Ministerio de Economía y Competitividad Gobierno de Canarias Universidad de La Laguna CSIC Centro de Excelencia Severo Ochoa

Astrophysics Research Projects

Physic of Stars, Planetary Systems and the Interstellar Medium

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Chemical Composition of Ionized Nebulae (P/308614)

J GARCÍA ROJAS

C. Esteban López, Laura Toribio San Cipriano, Simone Madonna

Colaboradores del IAC: Miguel Cerviño Saavedra

A.R. López-Sánchez (AAO, Australia); A. Mesa-Delgado (PUC, Chile); F. Bresolin (IfA, Hawai); C. Morisset, L. Carigi, M. Peimbert, M. Peña, G. Delgado-Inglada (IA-UNAM, MExico); M. Rodríguez, G. Domínguez-Guzmán (INAOE, Mexico); X. Fang (University of Hong Kong); N.C. Sterling (University of West Georgia); R. Wesson (UCL, UK); H. Monteiro (U. Itajubá, Brazil), H. Boffin (ESO, Germany)

Introduction

This project is devoted to study the structure, dynamics, physical conditions and chemical evolution of Galactic and extragalactic ionized nebulae through detailed analysis and modelization of their spectra.

Milestones

Deep spectra (taken with VLT and GTC) from several HII regions were analyzed in the spiral galaxies NGC 300 and M33. The gradients of O and C were determined finding that, in both cases, the C/H gradient is stepper than that of O/H. Comparing with other spiral galaxies, there is a strong correlation between the gradient slope of C/H (also N/H) and the absolute magnitude of the galaxy. Some H II regions located in outer zones of NGC 300 and M33 show a C/O more similar to typical dwarf galaxies than to H II regions in spirals. This may be related to the absence of flattening of the gradients in the outer parts of both galaxies.

The first direct image of the high-metallicity gas component in a planetary nebula (NGC 6778) has been obtained using the OSIRIS Blue Tunable Filter centered on the O II λ4649+50 Å optical recombination lines (ORLs) at the 10.4 m Gran Telescopio Canarias. The emission of these faint O II ORLs is concentrated in the central parts of the planetary nebula and is not spatially coincident either with emission coming from the bright [O III] λ5007 Å collisionally excited line (CEL) or the bright Hαrecombination line. The centrally peaked distribution of the O II emission and the differences with the [O III] and H I emission profiles are consistent with the presence of an H-poor gas whose origin may be linked to the binarity of the central star. However, determination of the spatial distribution of the ORLs and CELs in other PNe and a comparison of their dynamics are needed to further constrain the geometry and ejection mechanism of the metal-rich (H-poor) component and hence, understand the origin of the abundance discrepancy problem in PNe.

n-capture element emission lines have been detected for the first time inMagellanic Cloud PNe. Near-infrared spectra of 10 planetary nebulae (PNe) were obtained in the LMC and SMC, acquired with the FIRE and GNIRS spectrometers on the 6.5 m Baade and 8.1 m Gemini South Telescopes, respectively. The abundance analysis shows large s-process enrichments of Kr and Se in about half of the sample of PNe. Upper limits to Rb and Cd abundances in these objects have been also estimated. Abundance results for the LMC are consistent with the hypothesis that PNe with 2-3 M progenitors dominate the bright end of the PN luminosity function in young gas-rich galaxies. These results demonstrate that n-capture elements can be detected in PNe belonging to nearby galaxies with ground-based telescopes, allowing s-process enrichments to be studied in PN populations with well-determined distances.

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