Alpha Element Abundances in a Large Sample of Galactic Planetary Nebulae

Milingo, J. B.; Kwitter, K. B.; Henry, R. B. C.; Souza, S. P.

doi:10.1088/0004-637x/711/2/619

Cited by 61 publications

(69 citation statements)

References 40 publications

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“…These objects, observed in 2003 and 2004 with the Kitt Peak National Observatory 2.1 m telescope or the Cerro Tololo Inter-American Observatory (CTIO) 1.5 m telescope, are listed at the bottom of Table 1. See Section 2 in Milingo et al (2010) for details on the instrumental configurations and observing procedures. These data were also analyzed in the standard fashion using IRAF, as outlined above.…”

Section: Kpno and Ctio Observationsmentioning

confidence: 99%

“…Figure 1 is a plot of 12+log(O/H) versus galactocentric distance (Table 6, Column 3) in kpc for the 124 objects in our PN sample with well-measured distances. The PN sample is a compilation of objects from Henry et al (2004), Milingo et al (2010), plus those objects reported upon for the first time in this paper (HK10). Our sample contains only those objects classified as either Type I or Type II, i.e., objects whose location and kinematics indicate that their progenitors were members of the disk population.…”

Section: The Determination Of the Oxygen Gradientmentioning

confidence: 99%

“…While our earlier papers have looked at abundance gradients (Henry et al 2004) and element-to-element ratios (Milingo et al 2010) for several elements in great detail, for the current study we chose instead to carry out a rigorous statistical determination of the oxygen gradient since ions of oxygen, the most abundant alpha element, are readily observed, and accurate abundance measurements can be carried out.…”

Section: Introductionmentioning

confidence: 99%

“…First, our PN sample is completely homogeneous: we have performed all of the observations ourselves using only three instrumental systems (KPNO, CTIO, and APO), all data have been carefully reduced in a uniform way, and the temperatures, densities, and abundances have been computed in a consistent fashion using the same code-and the same atomic 8 There is some evidence that the original progenitor levels of O and Ne can be altered as a result of CNO processing (Péquignot et al 2000;Wang & Liu 2008;Milingo et al 2010). However, because this idea has yet to be firmly established, in this paper we shall assume that PN oxygen levels are unchanged from the levels inherited by the progenitor star from the ISM at birth.…”

Section: Introductionmentioning

confidence: 99%

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Abundances of Galactic Anticenter Planetary Nebulae and the Oxygen Abundance Gradient in the Galactic Disk

Henry

Kwitter

Jaskot

et al. 2010

ApJ

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125

150

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We have obtained spectrophotometric observations of 41 anticenter planetary nebulae (PNe) located in the disk of the Milky Way. Electron temperatures and densities, as well as chemical abundances for He, N, O, Ne, S, Cl, and Ar were determined. Incorporating these results into our existing database of PN abundances yielded a sample of 124 well-observed objects with homogeneously determined abundances extending from 0.9 to 21 kpc in galactocentric distance. We performed a detailed regression analysis which accounted for uncertainties in both oxygen abundances and radial distances in order to establish the metallicity gradient across the disk to be 12 + log(O/H) = (9.09 ± 0.05) − (0.058 ± 0.006) × R g , with R g in kpc. While we see some evidence that the gradient steepens at large galactocentric distances, more objects toward the anticenter need to be observed in order to confidently establish the true form of the metallicity gradient. We find no compelling evidence that the gradient differs between Peimbert Types I and II, nor is oxygen abundance related to the vertical distance from the galactic plane. Our gradient agrees well with analogous results for H ii regions but is steeper than the one recently published by Stanghellini & Haywood over a similar range in galactocentric distance. A second analysis using PN distances from a different source implied a flatter gradient, and we suggest that we have reached a confusion limit which can only be resolved with greatly improved distance measurements and an understanding of the natural scatter in oxygen abundances.

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Section: Kpno and Ctio Observationsmentioning

confidence: 99%

Section: The Determination Of the Oxygen Gradientmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Abundances of Galactic Anticenter Planetary Nebulae and the Oxygen Abundance Gradient in the Galactic Disk

Henry

Kwitter

Jaskot

et al. 2010

ApJ

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125

150

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“…Wang & Liu (2007) concluded that Ne and O production only occurs for 12+log(O/H)<8, below even the SMC, indicating that the first possibility is likely the correct one. references, see Milingo et al (2010). 6.3.…”

Section: Neonmentioning

confidence: 99%

Reduce, reuse, recycle: Planetary nebulae as green galactic citizens

Kwitter¹,

Henry²

2011

Proc. IAU

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Abstract. We review gas-phase abundances in PNe and describe their dual utility as archives of original progenitor metallicity via the α elements, as well as sources of processed material from nucleosynthesis during the star's evolution, i.e., C, N, and s-process elements. We describe the analysis of PN spectra to derive abundances and discuss the discrepancies that arise from different choices at each step. Abundance results for the Milky Way and Magellanic Clouds from various groups of investigators are presented; the observational results are compared with theoretical predictions of AGB stellar yields. Finally, we suggest areas where more work is needed to improve our abilities to determine abundances in PNe.

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IFU Spectroscopy of Southern Planetary Nebulae V: Low-Ionisation Structures

Ali

Dopita

2017

Publ. Astron. Soc. Aust.

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In this 5th paper of the series, we examine the spectroscopy and morphology of four southern Galactic planetary nebulae Hen 2-141, NGC 5307, IC 2553, and PB 6 using new integral field spectroscopy data. The morphologies and ionization structures of the sample are given as a set of emission-line maps. In addition, the physical conditions, chemical compositions, and kinematical characteristics of these objects are derived. The results show that PB 6 and Hen 2-141 are of very high excitation classes and IC 2553 and NGC 5307 are mid to high excitation objects. The elemental abundances reveal that PB 6 is of Type I, Hen 2-141 and IC 2553 are of Type IIa, and NGC 5307 of Type IIb/III. The observations unveil the presence of welldefined low-ionization structures or "knots" in all objects. The diagnostic diagrams reveal that the excitation mechanism of these knots is probably by photo-ionization of dense material by the nebular central stars. The physical analysis of six of these knots show no significant differences with their surrounding nebular gas, except their lower electron densities. In spite of the enhancement of the low-ionization emission lines of these knots, their chemical abundances are nearly comparable to their surrounding nebulae, with the exception of perhaps slightly higher nitrogen abundances in the NGC 5307 knots. The integrated spectrum of IC 2553 reveals that nearly all key lines that have led researchers to characterize its central star as a weak-emission line star type are in fact of nebular origin.

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Alpha Element Abundances in a Large Sample of Galactic Planetary Nebulae

Cited by 61 publications

References 40 publications

Abundances of Galactic Anticenter Planetary Nebulae and the Oxygen Abundance Gradient in the Galactic Disk

Abundances of Galactic Anticenter Planetary Nebulae and the Oxygen Abundance Gradient in the Galactic Disk

Reduce, reuse, recycle: Planetary nebulae as green galactic citizens

IFU Spectroscopy of Southern Planetary Nebulae V: Low-Ionisation Structures

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