stellar mass i.e. environmental conditions.

In this talk I’ll first present current DES supernova (SN) cosmology results and then move towards the future of SN cosmology and time-domain astronomy with LSST by introducing Fink, a broker development.

DES performed a time-domain survey during 5 years to obtain a large sample of type Ia supernovae (SNe Ia) for cosmology. I will present our first 3-year cosmology results with 207 spectroscopically confirmed SNe Ia. Our new cosmological analysis with the whole five years of data uses approximately two thousand photometrically-typed SNe Ia from DES. I will highlight key features of our current cosmology analysis including photometric classifiers which will be crucial for next generation experiments such as LSST.

LSST is expected to detect 10,000 transient candidates every 30 seconds, within these alerts there will be a small fraction of supernovae. To fully harness the power of these LSST, new methods must be developed to deal with large data volumes and to coordinate resources for follow-up of promising candidates. I will present Fink, an IN2P3 initiative being developed to face these challenges. Fink is designed to use state-of-the-art machine learning methods to allow selecting early supernovae for follow-up coordination and understand the nature of these explosions while enabling diverse time-domain astronomy studies.

MATISSE (Multi-AperTure mid-Infrared SpectroScopic Experiment) is the second generation VLTI (Very Large Telescope) instrument which entered in standard operations in April 2019. The instruments observing window is the thermal infrared from 3 up to 13 microns. The 3 – 5 microns region is a new territory for interferometers with 4 telescopes beam combiner. It is well known that interferometric observations are heavily dependent on calibrators which need to be well characterized, as bright as the science source, single objects, point source, not dust enshrouded, and not variable. All these constraints make very difficult finding a good calibrator, and this is even more true for the previously unexplored thermal infrared LM-band range. This project aimed at strengthen the calibration scheme of MATISSE complementing the study of the MATISSE consortium which is focussed on faint sources and L-band, with analysis of bright calibrators and N-band data.

Water masers are stellar lighthouses usually present in star forming regions. We analyzed a sample of twenty high- to low- mass young stellar objects recently surveyed by us with the APEX telescope at 321 and 325 GHz water maser transitions. Maser emission has been previously detected in our sample at the 22 GHz line, which is the most common one. The motivation for extending these studies to other water maser transitions is to better understand what are the excitation conditions of this emission. For this we study detection rates and velocity components over different maser transitions and their relation with the bolometric luminosity of the central protostar. We also present some variability studies on a subsample of our survey.

Ultra-faint dwarf galaxies are often no brighter than a single massive star and are notable because they are strongly dark matter dominated with very sparse, and old, stellar content. This in principle makes them excellent laboratories for studying dark matter, but this requires an extensive sample of spectra of the stars within the dwarfs which can be challenging due to both foreground and background  contamination as well as the faintness of the stars. Here we will present the first results from MUSE-Faint, a MUSE GTO survey of ultra-faint dwarf galaxies around the Milky Way with the aim to understand better the early formation of these faint sources and to constrain the nature of dark matter. We will give a brief overview of the survey, but the focus will be on Eridanus 2 which has a putative stellar cluster which allows us to place constraints on the contribution of MAssive Compact Halo Objects (MACHO)  to dark matter. (Zoutendijk et al, 2020).  We will also show first results for the determination of the dark matter density profile in these galaxies - a potential discriminator between different dark matter models.

MUSE is known as a high-performance instrument at the VLT that has made integral field spectroscopy (IFS) a powerful tool for high redshift galaxy surveys, but also the study of extended objects such as galaxies or nebulae over a very large field-of-view, compared with first generation IFUs some 15 years ago. I will discuss the capabilities of MUSE for the study of resolved stellar populations, using the new method of point-spread-function-fitting crowded field IFS, analogous to the well-established technique of crowded field photometry with image sensors. I review early pioneering work with first-generation integral field spectrographs, the breakthrough achieved with MUSE at the Very Large Telescope, the remarkable progress accomplished with MUSE in the study of globular clusters, and first results on nearby galaxies. I will discuss the synergy of MUSE with future facilities such at the ELT, and conclude with an overview of the recently proposed BlueMUSE instrument.

The brightest X-ray sources in the sky are X-ray binaries: accreting black holes and neutron stars in our galaxy. When these X-ray binaries have outbursts, they can produce relativistic outflows in the form of collimated jets. The jets produce synchrotron emission from radio to infrared/optical wavelengths. The jet power can be a significant fraction of the accreting inflow power. However, the jet power can only be measured accurately if the broadband jet spectrum can be well measured. These jets are notoriously difficult to detect in the mid-IR to mm regime due to their faintness, highly variable nature, and lack of sensitive instrumentation.
This has been greatly improved with detections of X-ray binaries with VISIR on the VLT at 5-12 microns. For several years we have been detecting X-ray binaries at mid-IR wavelengths with VISIR, and some at mm with ALMA. We have discovered that the break in the jet spectrum lies in the mid-IR range, and shifts to longer (mm) wavelengths when these jets weaken during state transitions. I will showcase some broadband spectral energy distributions of X-ray binaries, highlighting the essential contribution of VISIR. In some cases we can see dramatic evolution of the jet spectrum when the accretion state is changing, which provides an insight into the physical processes responsible for suppressing and reactivating the jet, and has implications for the conditions required for jets to be produced, and hence their launching process. We also present the first mid-IR variability study of an X-ray binary on short (minute) timescales. On some dates the mid-IR flux of MAXI J1535-571 varied by a factor of two in less than 15 minutes. The mid-IR fractional rms variability on minute timescales is ~ 15%. The spectrum and variability amplitude are consistent with a jet internal shock model. These results demonstrate how rich, multiwavelength time-resolved data of X-ray binaries can help refine models of the disc-jet connection and jet launching in these systems.

Looking for bright galaxies born in the early universe is fundamental to investigating the Epoch of Reionization, the era when the first stars and galaxies ionized the intergalactic medium. We utilize Hubble Space Telescope pure parallel imaging to select galaxy candidates at a time 500 to 650 million years after the Big Bang, which corresponds to redshifts z~ 8-10. These data come from the Brightest of Reionizing Galaxies Survey (BoRG) Cycle 22 dataset, which consists of pure-parallel imaging in ~ 90 different lines of sight that sum up to an area of ~ 420 . This survey uses five filters and has the advantage of including imaging in the JH140 band, covering continuous wavelengths from the visible to near-infrared (= 0.35μm – 1.7μm). This allows us to perform reliable selection of galaxies at z>8 using the photometric redshift technique. We use these galaxy candidates to constrain the bright end of the rest-frame ultraviolet luminosity function in this epoch. These candidates are excellent targets for follow-up observations, particularly with the James Webb Space Telescope.

Class 0 protostars are the first protostars, experiencing such vigorous accretion that most of the final stellar mass will be accreted onto the central protostellar object in less than 105 yrs. During this crucial star-building phase, the material from the circumstellar envelope must redistribute most of its initial angular momentum outward while being accreted, or centrifugal forces will prevent further star growth: this is the long standing problem of angular momentum for star formation. How this is done exactly remains poorly understood: several key questions tied to this angular momentum problem still remain open, such as the role of magnetic fields and envelope rotation for building protostellar disks and launching jets. Solving these questions is of paramount importance not only to better understand the origin of our own solar system, but also depicting the pristine conditions leading to the formation of most stars and planets. Ultimately, it relies on characterizing the physics at work in young accreting protostars. 

We present a method to measure the extinction curves, parametrized by the total-to-selective extinction ratio Rv, by means of fitting spectral energy distribution (SED) of galaxies. Prospector SED-fitting framework takes advantage of the Bayesian approach to provide reliable error bars of the fitted parameters. We use this tool to validate our method for measuring Rv, using simulated spectral and photometric data. Fitting the mock data allows us to test the possibility to recover the expected values with different configuration of data. A model spectrum of spectral range 3750-7500 Angs is fitted against a MUSE-like spectral range to test the effect of the blue part of the spectrum. Mock data from bluer photometric bands are also combined with the MUSE-like spectrum to mitigate the effect of censoring the bluer spectral range. A 3\% level of noise (SNR of 30) is found to be sufficient to measure the extinction with our method. Extinction curves have been found steeper than the standard Rv = 3.1, with unusual low values inferred from Type Ia supernovae (SN Ia) photometric observations, revealing peculiar dust properties of the interstellar medium (ISM) and possible presence of circumstellar dust. Hence, we apply our methodology to the test case of NGC7721, host of a SN Ia (SN2007le), observed with MUSE as part of AMUSING SN host galaxies survey and with Tek5 camera at Du Pont 2.5-meter telescope by the Carnegie Supernova Project (CSP).

The Pipe Nebula is an apparently boring, quiescent dark cloud. Active (low-mass) star formation appears only in the tip of the Pipe, in the Barnard 59 (B59) dense molecular core.  [BHB2007] 11, a Class I protostellar system, is the youngest member of the small young stellar cluster around B59. In this talk I will discuss what ALMA and VLA observations have revealed in this binary system, including complex morphology and kinematics. The two young stars have small, ~3 au radii disks that are surrounded by a circumbinary disk comprising a complex network of filaments. There is also a flattened envelope around the circumbinary disk. A low velocity bipolar molecular outflow is launched from the border of the circumbinary disk; this outflow is probably associated with the centrifugal barrier. The dust polarization appears to trace grains aligned with the magnetic field, with the polarization direction being perpendicular to the field direction. We interpreted the magnetic field morphology as a combination of poloidal and toroidal field, but with a clear predominance of the poloidal (hourglass) component. However, recent developments in the theory of the dust polarization properties of grains suggest a different and puzzling interpretation of the magnetic field structure.

The study of absorptions along the lines of sight to bright high-redshift QSOs is an invaluable cosmological tool that provides a wealth of information on the inter-/circum-galactic medium, Dark Matter, primordial elements, reionization, fundamental constants, and General Relativity. Unfortunately, the number of bright (i<18) QSOs at z > 2 in the Southern hemisphere is much lower than in the North, due to the lack of wide multi-wavelength surveys at declination < 0, hampering the effectiveness of
observations from southern observatories. Thanks to the availability of precious (new) databases such as Skymapper, Gaia DR2, WISE, 2MASS, and new statistical methods specifically trained for our purposes, we have produced samples of candidates to fill this gap. Our first list included 1476 sources with i < 18 over 12,400 square degrees in the southern hemisphere. With a few observing campaigns, including the ESO NTT,  we observed spectroscopically a significant fraction of them,
corresponding to a success rate of our method of about 80%,  confirming many new bright QSOs at z > 2, including two super-bright at z=3.9 and 4.15. Furthermore, we estimate completeness of about 90% at completion of our observation campaign. The new QSOs confirmed by this first and the forthcoming campaigns will be the targets of subsequent studies using higher resolution spectrographs, like X-shooter, ESPRESSO, UVES,  and (in the long term) ELT/HIRES.

Large-scale organised magnetic fields of kG order are present in 5–10% of the upper main-sequence stars. The rotation periods of these stars span 5 or 6 orders of magnitude, with no evidence for evolution besides conservation of the angular momentum during their main-sequence lifteime. Explaining how period differentiation over such a wide range is achieved in stars that are essentially at the same evolutionary stage represents a major challenge. To address it, improved knowledge of the distribution of the rotation periods is a pre-requisite. Space- and ground-based photometric surveys have already enabled considerable progress to be achieved in the study of the periods of days to months, and they will continue to do so in the coming years. Magnetic field measurements lend themselves better to the monitoring of the longer periods. The most extreme among the latter, which may reach decades to centuries, are of particular interest, but constraining them is also the most challenging endeavour. Recent progress in this area will be reviewed, and future prospects and concerns will be discussed.

Evolved Stars play key roles, enriching galaxies with dust, gas that fuels star formation and the products of nucleosynthesis through their mass loss.For low- and intermediate-mass stars, a large part of this mass loss occurs on the Asymptotic Giant Branch through a dusty wind, while the more massive Red Supergiants undergo similar processes. I will review some recent progress in understanding the mechanisms driving this mass loss and how it enriches the ISM. I will then present some initial results from the ongoing JCMT large program the Nearby Evolved Stars Survey, which is observing a statistical sample of evolved stars in the Solar Neighbourhood. NESS aims to determine the total mass return to the Solar Neighbourhood and obtain a statistical picture of the physics of mass loss. Finally, I will explore some important avenues for future work in this field.

During the early stages of star formation, a protostar is deeply embedded and heavily accreting from a gaseous and dusty envelope, and thus it is very difficult to measure its mass. The most widely used method to estimate masses uses the Keplerian rotation of the gas in the disk around the protostar, observed only in a few and mostly isolated objects in the earliest stages. However, due to the active accretion, the gas motions can deviate from a standard Keplerian profile, and hence the masses measured may not reflect the true protostellar masses. Constraining orbital parameters in multiple systems is the only direct method to measure protostellar masses, and thus embedded multiple systems are the best laboratory to weight stars during the assembly stages. In this talk, I will present VLA and ALMA observations of the relative trajectory of a pair of bound protostars leading to a first robust determination of the orbital trajectory and total protostellar mass in an embedded multiple system. This is the most embedded multiple for which protostellar masses are directly determined by orbital motions.

Increasing our knowledge of the interior structure, composition, and density distribution of exoplanets is crucial to make progress in the understanding of exoplanetary formation, migration and habitability. However, the directly measurable mass and radius values offer little constraint on interior structure, because the inverse problem is highly degenerate. Therefore, there is a clear need for a third observable of exoplanet interiors. This third observable can be the k2 fluid Love number which measures the central mass concentration of an exoplanet. We explain what Love-number is, how one can use it to constrain planetary and stellar interiors, and what progress we made in the field.

I present new accurate Period-Luminosity (PL) and Period-Wesenheit (PW) relations in the V,J,Ks bands based on a sample of more than 4000 Cepheids in the Large Magellanic Cloud (LMC) whose photometry was obtained in the context of the VISTA Magellanic Could (VMC) Survey. The excellent precision of these data allows us to study the geometry of the LMC and to establish a solid baseline for extra-galactic distance scale studies.  To calibrate the zero points of these PL/PW relations, we adopted Gaia Data Release 2 parallaxes for more than 1500 Milky Way Cepheids. The implications in the context of the Hubble constant tension are discussed.