526 research outputs found
Three contributions to the \"A Half Century of Stellar Pulsation Interpretations\" proceedings
No full textPaper I: "RR Lyrae Variables in Globular Clusters and the Second-Parameter Phenomenon" Authors: M. Catelan, A. V. Sweigart, J. Borissova Abstract: We propose to use RR Lyrae variables in globular clusters to probe the origin of the second-parameter phenomenon. Paper II: "New Possible Variables in the Outer-Halo Globular Cluster Palomar 3" Authors: J. Borissova, N. Spassova, M. Catelan, V. D. Ivanov Abstract: We present a list of ten possible variable stars in the globular cluster Pal 3. Seven are new suspected variables. The variability of the RR Lyr candidate reported by Burbidge & Sandage (1958), as well as of the Pop. II Cepheid and RR Lyr from Gratton & Ortolani (1984), are confirmed. Paper III: "On the Production of Bright RR Lyrae Variables in Metal-Rich Globular Clusters" Authors: A. V. Sweigart, M. Catelan Abstract: See astro-ph/9708174...
Identity in the novels of Marcio Veloz Maggiolo
No full text(in English): The aim of this diploma thesis is to analyse the Dominican identity in the works of the Dominican author Marcio Veloz Maggiolo. At first, the thesis briefly summarizes the evolution of the Dominican literature and mentions its most significant figures. Secondly, it deals with the evolution of the dominicaness from the colonial period up to the present and explains the reasons of the rooted antihaitianism. The second part consists of a detailed analysis of the novels The Diffuse Biography of Sombra Castañeda and The Accordion Man by Marcio Veloz Maggiolo, emphasizing the symbols of the official government's discourse, and also a more opened perspective of the dominicaness
The Trimodal Horizontal Branch of M75 (NGC 6864)
No full textDeep UBVI photometry for a large field covering the distant globular cluster M75 (NGC 6864) is presented. We confirm a previous suggestion (Catelan et al. 1998) that M75 possesses a bimodal horizontal branch (HB) bearing striking resemblance to the well-know case of NGC 1851. In addition, we detect a third, smaller grouping of stars may correspond to the upper part of a very extended, though thinly populated, blue tail. Thus M75 appears to have a trimodal HB. The presence of the "Grundahl jump" is verified using the broadband U filter
Socio-spatial differentiation and inequality in local cities: Adamantina and Dracena
No full textEsta tese buscou analisar e compreender a influência dos agentes econômicos e sociais na dinâmica
da expansão territorial urbana e na diferenciação da desigualdade socioespacial nas cidades de
Adamantina e Dracena. Tais cidades compõe a região de influência de Presidente Prudente/SP
(município de médio porte), de acordo com estudos do Instituto Brasileiro de Geografia e
Estatística (IBGE) (2018). A pesquisa foi realizada em três etapas, envolvendo o levantamento de
informações de caráter quantitativo e qualitativo, optando-se por uma metodologia mista ou
multimetodológica. A primeira etapa abrangeu a análise e compreensão do processo de expansão
territorial e da diferenciação socioespacial nas cidades objeto de estudo. Para tanto, foram
realizados levantamentos bibliográficos, pesquisa documental e coleta de dados primários e
secundários que auxiliaram na construção de uma caracterização das cidades, com foco nos
processos de diferenciação e da desigualdade socioespacial. Na segunda etapa foram realizados
trabalhos de campo, pela aplicação de questionário, realização de entrevistas e também pelas bases
de dados de disponíveis. A terceira etapa elaborou os gráficos, tabelas, quadros, mapas e figuras
que viabilizaram a representação das informações coletadas, bem como a análise dos dados da
pesquisa. Ao término, realizou-se uma comparação entre as duas cidades, sintetizando as análises
das cidades objeto de estudo. Destaca-se que esta tese pode confrontar e reavaliar a compreensão
do conceito de cidades pequenas e de cidades locais, frente à compreensão do cotidiano das cidades
objeto de estudo.This thesis aimed to analyze and understand the influence of economic and social agents on the dynamics of urban territorial expansion and the differentiation of socio-spatial inequality in the cities of Adamantina and Dracena. These cities make up the influence region of Presidente Prudente/SP (a medium-sized municipality), according to studies by the Brazilian Institute of Geography and Statistics (IBGE) (2018). The research was conducted in three stages, involving the collection of quantitative and qualitative information, using a mixed or multimethodological approach. The first stage involved the analysis and understanding of the process of territorial expansion and socio-spatial differentiation in the cities under study. To do so, bibliographical research, document analysis, and the collection of primary and secondary data were conducted to build a characterization of the cities, focusing on the processes of differentiation and socio-spatial inequality. In the second stage, fieldwork was conducted through surveys, interviews, and the use of available databases. The third stage involved the creation of graphs, tables, charts, maps, and figures that facilitated the representation of the collected information, as well as the analysis of the research data. Finally, a comparison was made between the two cities, summarizing the analyses of the cities under study. It is worth noting that this thesis may challenge and reevaluate the understanding of the concepts of small towns and local cities in light of the everyday life of the cities under study.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)CAPES: 00
RR Lyrae variables in globular clusters and nearby galaxies
No full textI point out that the Oosterhoff dichotomy for globular cluster and field RR Lyrae stars may place the strongest constraints so far on the number of dwarf spheroidal-like protogalactic fragments that may have contributed to the formation of the Galactic halo. The first calibration of the RR Lyrae period-luminosity relation in I, J, H, K taking evolutionary effects into account is provided. Problems in the interpretation of RR Lyrae light curves and evolutionary properties are briefly reviewed...
The ages of stars: The horizontal branch
No full textHorizontal branch (HB) stars play a particularly important role in the “age debate,” since they are at the very center of the long-standing “second parameter” problem. In this review, I discuss some recent progress in our understanding of the nature and origin of HB stars
The ages of (the oldest) stars
No full textMuch progress has been achieved in the age-dating of old stellar systems, and even of individual stars in the field, in the more than sixty years since the evolution of low-mass stars was first correctly described. In this paper, I provide an overview of some of the main methods that have been used in this context, and discuss some of the issues that still affect the determination of accurate ages for the oldest stars
Selected topics in the evolution of low-mass stars
No full textLow-mass stars play a key role in many different areas of astrophysics. In this article, I provide a brief overview of the evolution of low-mass stars, and discuss some of the uncertainties and problems currently affecting low-mass stellar models. Emphasis is placed on the following topics: the solar abundance problem, mass loss on the red giant branch, and the level of helium enrichment associated to the multiple populations that are present in globular clusters
The RR Lyrae Period-Luminosity-(Pseudo)Color and Period-Color-(Pseudo)Color Relations in the Strömgren Photometric System: Theoretical Calibration
No full textWe present a theoretical calibration of the RR Lyrae period-luminosity-color and period-color-color relations in the multiband uvby Strömgren photometric system. Our theoretical work is based on calculations of synthetic horizontal branches (HBs) for four different metallicities, fully taking into account evolutionary effects for a wide range in metallicities and HB morphologies. While our results show that "pure" period-luminosity and period-color relations do not exist in the Strömgren system, which is due to the large scatter that is brought about by evolutionary effects when the uvby bandpasses are used, they also reveal that such scatter can be almost completely taken into account by incorporating Strömgren pseudocolor [C0 ≡ (u - v)0 - (v - b)0] terms into those equations, thus leading to tight period-luminosity-pseudocolor (PLpsC) and period-color-pseudocolor (PCpsC) relations. We provide the latter in the form of analytical fits, so that they can be applied with high precision even in the case of field stars. In view of the very small sensitivity of C0 to interstellar reddening, our PLpsC and PCpsC relations should be especially useful for the derivation of high-precision distance and reddening values. In this sense, we carry out a first application of our relations to field RR Lyrae stars, finding evidence that the stars RR Lyr, SU Dra, and SS Leo, but not SV Hya, are somewhat overluminous (by amounts ranging from simeq0.05 to 0.20 mag in y, and thus V) with respect to the average for other RR Lyrae stars of similar metallicity...
Semi-Empirical Determination of the Mass Distribution of Horizontal Branch Stars in M3
No full textWe determine, by means of a semi-empirical study, the masses of horizontal branch stars in the globular cluster M3 (NGC 5272). We used the most recent and reliable observational datasets (broadband BVI photometry) available for the cluster, both for variable and nonvariable stars, to infer the most likely masses of individual horizontal branch stars by comparison against theoretical evolutionary tracks, suitably transformed to the observational planes. We found a mass distribution that is adequately described by a Gaussian, with < M > = 0.64 M⊙ and σ = 0.020 M⊙...
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