Diss.--Philosophische Fakultät--Freiburg i. Br.--Albert-Ludwig-Universität, 1991.

Thesis (Ph. D.)--Columbia University, 1986. / Includes bibliographical references (leaves 358-388).

La photométrie des transits permet de détecter des planètes extrasolaires en mesurant leur rayon. Dans cet objectif, le télescope spatial CoRoT (Convection, Rotation et Transit planétaires), lancé en décembre 2006, est doté d'un photomètre de haute précision permettant à la fois l'étude de la structure interne des étoiles par astérosismologie et la détection de planètes par la méthode des transits. Pour cette thèse, j'ai développé différents outils informatiques permettant la détection, l'analyse détaillée de transits dans les courbes de lumière de CoRoT. J'ai appliqué ces outils aux quelques 12 000 étoiles observées durant chacune des dix premières campagnes d'observation. La collaboration des équipes de détection et de suivi au sol par d'autres méthodes d'observation a permis, à ce jour, la découverte de quinze planètes et deux naines brunes.Il est possible de contraindre les modèles de ces exoplanètes grâce à la connaissance des paramètres (masse, rayon): gazeuses, de glace, telluriques, ou d'autres types mixtes.La recherche de planètes rocheuses en particulier est un objectif motivé tant par la rareté des détections de ces objets jusqu'à présent (liée à leur faibles rayon et masse), que par la grande variété potentielle de leur nature.Ainsi, la découverte de CoRoT-7b, la première exoplanète compatible avec un modèle rocheux et dont le rayon (1,6 rayon terrestre) et la masse (environ 7 masses terrestres) ont pu être mesurés, a permis d'élaborer un modèle physique auquel j'ai contribué.J'ai étudié la possibilité d'observer cette planète très chaude en proche infrarouge avec le JWST, au cours de son orbite, afin d'estimer le contraste de température entre les faces jour et nuit. Ceci doit permettre de confirmer / invalider notre modèle qui suppose l'absence d'une atmosphère suffisamment dense pour redistribuer la chaleur à la surface de CoRoT-7b. / The transit photometry makes it possible to detect exoplanets by measuring their radii. Pursuing this goal, the space telescope CoRoT (Convection, Rotation and planetary Transits), launched in December 2006, is equiped with a high-precision photometer allowing both planet detection by transit photometry, and stellar physics studies (asteroseismology).For this PhD thesis, I have developed various computing tools for the detection and detailed analysis of the transits in CoRoT light curves. I have applied these tools to almost 12 000 stars observed during each of the first ten campaigns of observation. The collaboration between the detection and ground based follow-up teams led to the discovery, up to now, of fifteen planets and two brown dwarfs.It is possible to constrain the physical natures of these exoplanets thanks to the knowledge of the masses and radii: they can be gazeous, icy, rocky or with an mixed nature.The search for rocky planets in particular, is a goal motivated by their singular nature, and both by the paucity of detections of these objects (due to their low masses and radii), Thus, the discovery of CoRoT-7b -- the first exoplanet compatible with a rocky model and whith measured radius (1.6 Earth radius) and mass (around 7 Earth masses) -- allowed us to develope a physical model to which I contributed :I studied the possibility of observing this very hot planet in the near infrared range with JWST, during its orbit, to estimate the temperature contrast between the day and the night faces. This should allow to confirm / invalidate our model with atmosphere dense enough to redistribute heat at the surface of CoRoT-7b.

Diss.--Köln, 1985--Philosophische Fakultät. / Bibliogr. p. 315-341. Index.

La photométrie des transits permet de détecter des planètes extrasolaires en mesurant leur rayon. Dans cet objectif, le télescope spatial CoRoT (Convection, Rotation et Transit planétaires), lancé en décembre 2006, est doté d'un photomètre de haute précision permettant à la fois l'étude de la structure interne des étoiles par astérosismologie et la détection de planètes par la méthode des transits. Pour cette thèse, j'ai développé différents outils informatiques permettant la détection, l'analyse détaillée de transits dans les courbes de lumière de CoRoT. J'ai appliqué ces outils aux quelques 12 000 étoiles observées durant chacune des dix premières campagnes d'observation. La collaboration des équipes de détection et de suivi au sol par d'autres méthodes d'observation a permis, à ce jour, la découverte de quinze planètes et deux naines brunes.Il est possible de contraindre les modèles de ces exoplanètes grâce à la connaissance des paramètres (masse, rayon): gazeuses, de glace, telluriques, ou d'autres types mixtes.La recherche de planètes rocheuses en particulier est un objectif motivé tant par la rareté des détections de ces objets jusqu'à présent (liée à leur faibles rayon et masse), que par la grande variété potentielle de leur nature.Ainsi, la découverte de CoRoT-7b, la première exoplanète compatible avec un modèle rocheux et dont le rayon (1,6 rayon terrestre) et la masse (environ 7 masses terrestres) ont pu être mesurés, a permis d'élaborer un modèle physique auquel j'ai contribué.J'ai étudié la possibilité d'observer cette planète très chaude en proche infrarouge avec le JWST, au cours de son orbite, afin d'estimer le contraste de température entre les faces jour et nuit. Ceci doit permettre de confirmer / invalider notre modèle qui suppose l'absence d'une atmosphère suffisamment dense pour redistribuer la chaleur à la surface de CoRoT-7b.

O satélite franco-europeu com participação brasileira, CoRoT (Convention, Rotation and planetary Transits), faz parte de uma missão espacial dedicada à sismologia estelar e à busca por exoplanetas. Para a descoberta de exoplanetas, o objetivo é detectar a ocultação temporária da estrela ao redor da qual orbita o planeta em questão, ou seja, detectar um trânsito planetário que pode ser traduzido por uma diminuição tênue do fluxo de fótons estelar coletado pelos CCDs do fotômetro. Existem alguns ruídos e diversas fontes de luz que atingem os CCDs e que não são provenientes das estrelas em estudo. Tais ruídos e fontes de luz geram uma iluminação chamada de fundo de céu nos CCDs que é não homogênea e que precisa ser corrigida antes do início da exploração científica dos dados obtidos nas observações do satélite. A correção de fundo de céu é um procedimento padrão na redução de dados fotométricos, e consiste na subtração do nível médio de fundo de céu das medições fotométricas de uma estrela. Para a determinação do fundo de céu o CoRoT utiliza um conjunto de janelas de fundo de céu. Este trabalho propõem métodos alternativos para a alocação destas janelas de fundo de céu e estimação do ruído de fundo de céu para o canal de exoplanetas do satélite CoRoT. São apresentados dois novos métodos de alocação de janelas e são testados diversos métodos de estimação de ruído de fundo de céu. Os testes realizados neste trabalho sugerem fortemente a utilização do método chamado k-min para a alocação de janelas e do método mediana e 5 vizinhos para a estimação de ruído de fundo de céu. O método k-min procura alocar as janelas de maneira homogênea e em locais de mínimo de uma imagem do céu observado pelo satélite e o método mediana e 5 vizinhos estima o ruído de fundo de céu a partir da mediana de todas as janelas de fundo de céu com nível DC corrigido pela mediana das cinco janelas vizinhas mais próximas. / The French-European satellite with Brazilian participation, CoRoT (Convention, Rotation and planetary Transits), is part of a space mission dedicated to stellar seismology and exoplanets search. Both scientific programs are based on a high-precision photometry and require long-term uninterrupted observations. The satellite uses stellar photometry from images captured on CCD (charged coupled devices), known as photometry by mask. For the discovery of exoplanets, the goal is to detect the temporary hiding of the star which around orbits the planet in question, that is, to detect a planetary transit, which can be translated by a slight decrease in the stellar photon flux collected by the CCDs of the photometer. There are some noise and various sources of light that reaches the CCD and are not from the stars under study. Such noise and light sources produce a light called \"sky background\" in CCDs that is not homogeneous and that must be corrected before the scientific exploration of the data obtained from satellite observations. The sky background correction is a standard procedure in the reduction of photometric data. It consists in subtracting the average level of sky background of photometric measurements of a star. To determine the sky background noise, CoRoT uses a set of sky background windows and this work proposes alternative methods for allocating these windows and for estimating the sky background noise to the CoRoT exoplanet channel. Here are present two new methods of windows allocation and are tested several methods of estimating the sky background noise. Tests conducted in this study strongly suggest the use of the method called k-min for windows allocation and the method \"median and 5 neighbors\" to the estimation of sky background noise. The k-min method tries to allocate windows homogeneously and in minimum locals of image of the sky observed by the satellite, and the method \"median and 5 neighbors estimates the sky background noise by the median of all background windows with DC level corrected by the median of the five nearest neighbors.

O satélite franco-europeu com participação brasileira, CoRoT (Convention, Rotation and planetary Transits), faz parte de uma missão espacial dedicada à sismologia estelar e à busca por exoplanetas. Para a descoberta de exoplanetas, o objetivo é detectar a ocultação temporária da estrela ao redor da qual orbita o planeta em questão, ou seja, detectar um trânsito planetário que pode ser traduzido por uma diminuição tênue do fluxo de fótons estelar coletado pelos CCDs do fotômetro. Existem alguns ruídos e diversas fontes de luz que atingem os CCDs e que não são provenientes das estrelas em estudo. Tais ruídos e fontes de luz geram uma iluminação chamada de fundo de céu nos CCDs que é não homogênea e que precisa ser corrigida antes do início da exploração científica dos dados obtidos nas observações do satélite. A correção de fundo de céu é um procedimento padrão na redução de dados fotométricos, e consiste na subtração do nível médio de fundo de céu das medições fotométricas de uma estrela. Para a determinação do fundo de céu o CoRoT utiliza um conjunto de janelas de fundo de céu. Este trabalho propõem métodos alternativos para a alocação destas janelas de fundo de céu e estimação do ruído de fundo de céu para o canal de exoplanetas do satélite CoRoT. São apresentados dois novos métodos de alocação de janelas e são testados diversos métodos de estimação de ruído de fundo de céu. Os testes realizados neste trabalho sugerem fortemente a utilização do método chamado k-min para a alocação de janelas e do método mediana e 5 vizinhos para a estimação de ruído de fundo de céu. O método k-min procura alocar as janelas de maneira homogênea e em locais de mínimo de uma imagem do céu observado pelo satélite e o método mediana e 5 vizinhos estima o ruído de fundo de céu a partir da mediana de todas as janelas de fundo de céu com nível DC corrigido pela mediana das cinco janelas vizinhas mais próximas. / The French-European satellite with Brazilian participation, CoRoT (Convention, Rotation and planetary Transits), is part of a space mission dedicated to stellar seismology and exoplanets search. Both scientific programs are based on a high-precision photometry and require long-term uninterrupted observations. The satellite uses stellar photometry from images captured on CCD (charged coupled devices), known as photometry by mask. For the discovery of exoplanets, the goal is to detect the temporary hiding of the star which around orbits the planet in question, that is, to detect a planetary transit, which can be translated by a slight decrease in the stellar photon flux collected by the CCDs of the photometer. There are some noise and various sources of light that reaches the CCD and are not from the stars under study. Such noise and light sources produce a light called \"sky background\" in CCDs that is not homogeneous and that must be corrected before the scientific exploration of the data obtained from satellite observations. The sky background correction is a standard procedure in the reduction of photometric data. It consists in subtracting the average level of sky background of photometric measurements of a star. To determine the sky background noise, CoRoT uses a set of sky background windows and this work proposes alternative methods for allocating these windows and for estimating the sky background noise to the CoRoT exoplanet channel. Here are present two new methods of windows allocation and are tested several methods of estimating the sky background noise. Tests conducted in this study strongly suggest the use of the method called k-min for windows allocation and the method \"median and 5 neighbors\" to the estimation of sky background noise. The k-min method tries to allocate windows homogeneously and in minimum locals of image of the sky observed by the satellite, and the method \"median and 5 neighbors estimates the sky background noise by the median of all background windows with DC level corrected by the median of the five nearest neighbors.

Made available in DSpace on 2015-03-03T15:16:25Z (GMT). No. of bitstreams: 1 SauloCM_TESE.pdf: 2950789 bytes, checksum: d10187bfbd3f161c4305c3a9fa050100 (MD5) Previous issue date: 2011-08-18 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Sessenta e cinco sistemas bin?rios eclipsantes, identificados nos objetivos da miss?o espacial CoRoT, foram selecionados para a an?lise. Destes, cinquenta e nove curvas de luz fotom?tricas que foram analisadas e processadas neste estudo s?o curvas crom?ticas (simultaneamente observadas nos tr?s filtros azul, verde e vermelho do sat?lite), fornecendo uma importante informa??o que ajuda a distinguir falsos positivos e genu?nos sistemas bin?rios eclipsantes. Neste sentido, este estudo fornece um cat?logo de sistemas bin?rios eclipsantes com suas respectivas solu??es fotom?tricas, baseadas nas curvas de luz CoRoT. Os sistemas selecionados incluem ambos, sistemas de n?o contato e de contato para os quais s?o apresentados uma variedade de par?metros f?sicos, incluindo per?odo orbital, o ?ngulo de inclina??o da orbita, raz?o de temperaturas, raz?o de raios e raz?o de luminosidades. Em adicional, e poss?vel estimar, aproximadamente, os par?metros absolutos de tais sistemas tomando como refer?ncia os valores t?picos a partir dos tipos espectrais conhecidos. O trabalho contribui para um aumento significativo no n?mero e na diversidade de sistemas bin?rios eclipsantes estudados a partir da base de dados CoRoT

The general objective of the present work is to contribute to the knowledge of the physics of Be Stars. In particular, we are interested in studying and characterizing their pulsational properties. A very suitable tool to reach this goal is the study and analysis of photometric time series with the maximum time baseline, density and photometric accuracy.The space mission COROT scheduled to be launched in December 2006, will provide ultra high precision, relative stellar photometry for very long continuous observing runs. Up to ten stars will be observed in the seismology fields with a photometric accuracy of a few 10-4 and color information during 150 days.The observations of Be stars with COROT will provide photometric time series with unprecedented quality. Their analysis will allow us to qualitatively improve our knowledge and understanding of the pulsational characteristics of Be stars. In consequence, we have started a research project aimed at observing Be stars both in the seismology and exoplanet fields of COROT.In this thesis we present the first step of this project, which is the preparation and study of the sample of Be stars that will be observed by COROT. We have performed photometric analysis of all Be stars located in the seismology fields (Chap. 2). Special emphasis has been given to two stars (NW Ser and V1446 Aql) in which we have detected multiperiodic variability and these variations have been modeled in terms of stellar pulsations (Chap. 3). We have also performed an in-depth spectroscopic study of NW Ser and identified the non-radial pulsating modes taking into account the rotational effects (Chap. 4). A technique to search for faint Be stars based on CCD photometry has been developed and is presented in Chap. 5. We also present a list of faint Be stars located in the exoplanet fields of COROT detected with this technique and which we propose as targets for COROT. In addition, we have proven that our period-analysis techniques are suitable to detect multiperiodicity in large temporal baseline data. In particular, we have detected non-radial pulsations in some Be stars in the low-metallicity galaxy Small Magellanic Clouds (Chap. 6). The current theoretical models do not predict the presence of pulsational instabilities in such low-metallicity environment, and therefore, our results point towards the necessity of new and improved models.

La recherche et caractérisation de planètes extrasolaires en transit (i.e., qui passent devant leur étoile, vue depuis la Terre) est un domaine important de la planétologie car ces planètes permettent de contraindre les processus de formation, d'évolution et de migration des systèmes planétaires. Les missions spatiales CoRoT et Kepler ont permis, ces dernières années, de découvrir plusieurs milliers de candidats-planètes en transit. Cependant, ces candidats-planètes doivent être confirmés afin d'exclure tout scénario de faux-positifs pouvant imiter un transit d'une exo-planète. Pour cela, l'une des méthodes possible consiste à mener des observations complémentaires de vitesse radiale permettant de mesurer la masse et les paramètres orbitaux de l'objet qui transite et ainsi de pouvoir déterminer la nature des candidats-planètes. Au cours de ma thèse, je me suis attaché à résoudre la nature des candidats-planètes en transit issues des missions spatiales CoRoT et Kepler en menant des observations avec les spectrographes SOPHIE et HARPS, ce qui m'a permis d'identifier plusieurs nouvelles planètes extrasolaires en transit. J'ai également pu mesurer le taux de faux-positif de la mission Kepler, égal à 35% pour les candidats planètes-géantes à courte période orbitale, contredisant les précédentes estimations, beaucoup plus optimistes. J'ai également participé au développement d'un nouveau logiciel, "PASTIS", qui permet de valider statistiquement des planètes extrasolaires de faible masse, trop petites pour être caractérisées grâce aux spectrographes actuels. Ce logiciel permettra, à terme, de valider des dizaines de planètes de faible masse issues des missions CoRoT et Kepler. / The search and characterization of transiting extrasolar planets (i.e. that pass in front of their host star, as seen from the Earth) is an important domain of planetology since these planets constrain the formation, evolution and migration process of planetary systems. The CoRoT (CNES) and Kepler (NASA) space missions permit, these last years, to discover several thousand of transiting-planet candidates. However, these planet candidates need to be confirmed in order to exclude all false positive scenario that can mimic a planetary transit. For that, one of the method consist on performing radial velocity follow-up observations to measure the transiting object's mass and orbital parameters and thus, to determine the nature of planet candidates.During my PhD thesis, I tried to resolve the nature of transiting planet candidates from the CoRoT and Kepler space missions. For that, I performed follow-up observations with the SOPHIE (OHP) and HARPS (ESO) spectrographs that were used to discover several new transiting extrasolar planets. I also measured the Kepler false-positive rate, equal to 35% for giant close-in exoplanet candidates, contradicting previous estimations, much more optimistic.I also participate to the development of a new software, called "PASTIS", which objective is to validate statistically low-mass transiting exoplanets out of reach for current spectrographs. This new tool will, in a near future, validate tens of low-mass planets from the CoRoT and Kepler space missions.