Oxygen enrichment in carbon-rich planetary nebulae

Delgado-Inglada, G.; Rodríguez, Mónica; Peimbert, M.; Stasińska, G.; Morisset, Charles

doi:10.1093/mnras/stv388

Cited by 75 publications

(123 citation statements)

References 76 publications

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“…As we already mentioned before, our sample A DC PNe is biased towards compact (<4 in diameter, with the exception of H 1-50 and M 1-60 which are 10 in diameter) and (presumably) young PNe but, accidentally, it is mostly composed (6/9) by sub-solar metallicity objects with no significant He and N enrichment. This kind of objects do not dominate the bulk of compact and presumably young DC PNe previously studied by García-Hernández & Górny (2014) neither the DC PNe samples B and C previously studied in the literature (García-Rojas et al 2013;Delgado-Inglada et al 2015;García-Hernández et al 2016b). In principle, both sample B and C objects are also relatively compact.…”

Section: Discussionmentioning

confidence: 71%

C/O ratios in planetary nebulae with dual-dust chemistry from faint optical recombination lines

García‐Rojas

Delgado-Inglada

García–Hernández

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present deep high-resolution (R∼15,000) and high-quality UVES optical spectrophotometry of nine planetary nebulae with dual-dust chemistry. We compute physical conditions from several diagnostics. Ionic abundances for a large number of ions of N, O, Ne, S, Cl, Ar, K, Fe and Kr are derived from collisionally excited lines. Elemental abundances are computed using state-of-the-art ionization correction factors. We derive accurate C/O ratios from optical recombination lines. We have re-analyzed additional high-quality spectra of 14 PNe from the literature following the same methodology. Comparison with asymptotic giant branch models reveal that about half of the total sample objects are consistent with being descendants of low-mass progenitor stars (M < 1.5 M ). Given the observed N/O, C/O, and He/H ratios, we cannot discard that some of the objects come from more massive progenitor stars (M > 3-4 M ) that have suffered a mild HBB. None of the objects seem to be descendant of very massive progenitors. We propose that in most of the planetary nebulae studied here, the PAHs have been formed through the dissociation of the CO molecule. The hypothesis of a last thermal pulse that turns O-rich PNe into C-rich PNe is discarded, except in three objects, that show C/O>1. We also discuss the possibility of a He pre-enrichment to explain the most Heenriched objects. We cannot discard another scenarios like extra mixing, stellar rotation or binary interactions to explain the chemical abundances behaviour observed in our sample.

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Section: Discussionmentioning

confidence: 71%

C/O ratios in planetary nebulae with dual-dust chemistry from faint optical recombination lines

García‐Rojas

Delgado-Inglada

García–Hernández

et al. 2017

Monthly Notices of the Royal Astronomical Society

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“…Finally, Delgado-Inglada et al (2014) compute a large grid of photoionization models covering a wide range of physical parameters representative of PNe. This work includes an ICF (Cl 2+ /O + ) that can be applicable for H ii region conditions (Delgado-Inglada et al 2015). In Table 10 we compare our direct determinations of the Cl/H ratios for the H ii regions sample with the values we obtain using our quoted Cl 2+ /H + ratios and the ICF schemes mentioned above.…”

Section: An Empirical Ionization Factor For CLmentioning

confidence: 99%

The radial abundance gradient of chlorine in the Milky Way

Esteban¹,

García‐Rojas²,

Pérez-Mesa³

2015

Mon. Not. R. Astron. Soc.

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We determine the radial abundance gradient of Cl in the Milky Way from H ii regions spectra. For the first time, the Cl/H ratios are computed by simply adding ionic abundances and not using an ionization correction factor (ICF ). We use a collection of published very deep spectra of Galactic H ii regions. We have re-calculated the physical conditions, ionic and total abundances of Cl and O using the same methodology and updated atomic data for all the objects. We find that the slopes of the radial gradients of Cl and O are identical within the uncertainties: −0.043 dex kpc −1 . This is consistent with a lockstep evolution of both elements. We obtain that the mean value of the Cl/O ratio across the Galactic disc is log(Cl/O) = −3.42 ± 0.06. We compare our Cl/H ratios with those determined from Cl 2+ abundances and using some available ICF schemes of the literature. We find that our total Cl abundances are always lower than the values determined using ICF s, indicating that those correction schemes systematically overestimate the contribution of Cl + and Cl 3+ species to the total Cl abundance. Finally, we propose an empirical ICF (Cl 2+ ) to estimate the Cl/H ratio in H ii regions.

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“…The purpose of our investigation here is to confront recently published stellar model predictions of PN abundances with the observed abundances of He, C, N and O. We consider the models of four 2 We qualify this seemingly tidy picture by pointing out that oxygen enrichment in PN has been reported by Péquignot et al (2000) and more recently in C-rich PN by Delgado-Inglada et al (2015) and García-Hernández et al (2016).…”

Section: Introductionmentioning

confidence: 99%

On the production of He, C, and N by low- and intermediate-mass stars: a comparison of observed and model-predicted planetary nebula abundances

Henry

Stephenson

Bertolami

et al. 2017

Monthly Notices of the Royal Astronomical Society

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The primary goal of this paper is to make a direct comparison between the measured and modelpredicted abundances of He, C and N in a sample of 35 well-observed Galactic planetary nebulae (PN). All observations, data reductions, and abundance determinations were performed in house to ensure maximum homogeneity. Progenitor star masses (M ≤ 4 M ⊙ ) were inferred using two published sets of post-AGB model tracks and L and T ef f values. We conclude the following: 1) the mean values of N/O across the progenitor mass range exceeds the solar value, indicating significant N enrichment in the majority of our objects; 2) the onset of hot bottom burning appears to begin around 2 M ⊙ , i.e., lower than ∼ 5 M ⊙ implied by theory; 3) most of our objects show a clear He enrichment, as expected from dredge-up episodes; 4) the average sample C/O value is 1.23, consistent with the effects of third dredge-up; and 5) model grids used to compare to observations successfully span the distribution over metallicity space of all C/O and many He/H data points but mostly fail to do so in the case of N/O. The evident enrichment of N in PN and the general discrepancy between the observed and model-predicted N/O abundance ratios signal the need for extra-mixing as an effect of rotation and/or thermohaline mixing in the models. The unexpectedly high N enrichment that is implied here for low mass stars, if confirmed, will likely impact our conclusions about the source of N in the Universe.

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Oxygen enrichment in carbon-rich planetary nebulae

Cited by 75 publications

References 76 publications

C/O ratios in planetary nebulae with dual-dust chemistry from faint optical recombination lines

C/O ratios in planetary nebulae with dual-dust chemistry from faint optical recombination lines

The radial abundance gradient of chlorine in the Milky Way

On the production of He, C, and N by low- and intermediate-mass stars: a comparison of observed and model-predicted planetary nebula abundances

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