Fitting isochrones to open cluster photometric data III. Estimating metallicities from UBV photometry

The metallicity is a critical parameter that affects the correct determination fundamental characteristics stellar cluster and has important implications in Galactic and Stellar evolution research. Fewer than 10 % of the 2174 currently catalog open clusters have their metallicity determined in the literature. In this work we present a method for estimating the metallicity of open clusters via non-subjective isochrone fitting using the cross-entropy global optimization algorithm applied to UBV photometric data. The free parameters distance, reddening, age, and metallicity simultaneously determined by the fitting method. The fitting procedure uses weights for the observational data based on the estimation of membership likelihood for each star, which considers the observational magnitude limit, the density profile of stars as a function of radius from the center of the cluster, and the density of stars in multi-dimensional magnitude space. We present results of [Fe/H] for nine well-studied open clusters based on 15 distinct UBV data sets. The [Fe/H] values obtained in the ten cases for which spectroscopic determinations were available in the literature agree, indicating that our method provides a good alternative to determining [Fe/H] by using an objective isochrone fitting. Our results show that the typical precision is about 0.1 dex

Primeiro relato de Braga patagonica Schödte & Meinert, 1884 (Crustacea: Isopoda) parasitando peixes cultivados no Brasil.

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Rotating magnetic solution in three dimensional Einstein gravity

We obtain the magnetic counterpart of the BTZ solution, i.e., the rotating spacetime of a point source generating a magnetic field in three dimensional Einstein gravity with a negative cosmological constant. The static (non-rotating) magnetic solution was found by Clement, by Hirschmann and Welch and by Cataldo and Salgado. This paper is an extension of their work in order to include (i) angular momentum, (ii) the definition of conserved quantities (this is possible since spacetime is asymptotically anti-de Sitter), (iii) upper bounds for the conserved quantities themselves, and (iv) a new interpretation for the magnetic field source. We show that both the static and rotating magnetic solutions have negative mass and that there is an upper bound for the intensity of the magnetic field source and for the value of the angular momentum. The magnetic field source can be interpreted not as a vortex but as being composed by a system of two symmetric and superposed electric charges, one of the electric charges is at rest and the other is spinning. The rotating magnetic solution reduces to the rotating uncharged BTZ solution when the magnetic field source vanishes.Comment: Latex (uses JHEP3.cls), 12 pages. Published versio

Pair creation of higher dimensional black holes on a de Sitter background

We study in detail the quantum process in which a pair of black holes is created in a higher D-dimensional de Sitter (dS) background. The energy to materialize and accelerate the pair comes from the positive cosmological constant. The instantons that describe the process are obtained from the Tangherlini black hole solutions. Our pair creation rates reduce to the pair creation rate for Reissner-Nordstrom-dS solutions when D=4. Pair creation of black holes in the dS background becomes less suppressed when the dimension of the spacetime increases. The dS space is the only background in which we can discuss analytically the pair creation process of higher dimensional black holes, since the C-metric and the Ernst solutions, that describe respectively a pair accelerated by a string and by an electromagnetic field, are not know yet in a higher dimensional spacetime.Comment: 10 pages; 1 figure included; RexTeX4. v2: References added. Published version. v3: Typo in equation (46) fixe

Properties of Solutions in 2+1 Dimensions

We solve the Einstein equations for the 2+1 dimensions with and without scalar fields. We calculate the entropy, Hawking temperature and the emission probabilities for these cases. We also compute the Newman-Penrose coefficients for different solutions and compare them.Comment: 16 pages, 1 figures, PlainTeX, Dedicated to Prof. Yavuz Nutku on his 60th birthday. References adde

Estudo da adaptabilidade e estabilidade fenotípica de progênies de Eucalyptus grandis via metodologia AMMI.

Foram avaliadas a adaptabilidade e a estabilidade fenotípica de 200 progênies de Eucalyptus grandis procedentes de 10 localidades australianas, selecionadas pelo Programa Nacional de Pesquisa Florestal – coordenado pela Embrapa Florestas, e implantadas em sete testes de procedência e progênies nas regiões sul e sudeste do Brasil. Os resultados indicaram comportamentos diferenciados dos materiais avaliados, sendo a interação genótipo x ambiente significativa (p<0,01). O método AMMI (Additive Main Effects and Multiplicative Interaction Analysis) permitiu identificar as melhores combinações entre progênies e locais

A Simple Realization of the Inverse Seesaw Mechanism

Differently from the canonical seesaw mechanism, which is grounded in grand unified theories, the inverse seesaw mechanism lacks a special framework that realizes it naturally. In this work we advocate that the 3-3-1 model with right-handed neutrinos has such an appropriate framework to accommodate the inverse seesaw mechanism. We also provide an explanation for the smallness of the $\mu$ parameter and estimate the branching ratio for the rare lepton flavor violation process $\mu \rightarrow e\gamma$.Comment: About 14pages, no figures, basis corrected, to appear at the PR

Gravitational radiation in d>4 from effective field theory

Some years ago, a new powerful technique, known as the Classical Effective Field Theory, was proposed to describe classical phenomena in gravitational systems. Here we show how this approach can be useful to investigate theoretically important issues, such as gravitational radiation in any spacetime dimension. In particular, we derive for the first time the Einstein-Infeld-Hoffman Lagrangian and we compute Einstein's quadrupole formula for any number of flat spacetime dimensions.Comment: 32 pages, 10 figures. v2: Factor in eq. (3.11) fixed. References adde