2,577 research outputs found

    NTT infrared imaging of star cluster candidates towards the central parts of the Galaxy

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    We address the issue whether the central parts of the Galaxy harbour young clusters other than Arches, Quintuplet and the Nuclear Young Cluster. A large sample of centrally projected cluster candidates has been recently identified from the 2MASS J, H and Ks Atlas. We provide a catalogue of higher angular resolution and deeper images for 57 2MASS cluster candidates, obtained with the near-IR camera SOFI at the ESO NTT telescope. We classify 10 objects as star clusters, some of them deeply embedded in gas and/or dust clouds. Three other objects are probably star clusters, although the presence of dust in the field does not exclude the possibility of their being field stars seen through low-absorption regions. Eleven objects are concentrations of stars in areas of little or no gas, and are classified as dissolving cluster candidates. Finally, 31 objects turned out to be the blend of a few bright stars, not resolved as such in the low resolution 2MASS images. By combining the above results with other known objects we provide an updated sample of 42 embedded clusters and candidates projected within 7 degrees. As a first step we study Object 11 of Dutra & Bica (2000) projected at approximately 1 degree from the nucleus. We present H and Ks photometry and study the colour-magnitude diagram and luminosity function. Object 11 appears to be a less massive cluster than Arches or Quintuplet, and it is located at a distance from the Sun d=8 kpc, with a visual absorption Av=15.Comment: accepted to A&A, 9 pages, 10 figure

    Remarks on supersymmetry of quantum systems with position-dependent effective masses

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    We apply the supersymmetry approach to one-dimensional quantum systems with spatially-dependent mass, by including their ordering ambiguities dependence. In this way we extend the results recently reported in the literature. Furthermore, we point out a connection between these systems and others with constant masses. This is done through convenient transformations in the coordinates and wavefunctions.Comment: 8 pages, 1 figur

    Relativistic Mean-Field Hadronic Models under Nuclear Matter Constraints

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    Relativistic mean-field (RMF) models have been widely used in the study of many hadronic frameworks because of several important aspects not always present in nonrelativistic models, such as intrinsic Lorentz covariance, automatic inclusion of spin, appropriate saturation mechanism for nuclear matter, causality and, therefore, no problems related to superluminal speed of sound. With the aim of identifying the models which best satisfy well known properties of nuclear matter, we have analyzed 263263 parameterizations of seven different types of RMF models under three different sets of constraints related to symmetric nuclear matter, pure neutron matter, symmetry energy, and its derivatives. One of these (SET1) is formed of the same constraints used in a recent work [M. Dutra et al., Phys. Rev. C 85, 035201 (2012)] in which we analyzed 240240 Skyrme parameterizations. The results pointed to 22 models consistent with all constraints. By using another set of constraints, namely, SET2a, formed by the updated versions of the previous one, we found 44 models approved simultaneously. Finally, in the third set, named SET2b, in which the values of the constraints are more restrictive, we found 33 consistent models. Another interesting feature of our analysis is that the results change dramatically if we do not consider the constraint regarding the volume part of the isospin incompressibility (KÏ„,vK_{\tau,\rm v}). In this case, we have 3535 approved models in SET2a and 3030 in SET2b.Comment: 63 pages, 3 figures and 9 tables. Version accepted for publication in PR

    Germinação de sementes de leguminosas forrageiras em diferentes condições de estresse salino.

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    Resumo também publicado em: REUNIÃO ANUAL DA SOCIEDADE BRASILEIRA DE ZOOTECNIA, 37., 2000, Viçosa, MG. Resumos dos trabalhos apresentados. Viçosa, MG: Sociedade Brasileira de Zootecnia, 2000. p. 98

    Germinação de sementes de Pueraria phaseoloides: efeitos do pH, do nitrato e da salinidade.

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    Resumo publicado também em: REUNIÃO ANUAL DA SOCIEDADE BRASILEIRA DE ZOOTECNIA, 36., 1999, Porto Alegre. Resumos dos trabalhos apresentados... Porto Alegre: Sociedade Brasileira de Zootecnia, 1999. p. 105
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