The rich O II recombination spectrum of the planetary nebula NGC 7009: new observations and atomic data

Liu, X.-W.; Storey, P. J.; Barlow, M. J.; Clegg, R. E. S.

doi:10.1093/mnras/272.2.369

Cited by 134 publications

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“…Dust continuum has been measured in the infrared with ISO and a strong excess Article published by EDP Sciences A106, page 1 of 9 A&A 588, A106 (2016) between 28 and 44 μm has been attributed to crystalline silicate (Phillips et al 2010), in agreement with the C/O ratio of ∼0.5 (Liu et al 1995;Fang & Liu 2013). Diffuse X-ray emission indicative of a gas at ∼2 × 10 6 K is detected in the central core, within the inner shell, by XMM-Newton (Guerrero et al 2002) and Chandra (Kastner et al 2012), and an X-ray point source of median energy 0.7 keV is located at the position of the central star observed by Chandra (Kastner et al 2012).…”

Section: Introductionmentioning

confidence: 57%

The extinction and dust-to-gas structure of the planetary nebula NGC 7009 observed with MUSE

Walsh

Monreal-Ibero

Barlow

et al. 2016

A&A

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Context. Dust plays a significant role in planetary nebulae. Dust ejected with the gas in the asymptotic giant branch (AGB) phase is subject to the harsh environment of the planetary nebula (PN) while the star is evolving towards a white dwarf. Dust surviving the PN phase contributes to the dust content of the interstellar medium. Aims. The morphology of the internal dust extinction has been mapped for the first time in a PN, the bright nearby Galactic nebula NGC 7009. The morphologies of the gas, dust extinction and dust-to-gas ratio are compared to the structural features of the nebula. Methods. Emission line maps in H Balmer and Paschen lines were formed from analysis of MUSE cubes of NGC 7009 observed during science verification of the instrument. The measured electron temperature and density from the same cube were employed to predict the theoretical H line ratios and derive the extinction distribution across the nebula. After correction for the interstellar extinction to NGC 7009, the internal A V /N H has been mapped for the first time in a PN. Results. The extinction map of NGC 7009 has considerable structure, broadly corresponding to the morphological features of the nebula. The dust-to-gas ratio, A V /N H , increases from 0.7 times the interstellar value to >5 times from the centre towards the periphery of the ionized nebula. The integrated A V /N H is about 2× the mean ISM value. A large-scale feature in the extinction map is a wave, consisting of a crest and trough, at the rim of the inner shell. The nature of this feature is investigated and instrumental and physical causes considered; no convincing mechanisms were identified to produce this feature, other than AGB mass loss variations. Conclusions. Extinction mapping from H emission line imaging of PNe with MUSE provides a powerful tool for revealing the properties of internal dust and the dust-to-gas ratio.

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Section: Introductionmentioning

confidence: 57%

The extinction and dust-to-gas structure of the planetary nebula NGC 7009 observed with MUSE

Walsh

Monreal-Ibero

Barlow

et al. 2016

A&A

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“…In planetary nebulae (PNe), abundances of C, N, and O derived from ORLs have been shown to be systematically larger than those derived from CELs typically by a factor of 2. Discrepancies of much larger magnitudes, say by more than a factor of 5, are also found for a small fraction of PNe (about 10%; Liu et al 1995, 2000, 2006b are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/530/A18…”

Section: Introductionmentioning

confidence: 99%

New effective recombination coefficients for nebular N ii lines

Fang

Storey

Liu

2011

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Aims. In nebular astrophysics, there has been a long-standing dichotomy in plasma diagnostics between abundance determinations using the traditional method based on collisionally excited lines (CELs), on the one hand, and (optical) recombination lines/continuum, on the other. A number of mechanisms have been proposed to explain the dichotomy. Deep spectroscopy and recombination line analysis of emission line nebulae (planetary nebulae and H ii regions) in the past decade have pointed to the existence of another previously unknown component of cold, H-deficient material as the culprit. Better constraints are needed on the physical conditions (electron temperature and density), chemical composition, mass, and spatial distribution of the postulated H-deficient inclusions in order to unravel their astrophysical origins. This requires knowledge of the relevant atomic parameters, most importantly the effective recombination coefficients of abundant heavy element ions such as C ii, O ii, N ii, and Ne ii, appropriate for the physical conditions prevailing in those cold inclusions (e.g. T e ≤ 1000 K). Methods. Here we report new ab initio calculations of the effective recombination coefficients for the N ii recombination spectrum. We have taken into account the density dependence of the coefficients arising from the relative populations of the fine-structure levels of the ground term of the recombining ion ( 2 P • 1/2 and 2 P • 3/2 in the case of N iii), an elaboration that has not been attempted before for this ion, and it opens up the possibility of electron density determination via recombination line analysis. Photoionization cross-sections, bound state energies, and the oscillator strengths of N ii with n ≤ 11 and l ≤ 4 have been obtained using the closecoupling R-matrix method in the intermediate coupling scheme. Photoionization data were computed that accurately map out the near-threshold resonances and were used to derive recombination coefficients, including radiative and dielectronic recombination. Also new is including the effects of dielectronic recombination via high-n resonances lying between the 2 P • 1/2 and 2 P • 3/2 levels. The new calculations are valid for temperatures down to an unprecedentedly low level (approximately 100 K). The newly calculated effective recombination coefficients allow us to construct plasma diagnostics based on the measured strengths of the N ii optical recombination lines (ORLs). Results. The derived effective recombination coefficients are fitted with analytic formulae as a function of electron temperature for different electron densities. The dependence of the emissivities of the strongest transitions of N ii on electron density and temperature is illustrated. Potential applications of the current data to electron density and temperature diagnostics for photoionized gaseous nebulae are discussed. We also present a method of determining electron temperature and density simultaneously.

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“…Pradhan 1976;Mendoza & Zeippen 1983). Optical recombination line data is also used within NEAT, and the atomic data come from a variety of sources (Davey et al 2000;Kisielius et al 1998;Liu et al 1995;Storey 1994;Pequignot et al 1991;Escalante & Victor 1990)-for a detailed breakdown, see Table 1 of Wesson et al (2012). Not all lines listed in Table 1 are able to be used as input to NEAT.…”

Section: Resultsmentioning

confidence: 99%

Abundances in Galactic bulge planetary nebulae from optical, ultraviolet and infrared observations

Smith

Zijlstra

Gęsicki

et al. 2017

Monthly Notices of the Royal Astronomical Society

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Iron suffers from high levels of depletion in the highly ionized environments of planetary nebulae, making the direct determination of undepleted elemental iron abundances difficult. Zinc, which does not suffer from the same depletion effects as iron, may be used as a surrogate element to measure iron abundances as there is an approximately constant zinc-to-iron ratio across a wide range of metallicities. In this paper, we report zinc abundances of six Galactic Bulge planetary nebulae determined from new observations taken with ISAAC on the Very Large Telescope, Chile, prior to the instrument's decommissioning as well as a further three based upon literature observations. UVES data of the sample planetary nebulae are presented and have been used to derive abundances, temperatures and densities of a variety of elements and ions. The abundances derived from the UVES data agree well with results from the literature. [Zn/H], determined from the ISAAC observations, is found to be generally sub-solar and [O/Zn] is found to be either consistent or enriched with respect to Solar.

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The rich O II recombination spectrum of the planetary nebula NGC 7009: new observations and atomic data

Cited by 134 publications

References 0 publications

The extinction and dust-to-gas structure of the planetary nebula NGC 7009 observed with MUSE

The extinction and dust-to-gas structure of the planetary nebula NGC 7009 observed with MUSE

New effective recombination coefficients for nebular N ii lines

Abundances in Galactic bulge planetary nebulae from optical, ultraviolet and infrared observations

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