11,087 research outputs found

    Microlensing path parametrization for Earth-like Exoplanet detection around solar mass stars

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    We propose a new parametrization of the impact parameter u0 and impact angle {\alpha} for microlensing systems composed by an Earth-like Exoplanet around a Solar mass Star at 1 AU. We present the caustic topology of such system, as well as the related light curves generated by using such a new parametrization. Based on the same density of points and accuracy of regular methods, we obtain results 5 times faster for discovering Earth-like exoplanet. In this big data revolution of photometric astronomy, our method will impact future missions like WFIRST (NASA) and Euclid (ESA) and they data pipelines, providing a rapid and deep detection of exoplanets for this specific class of microlensing event that might otherwise be lost.Comment: 8 pages, 7 figures, accepted to be published in The Astronomical Journa

    The Multi-Lane Capsule Network (MLCN)

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    We introduce Multi-Lane Capsule Networks (MLCN), which are a separable and resource efficient organization of Capsule Networks (CapsNet) that allows parallel processing, while achieving high accuracy at reduced cost. A MLCN is composed of a number of (distinct) parallel lanes, each contributing to a dimension of the result, trained using the routing-by-agreement organization of CapsNet. Our results indicate similar accuracy with a much reduced cost in number of parameters for the Fashion-MNIST and Cifar10 datsets. They also indicate that the MLCN outperforms the original CapsNet when using a proposed novel configuration for the lanes. MLCN also has faster training and inference times, being more than two-fold faster than the original CapsNet in the same accelerator

    Lithium abundance evolution in open clusters: Hyades, NGC752, and M67

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    Mixing mechanisms bring the Li from the base of the convective zone to deeper and warmer layers where it is destroyed. These mechanisms are investigated by comparing observations of Li abundances in stellar atmospheres to models of stellar evolution. Observations in open cluster are especially suitable for this comparison, since their age and metallicity are homogeneous among their members and better determined than in field stars. In this work, we compare the evolution of Li abundances in three different clusters: the Hyades, NGC752, and M67. Our models are calculated with microscopic diffusion and transport of chemicals by meridional circulation, and calibrated on the Sun. These comparisons allow us to follow the evolution of Li abundance as a function of stellar mass in each cluster and as a function of the age by comparing this evolution in each cluster. We evaluate the efficiency of the mixing mechanisms used in the models, and we try to identify the lacking mechanisms to reproduce the observed evolution of Li abundance.Comment: 6 pages, 4 figures, conference publication of "New advances in stellar physics: from microscopic to macroscopic processes

    Power-law statistics and stellar rotational velocities in the Pleiades

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    In this paper we will show that, the non-gaussian statistics framework based on the Kaniadakis statistics is more appropriate to fit the observed distributions of projected rotational velocity measurements of stars in the Pleiades open cluster. To this end, we compare the results from the Îș\kappa and qq-distributions with the Maxwellian.Comment: 13 pages, 3 figure

    Typification of names of Clusiaceae based on material collected by August Weberbauer in Peru

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    August Weberbauer was a German botanist who worked for most of his life in Peru. Many species have been described based on specimens collected by him, which were mainly deposited in the Berlin herbarium (B). After the bombing of the Berlin herbarium during World War II, it was assumed that most of these types had been destroyed, duplicates rarely existed and neotypes had to be designated. However, during visits to Peruvian herbaria we rediscovered some overlooked duplicates of specimens of Clusiaceae. In the present paper, we designate lectotypes of ten names based on these Weberbauer collections and report additional duplicates found in the herbarium G. Some former incorrect typifications are corrected, and the problem of destroyed types in herbarium B, often known mainly from photos made by J. F. Macbride, is briefly discussed.492193196CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP311744/2017-62012/51781-0; 2012/15542-
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