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Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (p. 183-190).

The goal of this study was to obtain photometry of three poorly studied close binary star systems. These observations were obtained at Lowell Observatory in Flagstaff, Arizona and the Ball State University Observatory. In both cases charged coupled device detectors were used. Light variations were detected in all three stars. For one of the binaries the temperatures of the component stars were found by fitting multi-color light curves with black body models. In addition, the temperature difference between the two hemispheres of the secondary star was found. This difference is believed to be the product of heating by the stellar companion. / Department of Physics and Astronomy

In the last few years, two major contributions to the asteroid database have been the eight-color and thermal radiometric surveys. The former consists of broad-band photometric measurements through eight filters spanning the 0.3 to 1.1 μm wavelength range. The latter consists of thermal flux measurements at 10 and/or 20 μm, and when combined with measures of the reflected light, can yield reliable estimates of their geometric albedos. Visual display of the eight-color survey data can be simplified by reducing the dimensionality of the problem. A principal components analysis was performed to accomplish this task. The analysis shows that 95 percent of the information contained in the seven independent color indices is contained in two principal components. This result is due to the fact that most asteroid spectra can be explained in terms of two absorption features, one at ultraviolet and the other at near-infrared wavelengths. The photometric and radiometric data sets were also used, along with cluster analysis techniques, to produce an improved asteroid taxonomic system. Seven major classes are now recognized and are designated A, C, D, E, M, P, and S. Three interesting minor classes are also identified: B, F, and G. Marginal evidence for an eighth major class, here called T, exists in the data, but the reality of this class awaits confirmation by further observations of potential members. Three asteroids do not fall into any of the above classes and are assigned unique designations: R (349 Dembowska), Q (1862 Apollo), and V (4 Vesta). Four E-class asteroids are now known to exist in the main belt, yet nearly twice this number exist in or near the Hungaria region. Twenty eight D-class asteroids have been identified in the outer belt, where they represent a significant fraction of the population. Five D asteroids exist in the main belt, which one lying near the inner edge of the belt, which is dominated by S-class asteroids. Two of the interesting minor classes are associated with particular dynamical families. The Nysa family, with the single exception of Nysa itself, consists entirely of class F asteroids, while the B asteroids are found almost exclusively in the Themis family. The earth-approaching population is represented by at least two objects similar to Vesta and Dembowska, which are as many as are in the entire main belt, while most of the earth-approachers are of class S.

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Orientador: José Anchieta Gomes Neto / Banca: Marisa Spirandeli Crespi / Banca: Jorge Luiz Raposo Júnior / Resumo: Foi desenvolvido um equipamento de baixo custo, portátil e multifuncional que integra num único dispositivo quatro técnicas analíticas: fotometria, turbidimetria, nefelometria e fluorimetria. Os principais componentes do equipamento proposto são: diodo emissor de luz (LED) como fontes de radiação; resistor dependente de luz (LDR) como fotodetector; multímetro digital como dispositivo de leitura; um bloco cilíndrico de Nylon preto. Para avaliar o desempenho do equipamento, fez-se a determinação de fósforo (fotometria) e de enxofre (turbidimetria) em fertilizante, de enxofre em material vegetal (nefelometria) e de quinina em água tônica (fluorimetria). As determinações também foram feitas em um equipamento comercial para fins comparativos. Para a determinação de fósforo pelo método do fosfovanadomolibdato, a faixa de trabalho foi de 0,07 a 6,52 mg L-1 (r= 0,9944) e o limite de detecção foi de 0,06 mg L-1. Para a determinação turbidimétrica de sulfato pelo método da precipitação de sulfato de bário, a calibração foi de 2,5 a 100 mg L-1 (r= 0,9982), sendo o limite de detecção 0,23 mg L-1. Na determinação nefelométrica de sulfato, a faixa linear foi de 0,2 a 1,8 mg L-1 (r= 0,9948) e o limite de detecção de 0,10 mg L-1. Na determinação fluorimétrica de quinina, a faixa linear foi de 0,16 a 8,0 mg L-1 (r= 0,9982) e limite de detecção de 0,011 mg L-1. Os resultados obtidos foram comparados com aqueles fornecidos por equipamentos comerciais e resultados concordantes foram observados ao nível de 95% de confiança. Materiais de referência foram analisados pelo equipamento proposto e os resultados para fósforo e enxofre foram concordantes com os respectivos valores certificados ao nível de 95% de confiança. Além do potencial analítico, o equipamento proposto apresenta utilidade como ferramenta didática. O aprendizado do conteúdo de métodos ópticos de análise pode ser estimulado quando há melhor... / Abstract: A new portable, low cost and multifunctional equipment comprising four analytical techniques (photometry, turbidimetry, nephelometry and fluorimetry) in one single device was developed The main components of the developed device are light emitting diode (LED) as radiation source, light-dependent resistor (LDR) as photodetector, digital multimeter as reading device, and a black plastic container. The performance of the device was checked by determining phosphorus in fertilizer (photometry), sulfur in fertilizer (turbidimetry), sulfur in vegetable samples (nephelometry) and quinine in tonic water (fluorimetry). All determinations were also made in commercial equipments for comparison purposes. The phosphovanadomolibdate method was employed for phosphorus determination within the 0.07 - 6.52 mg L-1 concentration range ((r= 0.9944), and the detection limit was 0.06 mg L-1. The precipitation of barium sulfate was employed for turbidimetric and nephelometric determination of sulfate. For the turbidimetric technique, the calibration range was in the 2.5 - 100 mg L-1 (r= 0.9982), and the detection limit was 0.23 mg L-1. For nephelometry, calibration within 0.2 - 1.8 mg L-1 (r= 0.9948) resulted in detection limit of 0.10 mg L-1. The fluorimetric determination of quinine in the 0.16 - 8.0 mg L-1 linear working range (r= 0.9982) resulted in 0.011 mg L-1 detection limit. Results found by the proposed device were in agreement with those obtained by commercial equipments at 95% confidence level. Standard reference materials were also analyzed, and results for P and S were in agreement with certified values. Besides analytical capabilities, the proposed device may be useful for teaching. The learning goals of some optical techniques may be easier using easy-to-make instruments. / Mestre

Thesis (M.S.)--University of Delaware, 2006. / Principal faculty advisor: John E. Gizis, Dept. of Physics & Astronomy. Includes bibliographical references.