Este trabalho tem como objetivo o ensino dos fundamentos da Astrofísica Estelar moderna a alunos do Ensino Médio através de uma abordagem empírica que usa como ferramentas principais da metodologia a observação, o registro, a análise e a interpretação das mudanças de brilho das estrelas variáveis ao longo do tempo. Mediante técnicas simples (fotometria visual) para a estimativa dos valores dos brilhos aparentes (magnitudes) dessas estrelas no decorrer de vários meses, o aluno coleta seus próprios dados observacionais. Em seguida, esses dados serão colocados em gráficos (curvas de luz), cuja análise permitirá a medida de seus períodos e amplitudes de variação, bem como a determinação de uma série de parâmetros que caracterizam as propriedades físicas das estrelas. O estudo é conduzido de uma forma que permite apresentar aos alunos vários dos grandes temas da Astrofísica contemporânea sem que eles percam o vínculo sensorial com a observação direta dos fenômenos celestes, seja com auxílio de instrumental modesto (binóculos ou pequenos telescópios), seja até mesmo a olho nu. O produto final de nosso trabalho é um Guia de Estudos intitulado Astrofísica Estelar para o Ensino Médio, em doze capítulos e mais de trezentas páginas, que está incluído em sua íntegra nesta monografia. O Guia foi desenvolvido tendo como alvos principais os alunos e professores do Ensino Médio formal. Não obstante, ele pode ser também utilizado por qualquer pessoa que tenha interesse no assunto e que possua os conceitos necessários de Matemática e Física do Ensino Médio; ou ainda em cursos do ensino não-formal que sejam ministrados, por exemplo, por planetários, museus de ciência e astrônomos amadores (situação essa testada com ótimos resultados pelo autor). Por fim, vale mencionar que, neste tipo de aprendizado (conhecido como research-based education, que poderíamos traduzir livremente como aprendizado vinculado à pesquisa), utilizamos intensivamente diversos recursos tecnológicos disponibilizados gratuitamente na internet pelas grandes entidades internacionais que se dedicam à pesquisa e ao estudo das estrelas variáveis tais como softwares específicos, bancos de dados, simulações e cartas para a estimativa das magnitudes. O uso dessa metodologia vinculada à pesquisa, em nossa experiência, se constitui em um fator valioso para desenvolver nos alunos a criatividade, o raciocínio crítico, a familiarização com o método científico e as habilidades para a pesquisa. / This work aims at teaching the fundamental aspects of Stellar Astrophysics to high school students through an empirical approach which uses variable stars observations, data collection, and the analysis and interpretation of brightness changes as key methodological tools. By using some simple techniques (visual photometry) to estimate the values of apparent brightness (magnitudes) of these stars over several months, the student collects his/her own observational data. Subsequently, that data will be plotted in graphs (light curves), whose analysis will in turn allow the determination of its periods and amplitudes of variation, as well as of a series of physical parameters that characterize the physical properties of the stars. The whole study is conducted in a way that shows students several of the major themes of contemporary Astrophysics without losing their sensory link with the direct observation of celestial phenomena - whether with the aid of modest instruments (binoculars or small telescopes) or even naked eye. The final product of our work is a Study Guide called \"Stellar Astrophysics for High School\" in twelve chapters and more than three hundred pages, which is included in their entirety in this monograph. The Guide was developed with the main targets being students and teachers of the formal high school level. Nevertheless, it can also be used by anyone who has an interest in the subject and who possesses the required concepts of high school Mathematics and Physics; or even in non-formal teaching courses that are taught, for example, by planetariums, science museums and amateur astronomers (a situation that has been tested with great results by the author). Last but not least, it is worth mentioning that in this type of learning (known as \"research-based education\") we intensively use various technological resources freely available on the internet from the great international entities that are dedicated to the research and study of variable stars such as specific softwares, databases, simulations and charts for estimating magnitudes. The use of research-based education, in our experience, is a valuable tool to foster and develop students creativity, critical thinking, and the familiarization with the scientific method and research skills.

Este trabalho tem como objetivo o ensino dos fundamentos da Astrofísica Estelar moderna a alunos do Ensino Médio através de uma abordagem empírica que usa como ferramentas principais da metodologia a observação, o registro, a análise e a interpretação das mudanças de brilho das estrelas variáveis ao longo do tempo. Mediante técnicas simples (fotometria visual) para a estimativa dos valores dos brilhos aparentes (magnitudes) dessas estrelas no decorrer de vários meses, o aluno coleta seus próprios dados observacionais. Em seguida, esses dados serão colocados em gráficos (curvas de luz), cuja análise permitirá a medida de seus períodos e amplitudes de variação, bem como a determinação de uma série de parâmetros que caracterizam as propriedades físicas das estrelas. O estudo é conduzido de uma forma que permite apresentar aos alunos vários dos grandes temas da Astrofísica contemporânea sem que eles percam o vínculo sensorial com a observação direta dos fenômenos celestes, seja com auxílio de instrumental modesto (binóculos ou pequenos telescópios), seja até mesmo a olho nu. O produto final de nosso trabalho é um Guia de Estudos intitulado Astrofísica Estelar para o Ensino Médio, em doze capítulos e mais de trezentas páginas, que está incluído em sua íntegra nesta monografia. O Guia foi desenvolvido tendo como alvos principais os alunos e professores do Ensino Médio formal. Não obstante, ele pode ser também utilizado por qualquer pessoa que tenha interesse no assunto e que possua os conceitos necessários de Matemática e Física do Ensino Médio; ou ainda em cursos do ensino não-formal que sejam ministrados, por exemplo, por planetários, museus de ciência e astrônomos amadores (situação essa testada com ótimos resultados pelo autor). Por fim, vale mencionar que, neste tipo de aprendizado (conhecido como research-based education, que poderíamos traduzir livremente como aprendizado vinculado à pesquisa), utilizamos intensivamente diversos recursos tecnológicos disponibilizados gratuitamente na internet pelas grandes entidades internacionais que se dedicam à pesquisa e ao estudo das estrelas variáveis tais como softwares específicos, bancos de dados, simulações e cartas para a estimativa das magnitudes. O uso dessa metodologia vinculada à pesquisa, em nossa experiência, se constitui em um fator valioso para desenvolver nos alunos a criatividade, o raciocínio crítico, a familiarização com o método científico e as habilidades para a pesquisa. / This work aims at teaching the fundamental aspects of Stellar Astrophysics to high school students through an empirical approach which uses variable stars observations, data collection, and the analysis and interpretation of brightness changes as key methodological tools. By using some simple techniques (visual photometry) to estimate the values of apparent brightness (magnitudes) of these stars over several months, the student collects his/her own observational data. Subsequently, that data will be plotted in graphs (light curves), whose analysis will in turn allow the determination of its periods and amplitudes of variation, as well as of a series of physical parameters that characterize the physical properties of the stars. The whole study is conducted in a way that shows students several of the major themes of contemporary Astrophysics without losing their sensory link with the direct observation of celestial phenomena - whether with the aid of modest instruments (binoculars or small telescopes) or even naked eye. The final product of our work is a Study Guide called \"Stellar Astrophysics for High School\" in twelve chapters and more than three hundred pages, which is included in their entirety in this monograph. The Guide was developed with the main targets being students and teachers of the formal high school level. Nevertheless, it can also be used by anyone who has an interest in the subject and who possesses the required concepts of high school Mathematics and Physics; or even in non-formal teaching courses that are taught, for example, by planetariums, science museums and amateur astronomers (a situation that has been tested with great results by the author). Last but not least, it is worth mentioning that in this type of learning (known as \"research-based education\") we intensively use various technological resources freely available on the internet from the great international entities that are dedicated to the research and study of variable stars such as specific softwares, databases, simulations and charts for estimating magnitudes. The use of research-based education, in our experience, is a valuable tool to foster and develop students creativity, critical thinking, and the familiarization with the scientific method and research skills.

Cette thèse s'inscrit dans le cadre de la mission spatiale Rosetta et porte sur les propriétés spectrophotométriques de la comète 67P/Churyumov-Gerasimenko à l’aide de l’instrument OSIRIS. Cet instrument est composé de deux caméras pour les observations du noyau et de la coma de la comète. Elles permettent d’acquérir des images avec des filtres qui opèrent dans la gamme du proche UV au proche IR. Dans un premier temps, j'ai analysé les courbes spectrophotométriques des taches claires qui sont apparues sur le noyau de la comète. Une étude comparative de celles-ci grâce aux données du spectro-imageur VIRTIS a ainsi permis de constater que les taches claires sont liées à la glace de H2O. Dans un second temps, j’ai entrepris une étude spectrophotométrique de la région Khonsu, qui a mis en évidence les variations saisonnières de la pente spectrale de différents terrains. Par la suite, j’ai élargi mon analyse des taches à tout le noyau de la comète. J’ai détecté plus de 50 taches claires dues à la présence de glace de H2O et j’ai produit une carte pour repérer leurs emplacements sur le noyau, afin d’étudier plus en détail leur répartition et leur évolution au cours de temps. Ceci m’a permis d’identifier quatre types de taches regroupés en fonction de leur morphologie et de constater qu'elles sont dues à différentes sources d'activité cométaire. / This thesis is based on the spectrophotometric properties of the comet 67P/Churyumov-Gerasimenko, using the OSIRIS instrument of Rosetta space mission. Composed of two scientific cameras to observe the nucleus and the coma of the comet, OSIRIS images are acquired with multiple filters, that span the near-UV to near-IR wavelength range. They were used to study the spectrophotometric curves of the exposed bright features that appeared on the surface of the cometary nucleus, leading to a comparative study, that was carried out in collaboration with the VIRTIS spectro-imager aboard Rosetta, that demonstrated, that these exposures are related to H2O ice, using its absorption band located at 2 microns. The thesis further details a spectrophotometric study of the Khonsu region in the southern latitudes of the comet, where the seasonal variation of the spectral slope of different types of terrains is explored. Finally, the results of an extended survey of exposed bright features are presented. More than 50 individual features are presented under four morphologies along with an albedo calculation, suggesting that different activity sources are responsible for their appearance on the nucleus.

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The theory of stellar evolution and stellar structure relies on the observation of stars in di erent phases of their evolutionary cycle. The relation between observations and theory can be strengthened by obtaining observational data of a large sample of stars in a particular evolutionary phase. The search for Cephei stars, as conducted in this study, can contribute to the sample of known Cephei stars, where these interesting stars are massive non-supergiant early B-type stars, displaying pulsating behaviour which is not well understood. Stars tend to form in clusters where it can therefore be expected that young massive stars can be found in open clusters. For this reason two young southern open clusters were observed in order to search for B-type pulsating stars. The region of NGC 6204 and Hogg 22 was observed over a period of thirteen nights in Johnson B, V and I bands. NGC 6204 is believed to be the oldest cluster of the two at a distance of 0.8 kpc while the much younger Hogg 22 is more distant at 2.8 kpc. These two open clusters are located 6 arcminutes apart which made it possible to observe them simultaneously with a 12.8 12.8 arcminute eld of view. The observations were done with the newly installed 1600 telescope of the North-West University, South Africa. In order to do a variability search, periodic stars need to be identi ed from the cluster data, where a typical data set may contain thousands of scienti c images. In addition to the main motivation for this study, a pipeline was created in order to automate the photometry and data reduction processes. A Lomb-Scargle transform was applied to the stellar light curves in order to identify periodic sources. 354 signi cantly periodic stars were identi ed from the 3182 observed stars. Amongst them, two new possible Cephei stars were found together with a possible slowly pulsating B star (SPB), and numerous eclipsing binary systems. By using photometry of this region obtained by Forbes & Short (1996), instrumental magnitudes were transformed to a standard system in order to compare photometry results. From the constructed colour magnitude diagram of the two clusters, it could be seen that some stars, indicated by Forbes & Short (1996) to be cluster members, were in fact eld stars belonging to neither cluster. The reduction and photometry pipeline was implemented successfully on the data set, which also highlighted the importance of instrumentation and correct data analysis procedures. Possible improvements were identi ed in order to overcome di culties experienced during this study. / Thesis (MSc (Space Physics))--North-West University, Potchefstroom Campus, 2013

The theory of stellar evolution and stellar structure relies on the observation of stars in di erent phases of their evolutionary cycle. The relation between observations and theory can be strengthened by obtaining observational data of a large sample of stars in a particular evolutionary phase. The search for Cephei stars, as conducted in this study, can contribute to the sample of known Cephei stars, where these interesting stars are massive non-supergiant early B-type stars, displaying pulsating behaviour which is not well understood. Stars tend to form in clusters where it can therefore be expected that young massive stars can be found in open clusters. For this reason two young southern open clusters were observed in order to search for B-type pulsating stars. The region of NGC 6204 and Hogg 22 was observed over a period of thirteen nights in Johnson B, V and I bands. NGC 6204 is believed to be the oldest cluster of the two at a distance of 0.8 kpc while the much younger Hogg 22 is more distant at 2.8 kpc. These two open clusters are located 6 arcminutes apart which made it possible to observe them simultaneously with a 12.8 12.8 arcminute eld of view. The observations were done with the newly installed 1600 telescope of the North-West University, South Africa. In order to do a variability search, periodic stars need to be identi ed from the cluster data, where a typical data set may contain thousands of scienti c images. In addition to the main motivation for this study, a pipeline was created in order to automate the photometry and data reduction processes. A Lomb-Scargle transform was applied to the stellar light curves in order to identify periodic sources. 354 signi cantly periodic stars were identi ed from the 3182 observed stars. Amongst them, two new possible Cephei stars were found together with a possible slowly pulsating B star (SPB), and numerous eclipsing binary systems. By using photometry of this region obtained by Forbes & Short (1996), instrumental magnitudes were transformed to a standard system in order to compare photometry results. From the constructed colour magnitude diagram of the two clusters, it could be seen that some stars, indicated by Forbes & Short (1996) to be cluster members, were in fact eld stars belonging to neither cluster. The reduction and photometry pipeline was implemented successfully on the data set, which also highlighted the importance of instrumentation and correct data analysis procedures. Possible improvements were identi ed in order to overcome di culties experienced during this study. / Thesis (MSc (Space Physics))--North-West University, Potchefstroom Campus, 2013

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Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-06-03T12:39:45Z No. of bitstreams: 1 claudiorobertobarbosasimoesrodrigues.pdf: 5762936 bytes, checksum: 8a7ae73391a9d56af3c18605a924763d (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-07-02T13:21:41Z (GMT) No. of bitstreams: 1 claudiorobertobarbosasimoesrodrigues.pdf: 5762936 bytes, checksum: 8a7ae73391a9d56af3c18605a924763d (MD5) / Made available in DSpace on 2016-07-02T13:21:41Z (GMT). No. of bitstreams: 1 claudiorobertobarbosasimoesrodrigues.pdf: 5762936 bytes, checksum: 8a7ae73391a9d56af3c18605a924763d (MD5) Previous issue date: 2012-12-17 / No intuito de aportar contribuições ao uso de diodos emissores de luz (ou LEDs, do inglês Light Emmiting Diodes) em sistemas de iluminação pública, cobrindo lacunas existentes no cenário nacional, este trabalho traz uma ampla análise sobre este tema. São apresentados conceitos básicos da fotometria clássica e um estudo sobre adaptações da fotometria para baixos níveis de luminância, que é a condição observada nas vias públicas durante o período noturno. Propõe-se a utilização de métricas escotópicas em sistemas de iluminação pública, uma vez que estas melhor representam a real sensação visual (se comparadas às métricas clássicas – fotópicas) nas condições de iluminamento típicas observadas nestes sistemas. Aspectos gerais da iluminação pública e um histórico da evolução do sistema nacional são brevemente apresentados bem como uma discussão sobre a situação atual deste sistema e das tecnologias utilizadas. O trabalho traz também um estudo sobre características ópticas, elétricas e mecânicas dos LEDs e uma análise dos diferentes tipos de LEDs brancos mais utilizados (HB – High Brightness – e HP – High Power – LEDs). Algumas normas e recomendações aplicáveis à utilização de LEDs em iluminação pública são analisadas e discutidas, com o intuito de se investigar lacunas ainda não cobertas pela normatização existente. Análises de resultados de ensaios de laboratório e de campo, inéditos no país, realizados com alguns modelos de luminárias LED para iluminação pública disponíveis no mercado, são também apresentadas. Um estudo sobre acionamento de LEDs é realizado, abordando técnicas de equalização de corrente entre arranjos série de LEDs associados em paralelo e diferentes tipos de circuitos de acionamento para LEDs. São propostas, analisadas e implementadas uma estrutura inédita de baixo custo para a equalização de corrente e um circuito para o acionamento de LEDs baseado na integração de dois conversores cc cc não isolados. A topologia de dois estágios proposta é composta por um conversor boost no primeiro estágio, utilizado para a correção do fator de potência e por um conversor buck no segundo estágio, utilizado para o controle da corrente nos LEDs. Por fim, o acompanhamento da implantação e do desempenho, ao longo de dez meses, do projeto piloto de iluminação pública empregando LEDs instalado no anel viário da Faculdade de Engenharia da UFJF é apresentado. / In order to present contributions to the use of light emitting diodes (LEDs) in public lighting systems, covering gaps on the national scenario, this work encompasses abroad analysis related to this issue. Basic concepts of classical photometry are presented and so a study of photometry’s adaptations for low luminance levels. It is proposed the use of scotopic metrics for street lighting systems, since they can better represent the actual visual sensation (when compared to the classical one – photopic metrics) on its typical nighty conditions. General aspects of street lighting and the history of the national’s public lighting system are briefly presented as well as a discussion about the current situation of the Brazilian system and technologies adopted. The work also brings a study of mechanical, electrical and optical characteristics of LEDs and an analysis of the two different types of commonly used white LEDs (HB – High Brightness – and HP – High Power - LEDs). Some standards and recommendations related to the use of LEDs in street lighting are analyzed and criticized, with the aim of show some gaps not yet covered by the existent standards. An unprecedented analysis regarding laboratory and field test benchmarking, taken for some luminaires available in commerce, is also presented. A study of LED driving is presented, covering equalization techniques for parallel LEDs strings and different types of LED driving circuits. It was proposed, analyzed and implemented a novel and low cost structure for current equalization and an LED driver, based on the integration of two non-isolated dc dc converters. This proposed two stages topology is composed by a boost converter, on the first stage, employed to the power factor correction and a buck converter, on the second stage, to control the LED’s current. Finally, the process of monitoring the installation and the performance, during ten months, of the LEDs public lighting pilot project, on the roadway belt of Engineering Faculty of UFJF is presented.

Il y a près d’une décennie, l'utilisation des supernovae de type Ia comme indicateurs de distances a permis de découvrir l'expansion accélérée de l'univers. Les expériences de seconde génération ont augmenté de manière significative la taille et la qualité des échantillons à grand décalage vers le rouge. Cependant, l'échantillon de référence des supernovae à faible décalage vers le rouge, nécessaire à la cosmologie restait très restreint. The Nearby Supernova Factory a mesuré, à l'aide d'un instrument spectro-photométrique dédié (the Supernova Integral Field Sepctrograph), près de 200 nouvelles supernovae de type Ia. Ma thèse de doctorat a été effectuée à l'Institut de Physique Nucléaire de Lyon et au Lawrence Berkeley National Laboratory dans le cadre du projet international the Nearby Supernova Factory et a pour but l'étalonnage spectro-photométrique du spectrographe à champ intégral. Afin d'atteindre la précision souhaitée, une attention particulière a été apportée à plusieurs aspects majeurs de la procédure d'étalonnage, incluant: la détermination de la réponse impulsionnelle de l'instrument en vue de l'extraction 3D de sources ponctuelles, l'estimation de la qualité photométrique d'une nuit, l'obtention de l'extinction atmosphérique par nuit sur un domaine de longueur d'onde étendu, sa modélisation en terme de composantes physiques et sa variabilité au cours d'une nuit donnée. Une chaîne d'étalonnage multi-standard a été mis en \oe{}uvre utilisant approximativement 4000 observations spectro-photométriques d'étoiles standards. J'exposerai également à la fin de ce manuscrit les résultats scientifiques préliminaires de la collaboration SNfactory. / Ten years ago, type Ia supernovae used as distances indicators led to the discovery of the accelerating expansion of the universe. Today, a second generation of surveys has significantly increased the high-redshift type Ia supernovae sample. The low-redshift sample was however still limiting the cosmological analysis using SNe. In this framework, the Nearby Supernova Factory has followed 200 nearby type Ia supernovae using the dedicated Supernovae Integral Field Spectrograph with spectro-photometric capacities. My PhD thesis has been carried out at the Institut de Physique Nucléaire de Lyon and at the Lawrence Berkeley National Laboratoryin the framework of the international cosmological project SNfactory. In order to reach the design spectrophotometric accuracy, attention has been focused on several key aspects of the calibration procedure, including: determination of a dedicated point spread function for 3D point source extraction, estimating the nightly photometric quality, derivation of the nightly sky extinction over the extended optical domain, its modeling in terms of physical components and its variability within a given night. A full multi-standards calibration pipeline has been implemented using approximately 4000 observations of spectrophotometric standard stars taken throughout the night over nearly 500 individual nights. Preliminary scientific results of the whole SNfactory collaboration will be presented at the end of this thesis.