86 research outputs found

    The VISCACHA survey -- VII. Assembly history of the Magellanic Bridge and SMC Wing from star clusters

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    The formation scenario of the Magellanic Bridge during an encounter between the Large and Small Magellanic Clouds 200\sim200\,Myr ago, as proposed by NN-body models, would be imprinted in the chemical enrichment and kinematics of its stars, and sites of ongoing star formation along its extension. We present an analysis of 33 Bridge star clusters using photometry obtained with the SOAR 4-m telescope equipped with adaptive optics for the VISCACHA survey. We performed a membership selection and derived self-consistent ages, metallicities, distances and reddening values via statistical isochrone fitting, as well as tidal radii and integrated masses from structure analysis. Two groups are clearly detected: 13 well-studied clusters older than the Bridge, with 0.56.80.5-6.8\,Gyr and [Fe/H]<0.6\rm{[Fe/H]}<-0.6\,dex; and 15 clusters with 0.5-0.5\,dex, probably formed in-situ. The old clusters follow the overall age and metallicity gradients of the SMC, whereas the younger ones are uniformly distributed along the Bridge. The main results are as follows: (i)(i) we derive ages and metallicities for the first time for 9 and 18 clusters, respectively; (ii)(ii) we detect two metallicity dips in the age-metallicity relation of the Bridge at 200\sim 200\,Myr and 1.51.5\,Gyr ago for the first time, possibly chemical signatures of the formation of the Bridge and Magellanic Stream; (iii)(iii) we estimate a minimum stellar mass for the Bridge of 35×105M3-5 \times 10^5\,M_\odot; (iv)(iv) we confirm that all the young Bridge clusters at RA<3h\rm{RA} < 3^h are metal-rich [Fe/H]0.4\rm{[Fe/H]} \sim -0.4\,dex.Comment: 15 pages, 13 figures + appendix. Accepted for publication in MNRA

    The VISCACHA survey-deep and resolved photometry of star clusters in the Magellanic Clouds

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    The VISCACHA (VIsible Soar photometry of star Clusters in tApii and Coxi HuguA†) Survey is an ongoing project based on deep and spatially resolved photometric observations of Magellanic Cloud star clusters, collected using the SOuthern Astrophysical Research (SOAR) telescope together with the SOAR Adaptive Module Imager. So far we have used >300h of telescope time to observe ∼150 star clusters, mostly with low mass (M < 104M⊠) on the outskirts of the LMC and SMC. With this high-quality data set, we homogeneously determine physical properties using deep colour-magnitude diagrams (ages, metallicities, reddening, distances, mass, luminosity and mass functions) and structural parameters (radial density profiles, sizes) for these clusters which are used as a proxy to investigate the interplay between the Magellanic Clouds and their evolution. We present the VISCACHA survey and its initial results, based on our first two papers. The project's long term goals and expected legacy to the community are also addressed.Fil: Dias, Bruno. European Southern Observatory Chile; Chile. Universidad Andrés Bello; ChileFil: Maia, Francisco. Universidade Federal do Rio de Janeiro; BrasilFil: Kerber, Leandro. Universidade Estadual de Santa Cruz; BrasilFil: Dos Santos, João F. C.. Universidade Federal de Minas Gerais; BrasilFil: Bica, Eduardo. Universidade Federal do Rio Grande do Sul; BrasilFil: Armond, Tina. Universidade Federal de São João del Rei; BrasilFil: Barbuy, Beatriz. Universidade de Sao Paulo; BrasilFil: Fraga, Luciano. Laboratório Nacional de Astrofísica; BrasilFil: Hernandez Jimenez, Jose A.. Universidad Andrés Bello; ChileFil: Katime Santrich, Orlando J.. Universidade Estadual de Santa Cruz; BrasilFil: Oliveira, Raphael A. P.. Universidade de Sao Paulo; BrasilFil: Pérez Villegas, Angeles. Universidade de Sao Paulo; BrasilFil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Quint, Bruno. Observatorio Gemini; ChileFil: Sanmartin, David. Observatorio Gemini; ChileFil: Angelo, Mateus S.. Centro Federal de Educação Tecnológica de Minas Gerais; BrasilFil: Souza, Stefano O.. Universidade de Sao Paulo; BrasilFil: Vieira, Rodrigo G.. Universidade de Sao Paulo; BrasilFil: Westera, Pieter. Universidad Federal Do Abc; BrasilFil: Parisi, Maria Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Geisler, Doug. Universidad de La Serena; Chile. Universidad de Concepción; ChileFil: Minniti, Dante. Universidad Andrés Bello; Chile. Millennium Institute of Astrophysics; Chile. Vatican Observatory; ItaliaFil: Saito, Roberto. Universidade Federal de Santa Catarina; BrasilFil: Bassino, Lilia Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: de Bórtoli, Bruno Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Figueiredo, André. Universidade de Sao Paulo; BrasilFil: Rímulo, Leandro. Universidad de los Andes; Colombi

    Avaliação das condições de segurança do trabalho na colheita e transporte florestal em propriedades rurais fomentadas no Estado do Espírito Santo Evaluation of work safety conditions of timber harvesting and transport in fomented farms of the state of Espírito Santo, Brazil

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    Este trabalho foi desenvolvido com informações obtidas de 70 proprietários rurais fomentados, responsáveis por 90 contratos de fomento florestal, com o objetivo de caracterizar as condições de segurança do trabalho na colheita e transporte florestal, em propriedades rurais fomentadas no Estado do Espírito Santo. A área fomentada por contrato variava entre 1,5 e 100,0 ha, sendo de até 30 ha em 86,7% dos contratos e com relevo montanhoso em 61,2%. A colheita e transporte florestais foram terceirizados em 70 e 80% dos contratos amostrados, respectivamente, e realizados por conta dos proprietários nos demais. A maioria dos prestadores de serviço terceirizados era contratada informalmente. Foi empregada a mão-de-obra contratada na maioria dos contratos com colheita própria, sendo a maior parte não qualificada e contratada informalmente. Grande parte dos trabalhadores deslocava-se por conta própria até o local de colheita. Ocorreram acidentes de trabalho em 16,3% dos contratos, sendo 60% na colheita e transporte florestal próprios. A maioria dos acidentes aconteceu na atividade de corte e atingiu, principalmente, os membros inferiores e superiores do trabalhador acidentado. Os trabalhadores não utilizavam equipamentos de proteção individual em 62,1% dos contratos com colheita própria e em 23,0% dos terceirizados. Observou-se carência de material de primeiros socorros, bem como falta de instrução para o socorro de trabalhadores acidentados na colheita florestal.<br>This research was developed with data obtained from 70 fomented farm owners in the State of Espírito Santo, Brazil, who were responsible for 90 forest contracts distributed in 22 cities of the State. The area fomented per contract ranged from 1.5 to 100 hectares, being 84.8% of contracts up to 30 ha and 59.8% with mountainous relief. Timber harvesting and log transport were outsourced and carried out by a subcontractor in 70% and 80% of the contracts respectively, whereas in the remaining contracts, they were carried out by the farm owners themselves. Most of the subcontractors were not formally hired with a signed contract. The workers of most contracts with timber harvesting carried out by farm owners were not formally hired and not qualified for the job. Great part of the workers used their own means of transport to the work place. Work accidents occurred in 16.3% of the contracts, with 60% of them taking place during timber harvesting and log transport by the farm owners. Most accidents took place in logging activities and causing injuries mainly to workers' inferior and superior limbs. The workers did not use personal protective equipment in 62.1% of the contracts with timber harvesting carried out by the farm owner and in 23% of outsourced contracts. It was verified lack of first aid materials and training to help injured workers during timber harvesting
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