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Experiências autoetnográficas com o trabalho: a estética da feira
(Universidade Federal de Goiás, 2022-12-30) Chaveiro, Eguimar Felício
By resorting to the methodological expedient of autoethnography, which validates the experiences of subjects in research situations, an interpretation of a literary text will be presented that focuses on my experience as a worker at Feira de Trindade, Goiás. The text – “The aesthetics of the fair”, an chronicle essay, was made through the agglutination between a critique of performative aesthetics and the report of the significance of the fair which, for some years, was the economic foundation of my family. For its elaboration, a reflection was developed on work as a life operator and as an instance that materializes spatially. The interpretation of the informal worker's experience materialized in a link of scales, dimensions and activities of subjects. The economic dimension of the fair, the spatial, temporal, affective and symbolic dimension and the different subjects were observed. The reading of the dimensions and subjects allowed us to see that the relationship between work, memory and narrative, established between the specific and the universal, reveals the space/time conditions and contradictions of Trindade and also of Brazilian society. By proceeding in this way, the autobiography, under the magnifying glass of theoretical interpretation, becomes a contribution of an ethnography of the country, as my personal experience reveals itself in the experience of my family, and of all workers.
Segurança hídrica e conflitos pela água no município de Cristalina-GO
(Universidade Federal de Goiás, 2023-12-20) Barros, Natália dos Santos; Silva, Elaine Barbosa da; Anjos, Antônio Fernandes dos
The objective was to demonstrate how irrigation and hydroelectric power generation have generated conflicts over water in Cristalina, which started to rely on center pivot irrigation from the mid-1980s, taking the water situation to a critical level, which was increased by the installation of the Batalha Hydroelectric Power Plant. Based on geographic and statistical information from the MapBiomas project, the National Water Agency and state agencies, the socio-environmental conditions and impacts caused by the use of water in Cristalina were analyzed. It was found that in 2020 9.47% of the municipal territory was occupied by center pivots. The presence of the hydroelectric plant increased pressure on the environment and conflicts with rural producers. Despite theeconomic dynamism, the municipality has low social development. Capitalist interests have made it difficult to observe reasonable environmental limits for water use.
A participação de artistas evangélicos nas eleições presidenciais de 2022: um olhar sobre o apoio à Bolsonaro a partir das redes sociais virtuais
(Universidade Federal de Goiás, 2023-12-20) Lima, Leandro Oliveira de
The article evaluates the participation of evangelical artists in in the 2022 presidential electionsbased on their posts on Instagram. Specifically, the text deals with a video published on October 28, 2022, shared by fourteen artists. The results identified engagement in a universe of 45 million followers, and the work, national anthem, the main symbol of national identity and captured by Christian nationalism, was viewed more than 37 million times. The survey aimed to contribute to the discussion of the effects of social networks on democracy and the political behavior of the evangelical segment and the algorithm in the electoral process, with emphasis on rigging communication in a niche segment, in the selection of selected gospel artists in Brazil in 2022.
A cartografia escolar no ensino de geografia: uma análise da produção científica em periódicos online entre os anos 2000 a 2020
(Universidade Federal de Goiás, 2023-08-31) Richter, Denis; Matos, Carlos Henrique Camilo
La Cartografía Escolar se constituyó como un campo de pesquisa en la enseñanza de Geografía en Brasil a partir de 1978. A lo largo del tiempo, varios abordajes y problemas de investigación han consolidado los estudios sobre el lenguaje cartográficoen el entorno escolar. Así, el presente artículo busca analizar la producción científica de la Cartografía Escolar en las revistas online brasileñas entre los años 2000 y 2020, con el objetivo de comprender las contribuciones y avances de esta línea de investigación para la enseñanza de la Geografía. Para ello, este estudio del tipo estado de conocimiento organizó una base de datos con 214 artículos publicados en este período, la cual se analizó bajo diferentes categorías. Como resultado, se pudo observar una consolidación en las publicaciones sobre Cartografía Escolar a partir del año 2011 y el fortalecimiento de las reflexiones teórico-metodológicas de esta temática articulada con el pensamiento espacial, así como el crecimiento de los estudios sobre Cartografía Social, Digital e Inclusiva. Además, este estudio busca contribuir al desarrollo de futuras investigaciones que podrán estructurarse con base en los resultados y análisis promovidos por este trabajo, potenciando las perspectivas para el campo de laCartografía Escolar.
Perda de solos no bioma cerrado: estudo comparativo entre áreas protegidas e não protegidas por unidades de conservação
(Universidade Federal de Goiás, 2023-08-31) Rosa, Lucas Espíndola; Cherem, Luís Felipe Soares; Siame, Lionel
The Biome of Brazilian savannah, Cerrado, an important ecological-economic region With a large production of commodities, has in its northern portion the recent agricultural frontier outside the Amazon. Problems derived from environmental degradation, such as erosive processes and the loss of soil productivity have shown their relevance. In this context, this paper analyses the space-time variabilities in soil losses rates calculated for watersheds draining the Emas National Park (PNE), and National Park of Brasília (PNB), and their surroundings by applying the Revised Universal Soil Loss Equation (RUSLE) for the years 1970, 1985 and 2018. Results indicate that the higher average rates were calculated for the surroundings of PNB, 10 ton.h''.a”, hanging from 3.8to 20.8. Oppositely, for the PNE soil loss rates were 10 times lower from those of PNB, where no significant differences were observed, with average rate of 0.3 ton.h”.a' (hanging from 0.1 to 0.5). Oppositely, the controlling factors of soil loss differed among the two sites, as for the PNB land-use changes controlled the time-space variabilities, and for the PNE only the morphologic differences played this role. The rates calculated for the PNE and surroundings differ from the general trend observed for other Savannahsin the world.
As transformações do Programa de Aquisição de Alimentos (PAA) no estado de Goiás (2010 -2020): limites e possibilidades para a construção da soberania alimentar
(Universidade Federal de Goiás, 2023-08-20) Horacio Galvan, Gabriel; Oliveira, Adriano Rodrigues de
The article presents a historical balance of the Food Acquisition Program, which was structured as one of the main public policies for the construction of Food Security and Sovereignty in Brazil. We took the state of Goiás, Brazil, as a territorial cut, from 2010 to 2020. We analyzed the transformations that occurred in the Program, as well as the bottlenecks (project versus reality) for the insertion and permanence of the peasants. We observed that even with the limited scope from the spatial and social point of view, the Food Acquisition Program if strengthened, has great potential to contribute to Food Sovereignty. It generates income in the countryside and offers healthy and diversified foods in the city. The results also show the need to ensure budget allocation, given the changes in the State's political guidelines, as well as the restructuring of health requirements aimed at incorporating the diversified production of peasant agriculture.
O imposto territorial rural e os desafios políticos para sua estruturação no Brasil
(Universidade Federal de Goiás, 2023-12-20) Aragão, Ana Luísa Santana; Oliveira, Adriano Rodrigues de
Desde los primeros intentos de su institución, el Impuesto al Territorio Rural (ITR) ha tropezado con problemas de carácter político, que a lo largo de los años han permitido la perpetuación de los privilegios fiscales, manteniendo la forma capitalista del Estado que poco avanza hacia el cumplimiento de las directrices establecidas en la Carta Magna de 1988. En el transcurso histórico del ITR, así como en la aplicación de la ley y de las resoluciones correspondientes, siempre ha quedado expuesta la raíz patrimonialista brasileña, sobre todo en los intereses de la bancada rural, lo que ha contribuido a limitar sustancialmente el impuesto. La justicia fiscal es una condición sine qua non para el mantenimiento del sistema de protección social, pero esto exige una reforma fiscal que sea rechazada por las fracciones de clase hegemónicas, beneficiadas por un sistema fiscal que mantiene sus privilegios mientras retroalimenta la dependencia brasileña en la economía mundial. A partir de la espacialización de los datos de la recaudación tributaria y del análisis de otros estudios que han propuesto un mejor uso del ITR, hemos identificado que algunos obstáculos, que podrían ser resueltos técnicamente, siguen sin serlo debido a la captura política ejercida por una fracción de clase hegemónica, con miras a mantener la acumulación ampliada de su capital.
Docência e o ensino de geografia nos anos iniciais
(Universidade Federal de Goiás, 2023-03-27) Rosa, Claudia do Carmo; Campos, Laís Rodrigues
This text presents reflections that emerge from Geography teaching and education at the first years of Elementary School. For that matter, the focus is given about teachers’ formation on teaching Geography in this stage of education and the possibilities of their professional practice, highlighting the role of this curricular subject at school and its meaning on children’s lives. Also on that perspective, the possibilities of educative practices that teachers can carry out, within different languages, so that the learning process at Geography is more meaningful to the students. We take as theoretical references authors who have dedicated their researches to this delimited thematic, with emphasis being placed on Callai (2010), Silva and Leão (2021), Rudolf and Rosinski (2021), Theves (2020), among others. The presented reflections work as a guiding principle to highlight that the initial formation given to Pedagogy teachers needs to be coherent with a conceptual and theoretical assumption which propose Geography thinking on facts and social phenomena from its study object and analysis categories. Besides, the Geography teaching and education at the first years of Elementary School may enhance children’s understanding about the world, amplifying the reading they make about it, as well as help them comprehend the relations among humankind and nature. In this regard, by considering that, at this specific moment, the first spatial abilities are built, so the usage of different languages, fulfilled with cultural artefacts, need to be articulated with childhood spatial experiences.
Spectroscopic validation of low-metallicity stars from rave
(2018) Placco, Vinicius Moris; Beers, Timothy C.; Santucci, Rafael Miloni; Chanamé, Julio; Paz Sepúlveda, María; Coronado, Johanna; Points, Sean D.; Kaleida, Catherine C.; Rossi, Silvia Cristina Fernandes; Kordopatis, Georges
We present results from a medium-resolution (R ∼ 2000) spectroscopic follow-up campaign of 1694 bright (V < 13.5), very metal-poor star candidates from the RAdial Velocity Experiment (RAVE). Initial selection of the low-metallicity targets was based on the stellar parameters published in RAVE Data Releases 4 and 5. Follow up was accomplished with the Gemini-N and Gemini-S, the ESO/NTT, the KPNO/Mayall, and the SOAR telescopes. The wavelength coverage for most of the observed spectra allows for the determination of carbon and α-element abundances, which are crucial for considering the nature and frequency of the carbon-enhanced metal poor (CEMP) stars in this sample. We find that 88% of the observed stars have Fe H [ ] −1.0, 61% have Fe H [ ] −2.0, and 3% have Fe H [ ] −3.0 (with four stars at Fe H [ ] −3.5). There are 306 CEMP star candidates in this sample, and we identify 169 CEMP Group I, 131 CEMP Group II, and 6 CEMP Group III stars from the A(C) versus [Fe/H] diagram. Inspection of the a C [ ] abundance ratios reveals that five of the CEMP Group II stars can be classified as “mono-enriched second-generation” stars. Gaia DR1 matches were found for 734 stars, and we show that transverse velocities can be used as a confirmatory selection criteria for low-metallicity candidates. Selected stars from our validated list are being followed-up with high-resolution spectroscopy to reveal their full chemical-abundance patterns for further studies.
Constraints on the galactic inner halo assembly history from the age gradient of blue horizontal-branch stars
(2019) Whitten, Devin D.; Beers, Timothy C.; Placco, Vinicius Moris; Santucci, Rafael Miloni; Denissenkov, Pavel; Tissera, Patricia Beatriz; Mejías, Andrea; Hernitschek, Nina; Carollo, Daniela
We present an analysis of the relative age distribution of the Milky Way halo, based on samples of blue horizontal branch (BHB) stars obtained from the Panoramic Survey Telescope and Rapid Response System and Galaxy Evolution Explorer photometry, as well a Sloan Digital Sky Survey spectroscopic sample. A machine-learning approach to the selection of BHB stars is developed, using support vector classification, with which we produce chronographic age maps of the Milky Way halo out to 40 kpc from the Galactic center. We identify a characteristic break in the relative age profiles of our BHB samples, corresponding to a Galactocentric radius of RGC ∼ 14 kpc. Within the break radius, we find an age gradient of −63.4 ± 8.2 Myr kpc−1 , which is significantly steeper than obtained by previous studies that did not discern between the inner- and outer-halo regions. The gradient in the relative age profile and the break radius signatures persist after correcting for the influence of metallicity on our spectroscopic calibration sample. We conclude that neither are due to the previously recognized metallicity gradient in the halo, as one passes from the inner-halo to the outer-halo region. Our results are consistent with a dissipational formation of the inner-halo population, involving a few relatively massive progenitor satellites, such as those proposed to account for the assembly of Gaia-Enceladus, which then merged with the inner halo of the Milky Way.
Abundance patterns of α and neutron-capture elements in the helmi stream
(2021) Limberg, Guilherme; Santucci, Rafael Miloni; Rossi, Silvia Cristina Fernandes; Queiroz, Anna Bárbara de Andrade; Leite, Cristina Chiappini Moraes; Souza, Stefano Oliveira de; Perottoni, Hélio Dotto; Perez Villegas, Maria de los Angeles; Barbosa, Fabrícia Oliveira
We identified eight additional stars as members of the Helmi stream (HStr) in the combined GALAH+ DR3 and Gaia EDR3 catalog. By consistently reevaluating claimed members from the literature, we consolidate a sample of 22 HStr stars with parameters determined from high-resolution spectroscopy and spanning a considerably wider (by ∼0.5 dex) metallicity interval (− 2.5  [Fe/H] < − 1.0) than previously reported. Our study focuses on α (Mg and Ca) and neutron-capture (Ba and Eu) elements. We find that the chemistry of HStr is typical of dwarf spheroidal (dSph) galaxies, in good agreement with previous N-body simulations of this merging event. Stars of HStr constitute a clear declining sequence in [α/Fe] for increasing metallicity up to [Fe/H] ∼ −1.0. Moreover, stars of HStr show a median value of +0.5 dex for [Eu/Fe] with a small dispersion (±0.1 dex). Every star analyzed with [Fe/H] < −1.2 belongs to the r-process enhanced ([Eu/Fe] > +0.3 and [Ba/Eu] < 0.0) metal-poor category, providing remarkable evidence that, at such a low-metallicity regime, stars of HStr experienced enrichment in neutron-capture elements predominantly via r-process nucleosynthesis. Finally, the extended metallicity range also suggests an increase in [Ba/Eu] for higher [Fe/H], in conformity with other surviving dwarf satellite galaxies of the Milky Way. Unified Astronomy
Targeting bright metal-poor stars in the disk and halo systems of the galaxy
(2021) Limberg, Guilherme; Santucci, Rafael Miloni; Rossi, Silvia Cristina Fernandes; Shank, Derek; Placco, Vinicius Moris; Beers, Timothy C.; Schlaufman, Kevin C.; Casey, Andrew R.; Perottoni, Hélio Dotto; Young, Sun Lee
We present the results of spectroscopic follow-up for 1897 low-metallicity star candidates, selected from the Best & Brightest (B&B) Survey, carried out with the GMOS-N/S (Gemini North/South telescopes) and Goodman (SOAR Telescope) spectrographs. From these low-resolution (R ∼ 2000) spectra, we estimate stellar atmospheric parameters, as well as carbon and magnesium abundance ratios. We confirm that 56% of our program stars are metal-poor ([Fe/H] < − 1.0), 30% are very metal-poor (VMP; [Fe/H] < − 2.0), and 2% are extremely metal-poor (EMP; [Fe/H] < − 3.0). There are 191 carbon-enhanced metal-poor (CEMP) stars, resulting in CEMP fractions of 19% and 43% for the VMP and EMP regimes, respectively. A total of 94 confirmed CEMP stars belong to Group I (A(C)  7.25) and 97 to Group II (A(C)  7.25) in the Yoon–Beers A(C)−[Fe/H] diagram. Moreover, we combine these data with Gaia EDR3 astrometric information to delineate new target-selection criteria, which have been applied to the Goodman/SOAR candidates, to more than double the efficiency for identification of bona fide VMP and EMP stars in comparison to random draws from the B&B catalog. We demonstrate that this target-selection approach can achieve success rates of 96%, 76%, 28%, and 4% for [Fe/H] − 1.5, − 2.0, − 2.5 and − 3.0, respectively. Finally, we investigate the presence of dynamically interesting stars in our sample. We find that several VMP/EMP ([Fe/H] − 2.5) stars can be associated with either the disk system or halo substructures like Gaia-Sausage/Enceladus and Sequoia.
Dynamically tagged groups of very metal-poor halo stars from the HK and Hamburg/ESO Surveys
(2021) Limberg, Guilherme; Rossi, Silvia Cristina Fernandes; Beers, Timothy C.; Perottoni, Hélio Dotto; Perez Villegas, Maria de los Angeles; Santucci, Rafael Miloni; Oliveira, Yuri Abuchaim de; Placco, Vinicius Moris; Young, Sun Lee; Christlieb, Norbert; Norris, John E.; Bessell, Michael S.; Ryan, Sean Gerard; Wilhelm, Ronald; Rhee, Jaehyon; Frebel, Anna
We analyze the dynamical properties of ∼1500 very metal-poor (VMP; [Fe/H]  −2.0) halo stars, based primarily on medium-resolution spectroscopic data from the HK and Hamburg/ESO surveys. These data, collected over the past 30 yr, are supplemented by a number of calibration stars and other small samples, along with astrometric information from Gaia DR2. We apply a clustering algorithm to the 4D energy-action space of the sample, and identify a set of 38 dynamically tagged groups (DTGs), containing between 5 and 30 member stars. Many of these DTGs can be associated with previously known prominent substructures such as Gaia-Sausage/Enceladus (GSE), Sequoia, Helmi Stream (HStr), and Thamnos. Others are associated with previously identified smaller dynamical groups of stars and streams. We identify 10 new DTGs as well, many of which have strongly retrograde orbits. We also investigate possible connections between our DTGs and ∼300 individual r-process-enhanced (RPE) stars from a recent literature compilation. We find that several of these objects have similar dynamical properties to GSE (5), the HStr (4), Sequoia (1), and Rg5 (1), indicating that their progenitors might have been important sources of RPE stars in the Galaxy. Additionally, a number of our newly identified DTGs are shown to be associated with at least two RPE stars each (DTG-2: 3, DTG-7: 2; DTG-27: 2). Taken as a whole, these results are consistent with ultra-faint and/or dwarf spheroidal galaxies as birth environments in which r-process nucleosynthesis took place, and then were disrupted by the Milky Way.
The SDSS-Gaia view of the color-magnitude relation for blue horizontal-branch stars
(2022) Barbosa, Fabricia Oliveira; Santucci, Rafael Miloni; Rossi, Silvia Cristina Fernandes; Limberg, Guilherme; Perez Villegas, Maria de los Angeles; Perottoni, Hélio Dotto
We present an updated sample of blue horizontal-branch (BHB) stars selected from the photometric and spectroscopic data from Sloan Digital Sky Survey and its associated project Sloan Extension for Galactic Understanding and Exploration (SEGUE). With these data, we selected candidates for A-type stars in the color– color space and then a mixture modeling technique was implemented in order to distinguish between BHB and main-sequence/blue-straggler stars based on their surface gravity values (log g) estimated by the SEGUE Stellar Parameter Pipeline. Our robust approach allows us to attribute individual probabilities of each star truly being in the BHB stage. Hence, our method is advantageous in comparison to previous SEGUE BHB selections that adopted simple log g cuts. We also revisit the color–magnitude relation for these stars and propose two calibrations, based on updated distances for Galactic globular clusters, to estimate absolute magnitudes with (g − r)0 and (u − r)0 colors.
The unmixed debris of gaia-sausage/enceladus in the form of a pair of halo stellar overdensities
(2022) Perottoni, Hélio Dotto; Limberg, Guilherme; Amarante, João Antônio Silveira do; Rossi, Silvia Cristina Fernandes; Queiroz, Anna Bárbara de Andrade; Santucci, Rafael Miloni; Perez Villegas, Maria de los Angele; Leite, Cristina Chiappini Moraes
In the first billion years after its formation, the Galaxy underwent several mergers with dwarf satellites of various masses. The debris of Gaia-Sausage/Enceladus (GSE), the galaxy responsible for the last significant merger of the Milky Way, dominates the inner halo and has been suggested to be the progenitor of both the Hercules-Aquila Cloud (HAC) and Virgo Overdensity (VOD). We combine SEGUE, APOGEE, Gaia, and StarHorse distances to characterize the chemodynamical properties and verify the link between HAC, VOD, and GSE. We find that the orbital eccentricity distributions of the stellar overdensities and GSE are comparable. We also find that they have similar, strongly peaked, metallicity distribution functions, reinforcing the hypothesis of common origin. Furthermore, we show that HAC and VOD are indistinguishable from the prototypical GSE population within all chemical-abundance spaces analyzed. All these evidences combined provide a clear demonstration that the GSE merger is the main progenitor of the stellar populations found within these halo overdensities.
Reconstructing the disrupted dwarf galaxy gaia-sausage/enceladus using its stars and globular clusters
(2022) Limberg, Guilherme; Souza, Stefano Oliveira de; Perez Villegas, Maria de los Angeles; Rossi, Silvia Cristina Fernandes; Perottoni, Hélio Dotto; Santucci, Rafael Miloni
We combine spectroscopic, photometric, and astrometric information from APOGEE data release 17 and Gaia early data release 3 to perform a self-consistent characterization of Gaia-Sausage/Enceladus (GSE), the remnant of the last major merger experienced by the Milky Way, considering stars and globular clusters (GCs) altogether. Our novel set of chemodynamical criteria to select genuine stars of GSE yields a metallicity distribution function with a median [Fe/H] of −1.22 and 0.23 dex dispersion. Stars from GSE present an excess of [Al/Fe] and [Mg/Mn] (also [Mg/Fe]) in comparison to surviving Milky Way dwarf satellites, which can be explained by differences in star formation efficiencies and timescales between these systems. However, stars from Sequoia, another proposed accreted halo substructure, essentially overlap the GSE footprint in all analyzed chemical-abundance spaces, but present lower metallicities. Among the probable GCs of GSE with APOGEE observations available, we find no evidence for atypical [Fe/H] spreads with the exception of ω Centauri (ωCen). Under the assumption that ωCen is a stripped nuclear star cluster, we estimate the stellar mass of its progenitor to be Må ≈ 1.3 × 109Me, well within literature expectations for GSE. This leads us to envision GSE as the best available candidate for the original host galaxy of ωCen. We also take advantage of Gaiaʼs photometry and APOGEE metallicities as priors to determine fundamental parameters for eight high-probability (>70%) GC members of GSE via statistical isochrone fitting. Finally, the newly determined ages and APOGEE [Fe/H] values are utilized to model the age–metallicity relation of GSE.
Dynamically tagged groups of metal-poor stars from the best and brightest survey
(2022) Shank, Derek; Beers, Timothy C.; Placco, Vinicius Moris; Limberg, Guilherme; Jaques, Emma; Zhen, Yuan; Schlaufman, Kevin C.; Casey, Andrew R.; Yang, Huang; Young, Sun Lee; Hattori, Kohei; Santucci, Rafael Miloni
Orbital characteristics based on Gaia Early Data Release 3 astrometric parameters are analyzed for ∼4000 metal poor stars ([Fe/H] −0.8) compiled from the Best and Brightest survey. Selected as metal-poor candidates based on broadband near- and far-IR photometry, 43% of these stars had medium-resolution (1200  R  2000) validation spectra obtained over a 7 yr campaign from 2014 to 2020 with a variety of telescopes. The remaining stars were chosen based on photometric metallicity determinations from the Huang et al. recalibration of the Sky Mapper Southern Survey. Dynamical clusters of these stars are obtained from the orbital energy and cylindrical actions using the HDBSCAN unsupervised learning algorithm. We identify 52 dynamically tagged groups (DTGs) with between five and 21 members; 18 DTGs have at least 10 member stars. Milky Way (MW) substructures such as Gaia-Sausage-Enceladus, the Metal-Weak Thick-Disk, Thamnos, the Splashed Disk, and the Helmi Stream are identified. Associations with MW globular clusters are determined for eight DTGs; no recognized MW dwarf galaxies were associated with any of our DTGs. Previously identified dynamical groups are also associated with our DTGs, with emphasis placed on their structural determination and possible new identifications. Chemically peculiar stars are identified as members of several DTGs, with six DTGs that are associated with r-process enhanced stars. We demonstrate that the mean carbon and α-element abundances of our DTGs are correlated with their mean metallicity in an understandable manner. Similarly, we find that the mean metallicity, carbon, and α-element abundances are separable into different regions of the mean rotational-velocity space.
Reinventando o método de Aristarco
(2021) Freitas, Lucas V.; Santucci, Rafael Miloni; Marques, Ivo de Almeida
The greek mathematician and astronomer Aristarchus of Samos, 3rd century BC, was the first person to systematize a method to estimating relative distances and sizes between Earth, Sun and Moon. He was also the first to propose that the Earth revolves around the Sun. In the present work, we carried out a review, in modern language, of the method proposed by Aristarchus to estimate the distance from the Sun to the Earth, S, in relation to the distance from the Moon to the Earth, L. After that we present the model proposed by us to do the experimental determination of the ratio S/L and the angular diameter of the Sun and Moon, as well as the experimental setup used. We performed two experiments, one with the Crescent Moon and one with the Waning Moon. We emphasize that our main objective is to deal with calculating astronomical distances with the use of geometric models. We expect that teachers of mathematics, physics and astronomy will use this material in their classes and presentations, discussing with students the technical and historical difficulties and the physical and geometric aspects involved. And, if possible, that they reproduce the measures.
The r-process Alliance: spectroscopic follow-up of low-metallicity star candidates from the best & brightest survey
(2019) Placco, Vinicius Moris; Santucci, Rafael Miloni; Beers, Timothy C.; Chanamé, Julio; Paz Sepúlveda, María; Coronado, Johanna; Rossi, Silvia Cristina Fernandes; Young, Sun Lee; Starkenburg, Else; Youakim, Kris
We present results from an observing campaign to identify low-metallicity stars in the Best & Brightest Survey. From medium-resolution (R ∼ 1200–2000) spectroscopy of 857 candidates, we estimate the stellar atmospheric parameters (Teff, log g, and Fe H [ ]), as well as carbon and α-element abundances. We find that 69% of the observed stars have Fe H [ ] −1.0, 39% have Fe H [ ] −2.0, and 2% have Fe H [ ] −3.0. There are also 133 carbon-enhanced metal-poor (CEMP) stars in this sample, with 97 CEMP Group I and 36 CEMP Group II stars identified in the A(C) versus [Fe/H] diagram. A subset of the confirmed low-metallicity stars were followed-up with high-resolution spectroscopy, as part of the R-process Alliance, with the goal of identifying new highly and moderately r-process-enhanced stars. Comparison between the stellar atmospheric parameters estimated in this work and from high-resolution spectroscopy exhibit good agreement, confirming our expectation that medium-resolution observing campaigns are an effective way of selecting interesting stars for further, more targeted, efforts.
Desmids (Zygnematophyceae) from the littoral zone of an urban artificial lake: taxonomic aspects and geographical distribution
(2018) Aquino, Camila Akemy Nabeshima; Medeiros, Gabriela; Bortolini, Jascieli Carla; Favaretto, Cinthia Coutinho Rosa; Ticiani, Douglas; Cerqueira, Fiorindo José; Bueno, Norma Catarina
Aim: The aim of this study was to assess the taxonomic aspects and geographical distribution of the periphytic desmids from two different substrates in the littoral zone of an urban artificial lake. Methods: Samples of epiphytic and epilithic desmids were collected by grass and rock scraping, respectively, in two stations in the Cascavel municipal lake, Paraná, during April 2015, and March 2016 and 2017. In the laboratory, the taxa obtained from the samples were photographed and their morphometric characteristics recorded. The species composition of the desmid was characterized, and the frequency of occurrence as well as the geographic distribution of each taxon in the Paraná State were recorded. Results: We identified 35 taxa, distributed in 10 genera. The most representative were Closterium Nitzsch ex Ralfs and Cosmarium Corda ex Ralfs. A high occurrence of sporadic taxa (60%) was observed and among the recorded taxa, the most frequent were Cosmarium pseudoconnatum Nordstedt var. pseudoconnatum and Desmidium grevillei (Kützing ex Ralfs) De Bary. Nine taxa were exclusive to the epilithic substrate and only Netrium digitus (Ralfs) Itzigsohn & Rothe var. digitus was exclusive to the epiphytic substrate, while the remaining 25 taxa occurred in both substrates. Seven taxa are new records for the Paraná State. Conclusion: Although our results are of qualitative nature, they provide baseline data on the biogeographic distribution of taxa, which are crucial for future taxonomic and ecological studies that might contribute to the preservation of the biodiversity.

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