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The mystery of Canis Major overdensity is addressed. We discuss concurrent methods and their limitations on the determination of interstellar reddening. We establish a new way to determine line of sight interstellear reddening by observing stellar spectral lines and UBV colors. We observe and analyze spectra of 22 stars in different open clusters. We find that Hydrogen Balmer line at 4861 angstrom can predict the stellar atmospheric parameters and intrinsic colors with reasonable accuracy. Comparing with observed colors we derive the reddening of the stars. We compare our results with standard database WEBDA and find that within 90% probability limit the standard deviation of the error is 0.102798. This is improved by taking the absolute maximum probabilities and the scatter becomes 0.0688865.

Made available in DSpace on 2017-07-21T19:25:56Z (GMT). No. of bitstreams: 1 TAIZAALISSUL.pdf: 1898582 bytes, checksum: 83c6ea30230ef658e8eedb8018b6d20d (MD5) Previous issue date: 2008-04-08 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / One of the main theories to explain the Be phenomenon is that they are hot stars with rotation speed close to the critical limit, ejecting matter and forming a gaseous disk around. Its geometry and kinematics is still a controversial subject. Those objects present H® line in emission among other phenomena. In this work are present observations of hot stars in young open clusters and the detection of Be stars. The study of Be stars in open clusters is a matter of interest because these objects keep the initial signatures of their initial formation. Most of Be stars known in open clusters were identified inside the Milky Way Galaxy, but not all were observed. Most of the observations concentrate on seeking the characteristics lines in emission for stars with low magnitude. As a consequence the complete scenario of incidence of Be stars in open clusters is still uncertain, what incentives its observation. In this work, we studied thirty two stars of the spectral type B, from NGC 4755 and NGC 6530 stellar clusters. As a first step we accomplished an analysis of the stars that present the Be phenomenon. Than, we estimate physical parameters of B and Be stars using the lines of HeI 4471 and MgII 4481 Å. We also accomplished a comparison among the vseni values calculated by several methods including the AMOEBA algorithm and other two methods elaborated using the IDL platform. For high-speeds (» 300 Km/s), there is a superestimative of the FWHM method for both clusters. But for low-speeds, there is consistence between values of vseni obtained with the FWHM method and AMOEBA. / Uma das principais teorias para explicar o fenômeno Be é que são estrelas quentes com velocidade de rotação próxima da velocidade crítica, ejetando matéria formando um disco gasoso ao seu redor. Sua geometria e cinemática ainda é um assunto calorosamente discutido. Esses objetos apresentam emissões nas linhas de Balmer, entre outros fenômenos. Neste trabalho são apresentadas observações de estrelas quentes em aglomerados jovens abertos e a detecção de Be nestes. O estudo de estrelas Be em aglomerados abertos é de particular interesse porque estes objetos guardam as assinaturas das condições iniciais de sua formação. A maioria das estrelas Be conhecidas em aglomerados abertos foram identificadas na Via Láctea, a maioria das observações concentra-se em procurar as linhas em emissão características nas estrelas de baixa magnitude. Como conseqüência a completeza de incidência de estrelas Be em aglomerados abertos é incerta, o que leva a um estímulo para o seu estudo. Nesse trabalho, foram estudadas trinta e duas estrelas do tipo espectral B, selecionadas dos aglomerados NGC 4755 e NGC 6530. Em uma primeira etapa, foi realizada uma análise das estrelas que apresentam o fenômeno Be. Depois, foram determinados os parâmetros físicos de estrelas B e Be utilizando as linhas de HeI 4471 e MgII 4481 Å. Foi realizada, ainda, uma comparação entre os valores de vseni calculados com o algoritmo AMOEBA e os valores obtidos com os programas elaborados no IDL. Para altas velocidades (» 300 Km/s), há superestimativas do método FWHM, para ambos os aglomerados. Mas para baixas velocidades, há consistência entre os valores de vseni obtidos com o método FWHM e AMOEBA.

We present a unique design of a post-focal instrument suitable to detect fast changes of flux in waveband 350 - 440 nm. As it is not possible to measure the Sun as a star because of a strong background radiation in this waveband and using a thin slit makes it impossible to measure the whole flaring area we made a set of circular diaphragms of different sizes able to collect light only from a limited part of the Sun's atmosphere. For our data we also evolved new software technique based on statistical methods that even more increases a sensitivity on any changes in spectra. First results of observations of three X-class solar flares obtained in June 2014 proved significant increase of flux in Balmer continuum. One of these flares was measured from 20 minutes before a peak in SXR (GOES) so we were able to compare a whole impulsive phase with a state with no signs of a flare before it. Data suggest a radiation at Balmer limit (364,5 nm) of up to 5,5 stronger from flaring kernels compared to the quiet Sun. Powered by TCPDF (www.tcpdf.org)

本研究では、低粒子エネルギー領域における金属表面からの反射水素原子を水素原子バルマーアルファ（Hα）発光ドップラー分光計測によって検出する実験系を構築し、ヘリウムによるタングステン表面の微細構造化が水素粒子反射特性に与える影響を調査した。表面構造を持たないタングステンと比較して、Fuzz構造をもつタングステン試料では200 - 300 eVの入射粒子エネルギー領域にて粒子反射係数が1/2程度まで減少することが明らかになった。 / In this study, the author developed a measurement technique to detect hydrogen atoms reflected from a metal surface based upon the Doppler-spectroscopy of hydrogen Balmer-(Hα) emission. The developed measurement technique is a promising method to investigate the hydrogen particle reflection properties in low incident particle energy range, which has been considered difficult. The author applied the developed method into practice to clarify the effects of helium (He) induced tungsten (W) surface nanostructure upon the low energy hydrogen particle reflection. A W-fuzz sample was found to reduce the particle reflection coefficient by 1/2 of the flat reference W surface in low incident particle energy range of 200-300 eV. / 博士(工学) / Doctor of Philosophy in Engineering / 同志社大学 / Doshisha University

Les électrons et les protons suprathermiques, issus du soleil et précipitant dans l'atmosphère des hautes latitudes, constituent une source d'énergie de l'ionosphère terrestre. Ces particules interagissent avec le gaz thermique ambiant par collisions. L'équation de Boltzmann, fournissant les flux de particules en altitude, énergie et angle d'attaque, permet une description des plus complètes du transport de ces particules. Nous la redémontrons dans le cas dissipatif, le plus général, et nous proposons une résolution originale des équations de transport des protons et des atomes d 'hydrogène, équations couplées via les réactions de changement de charge. Cette résolution, fondée sur l'introduction de forces dissipatives pour décrire la dégradation énergétique des particules précipitant, permet la prise en compte des redistributions angulaires, d'origine collisionnelle ou magnétique, jusqu'alors négligées. Pourtant, leur effet a été observé, depuis le sol, sur les émissions des atomes d 'hydrogène, comme en témoigne la composante, décalée vers le rouge, du profil Doppler selon le zénith magnétique. La résolution adoptée ici est validée par comparaison avec un autre modèle, dans le cas classique sans redistribution angulaire. L'influence de l'effet de miroir magnétique est discutée: cet effet ne semble pas pouvoir expliquer, à lui seul, le décalage vers le rouge observé. La redistribution angulaire collisionnelle doit jouer un rôle significatif. Enfin, une comparaison de notre modèle avec les données de la fusée Proton 1 est proposée.

Lisa Markley, a.k.a. "Miz Markley", is a genuinely happy person even if she is not particularly financially successful as a musician. In an effort to validate my own choices as an artist, I chose to follow her. What was intended to be a portrait of a working musician, becomes instead a feminist musical essay film about the transformative power of art making.