Context. In the era of large high-resolution spectroscopic surveys such as Gaia-ESO and APOGEE, high-quality spectra can contribute to our understanding of the Galactic chemical evolution by ...providing abundances of elements that belong to the different nucleosynthesis channels, and also by providing constraints to one of the most elusive astrophysical quantities: stellar age. Aims. Some abundance ratios, such as C/N, have been proven to be excellent indicators of stellar ages. We aim at providing an empirical relationship between stellar ages and C/N using open star clusters, observed by the Gaia-ESO and APOGEE surveys, as calibrators. Methods. We used stellar parameters and abundances from the Gaia-ESO Survey and APOGEE Survey of the Galactic field and open cluster stars. Ages of star clusters were retrieved from the literature sources and validated using a common set of isochrones. We used the same isochrones to determine for each age and metallicity the surface gravity at which the first dredge-up and red giant branch bump occur. We studied the effect of extra-mixing processes in our sample of giant stars, and we derived the mean C/N in evolved stars, including only stars without evidence of extra mixing. By combining the Gaia-ESO and APOGEE samples of open clusters, we derived a linear relationship between C/N and (logarithmic) cluster ages. Results. We apply our relationship to selected giant field stars in the Gaia-ESO and APOGEE surveys. We find an age separation between thin- and thick-disc stars and age trends within their populations, with an increasing age towards lower metallicity populations. Conclusions. With this empirical relationship, we are able to provide an age estimate for giant stars in which C and N abundances are measured. For giant stars, the isochrone fitting method is indeed less sensitive than for dwarf stars at the turn-off. Our method can therefore be considered as an additional tool to give an independent estimate of the age of giant stars. The uncertainties in their ages is similar to those obtained using isochrone fitting for dwarf stars.
Context.
It is now well-known that pre-main-sequence models with inflated radii should be taken into account to simultaneously reproduce the colour-magnitude diagram and the lithium depletion pattern ...observed in young open star clusters.
Aims.
We tested a new set of pre-main-sequence models that include radius inflation due to the presence of starspots or to magnetic inhibition of convection. We used five clusters observed by the
Gaia
-ESO Survey that span the age range ∼10−100 Myr, in which these effects could be important.
Methods.
The
Gaia
-ESO Survey radial velocities were combined with astrometry from
Gaia
EDR3 to obtain clean lists of high-probability members for the five clusters. A Bayesian maximum likelihood method was adopted to fit the observed cluster sequences to theoretical predictions to derive the best model parameters and the cluster reddening and age. Models were calculated with different values of the mixing length parameter (
α
ML
= 2.0, 1.5 and 1.0) for the cases without spots or with effective spot coverage
β
spot
= 0.2 and 0.4. The models were also compared with the observed lithium depletion patterns.
Results.
To reproduce the colour-magnitude diagram and the observed lithium depletion pattern in Gamma Vel A and B and in 25 Ori, both a reduced convection efficiency, with
α
ML
= 1.0, and an effective surface spot coverage of about 20% are required. We obtained ages of 18
−4.0
+1.5
Myr and 21
−3.0
+3.5
Myr for Gamma Vel A and B, respectively, and 19
−7.0
+1.5
Myr for 25 Ori. However, a single isochrone is not sufficient to account for the lithium dispersion, and an increasing level of spot coverage as mass decreases seems to be required. On the other hand, the older clusters (NGC 2451 B at 30
−5.0
+3.0
Myr, NGC 2547 at 35
−4.0
+4.0
Myr, and NGC 2516 at 138
−42
+48
Myr) are consistent with standard models (i.e.
α
ML
= 2.0 and no spots) except at low masses: a 20% spot coverage appears to reproduce the sequence of M-type stars better and might explain the observed spread in lithium abundances.
Conclusions.
The quality of
Gaia
-ESO data combined with
Gaia
allows us to gain important insights on pre-main-sequence evolution. Models including starspots can provide a consistent explanation of the cluster sequences and lithium abundances observed in young clusters, although a range of starspot coverage is required to fully reproduce the data.
Context.
Determination and calibration of the ages of stars, which heavily rely on stellar evolutionary models, are very challenging, while representing a crucial aspect in many astrophysical areas.
...Aims.
We describe the methodologies that, taking advantage of
Gaia
-DR1 and the
Gaia
-ESO Survey data, enable the comparison of observed open star cluster sequences with stellar evolutionary models. The final, long-term goal is the exploitation of open clusters as age calibrators.
Methods.
We perform a homogeneous analysis of eight open clusters using the
Gaia
-DR1 TGAS catalogue for bright members and information from the
Gaia
-ESO Survey for fainter stars. Cluster membership probabilities for the
Gaia
-ESO Survey targets are derived based on several spectroscopic tracers. The
Gaia
-ESO Survey also provides the cluster chemical composition. We obtain cluster parallaxes using two methods. The first one relies on the astrometric selection of a sample of bona fide members, while the other one fits the parallax distribution of a larger sample of TGAS sources. Ages and reddening values are recovered through a Bayesian analysis using the 2MASS magnitudes and three sets of standard models. Lithium depletion boundary (LDB) ages are also determined using literature observations and the same models employed for the Bayesian analysis.
Results.
For all but one cluster, parallaxes derived by us agree with those presented in Gaia Collaboration (2017, A&A, 601, A19), while a discrepancy is found for NGC 2516; we provide evidence supporting our own determination. Inferred cluster ages are robust against models and are generally consistent with literature values.
Conclusions.
The systematic parallax errors inherent in the
Gaia
DR1 data presently limit the precision of our results. Nevertheless, we have been able to place these eight clusters onto the same age scale for the first time, with good agreement between isochronal and LDB ages where there is overlap. Our approach appears promising and demonstrates the potential of combining
Gaia
and ground-based spectroscopic datasets.
In addition to its search for extrasolar planets, the NASA Kepler mission provides exquisite data on stellar oscillations. We report the detections of oscillations in 500 solar-type stars in the ...Kepler field of view, an ensemble that is large enough to allow statistical studies of intrinsic stellar properties (such as mass, radius, and age) and to test theories of stellar evolution. We find that the distribution of observed masses of these stars shows intriguing differences to predictions from models of synthetic stellar populations in the Galaxy.
ABSTRACT
We present a new method to derive binary inclinations in quiescent black hole (BH) X-ray transients (XRTs), based on the depth of the trough (T) from double-peaked H α emission profiles ...arising in accretion discs. We find that the inclination angle (i) is linearly correlated with T in phase-averaged spectra with sufficient orbital coverage (≳50 per cent) and spectral resolution, following i(deg) = 93.5 × T + 23.7. The correlation is caused by a combination of line opacity and local broadening, where a leading (excess broadening) component scales with the deprojected velocity of the outer disc. Interestingly, such scaling allows to estimate the fundamental ratio M1/Porb by simply resolving the intrinsic width of the double-peak profile. We apply the T–i correlation to derive binary inclinations for GRO J0422+32 and Swift J1357−0933, two BH XRTs where strong flickering activity has hindered determining their values through ellipsoidal fits to photometric light curves. Remarkably, the inclination derived for GRO J0422+32 (i = 55.6 ± 4.1○) implies a BH mass of $2.7^{+0.7}_{-0.5}$ M⊙ thus placing it within the gap that separates BHs from neutron stars. This result proves that low-mass BHs exist in nature and strongly suggests that the so-called ‘mass gap’ is mainly produced by low number statistics and possibly observational biases. On the other hand, we find that Swift J1357−0933 contains a $10.9^{+1.7}_{-1.6}$ M⊙ BH, seen nearly edge on ($i=87.4^{+2.6}_{-5.6}$ deg). Such extreme inclination, however, should be treated with caution since it relies on extrapolating the T–i correlation beyond i ≳ 75○, where it has not yet been tested.
ABSTRACT
We present two contiguous nights of simultaneous time-resolved Gran Telescopio Canarias spectroscopy and William Herschel Telescope photometry of the black hole X-ray transient XTE ...J1859+226, obtained in 2017 July during quiescence. Cross-correlation of the individual spectra against a late K-type spectral template enabled us to constrain the orbital period to 0.276 ± 0.003 d and the radial velocity semi-amplitude of the donor star to K2 = 550 ± 59 km s−1. An ellipsoidal modulation is detected in the photometric r- and i-band light curves, although it is strongly contaminated by flickering activity. By exploiting correlations between the properties of the double-peaked H α emission-line profile and the binary parameters, we derived an orbital inclination of 66.6 ± 4.3 deg, a refined K2 = 562 ± 40 km s−1 and mass ratio q = M2/M1 = 0.07 ± 0.01. From these values, we obtained an updated black hole mass of M1 = 7.8 ± 1.9 M⊙. An independent mass estimate based on X-ray timing agrees well with our value, which gives further support for the outburst quasi-periodic oscillation triplet being explained by the relativistic precession model. We also obtained a companion star mass M2 = 0.55 ± 0.16 M⊙, which is consistent with its K5-K7 V spectral type.
The global crisis of bacterial resistance urges the scientific community to implement intervention programs in healthcare facilities to promote an appropriate use of antibiotics. However, the ...clinical benefits or the impact on resistance of these interventions has not been definitively proved.
We designed a quasi-experimental intervention study with an interrupted time-series analysis. A multidisciplinary team conducted a multifaceted educational intervention in our tertiary-care hospital over a 5-year period. The main activity of the program consisted of peer-to-peer educational interviews between counselors and prescribers from all departments to reinforce the principles of the proper use of antibiotics. We assessed antibiotic consumption, incidence density of Candida and multidrug-resistant (MDR) bacteria bloodstream infections (BSIs) and their crude death rate per 1000 occupied bed days (OBDs).
A quick and intense reduction in antibiotic consumption occurred 6 months after the implementation of the intervention (change in level, -216.8 defined daily doses per 1000 OBDs; 95% confidence interval, -347.5 to -86.1), and was sustained during subsequent years (average reduction, -19,9%). In addition, the increasing trend observed in the preintervention period for the incidence density of candidemia and MDR BSI (+0.018 cases per 1000 OBDs per quarter; 95% confidence interval, -.003 to .039) reverted toward a decreasing trend of -0.130 per quarter (change in slope, -0.029; -.051 to -.008), and so did the mortality rate (change in slope, -0.015; -.021 to -.008).
This education-based antimicrobial stewardship program was effective in decreasing the incidence and mortality rate of hospital-acquired candidemia and MDR BSI through sustained reduction in antibiotic use.
•What is the primary question addressed by this study? We examined the frequency of mixed depressive and manic mood symptoms among older adults with bipolar disorder (OABD) in a global, integrated ...dataset and whether subgroups with varying current symptom mixity differed in everyday functioning and demographics.•What is the main finding of this study? The group with mixed symptoms (almost 70% of the global OABD sample) had poorer everyday function compared to the depressed only or manic only groups, despite similar demographic features and depressive and mania symptom severity. Within the mixed group, depression but not mania severity was related to poorer functioning.•What is the meaning of the finding? Mixed symptoms in OABD are prevalent and associated with poorer everyday function; since the severity of depression is particularly associated with disability among those with mixed symptoms, treatment should focus on ameliorating bipolar depression in OABD.
Some individuals with bipolar disorder (BD) experience manic and depressive symptoms concurrently, but data are limited on symptom mixity in older age bipolar disorder (OABD). Using the Global Aging & Geriatric Experiments in Bipolar Disorder Database, we characterized mixity in OABD and associations with everyday function.
The sample (n = 805), from 12 international studies, included cases with both mania and depression severity ratings at a single timepoint. Four mixity groups were created: asymptomatic (A), mixed (Mix), depressed only (Dep), and manic only (Man). Generalized linear mixed models used mixity group as the predictor variable; cohort was included as a random intercept. Everyday function was assessed with the Global Assessment of Functioning score.
Group proportions were Mix (69.6%; n = 560), followed by Dep (18.4%; n = 148), then A (7.8%; n = 63), then Man (4.2%; n= 34); levels of depression and mania were similar in Mix compared to Dep and Man, respectively. Everyday function was lowest in Mix, highest in A, and intermediate in Man and Dep. Within Mix, severity of depression was the main driver of worse functioning. Groups differed in years of education, with A higher than all others, but did not differ by age, gender, employment status, BD subtype, or age of onset.
Mixed features predominate in a cross-sectional, global OABD sample and are associated with worse everyday function. Among those with mixed symptoms, functional status relates strongly to current depression severity. Future studies should include cognitive and other biological variables as well as longitudinal designs to allow for evaluation of causal effects.
The aerosols (clouds and hazes) on Uranus are one of the main elements for understanding the thermal structure and dynamics of its atmosphere. Aerosol particles absorb and scatter the solar ...radiation, directly affecting the energy balance that drives the atmospheric dynamics of the planet. In this sense, aerosol information such as the vertical distribution or optical properties is essential for characterizing the interactions between sunlight and aerosol particles at each altitude in the atmosphere and for understanding the energy balance of the planet’s atmosphere. Moreover, the distribution of aerosols in the atmosphere provides key information on the global circulation of the planet (e.g., regions of upwelling or subsidence).
To address this challenge, we propose the Uranus Multi-experiment Radiometer (UMR), a lightweight instrument designed to characterize the aerosols in Uranus’ atmosphere as part of the upcoming Uranus Flagship mission’s descending probe payload. The scientific goals of UMR are: (1) to study the variation of the solar radiation in the ultra-violet (UV) with altitude and characterize the energy deposition in the atmosphere; (2) to study the vertical distribution of the hazes and clouds and characterize their scattering and optical properties; (3) to investigate the heating rates of the atmosphere by directly measuring the upward and downward fluxes; and (4) to study the cloud vertical distribution and composition at pressures where sunlight is practically negligible (p > 4-5 bars).
The instrument includes a set of photodetectors, field-of-view masks, a light infrared lamp, and interference filters. It draws on the heritage of previous instruments developed at the Instituto Nacional de Técnica Aeroespacial (INTA) that participated in the exploration of Mars, where similar technology has demonstrated its endurance in extreme environments while utilizing limited resources regarding power consumption, mass and volume footprints, and data budget. The radiometer’s design and characteristics make it a valuable complementary payload for studying Uranus’ atmosphere with a high scientific return.
Variations in mercury (Hg) isotopic compositions have been scarcely investigated until now in the Almadén mining district (Spain), which is one of the most impacted Hg areas worldwide. In this work, ...we explore and compare Hg isotopic signatures in sediments and lichens from Almadén mining district and its surroundings in order to identify and trace Hg aquatic and atmospheric contamination sources. No statistically significant mass independent fractionation was observed in sediments, while negative Δ201Hg values from −0.12 to −0.21‰ (2SD = 0.06‰) were found in lichens. A large range of δ202Hg values were reported in sediments, from −1.86 ± 0.21‰ in La Serena Reservoir sites far away from the pollution sources to δ202Hg values close to zero in sediments directly influenced by Almadén mining district, whereas lichens presented δ202Hg values from −1.95 to −0.40‰ (2SD = 0.15‰). A dilution or mixing trend in Hg isotope signatures versus the distance to the mine was found in sediments along the Valdeazogues River-La Serena Reservoir system and in lichens. This suggests that Hg isotope fingerprints in these samples are providing a direct assessment of Hg inputs and exposure from the mining district, and potential information on diffuse atmospheric contamination and/or geochemical alteration processes in less contaminated sites over the entire hydrosystem. This study confirms the applicability of Hg isotope signatures in lichens and sediments as an effective and complementary tool for tracing aquatic and atmospheric Hg contamination sources and a better constraint of the spatial and temporal fate of Hg released by recent or ancient mining activities.
•Hg isotope signatures have enabled tracing aquatic and atmospheric Hg sources.•Hg isotope composition and contamination displayed a dilution downstream the mines.•MDF of Hg isotopes allowed to track biogeochemical alterations downstream Hg mines.•Sediments and lichens can act as complementary Hg reservoirs as revealed by MIF signatures.•Isotopic data from this emblematic mining district can be used as an isotopic reference.
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