Ca II triplet spectroscopy of small magellanic cloud red giants. II. abundances for a sample of field stars

We have obtained metallicities of ∼360 red giant stars distributed in 15 Small Magellanic Cloud (SMC) fields from near-infrared spectra covering the Ca II triplet lines using the VLT + FORS2. The errors of the derived [Fe/H] values range from 0.09 to 0.35 dex per star, with a mean of 0.17 dex. The metallicity distribution (MD) of the whole sample shows a mean value of [Fe/H] = -1.00 ± 0.02, with a dispersion of 0.32 0.01, in agreement with global mean [Fe/H] values found in previous studies. We find no evidence of a metallicity gradient in the SMC. In fact, on analyzing the MD of each field, we derived mean values of [Fe/H] = -0.99 ± 0.08 and [Fe/H] = -1.02 ± 0.07 for fields located closer and farther than 4° from the center of the galaxy, respectively. In addition, there is a clear tendency for the field stars to be more metal-poor than the corresponding cluster they surround, independent of their positions in the galaxy and of the clusters' age. We argue that this most likely stems from the field stars being somewhat older and therefore somewhat more metal-poor than most of our clusters. © 2010. The American Astronomical Society.Fil: Parisi, Maria Celeste. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; ArgentinaFil: Geisler, Doug. Universidad de Concepción; ChileFil: Grocholski, A. J.. University of Florida; Estados Unidos. Space Telescope Science Institute; Estados UnidosFil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; ArgentinaFil: Sarajedini, A.. University of Florida; Estados Unido

Photometric observations and Coravel radial velocities of red giant candidates in open clusters

Presentamos fotometrıa fotoelectrica multicolor de alta precision y velocidades radiales (VRs) Coravel para una muestra de candidatas a gigantes rojas (GRs) en nueve cumulos abiertos galacticos. Encontramos que aproximadamente el 82 % de las estrellas analizadas son GRs de los cumulos, de acuerdo a criterios fotometricos, en excelente acuerdo con los resultados inferidos a partir de las VRs Coravel. Se determinan excesos de color E(B − V ), temperaturas efectivas y metalicidades para las gigantes de los cumulos. Una nueva binaria espectroscopica fue descubierta entre las GRs de NGC 2482.We present high precision multicolour photoelectric photometry together with Coravel radial-velocity data for a sample of red giant (RG) candidates in nine Galactic open clusters. Nearly 82% of the analized stars are found to be cluster RGs from photometric criteria, in excellent agreement with the Coravel membership probabilities. E(B − V ) colour excesses, effective temperatures and metallicities are derived for the cluster giants. A new spectroscopic binary was discovered among the RGs of NGC 2482.Fil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; ArgentinaFil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Mermilliod, J. C.. Ecole Polytechnique Federale de Lausanne; FranciaFil: Palma, T.. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentin

Multicolour photometry and Coravel observations of stars in the southern open cluster IC 2488

We preseent new UBV photoelectric observations of 119 stars in the field of the southern open cluster IC 2488, supplemented by DDO and Washington photometry and Coravel radial velocities for a sample of red giant candidates. Nearly 50% of the stars sampled - including three red giants and one blue straggler - are found to be probable cluster members. Photometric membership probabilities of the red giant candidates show good agreement with those obtained from Coravel data. A mean radial velocity of (-2.63 +/- 0.06) km/s is derived for the cluster giants. The reddening across the cluster is found to be E(B-V) = 0.24 +/- 0.04. IC 2488, located at a distance of (1250 +/- 120) pc from the Sun and 96 below the Galactic plane, is most probably not related to the planetary nebulae ESO 166-PN21. A metal abundance 0.10 +/- 0.06 relative to the Sun is determined from DDO data of the red giant members, in good agreement with the metallicity values derived from five independent Washington abundance indices. An age of 180 Myr is determined from the fitting of isochrones computed with convective overshooting for Z = 0.019. The isochrone for log t = 8.25 reproduces remarkably well not only the morphology of the upper main sequence but also the observed red giant pattern.Fil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Lapasset Gomar, Emilio. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mermilliod, J. C.. Universite de Lausanne; Suiz

Multicolour photometry and CORAVEL radial velocities of stars of the open cluster NGC 2489

Presentamos fotometría CCD BVI en la regi´on del c´umulo abierto NGC 2489, juntamente con velocidades radiales (VRs) CORAVEL de 7 candidatas a gigantes rojas. En base a recuentos estelares estimamos el radio lineal del c´umulo en (3.5 ± 0.3) pc. La comparaci´on de los diagramas color-magnitud con is´ocronas del grupo de Padova para Z = 0.019 condujo a los siguientes valores: E(B-V) = 0.30 ± 0.05, E(V-I) = 0.40 ± 0.05, V-MV = 12.20 ± 0.25 y log t (edad) = 8.70. El an´alisis de las VRs permitió confirmar la condici´on de miembros de 6 de las 7 candidatas a gigantes rojas, una de las cuales result´o ser una binaria espectrosc´opica. Analizamos adem´as las propiedades de una decena de c´umulos abiertos proyectados casi en la misma direcci´on que NGC 2489.We present CCD BVI photometry in the field of the open cluster NGC 2489, supplemented with CORAVEL radial velocities (RVs) for 7 red giant candidates. A cluster angular radius of (3.5 ± 0.3) pc is estimated from star counts. The comparison of the cluster colourmagnitude diagram with isochrones of the Padova group yields E(B-V) = 0.30 ± 0.05, E(V-I) = 0.40 ± 0.05, and V-MV = 12.20 ± 0.25 for log age = 8.70 and Z = 0.019. The analysis of the RVs allowed us to confirm cluster membership for 6 red giants, one of them being a spectroscopic binary. The properties of a sample of open clusters aligned along the line-of-sight to NGC 2489 are examined.Fil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; ArgentinaFil: Mermilliod, J. C.. Ecole Polytechnique Federale de Lausanne; SuizaFil: Parisi, M. C.. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; ArgentinaFil: Ahumada, Andrea Veronica. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Espectros integrados EFOSC2/NTT de 10 cúmulos estelares pertenecientes a las Nubes de Magallanes

We present integrated spectra in the optical range for 10 concentrated Magellanic Clouds’ (MCs) stellar clusters, six of them belonging to the Large Magellanic Cloud, and the other four to the Small Magellanic Cloud. The spectra were obtained with the EFOSC2 spectrograph (NTT-ESO, La Silla, Chile). We estimate simultaneously age and foreground reddening by comparing the continuum distribution and line strengths of the cluster spectra with those of template spectra. The present cluster sample complements previous ones, in an effort to create a spectral library for the MCs with several clusters per age bin.Se presentan espectros integrados en el rango optico obtenidos con el espectrografo EFOSC2 (NTT-ESO, La Silla, Chile) de 6 cumulos estelares (CEs) de la Nube Mayor de Magallanes (NMM) y 4 de la Nube Menor (NmM). Las edades y enrojecimientos se determinaron comparando la distribucion del continuo y la intensidad de lıneas espectrales con estas mismas caracterısticas en espectros patrones (templates). Los 10 cumulos estudiados abarcan un amplio rango de edad y estan levemente enrojecidos. Estos espectros seran de gran utilidad para actualizar las bases de templates actualmente existentes para la metalicidad tıpicamente subsolar de las Nubes de Magallanes (NMs).Fil: Ahumada, Andrea Veronica. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; ArgentinaFil: Benítez Llambay, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomia Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomia Teórica y Experimental; ArgentinaFil: Santos, J. F. C.. Universidade Federal do Minas Gerais; BrasilFil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; ArgentinaFil: Bica, E.. Universidade Federal do Rio Grande do Sul; BrasilFil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentin

New old star clusters in the Small Magellanic Cloud

Using Ca triplet spectroscopy and P SF photometry performed on data taken with the “Very Large Telescope” (Chile), we derived reliable ages and metallicities of 15 Small Magellanic Cloud (SMC) star clusters. Three of them were found to be very old clusters so that the determination of their fundamental properties allows us to improve our current knowledge on the SMC chemical evolution during the earliest epochs. Based on our new data, we further discuss the age-metallicity relation. The procedures and results included in this article will be presented in a more extensive and detailed way in Parisi et al. (2011 - in preparation).Usando espectroscopıa del Triplete del Calcio Ionizado y fotometrıa P SF realizada sobre datos tomados con el “Very Large Telescope” (Chile), derivamos edades y metalicidades confiables de 15 cumulos estelares de la Nube Menor de Magallanes (NmM). Encontramos que 3 de ellos son cumulos muy viejos, por lo que la determinacion de sus propiedades fundamentales permite mejorar nuestro actual conocimiento sobre la evolucion quımica de la NmM durante su etapa mas temprana. Basados en nuestros nuevos datos, rediscutimos la relacion edad-metalicidad en esta galaxia. Los procedimientos y resultados incluidos en este artıculo, seran presentados de manera mas extensa y detallada en Parisi et al. (2011 - en preparacion).Fil: Parisi, M. C.. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; ArgentinaFil: Geisler, D.. Universidad de Concepción; ChileFil: Grocholski, A. J.. University of Florida; Estados UnidosFil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; ArgentinaFil: Carraro, G.. European Southern Observatory; ChileFil: Costa, E.. Universidad de Chile; ChileFil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Sarajedini, A.. University of Florida; Estados UnidosFil: Leiton, R.. Universidad de Concepción; Chil

Optical Light Curve of the Type Ia Supernova 1998bu in M96 and the Supernova Calibration of the Hubble Constant

We present the UBVRI light curves of the Type Ia supernova SN 1998bu which appeared in the nearby galaxy M96 (NGC 3368). M96 is a spiral galaxy in the Leo I group which has a Cepheid-based distance. Our photometry allows us to calculate the absolute magnitude and reddening of this supernova. These data, when combined with measurements of the four other well-observed supernovae with Cepheid based distances, allow us to calculate the Hubble constant with respect to the Hubble flow defined by the distant Calan/Tololo Type Ia sample. We find a Hubble constant of 64.0 +/- 2.2(internal) +/- 3.5(external) km/s/Mpc, consistent with most previous estimates based on Type Ia supernovae. We note that the two well-observed Type Ia supernovae in Fornax, if placed at the Cepheid distance to the possible Fornax spiral NGC 1365, are apparently too faint with respect to the Calan/Tololo sample calibrated with the five Type Ia supernovae with Cepheid distances to the host galaxies.Comment: AAS LaTeX, 20 pages, 4 figures, 6 tables, accepted for publication in the Astronomical Journal. Figure 1 (finding chart) not include

PREDICT identifies precipitating events associated with the clinical course of acutely decompensated cirrhosis

Background & Aims: Acute decompensation (AD) of cirrhosis may present without acute-on-chronic liver failure (ACLF) (ADNo ACLF), or with ACLF (AD-ACLF), defined by organ failure(s). Herein, we aimed to analyze and characterize the precipitants leading to both of these AD phenotypes. Methods: The multicenter, prospective, observational PREDICT study (NCT03056612) included 1,273 non-electively hospitalized patients with AD (No ACLF = 1,071; ACLF = 202). Medical history, clinical data and laboratory data were collected at enrolment and during 90-day follow-up, with particular attention given to the following characteristics of precipitants: induction of organ dysfunction or failure, systemic inflammation, chronology, intensity, and relationship to outcome. Results: Among various clinical events, 4 distinct events were precipitants consistently related to AD: proven bacterial infections, severe alcoholic hepatitis, gastrointestinal bleeding with shock and toxic encephalopathy. Among patients with precipitants in the AD-No ACLF cohort and the AD-ACLF cohort (38% and 71%, respectively), almost all (96% and 97%, respectively) showed proven bacterial infection and severe alcoholic hepatitis, either alone or in combination with other events. Survival was similar in patients with proven bacterial infections or severe alcoholic hepatitis in both AD phenotypes. The number of precipitants was associated with significantly increased 90day mortality and was paralleled by increasing levels of surrogates for systemic inflammation. Importantly, adequate first-line antibiotic treatment of proven bacterial infections was associated with a lower ACLF development rate and lower 90-day mortality. Conclusions: This study identified precipitants that are significantly associated with a distinct clinical course and prognosis in patients with AD. Specific preventive and therapeutic strategies targeting these events may improve outcomes in patients with decompensated cirrhosis. Lay summary: Acute decompensation (AD) of cirrhosis is characterized by a rapid deterioration in patient health. Herein, we aimed to analyze the precipitating events that cause AD in patients with cirrhosis. Proven bacterial infections and severe alcoholic hepatitis, either alone or in combination, accounted for almost all (96-97%) cases of AD and acute-on-chronic liver failure. Whilst the type of precipitant was not associated with mortality, the number of precipitant(s) was. This study identified precipitants that are significantly associated with a distinct clinical course and prognosis of patients with AD. Specific preventive and therapeutic strategies targeting these events may improve patient outcomes. (c) 2020 European Association for the Study of the Liver. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Photometric and kinematic study of red giants in open clusters located in the galactic center direction

We present CORAVEL radial velocities and high precision UBV and DDO photoelectric photometry for a sample of red giant candidates of the open clusters NGC 6192, NGC 6208 and NGC 6268. We discovered 3 new spectroscopic binaries and determined mean radial velocity, reddening and metallicity for the three clusters. We also examined the properties of a sample of 42 inner disk open clusters projected towards almost the same direction.Presentamos velocidades radiales CORAVEL y fotometría fotoeléctrica UBV y DDO de alta precisión de candidatas a gigantes rojas de los cúmulos abiertos NGC 6192, NGC 6208 y NGC 6268. Descubrimos 3 nuevas binarias espectroscópicas y determinamos velocidad radial media, enrojecimiento y metalicidad para los tres cúmulos. Examinamos además las propiedades de 42 cúmulos abiertos del disco interior proyectados casi en la misma dirección.Fil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mermilliod, J. C.. Ecole Polytechnique Federale de Lausanne; SuizaFil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Parisi, Maria Celeste. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin