Context. One of the most enigmatic phenomena related to solar activity is the so-called Maunder minimum phase. It consists in the lowest sunspot count ever registered for the Sun and has not been confirmed for other stars to date. Since the spectroscopic observations of stellar activity at the Mount Wilson Observatory, the solar analog HD 43587 has shown a very low and apparently invariant activity level, which makes it a Maunder minimum candidate. Aims. We aim to analyze the chromospheric activity evolution of HD 43587 and its evolutive status, with the intention of unraveling the reasons for this low and flat activity. Methods. We used an activity measurements dataset available in the literature, and computed the S-index from HARPS and NARVAL spectra to infer a cycle period. Additionally, we analyzed the CoRoT light curve of HD 43587, and applied gyrochronology and activity calibrations to determine its rotation period. Finally, based on an evolutionary model and the inferred rotation period, we used the EULAG-MHD code to perform global MHD simulations of HD 43587 to get some insight into its dynamo process. Results. We confirm the almost flat activity profile, with a cycle period Pcyc = 10.44 ± 3.03 yr deduced from the S-index time series, and a long-term trend that might be a period of more than 50 yr. It was impossible to define a rotation period from the light curve, however gyrochronology and activity calibrations allow us to infer an indirect estimate of ¯Prot = 22.6 ± 1.9 d. Furthermore, the MHD simulations confirm an oscillatory dynamo with a cycle period in good agreement with the observations and a low level of surface magnetic activity. Conclusions. We conclude that this object might be experiencing a “natural” decrease in magnetic activity as a consequence of its age. Nevertheless, the possibility that HD 43587 is in a Maunder minimum phase cannot be ruled out.

Protoplanetary disks orbiting intermediate-mass stars, Herbig Ae/Be stars, that have formed in a metal-poor environment may evolve differently than their Galactic cousins. A study of the planet-formation process in such an environment requires identification and characterization of a sample of candidates. We have observed several stars in the Small Magellanic Cloud, a nearby metal-poor dwarf galaxy, that have optical spectral properties of Herbig Ae/Be stars, including strong Hα emission, blue continuum excess, and spectral types ranging from early G to B. Infrared spectra of these sources from the Spitzer Space Telescope show strong excess emission indicating the presence of silicate dust, molecular and atomic gas, and polycyclic aromatic hydrocarbons. We present an analysis of the likelihood that these candidates are Herbig Ae/Be stars. This identification is the necessary first step to future investigations that will examine the role of metallicity in the evolution of protoplanetary disks.

Abstract. The large adoption of the ENEM grade as an instrument to evaluate students in higher education, the number of people performing this test increased significantly. Among the evaluation methods, this test includes an essay. In this exam is required to respect human rights. In this context, this work proposes the analysis of different algorithms for the identification of hate speech in essays. It adopts a hybrid approach combining machine learning techniques and lexical dictionaries. Several experiments were conducted and in the best case the proposal reached a f-measure of 82.10%. Finally, a qualitative study was carried out where essays evaluators indicated that the adoption of the proposed tool would aid in the correction of essays.Resumo. Com a grande adoção da nota ENEM como instrumento para avaliar estudantes no ingresso do ensino superior, o número de pessoas que passou a fazer essa prova aumentou significativamente. Dentre as etapas da prova existe uma redação que avalia, entre outras coisas, se o estudante fez o seu texto respeitando os direitos humanos. Diante disto, este trabalho propõe a análise de diferentes algoritmos para identificação de frases preconceituosas em redações. Para isso, foi utilizada uma abordagem híbrida combinando técnicas de aprendizagem de máquina e dicionários léxicos. Foram realizados diversos experimentos, no melhor caso a proposta atingiu uma f-measure de 82,10%. Por fim, foi realizado um estudo qualitativo onde avaliadores de redação indicaram que a adoção da ferramenta proposta auxiliaria na correção de redações.

This investigation was derived from the observation and teaching process carried out in elementary classes at the Brigadeiro Eduardo Gomes Municipal Middle School (Natal, Brazil) at the end of 2019. The sciences classes taught were the following: the development of astronomy and astronautics from antiquity to the modern era and, introduction to stellar evolution. The goal was to focus on preparing for the Brazilian Astronomical Olympics (OBA) for students in these classes. The results, both quantitative and qualitative, were quite satisfactory. Taking into account the region’s socio-economic vulnerability profile. In this context, the study of Astronomy in the classroom in search of creating new mechanisms to improve pedagogical activities encourages the critical and creative development of students, showing that they have the potential and want to make use of it.

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