Chemical abundances for Hf 2-2, a planetary nebula with the strongest-known heavy-element recombination lines

Xw, Liu; Barlow, M. J.; Zhang, Yong; Bastin, RJ; Storey, P. J.

doi:10.1111/j.1365-2966.2006.10283.x

Cited by 98 publications

(171 citation statements)

References 29 publications

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“…In PNe, these estimatives show high values. As examples, Liu et al (2006) found t 2 ≈ 0.14 for Hf 2-2, and Krabbe & Copetti (2006) found t 2 ≈ 0.09 for NGC 3242 and NGC 7009 to obtain consistent O ++ /H + estimates derived from RLs and CELs. A discrete estimation of t 2 on the plane of the sky can be computed from point-to-point measurements of temperature, following the procedure proposed by Liu (1998).…”

Section: Magnitude Of the Electron Temperature Fluctuationsmentioning

confidence: 73%

Spectroscopic mapping of the planetary nebula NGC 6302

Rauber

Copetti

Krabbe

2014

A&A

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Context. Most spectroscopic studies of planetary nebulae (PNe) are based on data from specific parts of the objects. Considering the high complexity of their morphological structures, integrated or average values across an observed region can only provide limited information of their ionic, density, and temperature structures. Aims. We investigate the spatial variation of the physical and chemical properties of NGC 6302, a high-ionization PNe, with a complex bipolar structure. Methods. Spatially resolved long-slit spectroscopic data were obtained from 11 parallel and equally spaced directions over the nebula. Integrated spectra were also obtained and 142 lines were identified. Results. The electron density maps show a peaked distribution, with the densest area at the circumstellar region, reaching N e ≈ 40 000 cm −3 , and decreasing to N e ≤ 1000 cm −3 at the lobes. Knots were observed in the N e (S ii) map, with 2000 cm −3 < N e < 3000 cm −3 . The N e (Ar iv) map suggests the presence of an inner region with N e ≈ 20 000 cm −3 that extends from the center through the east lobe. A homogeneous temperature distribution was found for both T e (O iii) and T e (N ii). Small temperature fluctuations on the plane of the sky of t 2 s (N ii) = 0.0071 and t 2 s (O iii) = 0.0043 were estimated.Conclusions. In general, the total abundances obtained are similar to the maximum found in the ionic abundance maps of the dominant ionic species. This demonstrates the potential of spatially resolved abundance studies for establishing lower limits of the total abundances based on ionic abundances, for checking the ionization correlation factors, and in some cases, for determining the total abundances directly from maps of ionic abundances.

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Section: Magnitude Of the Electron Temperature Fluctuationsmentioning

confidence: 73%

Spectroscopic mapping of the planetary nebula NGC 6302

Rauber

Copetti

Krabbe

2014

A&A

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“…Liu et al (2006) presented an extreme abundance discrepancy factor (ADF) of about 70 for this nebula (the typical ADF is ∼ 2 for most PNe). The ADF is a quantification of the abundance discrepancy, found in PNe and HII regions, between abundances determined from optical recombination lines and those found from collisionally excited lines (Liu 2006).…”

Section: Hf 2-2 (Png0051-089)mentioning

confidence: 92%

A pilot study of the radio‐continuum emission from MASH planetary nebulae

et al. 2011

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Key words astronomical data bases: miscellaneous -planetary nebulae: general -radiation mechanisms: thermal -radio continuum: ISM We report an Australia Telescope Compact Array (ATCA) radio-continuum observations of 26 planetary nebulae (PNe) at wavelengths of 3 and 6 cm. This sample of 26 PNe were taken from the Macquarie/AAO/Strasbourg Hα PNe (MASH) catalogue and previous lists. We investigate radio detection quality including measured and derived parameters for all detected or marginally detected PNe from this combined sample. Some 11 objects from the observed sample have been successfully detected and parametrized. Except for one, all detected PNe have very low radio surface brightnesses. We use a statistical distance scale method to calculate distances and ionised masses of the detected objects. Nebulae from this sample are found to be large (>0.2 pc in diameter) and highly diluted which indicates old age. For 21 PNe from this sample we list integrated Hα fluxes and interstellar extinction coefficients, either taken from the literature or derived here from the Balmer decrement and radio to Hα ratio methods. Finally, our detected fraction of the MASH pilot sample is relatively low compared to the non-MASH sub-sample. We conclude that future radio surveys of the MASH sample must involve deeper observations with better uv coverage in order to increase the fraction of detected objects and improve the quality of the derived parameters.

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“…Owing to this procedure, the RLs abundances for PNe should be considered as only indicative. Liu et al (2006) report that for most galactic PNe, ADFs are in the range of 1.6 to 3. Likewise, Peimbert et al (1995a) determined ADFs for many galactic PNe and computed similar ADF values.…”

Section: Observational Constraintsmentioning

confidence: 99%

Planetary nebulae as observational constraints in chemical evolution models for NGC 6822

Hernández-Martínez

Carigi

Peña

et al. 2011

A&A

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Aims. Chemical evolution models are useful for understanding the formation and evolution of stars and galaxies. Model predictions will be more robust when more observational constraints are used. We present chemical evolution models for the dwarf irregular galaxy NGC 6822 using chemical abundances of old and young planetary nebulae (PNe) and H ii regions as observational constraints. We use two sets of chemical abundances, one derived from collisionally excited lines (CELs) and one from recombination lines (RLs). We use our models as a tool to distinguish between both procedures for abundance determinations. Methods. In our chemical evolution code the chemical contribution of low and intermediate mass stars is time-delayed, while for the massive stars the chemical contribution follows the instantaneous recycling approximation. Our models have two main free parameters: the mass-loss rate of a well-mixed outflow and the upper mass limit, M up , of the initial mass function (IMF). To reproduce the gaseous mass and the present-day O/H value we need to vary the outflow rate and the M up value. Results. We calculate two models with different M up values that reproduce the constraints adequately. The abundances of old PNe agree with our models and support the star-formation history derived independently from photometric data. Both require an early wellmixed wind, lasting 5.3 Gyr, to reproduce the observed gaseous mass in the galaxy. In addition, by assuming a fraction of binaries producing SNIa of 1%, the models fit the Fe/H abundance ratio as derived from A supergiants. The first model (M4C), which assumes M up = 40 M , fits within errors smaller than 2σ the O/H, Ne/H, S/H, Ar/H and Cl/H abundances obtained from CELs for old and young PNe and H ii regions. The second model (M1R), which adopts M up = 80 M , reproduces within 2σ errors the O/H, C/H, Ne/H and S/H abundances adopted from RLs. Both models reproduce the increase of the O, Ne, S, and Ar elements during the last 6 Gyr. We are not able to match the observed N/O ratios in either case, which suggests that the N yields of LIMS need to be improved. Model M1R does not provide a good fit to the Cl/H and Ar/H ratios, because the SN yields of those elements for m > 40 M are not adequate and need to be improved (two sets of yields were tried). From these results we are unable to conclude which set of abundances (the one from CELs or the one from RLS) represents the real abundances in the ISM better. We discuss the predicted ΔY/ΔO values, finding that the value from model M1R agrees better with data for other galaxies from the literature than the value from model M4C.

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Chemical abundances for Hf 2-2, a planetary nebula with the strongest-known heavy-element recombination lines

Cited by 98 publications

References 29 publications

Spectroscopic mapping of the planetary nebula NGC 6302

Spectroscopic mapping of the planetary nebula NGC 6302

A pilot study of the radio‐continuum emission from MASH planetary nebulae

Planetary nebulae as observational constraints in chemical evolution models for NGC 6822

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