The Tip of the Red Giant Branch and Distance of the Magellanic Clouds: results from the DENIS survey

We present a precise determination of the apparent magnitude of the tip of the red giant branch (TRGB) in the I (0.8 micron), J (1.25 micron), and K_S (2.15 micron) bands from the luminosity function of a sample of data extracted from the DENIS catalogue towards the Magellanic Clouds (Cioni et al. 2000). From the J and Ks magnitudes we derive bolometric magnitudes m_bol. We present a new algorithm for the determination of the TRGB magnitude, which we describe in detail and test extensively using Monte-Carlo simulations. We note that any method that searches for a peak in the first derivative (used by most authors) or the second derivative (used by us) of the observed luminosity function does not yield an unbiased estimate for the actual magnitude of the TRGB discontinuity. We stress the importance of correcting for this bias, which is not generally done. We combine the results of our algorithm with theoretical predictions to derive the distance modulus of the Magellanic Clouds. We obtain m-M = 18.55 (0.04 formal, 0.08 systematic) for the Large Magellanic Cloud (LMC), and m-M = 18.99 (0.03 formal, 0.08 systematic) for the Small Magellanic Cloud (SMC). These are among the most accurate determinations of these quantities currently available, which is a direct consequence of the large size of our sample and the insensitivity of near infrared observations to dust extinction.Comment: 16 pages, 8 figures, revised version, accepted for publication in A&

Mass-loss rates and luminosity functions of dust-enshrouded AGB stars and red supergiants in the LMC

A radiative transfer code is used to model the spectral energy distributions of 57 mass-losing Asymptotic Giant Branch (AGB) stars and red supergiants (RSGs) in the Large Magellanic Cloud (LMC) for which ISO spectroscopic and photometric data are available. As a result we derive mass-loss rates and bolometric luminosities. A gap in the luminosity distribution around M_bol = -7.5 mag separates AGB stars from RSGs. The luminosity distributions of optically bright carbon stars, dust-enshrouded carbon stars and dust-enshrouded M-type stars have only little overlap, suggesting that the dust-enshrouded AGB stars are at the very tip of the AGB and will not evolve significantly in luminosity before mass loss ends their AGB evolution. Derived mass-loss rates span a range from Mdot about 10^-7 to 10^-3 M_sun/yr. More luminous and cooler stars are found to reach higher mass-loss rates. The highest mass-loss rates exceed the classical limit set by the momentum of the stellar radiation field, L/c, by a factor of a few due to multiple scattering of photons in the circumstellar dust envelope. Mass-loss rates are lower than the mass consumption rate by nuclear burning, Mdot_nuc, for most of the RSGs. Two RSGs have Mdot >> Mdot_nuc, however, suggesting that RSGs shed most of their stellar mantles in short phases of intense mass loss. Stars on the thermal pulsing AGB may also experience episodes of intensified mass loss, but their quiescent mass-loss rates are usually already higher than Mdot_nuc.Comment: 15 pages, 11 figures. Accepted for publication in Astronomy and Astrophysics Main Journa

IRAS04496-6958: A luminous carbon star with silicate dust in the Large Magellanic Cloud

We describe ISO observations of the obscured Asymptotic Giant Branch (AGB) star IRAS04496-6958 in the Large Magellanic Cloud (LMC). This star has been classified as a carbon star. Our new ISOCAM CVF spectra show that it is the first carbon star with silicate dust known outside of the Milky Way. The existence of this object, and the fact that it is one of the highest luminosity AGB stars in the LMC, provide important information for theoretical models of AGB evolution and understanding the origin of silicate carbon stars.Comment: 4 pages, 3 figures, accepted for publication in A&A Letter

ISO observations of obscured Asymptotic Giant Branch stars in the Large Magellanic Cloud

We present ISO photometric and spectroscopic observations of a sample of 57 bright Asymptotic Giant Branch stars and red supergiants in the Large Magellanic Cloud, selected on the basis of IRAS colours indicative of high mass-loss rates. PHOT-P and PHOT-C photometry at 12, 25 and 60 $\mu$m and CAM photometry at 12 $\mu$m are used in combination with quasi-simultaneous ground-based near-IR photometry to construct colour-colour diagrams for all stars in our sample. PHOT-S and CAM-CVF spectra in the 3 to 14 $\mu$m region are presented for 23 stars. From the colour-colour diagrams and the spectra, we establish the chemical types of the dust around 49 stars in this sample. Many stars have carbon-rich dust. The most luminous carbon star in the Magellanic Clouds has also a (minor) oxygen-rich component. OH/IR stars have silicate absorption with emission wings. The unique dataset presented here allows a detailed study of a representative sample of thermal-pulsing AGB stars with well-determined luminosities.Comment: 19 pages, 10 figures. Accepted for publication in Astronomy and Astrophysics Main Journa

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Observations millimétriques et modélisation infrarouge d'enveloppes circumstellaires d'étoiles de la branche asymptotique des géantes rouges et de pré-nébuleuses planétaires

Cette thèse est vouée principalement à l'étude des enveloppes circumstellaires des étoiles de la fin de la branche asymptotique des géantes rouges (AGB), ou dans la courte phase de transition des nébuleuses planétaires. L'attention a été portée sur les sources ayant une photosphère riche en carbone qui étaient jusqu'à présent moins étudiées que celles riches en oxygène. La thèse comporte trois aspects, des observations millimétriques des transitions rotationelles de CO et HCN, des modélisations de l'émission infrarouge des poussières, et des études systématiques des données du satellite IRAS. Le dernier point est le support observationel fondamental de ce mémoire sans lequel ce travail ne pourrait exister. Il est omni-présent dans la plupart des chapitres . La première partie de la thèse regroupe les observations millimétriques. Alors que la plupart des étoiles AGB riches en carbone sont facilement identifiables grâce à l'émission de SiC, celles qui sont proches de la fin de l'AGB, ou qui sont des PPN, n'ont souvent plus cette caractéristique. Le chapitre 1 présente une analyse d'un échantillon de ~ 230 de telles sources, propose des critères permettant de déterminer la richesse en carbone basés à la fois sur les données IRAS et des observations de CO et HCN, et déduit les proportions d'étoiles oxygénées et d'étoiles carbonées. Le chapitre 2 est une recherche de l'émission de CO dans des sources de l'hémisphère sud pouvant être des PPN; neuf d'entre elles ont pu être détectées, dont l'une présente des propriétés tout à fait remarquables et inhabituelles. Le chapitre 3 ne présente pas nos observations en particulier, mais est une compilation de toutes les enveloppes circumstellaires ayant une (ou plusieurs) détections de CO ou/et HCN publiées dans la littérature depuis 1985. Ceci constitue le premier catalogue des observations millimétriques des étoiles AGB, PPN, et PN ; il recense ~ 400 sources et ~ 1200 observations venant de plus de soixante dix références. Le chapitre 4 présente des cartographies soignées de l'émission de CO dans les transitions rotation elles (1- 0) et (2-1) de cinq sources pouvant être considérées comme des prototypes, et pour lesquelles nous sommes en mesure de donner une estimation de l'étendue de CO dans l'enveloppe. La deuxième partie de la thèse est consacrée à la modélisation de l'émission infrarouge des poussières. Nous y décrivons d'abord la mise au point d'un programme numérique de transfert radiatif dans le chapitre 5. Le chapitre 6 est une étude particulièrement détaillée de l'une des sources riches en carbone les plus optiquement épaisses connues, proche de la fin de l'AGB, RAFGL 3068. Les observations infrarouges disponibles, ainsi que les cartographies du chapitre 4, nous ont permis de contraindre la valeur de l'exposant de la loi d'émissivité des grains dans l'infrarouge. Le chapitre 7 est voué à l'étude des objets riches en carbone en transition entre la fin de l'AGB et le stade de nébuleuse planétaire. En reprenant l'échantillon de sources du chapitre 1, que nous avons élargi jusqu'à ~ 1000 sources, nous avons pu reconstituer l'évolution spectrale de ces PPN. Cette évolution est bien reproduite par les modélisations qui s'appuient sur le travail du chapitre précédent. L'un des problèmes les plus intéressant de l'évolution des étoiles AGB à l'heure actuelle est la transition entre les étoiles riches en oxygène et celles riches en carbone. Le chapitre 8 est un travail préparatoire à l'analyse d'observations de CN et HCN dans plusieurs objets différents, réalisées dans le but de tenter d'éclaircir un peu ce problème. Nous y analysons les propriétés IRAS (PSC) d'un échantillon de sources restreint, mais ayant des densités de flux IRAS fi ables, et en déduisons, pour cet échantillon, le pourcentage d'étoiles riches en carbone ayant une enveloppe fossile . Nous terminerons par la présentation des conclusions les plus importantes de la thèse.pas de résum

What is in SIMBAD?

International audienceSIMBAD is a dynamic database of astronomical objects. It provides the bibliography, as well as basic information such as the nature of each object, its coordinates, magnitudes, proper motions and parallax, velocity/redshift, angular size, spectral or morphological type, and the multitude of names (identifiers) given in the literature. The information in SIMBAD is a compilation built from what is published in the literature with expert cross-identification performed at the CDS based on the compatibility of several parameters, to the limit of reasonably good astrometry. We show the data integration processes in SIMBAD

JMS

While an increasing number of Informal CareGivers (ICGs) are assisting their dependent loved ones with the daily living tasks and medical care, they are rarely considered in the medical devices design process. The objective of this study is to identify the characteristics of ICGs impacting the use of the iHealth® Sense BP7 medical device, namely a connected wrist blood pressure monitor. For this purpose, user tests were conducted with 29 potential or actual ICGs. First, the participants filled out a socio-demographic questionnaire and then handled the blood pressure monitor. Finally, they completed the System Usability Scale questionnaire. The results revealed an impact of technophilia and age on usability dimensions. To conclude, the consideration of the ICG population in the design process of connected medical devices is discussed, particularly the age and level of technophilia.European Regional Development Fund (FEDER