Planetary Nebulae
Mostrando 1-12 de 17 artigos, teses e dissertações.
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1. Populações e evolução do bojo e região central da Galáxia / Populations and the evolution of the bulge and central region of the Galaxy
O presente trabalho propõe uma abordagem abrangente para descrever a evolução da região central da Via Láctea, compreendendo-se aí o bojo, a barra e as interfaces dos mesmos com o limite interno do disco e com a região central do halo. Pretende-se investigar as propriedades químicas e cinemáticas destas estruturas, que são interconectadas, com o ob
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 03/05/2012
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2. Modelagem de nebulosas planetárias com morfologia bipolar / Modelling of planetary nebulae with bipolar morphology
O presente trabalho propõe-se a mapear espacialmente as propriedades físicas de um conjunto destes objetos, de morfologia bipolar, e então efetuar sua modelagem. Para este mapeamento foram executadas observações do Observatório Pico dos Dias (LNA/MCT) através das técnicas observacionais de espectroscopia de fenda longa e de campo integral. As modelag
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 29/04/2011
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3. Emissão da molécula H2 em nebulosas planetárias / Molecular Hydrogen Emission of Planetary Nebulae
Na literatura, a análise e a interpretação das linhas de emissão de H2 em nebulosas planetárias são feitas, em geral, considerando que a molécula somente seja produzida em ambientes neutros, como as regiões de fotodissociação ou com choques. No entanto, existem fortes evidências observacionais de que ao menos parte da emissão seja proveniente da
Publicado em: 2007
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4. Determination of chemical abundances in yellow symbiotic stars from the southern hemsiphere / "Determinação de abundâncias químicas em simbióticas amarelas austrais"
The present work is a contribution to the study of chemical composition of southern symbiotic stars, scarcely studied in literature. We present a complete set of yellow southern symbiotic stars extracted from Belczynski. Some of the objects analyzed had no spectroscopic data in literature. The data were obtained using 1.6m telescope in LNA, Brazil and the IU
Publicado em: 2004
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5. A Molécula H2 em Nebulosas Planetárias / Molecular Hydrogen in Planetary Nebulae
O objetivo deste trabalho é o estudo das condições de existência e a determinação da concentração da molécula H2 em diferentes condições típicas de nebulosas planetárias, dentro da região ionizada. Para este cálculo, desenvolvemos sub-rotinas computacionais que se acoplam ao código de fotoionização unidimensional Aangaba que, até agora, so
Publicado em: 2002
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6. International Ultraviolet Explorer satellite observations of seven high-excitation planetary nebulae
Observations of seven high-excitation planetary nebulae secured with the International Ultraviolet Explorer (IUE) satellite were combined with extensive ground-based data to obtain electron densities, gas kinetic temperatures, and ionic concentrations. We then employed a network of theoretical model nebulae to estimate the factors by which observed ionic con
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7. PHOTOELECTRIC SPECTROPHOTOMETRY OF PLANETARY NEBULAE
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8. Nebular and auroral emission lines of [Cl iii] in the optical spectra of planetary nebulae
Electron impact excitation rates in Cl III, recently determined with the R-matrix code, are used to calculate electron temperature (Te) and density (Ne) emission line ratios involving both the nebular (5517.7, 5537.9 Å) and auroral (8433.9, 8480.9, 8500.0 Å) transitions. A comparison of these results with observational data for a sample of planetar
The National Academy of Sciences.
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9. Interpretation of two compact planetary nebulae, IC 4997 and NGC 6572, with aid of theoretical models.
Observations of two dense compact planetary nebulae secured with the Hamilton Echelle spectrograph at Lick Observatory combined with previously published UV spectra secured with the International Ultraviolet Explorer enable us to probe the electron densities and temperatures (plasma diagnostics) and ionic concentrations in these objects. The diagnostic diagr
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10. Theoretical emission line ratios for [Fe III] and [Fe VII] applicable to the optical and infrared spectra of gaseous nebulae
Recent calculations of electron impact excitation rates and Einstein A-coefficients for transitions among the 3d6 levels of Fe III and among the 3d2 levels of Fe VII are used to derive theoretical emission line ratios applicable to the optical and infrared spectra of gaseous nebulae. Results for [Fe III] are generated for electron temperatures Te = 7,
National Academy of Sciences.
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11. Chemical composition of gaseous nebula NGC 6302
The irregular emission nebula NGC 6302 exhibits a rich spectrum of lines ranging in excitation from [NI] to [FeVII]. An assessment of available spectroscopic data, covering a large intensity range, indicates excess of helium and nitrogen as compared with average planetary nebulae, but deficiencies in iron and calcium. These metals are presumably tied up in s
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12. The remarkably high excitation planetary nebula GC 6537
NGC 6537 is an unusually high excitation point symmetric planetary nebula with a rich spectrum. Its kinematical structures are of special interest. We are here primarily concerned with the high resolution spectrum as revealed by the Hamilton echelle Spectrograph at Lick Observatory (resolution ≈ 0.2 Å) and supplemented by UV and near-UV data. These exten
The National Academy of Sciences.