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Context. The dust- and gas-rich protoplanetary disks around young stellar systems play a key role in star and planet formation. While considerable progress has recently been made in probing these disks on large scales of a few tens of astronomical units (au), the central au requires further investigation. Aims.We aim to unveil the physical processes at play in the innermost regions of the strongly accreting T Tauri Star S CrA N by means of near-infrared interferometric observations. As recent spectropolarimetric observations suggest that S CrA N might undergo intense ejection processes, we focus on the accretion–ejection phenomena and on the star–disk interaction region. Methods. We obtained interferometric observations with VLTI/GRAVITY in the K-band during two consecutive nights in August 2022. The analysis of the continuum emission, coupled with the differential analysis across the Brγ line, allows us to constrain the morphology of the dust and the gas distribution in the innermost regions of S CrA N and to investigate their temporal variability. These observations are compared to magnetospheric accretion–ejection models of T Tauri stars and to previous observations in order to elucidate the physical processes operating in these regions. Results. The K-band continuum emission is well reproduced with an azimuthally modulated dusty ring with a half-light radius of 0.24 au (∼20 R*), an inclination of ∼30°, and a position angle of ∼150°. As the star alone cannot explain such a large sublimation front, we propose that magnetospheric accretion is an important dust-heating mechanism leading to this continuum emission. The Brγ-emitting region (0.05–0.06 au; 5–7 R*) is found to be more compact than the continuum, to be similar in size or larger than the magnetospheric truncation radius. The on-sky displacements across the Brγ spectral channels are aligned along a position angle offset by 45° from the disk, and extend up to 2 R*. This is in agreement with radiative transfer models combining magnetospheric accretion and disk winds. These on-sky displacements remain unchanged from one night to another, while the line flux decreases by 13%, suggesting a dominant contribution of wind to the origin of the Brγ line. Conclusions. Our observations support the scenario where the Brγ line originates from a combination of (variable) accretion–ejection processes in the inner disk region. [ABSTRACT FROM AUTHOR]

Aims. The physical properties of galactic molecular outflows are important as they could constrain outflow formation mechanisms. In this work, we study the properties of the southwest (SW) outflow streamer including gas kinematics, optical depth, dense gas fraction, and shock strength through molecular emission in the central molecular zone of the starburst galaxy NGC 253. Methods. We imaged the molecular emission in NGC 253 at a spatial resolution of 1.6″(∼27 pc at D ∼ 3.5 Mpc) based on data from the ALMA Comprehensive High-resolution Extragalactic Molecular Inventory (ALCHEMI) large program. We traced the velocity and velocity dispersion of molecular gas with the CO(1–0) line and studied the molecular spectra in the region of the SW streamer, the brightest CO streamer in NGC 253. We constrained the optical depth of the CO emission with the CO/13CO(1–0) ratio, the dense gas fraction with the HCN/CO(1–0), H13CN/13CO(1–0) and N2H+/13CO(1–0) ratios, as well as the shock strength with the SiO(2–1)/13CO(1–0) and CH3OH(2k–1k)/13CO(1–0) ratios. Results. The CO/13CO(1–0) integrated intensity ratio is ∼21 in the SW streamer region, which approximates the C/13C isotopic abundance ratio. The higher integrated intensity ratio compared to the disk can be attributed to the optically thinner environment of CO(1–0) emission inside the SW streamer. The HCN/CO(1–0) and SiO(2–1)/13CO(1–0) integrated intensity ratios both approach ∼0.2 in three giant molecular clouds (GMCs) at the base of the outflow streamers, which implies a higher dense gas fraction and strength of fast shocks in those GMCs than in the disk, while the HCN/CO(1–0) integrated intensity ratio is moderate in the SW streamer region. The contours of those two integrated intensity ratios are extended in the directions of outflow streamers, which connect the enhanced dense gas fraction and shock strength with molecular outflow. Moreover, the molecular gas with an enhanced dense gas fraction and shock strength located at the base of the SW streamer shares the same velocity as the outflow. Conclusions. The enhanced dense gas fraction and shock strength at the base of the outflow streamers suggest that star formation inside the GMCs can trigger shocks and further drive the molecular outflow. The increased CO/13CO(1–0) integrated intensity ratio coupled with the moderate HCN/CO(1–0) integrated intensity ratio in the SW streamer region are consistent with the picture that the gas velocity gradient inside the streamer may decrease the optical depth of CO(1–0) emission, as well as the dense gas fraction in the extended streamer region. [ABSTRACT FROM AUTHOR]

L’ambition de ce projet est de favoriser le développement équilibré d’un territoire emblématique de la Savoie, celui des alpages de Roselend dans le Beaufortain, en ayant recours aux formes les plus innovantes de concertation, de gouvernance et de financement. Il est né d’un constat partagé de multi-usages sur un secteur où l’hydroélectricité, le tourisme et le pastoralisme coexistent, depuis la construction du barrage, dans un espace riche d’une biodiversité remarquable. Avec le Projet Roselend, tous les acteurs se retrouvent dans un collectif, sous-tendu par des valeurs fortes, qui permet à chacun de comprendre et s’approprier les enjeux des autres et d’agir en co-responsabilité, pour le bien commun. La gouvernance territoriale partagée mise en place par les 4 partenaires fondateurs : EDF, la Commune de Beaufort, la Société d’Économie Alpestre de Savoie et le Conservatoire des Espaces Naturels de Savoie, permet de garantir l’organisation du cadre d’échanges, proposer des solutions adaptées et partagées et fédérer un écosystème dense d’acteurs privés, institutionnels et issus de la société civile. Le mode de financement des actions mêlant argent public et fonds privés, assure la pérennité du projet qui compte déjà 8 réalisations, 5 actions engagées et 8 projets en réflexion à suivre sur www.projetroselend.com.

The gas associated with the early stages of star formation contains traces of a large variety of molecular species, many of which are organic in nature. Interestingly, we observe a substantial chemical diversity among protostars, with some objects being enriched in what astrochemists label interstellar complex organic molecules (iCOMs), such as methyl formate (HCOOCH3), while others are overabundant in unsaturated carbon chains such as C4H. What is the cause of this diversity? And where should we place the proto-solar-system in this chemical context: was it rich in iCOMs, or in carbon chains, or in both? Thanks to the development of sensitive broadband (sub-)millimetre instrumentation, both in single-dish telescopes and interferometers, we are currently witnessing big steps forward in this area. The present contribution summarises what we have learnt, in the past decade or so, about the molecular contents in solar-mass protostellar sources, and suggests a few guidelines to stimulate progress in the field.

From the nutrition point of view, lipids are primarily considered as energy suppliers, their dietary intake having to be limited. In fact, lipids are sources of various fatty acids, and dietary recommendations include the required daily intakes in different fatty acids (fatty acid profile). Beyond these quantitative aspects, fatty acids are part of larger molecules, mainly triacylglycerols (TAG), that are organized in supramolecular structures as for example fat crystals and lipid droplets. Recent advances in nutrition research have demonstrated that these structures, and lipid organization in food matrices, influence digestibility and metabolism of fatty acids. Therefore, the members of the technological network Listral propose a synthesis of the knowledge about the influence of molecular and supramolecular structures of lipids on digestion and metabolic fate of dietary fatty acids originating from for the main food industry sectors. Fatty acids are mainly provided in the diet in the form of TAG, or phospholipids (PL) where they are esterified in external (sn-1, sn-3) or internal (sn-2) position of the glycerol backbone. They can also be found as ethyl esters (EE) in specific formulations. These molecular characteristics of the lipid molecules affect their hydrolysis and their absorption rate but also their metabolism in indifferent organs, as assessed in studies often using inter esterified fat sources. The results depend on the types of fatty acids (saturated or polyunsaturated fatty acids) but also on the model used for the studies: in vitro or in vivo studies; animal model, human newborn or adult, either healthy or exhibiting some diseases. Among others, it was found that the crystal form and fat melting point as affected by the fatty acid profiles and the lipid molecular structures directly impact fatty acid absorption kinetics through modifications of lipolytic enzyme activities. However, in these studies, the relative effect of the thermal properties of lipids and the proportion of saturated fatty acids chains in sn-2 position were hardly distinguished. Supramolecular structures, namely type and size of the fat droplets and their interfacial composition, of lipids, either in their native forms or obtained after food processes, also affect the digestibility and absorption of lipids. This aspect is reviewed with specific focus on dairy, marine, meat, oil plant and egg products. The impact of other nutritional components present in these food matrices on the absorption of lipids is also discussed.

Stars originate by the gravitational collapse of a turbulent molecular cloud of a diffuse medium, and are often observed to form clusters. Stellar clusters therefore play an important role in our understanding of star formation and of the dynamical processes at play. However, investigating the cluster formation is diffcult because the density of the molecular cloud undergoes a change of many orders of magnitude. Hierarchical-step approaches to decompose the problem into different stages are therefore required, as well as reliable assumptions on the initial conditions in the clouds. We report for the first time the use of the full potential of NASA Kepler asteroseismic observations coupled with 3D numerical simulations, to put strong constraints on the early formation stages of open clusters. Thanks to a Bayesian peak bagging analysis of about 50 red giant members of NGC 6791 and NGC 6819, the two most populated open clusters observed in the nominal Kepler mission, we derive a complete set of detailed oscillation mode properties for each star, with thousands of oscillation modes characterized. We therefore show how these asteroseismic properties lead us to a discovery about the rotation history of stellar clusters. Finally, our observational findings will be compared with hydrodynamical simulations for stellar cluster formation to constrain the physical processes of turbulence, rotation, and magnetic fields that are in action during the collapse of the progenitor cloud into a proto-cluster.

The Mediterranean area is prone to intense rainfall events triggering flash floods, characterized by very short response times that sometimes lead to dramatic consequences in terms of casualties and damages. These events can affect large territories, but their impact may be very local in catchments that are generally ungauged. These events remain difficult to predict and the processes leading to their generation still need to be clarified. The HyMeX initiative (Hydrological Cycle in the Mediterranean Experiment, 2010-2020) aims at increasing our understanding of the water cycle in the Mediterranean basin, in particular in terms of extreme events. In order to better understand processes leading to flash floods, a four-year experiment (2012-2015) was conducted in the Cévennes region (South-East) France as part of the FloodScale project. Both continuous and opportunistic measurements during floods were conducted in two large catchments (Ardèche and Gard rivers) with nested instrumentation from the hillslopes to catchments of about 1, 10, 100 to 1000 km2 covering contrasted geology and land use. Continuous measurements include distributed rainfall, stream water level, discharge, water temperature and conductivity and soil moisture measurements. Opportunistic measurements include surface soil moisture and geochemistry sampling during events and gauging of floods using non-contact methods: portable radars to measure surface water velocity or image sequence analysis using LS-PIV (Large Scale Particle Image Velocimetry). During the period 2012-2014, and in particular during autumn 2014, several intense events affected the catchments and provided very rich data sets. Data collection was complemented with modelling activity aiming at simulating observed processes. The modelling strategy was setup through a wide range of scales, in order to test hypotheses about physical processes at the smallest scales, and aggregated functioning hypothesis at the largest scales. During the project, a focus was also put on the improvement of rainfall fields characterization both in terms of spatial and temporal variability and in terms of uncertainty quantification. Rainfall reanalyses combining radar and rain gauges were developed. Rainfall simulation using a stochastic generator was also performed. Another effort was dedicated to the improvement of discharge estimation during floods and the quantification of streamflow uncertainties using Bayesian techniques. The paper summarizes the main results gained from the observations and the subsequent modelling activity in terms of flash flood process understanding at the various scales. It concludes on how the new acquired knowledge can be used for prevention and management of flash floods.