We present Herschel observations of the debris disk around γ Doradus (HD 27290, HIP 19893) from the Herschel Key Programme DEBRIS (Disc Emission via Bias-free Reconnaissance in the Infrared/Submillimetre). The disk is well-resolved with PACS at 70, 100 and 160 micron and detected with SPIRE at 250 and 350 micron. The 250 micron image is only resolved along the disk's long axis. The SPIRE 500 micron 3 σ detection includes a nearby background source. γ Dor's spectral energy distribution (SED) is sampled in the submillimetre for the first time and modelled with multiple modified-blackbody functions to account for its broad shape. Two approaches are used, both of which reproduce the SED in the same way: a model of two narrow dust rings and a model of an extended, wide dust belt. The former implies the dust rings have temperatures of ~90 and ~40 K, corresponding to blackbody radii of 25 and 135 AU, respectively. The latter model suggests the dust lies in a wide belt extending from 15 to 230 AU. The resolved images, however, show dust extending beyond ~350 AU. This is consistent with other debris disks whose actual radii are observed to be a factor of 2 - 3 times larger than the blackbody radii. Although it is impossible to determine a preferred model from the SED alone, the resolved images suggest that the dust is located in a smooth continuous belt rather than discrete narrow rings. Both models estimate that the dust mass is 6.7 x 10^{-3} Earth masses and that fractional luminosity is 2.5 x 10^{-5}. This amount of dust is within the levels expected from steady state evolution given the age of γ Dor and therefore a transient event is not needed to explain the dust mass. No asymmetries that would hint at a planetary body are evident in the disk at Herschel's resolution. However, the constraints placed on the dust's location suggest that the most likely region to find planets is within 20 AU of the star. / Graduate

This dissertation presents new Herschel observations at 70 micron, 160 micron, 250 micron, 350 micron, and 500 micron of the Perseus molecular cloud from the Herschel Gould Belt Survey. The Perseus molecular cloud is a nearby star-forming region consisting of seven main star-forming clumps. The Herschel observations are used to characterize and contrast the properties of these clumps, and to study their embedded core populations. First, we probed the exceptionally young clump, B1-E. Using complementary molecular line data, we demonstrate that B1-E is likely fragmenting into a first generation of dense cores in relative isolation. Such a core formation region has never been observed before. Second, we use complementary long wavelength observations at 850 micron to study the dust properties in the larger, more active B1 clump. We find that Herschel data alone cannot constrain well the dust properties of cold dust emission and that long wavelength observations are needed. Additionally, we find evidence of dust grain growth towards the dense cores in B1, where the dust emissivity index, beta, varies from the often assumed value of beta = 2. In the absence of long wavelength observations, however, assuming beta = 2 is preferable over measuring beta with the Herschel-only bands. Finally, we use the source extraction code, getsources, to identify the core populations within each clump from the Herschel data. In addition, we use complementary archival infrared observations to study their populations of young stellar objects (YSOs). We find that the more massive clumps have an excess of older stage YSOs, suggesting that these regions contracted first. Starless cores are typically associated with peaks in the column density, where those found towards regions of higher column density also have higher average densities and colder temperatures. Starless cores associated with a strong, local interstellar radiation field, however, have higher temperatures. We find that the clumps with the most prominent high column density tails also had the highest fractions of early-stage YSOs. This relation suggests that the quantity of high column density material corresponds to recent star formation activity. / Graduate / 0606

Thesis (M.A.) - Carleton University, 2003. / Includes bibliographical references (p. 219-224). Also available in electronic format on the Internet.

Thesis (M.Sc.) - Carleton University, 2005. / Includes bibliographical references (p. 138-141). Also available in electronic format on the Internet.

Thesis (M.Sc.) - Carleton University, 2005. / Includes bibliographical references (p. 66). Also available in electronic format on the Internet.

Thesis (M.Sc.) - Carleton University, 2005. / Includes bibliographical references (p. 125-130). Also available in electronic format on the Internet.

Thesis (M.Sc. (Physics & Electronics)) - Rhodes University, 2009. / A thesis submitted in partial fulfilment of the requirements for the degree of Master of Science.

Thesis (M. Sc.)--Carleton University, 1996. / Also available in electronic format on the Internet.

Using the Chandra X-ray Observatory, Martini et al. (2006) found that the AGN fraction of galaxy clusters was five times higher than previous optical studies suggested. Using visual observations only, Dressler et al. (1985) estimated the AGN fraction of field galaxies to be 5%, while that of clusters was thought to be 1%. To understand the role that the environment plays in AGN fueling, the author studied a variety of environments, ranging from the field to groups to clusters. Will the AGN fraction of groups also be higher than that of the field? The author demonstrates how the AGN fraction of groups compares to that of clusters. In the following sections, the author describes the mechanics of X-ray astronomy, the group environment, and the characteristics of active galactic nuclei. The author briefly describes the possible mechanisms for AGN fueling.

Em uma investigação das práticas torcedoras presentes em um estádio de futebol, esta pesquisa aborda a formação de memórias como elemento produtor de sujeitos. Estes torcedores mantêm vínculos muito particulares com o futebol e com uma instituição inserida no modelo de futebol de espetáculo, considerando-se a relação torcedor-torcedor e torcedor-clube. Com especial atenção aos rituais que acontecem antes, durante e depois dos jogos, o estudo traz a tona quais os dispositivos de memória são construídos a partir desses rituais. Com o auxílio da participação observante, é identificado como os torcedores do Grêmio Esportivo Brasil se relacionam e se manifestam no estádio do clube. Diante das singularidades da memória coletiva produzidas pelos torcedores – como em um jogo no ano 1946 – foram se construindo elementos que passaram a nomear a torcida através da figura do “índio xavante”. A violência e fidelidade que estão contidas nesse símbolo são produções que rondam os torcedores xavantes e com o tempo se alteram e são acessados por meio das práticas dos torcedores. Partindo da memória como elemento norteador do processo investigativo e analítico, o investimento nesta pesquisa se faz por meio de práticas sociais que toma o estádio de futebol e as práticas educativas relacionadas ao torcer como elemento de análise, tendo como foco as interações entre o fazer ciência e a produção dos sujeitos. Além disso, visa compreender como os discursos e as práticas atuam na produção de "verdades" e dos sujeitos – no caso desta pesquisa, os torcedores xavantes –, engendrados através das práticas da memória. Enfrentada pelo único limite que é a morte dos indivíduos, a memória social dos torcedores xavantes ocupa um espaço privilegiado para se pensar suas práticas torcedoras atuais. Após a criação de vínculos com o clube, realizadas por práticas cotidianas que se defrontam os sujeitos no estádio, o pertencimento clubístico parece demarcar fortemente o que se esquece e o que não se quer esquecer. Através da ligação entre torcedores e clube, encontrada em uma rede sociabilidade que é constituída dentro do Grêmio Esportivo Brasil, os torcedores se reconhecem como sujeitos torcedores deste clube. / In an investigation of fans practices in a football stadium, this research approaches the formation of memories as a subject’s producer. These fans are closed and keep special link with football and an institution in the soccer spectacle model, considering the relationship between fan-fan and fan-club. With special attention to the rituals that occur before, during and after the games, the study brings out which mechanisms of the memory are constructed from these rituals. With the help of observatory participation, is identified how the fans of Grêmio Esportivo Brasil are related and manifests themselves in the football stadium. The collective memory peculiarities produced by the fans - as in a game in 1946 - were built elements that configure the Xavante Indians simbols. Violence and loyalty that are contained in this symbol Xavante are fans productions which changes by time and are accessed through the practices of the fans. Starting from the memory as a guiding element of investigative and analytical process, the investment in this research is done through social practices that take the football stadium and educational practices related to support as analysis element, focusing on the interaction between doing science and production of subjects. Moreover, it aims to understand how discourses and practices operate in the production of “truths” and subjects – in the case of this research, xavante’s fan – engendered through memory’s practices. Faced by the only limit that is the death of individuals, the social memory of Xavante’s fans occupies a privileged space to think about their current fans practices. After the establishment of links with the club, made by everyday practices faced by subjects in the stadium, belonging to a club seems to strongly demarcate what is forgotten and what you do not want to forget. Through the connection between fans and club, found in a sociability’s network that is formed within Grêmio Esportivo Brasil, the fans recognizes themselves as subjects fans of this club.