The VIMOS upgrade programme

ABSTRACT The high multiplex advantage of VIMOS, the VLT visible imager and multi-object/integral-field spectrometer, makes it a powerful instrument for large-scale spectroscopic surveys of faint sources. Following community input and recommendations by ESO's Science and Technology Committee, in 2009 it was decided to upgrade the instrument. This included installing an active flexure compensation system and replacing the detectors with CCDs that have a far better red sensitivity and less fringing. Significant changes have also been made to the hardware, maintenance and operational procedures of the instrument with the aim of improving availability and productivity. Improvements have also been made to the data reduction pipeline. The upgrade will end in 2012 and the results of the program will be presented here

Height and body-mass index trajectories of school-aged children and adolescents from 1985 to 2019 in 200 countries and territories: a pooled analysis of 2181 population-based studies with 65 million participants

Summary Background Comparable global data on health and nutrition of school-aged children and adolescents are scarce. We aimed to estimate age trajectories and time trends in mean height and mean body-mass index (BMI), which measures weight gain beyond what is expected from height gain, for school-aged children and adolescents. Methods For this pooled analysis, we used a database of cardiometabolic risk factors collated by the Non-Communicable Disease Risk Factor Collaboration. We applied a Bayesian hierarchical model to estimate trends from 1985 to 2019 in mean height and mean BMI in 1-year age groups for ages 5–19 years. The model allowed for non-linear changes over time in mean height and mean BMI and for non-linear changes with age of children and adolescents, including periods of rapid growth during adolescence. Findings We pooled data from 2181 population-based studies, with measurements of height and weight in 65 million participants in 200 countries and territories. In 2019, we estimated a difference of 20 cm or higher in mean height of 19-year-old adolescents between countries with the tallest populations (the Netherlands, Montenegro, Estonia, and Bosnia and Herzegovina for boys; and the Netherlands, Montenegro, Denmark, and Iceland for girls) and those with the shortest populations (Timor-Leste, Laos, Solomon Islands, and Papua New Guinea for boys; and Guatemala, Bangladesh, Nepal, and Timor-Leste for girls). In the same year, the difference between the highest mean BMI (in Pacific island countries, Kuwait, Bahrain, The Bahamas, Chile, the USA, and New Zealand for both boys and girls and in South Africa for girls) and lowest mean BMI (in India, Bangladesh, Timor-Leste, Ethiopia, and Chad for boys and girls; and in Japan and Romania for girls) was approximately 9–10 kg/m2. In some countries, children aged 5 years started with healthier height or BMI than the global median and, in some cases, as healthy as the best performing countries, but they became progressively less healthy compared with their comparators as they grew older by not growing as tall (eg, boys in Austria and Barbados, and girls in Belgium and Puerto Rico) or gaining too much weight for their height (eg, girls and boys in Kuwait, Bahrain, Fiji, Jamaica, and Mexico; and girls in South Africa and New Zealand). In other countries, growing children overtook the height of their comparators (eg, Latvia, Czech Republic, Morocco, and Iran) or curbed their weight gain (eg, Italy, France, and Croatia) in late childhood and adolescence. When changes in both height and BMI were considered, girls in South Korea, Vietnam, Saudi Arabia, Turkey, and some central Asian countries (eg, Armenia and Azerbaijan), and boys in central and western Europe (eg, Portugal, Denmark, Poland, and Montenegro) had the healthiest changes in anthropometric status over the past 3·5 decades because, compared with children and adolescents in other countries, they had a much larger gain in height than they did in BMI. The unhealthiest changes—gaining too little height, too much weight for their height compared with children in other countries, or both—occurred in many countries in sub-Saharan Africa, New Zealand, and the USA for boys and girls; in Malaysia and some Pacific island nations for boys; and in Mexico for girls. Interpretation The height and BMI trajectories over age and time of school-aged children and adolescents are highly variable across countries, which indicates heterogeneous nutritional quality and lifelong health advantages and risks

Worldwide trends in underweight and obesity from 1990 to 2022: a pooled analysis of 3663 population-representative studies with 222 million children, adolescents, and adults

Background Underweight and obesity are associated with adverse health outcomes throughout the life course. We estimated the individual and combined prevalence of underweight or thinness and obesity, and their changes, from 1990 to 2022 for adults and school-aged children and adolescents in 200 countries and territories. Methods We used data from 3663 population-based studies with 222 million participants that measured height and weight in representative samples of the general population. We used a Bayesian hierarchical model to estimate trends in the prevalence of different BMI categories, separately for adults (age ≥20 years) and school-aged children and adolescents (age 5–19 years), from 1990 to 2022 for 200 countries and territories. For adults, we report the individual and combined prevalence of underweight (BMI <18·5 kg/m2) and obesity (BMI ≥30 kg/m2). For schoolaged children and adolescents, we report thinness (BMI <2 SD below the median of the WHO growth reference) and obesity (BMI >2 SD above the median). Findings From 1990 to 2022, the combined prevalence of underweight and obesity in adults decreased in 11 countries (6%) for women and 17 (9%) for men with a posterior probability of at least 0·80 that the observed changes were true decreases. The combined prevalence increased in 162 countries (81%) for women and 140 countries (70%) for men with a posterior probability of at least 0·80. In 2022, the combined prevalence of underweight and obesity was highest in island nations in the Caribbean and Polynesia and Micronesia, and countries in the Middle East and north Africa. Obesity prevalence was higher than underweight with posterior probability of at least 0·80 in 177 countries (89%) for women and 145 (73%) for men in 2022, whereas the converse was true in 16 countries (8%) for women, and 39 (20%) for men. From 1990 to 2022, the combined prevalence of thinness and obesity decreased among girls in five countries (3%) and among boys in 15 countries (8%) with a posterior probability of at least 0·80, and increased among girls in 140 countries (70%) and boys in 137 countries (69%) with a posterior probability of at least 0·80. The countries with highest combined prevalence of thinness and obesity in school-aged children and adolescents in 2022 were in Polynesia and Micronesia and the Caribbean for both sexes, and Chile and Qatar for boys. Combined prevalence was also high in some countries in south Asia, such as India and Pakistan, where thinness remained prevalent despite having declined. In 2022, obesity in school-aged children and adolescents was more prevalent than thinness with a posterior probability of at least 0·80 among girls in 133 countries (67%) and boys in 125 countries (63%), whereas the converse was true in 35 countries (18%) and 42 countries (21%), respectively. In almost all countries for both adults and school-aged children and adolescents, the increases in double burden were driven by increases in obesity, and decreases in double burden by declining underweight or thinness. Interpretation The combined burden of underweight and obesity has increased in most countries, driven by an increase in obesity, while underweight and thinness remain prevalent in south Asia and parts of Africa. A healthy nutrition transition that enhances access to nutritious foods is needed to address the remaining burden of underweight while curbing and reversing the increase in obesit

Heterogeneous contributions of change in population distribution of body mass index to change in obesity and underweight NCD Risk Factor Collaboration (NCD-RisC)

From 1985 to 2016, the prevalence of underweight decreased, and that of obesity and severe obesity increased, in most regions, with significant variation in the magnitude of these changes across regions. We investigated how much change in mean body mass index (BMI) explains changes in the prevalence of underweight, obesity, and severe obesity in different regions using data from 2896 population-based studies with 187 million participants. Changes in the prevalence of underweight and total obesity, and to a lesser extent severe obesity, are largely driven by shifts in the distribution of BMI, with smaller contributions from changes in the shape of the distribution. In East and Southeast Asia and sub-Saharan Africa, the underweight tail of the BMI distribution was left behind as the distribution shifted. There is a need for policies that address all forms of malnutrition by making healthy foods accessible and affordable, while restricting unhealthy foods through fiscal and regulatory restrictions

Première lumière de GRAVITY : une nouvelle ère pour l'interférométrie optique

International audienceWith the arrival of the second generation instrument GRAVITY, the Very Large Telescope Interferometer (VLTI) has entered a new era of optical interferometry. This instrument pushes the limits of accuracy and sensitivity by orders of magnitude. GRAVITY has achieved phase-referenced imaging at approximately milliarcsecond (mas) resolution and down to ~ 100-microarcsecond astrometry on objects that are several hundred times fainter than previously observable. The cutting-edge design presented in Eisenhauer et al. (2011) has become reality. This article sketches out the basic principles of the instrument design and illustrates its performance with key science results obtained during commissioning: phase-tracking on stars with K ~ 10 mag, phase-referenced interferometry of objects fainter than K ≳ 17 mag, minute-long coherent integrations, a visibility accuracy of better than 0.25 %, and spectro-differential phase and closure phase accuracy better than 0.5 degrees, corresponding to a differential astrometric precision of a few microarcseconds (μas).Avec l'arrivée de l'instrument de deuxième génération GRAVITY, qui repousse les limites de précision et de sensibilité en interférométrie optique de plusieurs ordres de magnitude, le très grand interféromètre de l'Observatoire Européen Austral (ESO/VLTI) est entré dans une nouvelle ère. GRAVITY a réalisé des images en référence de phase avec une résolution de l'ordre de la milli-seconde d'arc et des mesures astrométriques avec une précision atteignant 100 micro-secondes sur des objets plusieurs centaines de fois moins brillants qu'observable précédemment. Le concept de pointe, présenté dans [Eisenhauer, F. et al., The Messenger, 143, 16 (2011)] est devenu réalité. Cet article esquisse les principes de base de l'instrument et illustre ses performances avec les résultats scientifiques clé obtenus pendant les tests de mise en service : asservissement en phase sur des étoiles de magnitude K=10, imagerie en référence de phase sur des objets de magnitude supérieure à K=17, intégrations cohérentes de l'ordre de la minute, précision de mesure de visibilité inférieure à 0,25%, et précision de mesure sur les phases de clôture ou spectro-différentielles meilleure que 0,5 degrés, ce qui correspond à une précision astrométrique différentielle de quelques micro-arcsecondes

Multiple star systems in the Orion nebula

This work presents an interferometric study of the massive-binary fraction in the Orion Trapezium cluster with the recently comissioned GRAVITY instrument. We observed a total of 16 stars of mainly OB spectral type. We find three previously unknown companions for theta(1) Ori B, theta(2) Ori B, and theta(2) Ori C. We determined a separation for the previously suspected companion of NU Ori. We confirm four companions for theta(1) Ori A, theta(1) Ori C, theta(1) Ori D, and theta(2) Ori A, all with substantially improved astrometry and photometric mass estimates. We refined the orbit of the eccentric high-mass binary theta(1) Ori C and we are able to derive a new orbit for theta(1) Ori D. We find a system mass of 21.7 M-circle dot and a period of 53 days. Together with other previously detected companions seen in spectroscopy or direct imaging, eleven of the 16 high-mass stars are multiple systems. We obtain a total number of 22 companions with separations up to 600 AU. The companion fraction of the early B and O stars in our sample is about two, significantly higher than in earlier studies of mostly OB associations. The separation distribution hints toward a bimodality. Such a bimodality has been previously found in A stars, but rarely in OB binaries, which up to this point have been assumed to be mostly compact with a tail of wider companions. We also do not find a substantial population of equal-mass binaries. The observed distribution of mass ratios declines steeply with mass, and like the direct star counts, indicates that our companions follow a standard power law initial mass function. Again, this is in contrast to earlier findings of flat mass ratio distributions in OB associations. We excluded collision as a dominant formation mechanism but find no clear preference for core accretion or competitive accretion

Imagerie spectro-interférométrique du noyau de η Car avec l'instrument GRAVITY : images de la zone de collision de vent dans les raies Br γ et He I avec une résolution de la milli-seconde d'arc

International audienceContext. η Car is one of the most intriguing luminous blue variables in the Galaxy. Observations and models of the X-ray, ultraviolet, optical, and infrared emission suggest a central binary in a highly eccentric orbit with a 5.54 yr period residing in its core. 2D and 3D radiative transfer and hydrodynamic simulations predict a primary with a dense and slow stellar wind that interacts with the faster and lower density wind of the secondary. The wind-wind collision scenario suggests that the secondary’s wind penetrates the primary’s wind creating a low-density cavity in it, with dense walls where the two winds interact. However, the morphology of the cavity and its physical properties are not yet fully constrained.Aims. We aim to trace the inner ∼5–50 au structure of η Car’s wind-wind interaction, as seen through Brγ and, for the first time, through the He I 2s-2p line.Methods. We have used spectro-interferometric observations with the K-band beam-combiner GRAVITY at the VLTI. The analyses of the data include (i) parametrical model-fitting to the interferometric observables, (ii) a CMFGEN model of the source’s spectrum, and (iii) interferometric image reconstruction.Results. Our geometrical modeling of the continuum data allows us to estimate its FWHM angular size close to 2 mas and an elongation ratio ϵ = 1.06 ± 0.05 over a PA = 130° ± 20°. Our CMFGEN modeling of the spectrum helped us to confirm that the role of the secondary should be taken into account to properly reproduce the observed Brγ and He I lines. Chromatic images across the Brγ line reveal a southeast arc-like feature, possibly associated to the hot post-shocked winds flowing along the cavity wall. The images of the He I 2s-2p line served to constrain the 20 mas (∼50 au) structure of the line-emitting region. The observed morphology of He I suggests that the secondary is responsible for the ionized material that produces the line profile. Both the Brγ and the He I 2s-2p maps are consistent with previous hydrodynamical models of the colliding wind scenario. Future dedicated simulations together with an extensive interferometric campaign are necessary to refine our constraints on the wind and stellar parameters of the binary, which finally will help us predict the evolutionary path of η Car.Contexte : η Car est une des étoiles brillantes bleues variables les plus intrigante de notre galaxie. Les observations et les modèles des émissions X, UV et optique et IR suggèrent qu'une étoile binaire avec une orbite fortement excentrique de période 5,54 ans réside au centre de son coeur. Les simulations hydrodynamiques et de transfert radiatif 2D et 3D prédisent la présence d'une étoile primaire avec vent stellaire dense et lent, qui interagit avec le vent de densité moindre et plus rapide de l'étoile secondaire. Ce scénario de collision vent-vent suggère que le vent de l'étoile secondaire pénètre dans le vent de l'étoile primaire, créant dans ce dernier une cavité de faible densité, avec des murs denses où les deux vents interagissent. Cependant, la morphologie de cette cavité et ses propriétés physiques ne sont pas encore pleinement contraints.Objectifs. Nous visons à déterminer la structure interne de l’interaction vent-vent de Car dans une zone allant de 5 à 50 Unités Astronomiques, telle que vue à travers Br γ et, pour la première fois, à travers la transition 2s-2p de He I.Méthodes : Nous avons utilisé des observations spectro-interférométriques du combineur de faisceaux en bande K de GRAVITY au VLTI. Les analyses des données comprennent: (i) un ajustement de modèle paramétrique aux observables interférométriques, (ii) un modèle CMFGEN du spectre de la source, et (iii) des reconstructions d'image interférométriques.Résultats : Notre modélisation géométrique des données du continuum nous permet d'estimer sa taille angulaire FWHM proche de 2 mas et son coefficient d'allongement de 1,06 ± 0,05 sur un PA = 130° ± 20°. Notre modélisation CMFGEN du spectre nous a permis de confirmer que le rôle de l'étoile secondaire devrait être pris en compte pour reproduire correctement les émissions Br γ et He I observées. Les images spectrales dans la bande Br γ révèle une caractéristique semblable à un arc au sud-est, peut-être associé aux vents chauds post-choc circulant le long du mur de la cavité. Les images dans la bande He I 2s-2p ont servi à contraindre la structure de la région d'émission de la transition, avec une résolution de 20 millisecondes d'arc (50 UA). La morphologie observée de He I suggère que l'étoile secondaire est responsable de l'ionisationproduisant le profil de raie. Les deux images (en Br γ et He I 2s-2p) sont compatibles avec les modèles hydrodynamiques précédents du scénario de vent en collision. De futures simulations dédiées ainsi qu’une vaste campagne interférométrique sont nécessaires pour affiner nos contraintes sur le vent et les paramètres stellaires de la binaire, ce qui nous aidera enfin à prédire le chemin évolutif de η Car

Première lumière de GRAVITY : interférométrie optique avec référence de phase pour le mode interférométrique du Très Grand Télescope européen

International audienceGRAVITY is a new instrument to coherently combine the light of the European Southern Observatory Very Large Telescope Interferometer to form a telescope with an equivalent 130 m diameter angular resolution and a collecting area of 200 m2. The instrument comprises fiber fed integrated optics beam combination, high resolution spectroscopy, built-in beam analysis and control, near-infrared wavefront sensing, phase-tracking, dual-beam operation, and laser metrology. GRAVITY opens up to optical/infrared interferometry the techniques of phase referenced imaging and narrow angle astrometry, in many aspects following the concepts of radio interferometry. This article gives an overview of GRAVITY and reports on the performance and the first astronomical observations during commissioning in 2015/16. We demonstrate phase-tracking on stars as faint as mK ≈ 10 mag, phase-referenced interferometry of objects fainter than mK ≈ 15 mag with a limiting magnitude of mK ≈ 17 mag, minute long coherent integrations, a visibility accuracy of better than 0.25%, and spectro-differential phase and closure phase accuracy better than 0.5°, corresponding to a differential astrometric precision of better than ten microarcseconds (μas). The dual-beam astrometry, measuring the phase difference of two objects with laser metrology, is still under commissioning. First observations show residuals as low as 50 μas when following objects over several months. We illustrate the instrument performance with the observations of archetypical objects for the different instrument modes. Examples include the  Galactic center supermassive black hole and its fast orbiting star S2 for phase referenced dual-beam observations and infrared wavefront sensing, the high mass X-ray binary BP Cru and the active galactic nucleus of PDS 456 for a few μas spectro-differential astrometry, the T Tauri star S CrA for a spectro-differential visibility analysis, ξ Tel and 24 Cap for high accuracy visibility observations, and η Car for interferometric imaging with GRAVITY.GRAVITY est un nouvel instrument permettant la recombinaison interférométrique des télescopes du VLT (Very Large Telescope) de l'ESO (European Southern Observatory) pour former un télescope avec une limite de résolution équivalente à un diamètre 130 m et une surface collectrice de 200 m². L'instrument inclut un dispositif en optique intégré alimenté par fibre pour recombinaison des faisceaux, un spectromètre à haute résolution, des dispositifs intégrés d'analyse et de contrôle, un analyse de surface d'onde en infrarouge (IR) proche, un suiveur de frange, un mode double champ et une métrologie laser. GRAVITY fait office de précurseur en introduisant en interférométrie optique/IR les techniques de référence de phase et d'astrométrie à faible champ, inspirées des concepts développés en radio-interférométrie. Cet article donne un aperçu de GRAVITY et rend compte des performances et des premières observations astronomiques lors de la mise en service en 2015/16. Nous démontrons le suivi de phase sur des étoiles aussi faible que mK ≈ 10 mag, l'interférométrie par référence de phase sur des objets plus faibles que mK ≈ 15 mag avec une magnitude limite de mK ≈ 17 mag, des intégrations cohérentes pendant une minute, une précision de mesure de visibilité meilleure que 0,25%, et une précision sur la mesure des phases différentielles spectrales ou des clôtures de phase meilleure que 0,5 °, correspondant à une précision astrométrique différentielle meilleure que dix microsecondes d'arc (μas). L'astrométrie à double champ, mesurant la différence de phase entre deux objets avec métrologie laser, est encore en cours de test. Les premières observations montrent des résidus aussi bas que 50 μas en suivant des objets sur plusieurs mois. Nous illustrons la performance de l'instrument avec les observations d'objets archétypiques pour les différents modes d'instrument. Les exemples comprennent le trou noir supermassif du centre galactique et son étoile S2 en orbite rapide pour les observations à double champ avec référence de phase et analyse de front d'onde IR, l'étoile binaire massive BP Cru à émission X et le noyau galactique actif de PDS 456 pour quelques cas de spectro-astrométrie différentielle avec quelques μas de précision, l'étoile S CrA (de type T Tauri) pour une analyse spectro-différentielle de visibilité, les étoiles ξ Tel et 24 Cap pour des observations de visibilité de haute précision, et η Car pour une imagerie interférométrique avec GRAVITY

Diminishing benefits of urban living for children and adolescents’ growth and development

Optimal growth and development in childhood and adolescence is crucial for lifelong health and well-being1–6. Here we used data from 2,325 population-based studies, with measurements of height and weight from 71 million participants, to report the height and body-mass index (BMI) of children and adolescents aged 5–19 years on the basis of rural and urban place of residence in 200 countries and territories from 1990 to 2020. In 1990, children and adolescents residing in cities were taller than their rural counterparts in all but a few high-income countries. By 2020, the urban height advantage became smaller in most countries, and in many high-income western countries it reversed into a small urban-based disadvantage. The exception was for boys in most countries in sub-Saharan Africa and in some countries in Oceania, south Asia and the region of central Asia, Middle East and north Africa. In these countries, successive cohorts of boys from rural places either did not gain height or possibly became shorter, and hence fell further behind their urban peers. The difference between the age-standardized mean BMI of children in urban and rural areas was <1.1 kg m–2 in the vast majority of countries. Within this small range, BMI increased slightly more in cities than in rural areas, except in south Asia, sub-Saharan Africa and some countries in central and eastern Europe. Our results show that in much of the world, the growth and developmental advantages of living in cities have diminished in the twenty-first century, whereas in much of sub-Saharan Africa they have amplified