Tag Archives: oxygen

The chemical composition of Galactic ring nebulae around massive stars

C. Esteban (1,2), A. Mesa-Delgado (3), C. Morisset (4), J. Garcia-Rojas (1,2) (1) Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain. (2)Departamento de Astrofísica, Universidad de La Laguna, E-38206, La Laguna, Tenerife, Spain. (3) Instituto de Astrofísica, Facultad … Continue reading

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Physical properties of the interstellar medium using high-resolution Chandra spectra: O K-edge absorption

E. Gatuzz (1), J. García (2), C. Mendoza (1,3), T. R. Kallman (4), M. A. Bautista (3), T. W. Gorczyca (3) (1) Centro de Física, Instituto Venezolano de Investigaciones Científicas (IVIC), PO Box 20632, Caracas 1020A, Venezuela, (2) Harvard-Smithsonian Center … Continue reading

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Photoionization modeling of oxygen K absorption in the interstellar medium: the Chandra grating spectra of XTE J1817-330

E. Gatuzz (1), J. García (2), C. Mendoza (1,4), T. R. Kallman (3), M. Witthoeft (3), A. Lohfink (2), M. A. Bautista (5), P. Palmeri (6) and P. Quinet (7) ((1) Centro de Física, Instituto Venezolano de Investigaciones Científicas, PO … Continue reading

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Influence of Departures from LTE on Oxygen Abundance Determination

Sitnova, T. M. (1,2), Mashonkina, L. I. (1) and Ryabchikova, T. A. (1) ((1) Institut of Astronomy of RAS, Moscow, Russia; (2) Moscow M.V. Lomonosov State University, Moscow, 119991 Russia) We performed non-LTE calculations for O I with the plane-parallel … Continue reading

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Oxygen abundances from optical O I and O II recombination lines in planetary nebulae with [WC] central stars

Jorge García-Rojas (Instituto de Astrofísica de Canarias, Spain) I will present the analysis of very deep echelle spectra of a dozen planetary nebulae with [WC] or weak emission lines (wels) central stars. Physical conditions (electron density and temperature) are derived … Continue reading

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Temperature fluctuations in ionized nebulae and their effect on the oxygen abundance determination

Antonio Peimbert (Instituto de Astronomia–UNAM, Mexico) The two most common ways of determining chemical abundances on ionized regions are: 1.- the one that comes from assuming homogeneous temperature and using the observed collisionally excited line ratios (the direct method) and … Continue reading

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Oxygen abundances in ionized nebulae from photoionization model fitting

Christophe Morisset (Instituto de Astronomia-­UNAM, Mexico) In this talk I will present a review on the determination of oxygen abundance from photoionization models of nebulae. I will first describe the way models are performed using photoionization codes, explaining the necessary … Continue reading

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The reliability of atomic data used for oxygen abundance determinations

Claudio Mendoza (IVIC, Caracas,  and CeCalCULA, CPTM, Mérida, Venezuela) The reliability of the atomic data required in astrophysical applications, in particular in abundance determinations, has been a perennial concern to the few research groups that cater for this well-established data demand. In … Continue reading

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Temperature-­based oxygen abundances in H II regions and PNe: methods and uncertainties

Mónica Rodríguez ( INAOE, Mexico) The oxygen abundances of H II regions and planetary nebulae (PNe) provide crucial clues for our understanding of galactic chemical evolution, especially when they are compared with each other and with the abundances derived for stars of … Continue reading

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Oxygen abundance determinations in OB dwarfs and supergiants

Miguel A. Urbaneja (University of Hawaii, Institute for Astronomy, USA) OB type stars are part of a young stellar population in star-forming galaxies that is coeval with H II regions. Their optical spectra present a large number of oxygen lines, … Continue reading

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