Zobrazeno 1 - 10
of 141
pro vyhledávání: '"Costa, R. D. D."'
High nitrogen abundance is characteristic of Type I planetary nebulae as well as their highly filamentary structure. In the present work we test the hypothesis of shocks as a relevant excitation mechanism for a Type-I nebula, NGC 6302, using recently
Externí odkaz:
http://arxiv.org/abs/1908.08053
Autor:
Mollá, M., Díaz, Á. I., Cavichia, O., Gibson, B. K., Maciel, W. J., Costa, R. D. D., Ascasibar, Y., Few, C. G.
We study the evolution of oxygen abundance radial gradients as a function of time for the Milky Way Galaxy obtained with our {\sc Mulchem} chemical evolution model. We review the recent data of abundances for different objects observed in our Galacti
Externí odkaz:
http://arxiv.org/abs/1810.09182
Autor:
Maciel, W. J., Costa, R. D. D.
A sample of AGB/RGB stars with an excess of Li abundances is considered in order to estimate their mass loss rates. Our method is based on a correlation between the Li abundances and the stellar luminosity, using a modified version of Reimers formula
Externí odkaz:
http://arxiv.org/abs/1805.05164
Abundances in photoionized nebulae of the Local Group and nucleosynthesis of intermediate mass stars
Photoionized nebulae, comprising HII regions and planetary nebulae, are excellent laboratories to investigate the nucleosynthesis and chemical evolution of several elements in the Galaxy and other galaxies of the Local Group. Our purpose in this inve
Externí odkaz:
http://arxiv.org/abs/1702.03721
Planetary nebulae (PNe) constitute an important tool to study the chemical evolution of the Milky Way and other galaxies, probing the nucleosynthesis processes, abundance gradients and the chemical enrichment of the interstellar medium. In particular
Externí odkaz:
http://arxiv.org/abs/1702.02900
Photoionized nebulae comprise basically HII regions and planetary nebulae, and their abundances give important clues on the nucleosynthesis and chemical evolution of their host galaxies. There is presently a large amount of data on these objects, esp
Externí odkaz:
http://arxiv.org/abs/1612.04565
Planetary nebulae are the products of the evolution of low and intermediate mass stars. The chemical property studies of these objects give important information about the elemental abundances as He, O, Ne, Ar, S and their modifications associated wi
Externí odkaz:
http://arxiv.org/abs/1612.03672
Autor:
Mollá, M., Díaz, A. I., Ascasibar, Y., Gibson, B. K., Cavichia, O., Costa, R. D. D., Maciel, W. J.
The aim of this work is to present our new series of chemical evolution models computed for spiral and low mass galaxies of different total masses and star formation efficiencies. We analyze the results of models, in particular the evolution of the r
Externí odkaz:
http://arxiv.org/abs/1612.03348
We review the state of our chemical evolution models for spiral and low mass galaxies. We analyze the consequences of using different stellar yields, infall rate laws and star formation prescriptions in the time/redshift evolution of the radial distr
Externí odkaz:
http://arxiv.org/abs/1612.03064
Autor:
Maciel, W. J., Costa, R. D. D.
Most metal-rich AGB/RGB stars present strong Li underabundances, since this element is easily destroyed in the high temperatures of the stellar interiors. In spite of this fact, several of these stars are Li-rich, having Li abundances given by log (L
Externí odkaz:
http://arxiv.org/abs/1609.06505