The VMC survey - XV : The Small Magellanic Cloud-Bridge connection history as traced by their star cluster populations

Date of Acceptance: 19/03/2015We present results based on YJKs photometry of star clusters located in the outermost, eastern region of the Small Magellanic Cloud (SMC). We analysed a total of 51 catalogued clusters whose colour-magnitude diagrams (CMDs), having been cleaned from field-star contamination, were used to assess the clusters' reality and estimate ages of the genuine systems. Based on CMD analysis, 15 catalogued clusters were found to be possible non-genuine aggregates. We investigated the properties of 80 per cent of the catalogued clusters in this part of the SMC by enlarging our sample with previously obtained cluster ages, adopting a homogeneous scale for all. Their spatial distribution suggests that the oldest clusters, log(t/yr) ≥ 9.6, are in general located at greater distances to the galaxy's centre than their younger counterparts - 9.0 ≤ log(t/yr) ≤ 9.4 - while two excesses of clusters are seen at log(t/yr) ~9.2 and log(t yr-1) ˜ 9.7. We found a trail of younger clusters which follow the wing/bridge components. This long spatial sequence does not only harbour very young clusters, log(t yr-1) ~7.3, but it also hosts some of intermediate ages, log(t/yr) ~9.1. The derived cluster and field-star formation frequencies as a function of age are different. The most surprising feature is an observed excess of clusters with ages of log(t/yr) < 9.0, which could have been induced by interactions with the LMC.Peer reviewedFinal Accepted Versio

New quasars behind the Magellanic Clouds. Spectroscopic confirmation of near-infrared selected candidates

Context. Quasi-stellar objects (quasars) located behind nearby galaxies provide an excellent absolute reference system for astrometric studies, but they are difficult to identify because of fore- and background contamination. Deep wide-field, high angular resolution surveys spanning the entire area of nearby galaxies are needed to obtain a complete census of such quasars. Aims. We embarked on a program to expand the quasar reference system behind the Large and the Small Magellanic Clouds, the Magellanic Bridge, and the Magellanic Stream that connects the Clouds with the Milky Way. Methods. Hundreds of quasar candidates were selected based on their near-infrared colors and variability properties from the ongoing public ESO VISTA Magellanic Clouds survey. A subset of 49 objects was followed up with optical spectroscopy. Results. We confirmed the quasar nature of 37 objects (34 new identifications): four are low redshift objects, three are probably stars, and the remaining three lack prominent spectral features for a secure classification. The bona fide quasars, identified from their broad emisison lines, are located as follows: 10 behind the LMC, 13 behind the SMC, and 14 behind the Bridge. The quasars span a redshift range from z ~ 0.5 to z ~ 4.1. Conclusions. Upon completion the VMC survey is expected to yield a total of ~1500 quasars with Y&lt; 19.32 mag, J&lt; 19.09 mag, and Ks&lt; 18.04 mag

The VMC Survey. XXII. Hierarchical Star Formation in the 30 Doradus-N158-N159-N160 Star-forming Complex

We study the hierarchical stellar structures in a ∼1.5 deg2 area covering the 30 Doradus-N158-N159-N160 star-forming complex with the VISTA Survey of Magellanic Clouds. Based on the young upper main-sequence stars, we find that the surface densities cover a wide range of values, from log(pc2) ≲ -2.0 to log(pc2) ≳ 0.0. Their distributions are highly non-uniform, showing groups that frequently have subgroups inside. The sizes of the stellar groups do not exhibit characteristic values, and range continuously from several parsecs to more than 100 pc; the cumulative size distribution can be well described by a single power law, with the power-law index indicating a projected fractal dimension D2 = 1.6 ± 0.3. We suggest that the phenomena revealed here support a scenario of hierarchical star formation. Comparisons with other star-forming regions and galaxies are also discussed.Fil: Sun, Ning-Chen. Peking University; ChinaFil: Grijs, Richard De. Peking University; ChinaFil: Subramanian, Smitha. Peking University; ChinaFil: Cioni, Maria-Rosa L.. Universita Zu Berlin. Universita Postdam; AlemaniaFil: Rubele, Stefano. Università di Padova; ItaliaFil: Bekki, Kenji. University of Western Australia; AustraliaFil: Ivanov, Valentin D.. European Southern Observatory; ChileFil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; ArgentinaFil: Ripepi, Vincenzo. Osservatorio Astronomico di Capodimonte; Itali

Clinical signs and occurrence of antibodies anti-Chlamydophila abortus in ovines of Sao Paulo and Minas Gerais

A Chlamydophila abortusi, anteriormente conhecida como Chlamydia psittaci sovovar 1, é uma bactéria Gram negativa, intracelular obrigatória. Esse micro-organismo é frequentemente encontrado em distúrbios reprodutivos em ovinos, bovinos e caprinos, sendo o aborto epizoótico dos bovinos e o aborto enzoótico dos ovinos e caprinos as manifestações mais importantes. Considerando-se o pouco material literário a respeito da clamidofilose no Brasil, a pesquisa teve como objetivo determinar a presença de anticorpos fixadores de complemento anti-Chlamydophila abortusi, correlacionando os resultados obtidos com achados no exame clínico e histórico dos animais, além de alterações nos índices zootécnicos, em especial na esfera reprodutiva, tais como alto índice de repetição de cio, número elevado de abortamentos, elevado número de natimortos, entre outros. Foram testadas para prova de fixação do complemento 220 amostras de soro de ovinos, de 26 propriedades, distribuídas em 19 municípios, com relato de manifestação reprodutiva, obtendo-se 19,55% (43/220) de testes positivos para Chlamydophila abortusi, com ocorrência de foco constatada de 61,53%. No geral, a titulação de anticorpos encontrada foi baixa, com título não superior a 64. A frequência de manifestação reprodutiva mais observada foi o aborto, representando 65,12% (28/43) do número total de animais soropositivos, seguido de repetição de cio juntamente com nascimento de cordeiro fraco, com frequência de 6,98% (3/43) e, por fim, morte neonatal com 4,65% (2/43), sendo que não houve associação significativa entre animais que foram positivos ao teste e a esses fatores.The Chlamydophila abortus was previously known as Chlamydia psittaci sorovar 1, it is a Gram negative and obligate intracellular bacteria. This microorganism is frequently related with reproductive manifestation in ovines, goats and bovines. The major manifestation are Enzootic abortion in bovines and enzootic abortion in small ruminants. There are few literary material about clamidofilosis in Brazil, so the present research had the objective to determine the presence of complement fixing antibodies anti-Chlamydophila abortus, correlating the results with the clinical examination and historical of the animals, besides variation in the zootecnic index, especially in the reproductive characters like high index of cio repetition, high abortion number, high neonatal mortality number etc. It was tested for the complement fixation test 220 serum ovine samples, from 26 properties, distributed in 19 cities, with historical of reproductive manifestation. It was found 19.55% (43/220) of positive tests to Chlamydophila abortus, obtaining 61.53% of focus occurrence. In the study low antibodies titers were found, not superior of 64. Abortion was the major reproductive manifestation observed, expressing 65.12% (28/43) of the total number animals serum positive, followed by estrus repetition and weak lamb born, with a frequency of 6.98% (3/43) and, lastly, neonatal mortality death with 4.65% (2/43). No significant association was observed between serum positivity and these factors

Towards a fundamental astrometric reference system behind the Malleganic clouds : spectroscopic confirmation of new quasar candidates selected in the near-infrared

Quasi-stellar objects (quasars) located behind nearby galaxies provide an excellent absolute reference system for astrometric studies, but they are difficult to identify because of fore- and background contamination. We have embarked on a programme to expand the quasar reference system behind the Large and Small Magellanic Clouds, the Magellanic Bridge and Magellanic Stream. Hundreds of quasar candidates were selected, based on their near-infrared colours and variability properties from the ESO VISTA Magellanic Clouds (VMC) Public Survey. A subset of 49 objects was followed up with optical spectroscopy with FORS2. We confirmed the quasar nature of 37 objects (34 new identifications) that span a redshift range from z ~ 0.5 to 4.1

Clinical signs and occurrence of antibodies anti-Chlamydophila abortus in ovines of São Paulo and Minas Gerais

A Chlamydophila abortus, anteriormente conhecida como Chlamydia psittaci sovovar 1, é uma bactéria Gram negativa, intracelular obrigatória. Esse micro-organismo é frequentemente encontrado em distúrbios reprodutivos em ovinos, bovinos e caprinos, sendo o aborto epizoótico dos bovinos e o aborto enzoótico dos ovinos e caprinos as manifestações mais importantes. Considerando-se o pouco material literário a respeito da clamidofilose no Brasil, a pesquisa teve como objetivo determinar a presença de anticorpos fixadores de complemento anti-Chlamydophila abortus, correlacionando os resultados obtidos com achados no exame clínico e histórico dos animais, além de alterações nos índices zootécnicos, em especial na esfera reprodutiva, tais como alto índice de repetição de cio, número elevado de abortamentos, elevado número de natimortos, entre outros. Foram testadas para prova de fixação do complemento 220 amostras de soro de ovinos, de 26 propriedades, distribuídas em 19 municípios, com relato de manifestação reprodutiva, obtendo-se 19,55% (43/220) de testes positivos para Chlamydophila abortus, com ocorrência de foco constatada de 61,53%. No geral, a titulação de anticorpos encontrada foi baixa, com título não superior a 64. A frequência de manifestação reprodutiva mais observada foi o aborto, representando 65,12% (28/43) do número total de animais soropositivos, seguido de repetição de cio juntamente com nascimento de cordeiro fraco, com frequência de 6,98% (3/ 43) e, por fim, morte neonatal com 4,65% (2/43), sendo que não houve associação significativa entre animais que foram positivos ao teste e a esses fatores.The Chlamydophila abortus was previously known as Chlamydia psittaci sorovar 1, it is a Gram negative and obligate intracellular bacteria. This microorganism is frequently related with reproductive manifestation in ovines, goats and bovines. The major manifestation are Enzootic abortion in bovines and enzootic abortion in small ruminants. There are few literary material about clamidofilosis in Brazil, so the present research had the objective to determine the presence of complement fixing antibodies anti-Chlamydophila abortus, correlating the results with the clinical examination and historical of the animals, besides variation in the zootecnic index, especially in the reproductive characters like high index of cio repetition, high abortion number, high neonatal mortality number etc. It was tested for the complement fixation test 220 serum ovine samples, from 26 properties, distributed in 19 cities, with historical of reproductive manifestation. It was found 19.55% (43/220) of positive tests to Chlamydophila abortus, obtaining 61.53% of focus occurrence. In the study low antibodies titers were found, not superior of 64. Abortion was the major reproductive manifestation observed, expressing 65.12% (28/43) of the total number animals serum positive, followed by estrus repetition and weak lamb born, with a frequency of 6.98% (3/43) and, lastly, neonatal mortality death with 4.65% (2/43). No significant association was observed between serum positivity and these factors

The VMC Survey - XXI. New star cluster candidates discovered from infrared photometry in the Small Magellanic Cloud

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © : 2016 A. E. Piatti, et al., published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. To access the final edited and published version see DOI: 10.1093/mnras/stw1000We report the first search for new star clusters performed using the VISTA near-infrared YJKs Magellanic Clouds survey (VMC) data sets. We chose a pilot field of ~0.4 deg2 located in the South-west of the Small Magelllanic Cloud bar, where the star field is among the densest and highest reddened region in the galaxy. In order to devise an appropriate automatic procedure we made use of dimensions and stellar densities observed in the VMC data sets of the known clusters in this area. We executed different kernel density estimations over a sample of more than 358 000 stars with magnitudes measured in the three YJKs filters. We analysed the new cluster candidates whose colour-magnitude diagrams (CMDs), cleaned from field star contamination, were used to assess the clusters' reality and estimate reddenings and ages of the genuine systems. As a result 38 objects (≈ a 55 per cent increase in the known star clusters located in the surveyed field) of 0.15-0.40 arcmin (2.6-7.0 pc) in radius resulted to have near-infrared CMD features which resemble those of star clusters of young to moderate intermediate age (log(t yr-1) ~7.5-9.0). Most of the new star cluster candidates are hardly recognizable in optical images without the help of a sound star field decontaminated CMD analysis. For highly reddened star cluster candidates (E(B-V) ≥ 0.6 mag) the VMC data sets were necessary in order to recognize them.Peer reviewe

The VMC survey - XVII : The proper motions of the Small Magellanic Cloud and the Milky Way globular cluster 47 Tucanae

In this study we use multi-epoch near-infrared observations from the VISTA survey of the Magellanic Cloud system (VMC) to measure the proper motion of different stellar populations in a tile of 1.5 deg sq. in size in the direction of the Galactic globular cluster 47 Tuc. We obtain the proper motion of the cluster itself, of the Small Magellanic Cloud (SMC), and of the field Milky Way stars. Stars of the three main stellar components are selected from their spatial distribution and their distribution in colour-magnitude diagrams. Their average coordinate displacement is computed from the difference between multiple Ks-band observations for stars as faint as Ks=19 mag. Proper motions are derived from the slope of the best-fitting line among 10 VMC epochs over a time baseline of ~1 yr. Background galaxies are used to calibrate the absolute astrometric reference frame. The resulting absolute proper motion of 47 Tuc is (mu_alpha cos(delta), mu_delta)=(+7.26+/-0.03, -1.25+/-0.03) mas/yr. This measurement refers to about 35000 sources distributed between 10 and 60 arcmin from the cluster centre. For the SMC we obtain (mu_alpha cos(delta), mu_delta)=(+1.16+/-0.07, -0.81+/-0.07) mas/yr from about 5250 red clump and red giant branch stars. The absolute proper motion of the Milky Way population in the line-of-sight (l =305.9, b =-44.9) of this VISTA tile is (mu_alpha cos(delta), mu_delta)=(+10.22+/-0.14, -1.27+/-0.12) mas/yr and results from about 4000 sources. Systematic uncertainties associated to the astrometric reference system are 0.18 mas/yr. Thanks to the proper motion we detect 47 Tuc stars beyond its tidal radius.Peer reviewe

Towards a Fundamental Astrometric Reference System behind the Magellanic Clouds: Spectroscopic Confirmation of New Quasar Candidates Selected in the Near-infrared

Quasi-stellar objects (quasars) locatedbehind nearby galaxies provide anexcellent absolute reference system forastrometric studies, but they are diffi-cult to identify because of fore- andbackground contamination. We haveembarked on a programme to expandthe quasar reference system behindthe Large and Small Magellanic Clouds,the Magellanic Bridge and MagellanicStream. Hundreds of quasar candidateswere selected, based on their near-infrared colours and variability proper-ties from the ESO VISTA MagellanicClouds (VMC) Public Survey. A subsetof 49 objects was followed up with opti-cal spectroscopy with FORS2. We con-firmed the quasar nature of 37 objects(34 new identifications) that span a red-shift range from z ~ 0.5 to 4.1.Fil: Ivanov, Valentin D.. No especifíca;Fil: Cioni, Maria Rosa L.. Universitat Potsdam; Alemania. Leibniz-Institut für Astrophysik Potsdam; Alemania. University of Hertfordshire; Reino UnidoFil: Bekki, Kenji. The University of Western Australia; AustraliaFil: de Grijs, Richard. Peking University; China. International Space Science Institute; ChinaFil: Emerson, Jim. Queen Mary University of London; Reino UnidoFil: Gibson, Brad K.. University of Hull; Reino UnidoFil: Kamath, Devika. Instituut voor Sterrenkunde; BélgicaFil: van Loon, Jacco Th.. Keele University; Reino UnidoFil: Piatti, Andres Eduardo. Universidad Nacional de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: For, Bi Qing. The University of Western Australia; Australi