A survey of chemical compositions of H II regions in the Magellanic Clouds

Pagel, B. E. J.; Edmunds, M. G.; Fosbury, R. A. E.; Webster, B. Louise

doi:10.1093/mnras/184.3.569

Cited by 157 publications

(122 citation statements)

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“…This homogeneity of the ISM is consistent with similar results in other irregular galaxies like the Magellanic Clouds (Pagel et al 1978;Dufour 1984), NGC 6822 (Hernández-Martínez et al 2009) and others. Considering all these examples, a nearly constant O abundance is expected for irregular galaxies, and this is found over the optical extension of NGC 3109.…”

Section: Abundances In H II Regions and Chemical Gradientssupporting

confidence: 91%

Kinematic and chemical study of planetary nebulae and H II regions in NGC 3109

Flores-Durán

Peña

Ruíz

2017

A&A

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Aims. We present high-resolution spectroscopy of a number of planetary nebulae (PNe) and H ii regions distributed along the dwarf irregular galaxy NGC 3109 and compare their kinematical behavior with that of H i data. We aim to determine if there is a kinematical connection among these objects. We also aim to determine the chemical composition of some PNe and H ii regions in this galaxy and discuss it in comparison with stellar evolution models.Methods. Data for eight PNe and one H ii region were obtained with the high-resolution spectrograph Magellan Inamori Kyocera Echelle (MIKE) at Las Campanas Observatory, Chile. Data for three PNe, six compact H ii regions, and nine knots or clumps in extended H ii regions were obtained with the high-resolution spectrograph Manchester Echelle Spectrometer (MES) attached to the 2.1m telescope at the Observatorio Astronómico Nacional, SPM, B.C., Mexico. An additional object was obtained from The SPM Catalogue of Extragalactic Planetary Nebulae. Thus, in total we have high-quality data for nine of the 20 PNe detected in this galaxy, and many H ii regions. In the wavelength calibrated spectra, the heliocentric radial velocities were measured with a precision better than 7.8 km s −1 . Data for blue supergiant stars were collected from the literature to be included in the analysis. The heliocentric radial velocities of the different objects were compared to the velocities of the H i disk at the same position. Physical conditions and ionic abundances of PNe and H ii regions were obtained from the emission lines, and we used recent ionization correction factors to derive the total chemical abundances.Results. From the analysis of radial velocities we found that H ii regions in NGC 3109 share the kinematics of the H i disk at the same projected position with very low dispersion in velocities. Blue supergiant stars and PNe rotate in the same direction as the H i disk but these objects have much larger dispersion; this larger dispersion is possibly because these objects belong to a different population that is located in the central stellar bar reported for this galaxy. From the chemical abundance determinations we demonstrate that PNe are enriched in O and Ne. The average O abundance in H ii regions is 12 + log O/H = 7.74 ± 0.09 and PNe show significantly higher oxygen abundance by 0.43 dex in average. Ne abundance are about three times larger in PNe than in H ii regions. This is a very important result showing that because of the low metallicity in the galaxy, O and Ne in PNe have been enriched by their progenitors in nucleosynthesis processes and brought to the surface during third dredge-up events. Our PN abundances are better reproduced by some nonstandard stellar evolution models for a metallicity of Z = 0.001, similar to the metallicity of H ii regions. Abundances in H ii regions show no metallicity gradient in this galaxy. We discuss a possible connection between the kinematics and chemistry.

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Section: Abundances In H II Regions and Chemical Gradientssupporting

confidence: 91%

Kinematic and chemical study of planetary nebulae and H II regions in NGC 3109

Flores-Durán

Peña

Ruíz

2017

A&A

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“…Low metallicity.-It is likely that the column density ratio N Na i /N H i is in proportion to the metallicity. Vladilo et al (1993) found that the column density ratio in the Large Magellanic Cloud (LMC) decreases in proportion to the metallicity ($0.3 Z ; Peimbert & Torres-Peimbert 1974;Pagel et al 1978). Because the metallicities of the z abs ¼ 1:062 and 1.181 DLAs are estimated to be in the range of 0.3-1.0 Z (Petitjean et al 2000), it is appropriate to interpret the estimated N H i in these systems as lower limits.…”

Section: H I Column Densities Of Each Velocity Componentmentioning

confidence: 99%

First Detection of NaiD Lines in High‐Redshift Damped Lyα Systems

Kondo

Kobayashi

Minowa

et al. 2006

ApJ

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An NIR (1.18-1.35 m) high-resolution spectrum of the gravitationally lensed QSO APM 08279+5255 was obtained with the Subaru Telescope IRCS using the AO system. We have detected strong Na i D kk5891, 5897 doublet absorption in high-redshift DLAs at z abs ¼ 1:062 and 1.181, confirming the presence of Na i, which was first reported for the rest-frame UV Na i kk3303.3, 3303.9 doublet by Petitjean et al. This is the first detection of Na i D absorption in a high-redshift (z > 1) DLA. We have also detected a new Na i component in the z abs ¼ 1:062 DLA and four new components in the z abs ¼ 1:181 DLA. Using an empirical relationship between Na i and H i column density, we found that all components have large H i column density ( log N H i ½cm À2 k 20:3), so each component is classified as DLA absorption. We also detected strong Na i D absorption associated with a Mg ii system at z abs ¼ 1:173. Because no other metal absorption lines were detected in this system at the velocity of the Na i absorption in previously reported optical spectra, we infer that this Na i absorption cloud probably appeared in the line of sight toward the QSO after the optical observation. This newly found cloud is likely to be a DLA based on its large estimated H i column density. We found that the N Na i /N Ca ii ratios in these DLAs are systematically smaller than those observed in the Galaxy; they are more consistent with the ratios seen in the LMC. This is consistent with dust depletion generally being smaller in lower metallicity environments. However, all five clouds of the z abs ¼ 1:181 system have a high N Na i /N Ca ii ratio, which is characteristic of cold dense gas. We tentatively suggest that the host galaxy of this system may be the most significant contributor to the gravitational lens toward APM 08279+5255.

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“…Because of its proximity, its high angular dimensions, and its high surface brightness, 30 Doradus (NGC 2070) is the most spectacular extragalactic H ii region and thus has been the subject of many spectrophotometric studies (e.g., Peimbert & Torres-Peimbert 1974;Aller et al 1974;Dufour 1975;Pagel et al 1978;Boeshaar et al 1980;Dufour, Shields, & Talbot 1982;Shaver et al 1983;Mathis, Chu, & Peterson 1985;Rosa & Mathis 1987;Vermeij & van der Hulst 2002;Tsamis et al 2002).…”

Section: Introductionmentioning

confidence: 99%