Low-ionization structures in planetary nebulae -- II. Densities, temperatures, abundances and excitation of 6 PNe

Abstract

Here we present the spatially resolved study of six Galactic planetary nebulae (PNe), namely IC 4593, Hen 2-186, Hen 2-429, NGC 3918, NGC 6543 and NGC 6905, from intermediate-resolution spectra of the 2.5 m Isaac Newton Telescope and the 1.54 m Danish telescope. The physical conditions (electron densities, N${}_e$, and temperatures, T${}_e$), chemical compositions and dominant excitation mechanisms for the different regions of these objects are derived, in an attempt to go deeper on the knowledge of the low-ionization structures (LISs) hosted by these PNe. We reinforce the previous conclusions that LISs are characterized by lower (or at most equal) N${}_e$ than their associated rims and shells. As for the T${}_e$, we point out a \textit{possible} different trend between the N and O diagnostics. T${}_e$[NII] does not show significant variations throughout the nebular components, whereas T${}_e$[OIII] appears to be slightly higher for LISs. The much larger uncertainties associated with the T${}_e$[OIII] of LISs do not allow robust conclusions. Moreover, the chemical abundances show no variation from one to another PN components, not even contrasting LISs with rims and shells, as also found in a number of other works. By discussing the ionization photon flux due to shocks and stellar radiation, we explore the possible mechanisms responsible for the excitation of LISs. We argue that the presence of shocks in LISs is not negligible, although there is a strong dependence on the orientation of the host PNe and LISs.

References in corpus (64)

• Improving Predictions for Helium Emission Lines
• The Hα surface brightness - radius relation: a robust statistical distance indicator for planetary nebulae
• Ionization Correction Factors for Planetary Nebulae: I- Using optical spectra
• Sulfur, Chlorine, and Argon Abundances in Planetary Nebulae. IV: Synthesis and the Sulfur Anomaly
• Binary planetary nebulae nuclei towards the Galactic bulge. II. A penchant for bipolarity and low-ionisation structures
• A deep survey of heavy element lines in planetary nebulae - I. Observations and forbidden-line densities, temperatures and abundances
• Low-ionization structures in planetary nebulae: confronting models with observations
• Planetary Nebula Abundances and Morphology: Probing the Chemical Evolution of the Milky Way
• Knots in the Helix Nebula found in H2
• HST Measurements of the Expansion of NGC 6543: Parallax Distance and Nebular Evolution
• Common Envelope Shaping of Planetary Nebulae
• Understanding and reducing statistical uncertainties in nebular abundance determinations
• On expansion parallax distances for planetary nebulae
• Catalogue of central stars of planetary nebulae: Expanded edition
• Analysis of chemical abundances in planetary nebulae with [WC] central stars. II. Chemical abundances and the abundance discrepancy factor
• Chemical compositions and plasma parameters of planetary nebulae with Wolf-Rayet and wels type central stars
• Sulfur, Chlorine, and Argon Abundances in Planetary Nebulae. III: Observations and Results for a Final Sample
• The Iron abundance in Galactic Planetary Nebulae
• Three-dimensional photoionization modelling of the planetary nebula NGC 3918
• S-process enrichment in the planetary nebula NGC 3918. Results from deep echelle spectrophotometry
• Shaping Planetary Nebulae by Light Jets
• High-velocity collimated outflows in planetary nebulae: NGC 6337, He 2-186, and K 4-47
• A New Look At Carbon Abundances In Planetary Nebulae. III. DDDM1, IC 3568, IC4593, NGC 6210, NGC 6720, NGC 6826, & NGC 7009
• IPHAS extinction distances to Planetary Nebulae
• The Dynamical Evolution of Planetary Nebulae After the Fast Wind
• The physical parameters, excitation and chemistry of the rim, jets and knots of the planetary nebula NGC 7009
• Jets, knots and tails in planetary nebulae: NGC 3918, K 1-2 and Wray 17-1
• On the nitrogen abundance of FLIERs: the outer knots of the planetary nebula NGC 7009
• H${}_2$ in low-ionization structures of planetary nebulae
• A Detailed Morpho-Kinematic Model of the Eskimo, NGC 2392. A Unifying View with the Cat's Eye and Saturn Planetary Nebulae
• On the Production of He, C and N by Low and Intermediate Mass Stars: A Comparison of Observed and Model-Predicted Planetary Nebula Abundances
• The evolution of Galactic planetary nebula progenitors through the comparison of their nebular abundances with AGB yields
• The extinction and dust-to-gas structure of the planetary nebula NGC 7009 observed with MUSE
• Models of the Mass-Ejection Histories of pre Planetary Nebulae, IV. Magnetized Winds and the Origins of Jets, Bullets, and FLIERs
• FLIERs as stagnation knots from post-AGB winds with polar momentum deficiency
• Common Envelope Shaping of Planetary Nebulae. II. Magnetic Solutions and Self-Collimated Outflows
• Extended Structures of Planetary Nebulae Detected in H${}_2$ Emission
• Common Envelope Shaping of Planetary Nebulae. III. The Launching of Jets in Proto-Planetary Nebulae
• On the relationship between the H2 emission and the physical structure of planetary nebulae
• Low-ionization pairs of knots in planetary nebulae: physical properties and excitation
• K 4-47: a planetary nebula excited by photons and shocks
• Hu1-2: a metal-poor bipolar planetary nebula with fast collimated outflows
• Space Velocity and Time Span of Jets in Planetary Nebulae
• Recombination Line vs. Forbidden Line Abundances in Planetary Nebulae
• The MUSE view of the planetary nebula NGC 3132
• Exploring the differences of integrated and spatially resolved analysis using integral field unit data: The case of Abell 14
• An Imaging Spectroscopic Survey of the Planetary Nebula NGC 7009 with MUSE
• Independent Emission and Absorption Abundances for Planetary Nebulae
• High velocity string of knots in the outburst of the Planetary Nebula Hb4
• Models of the Mass-Ejection Histories of pre Planetary Nebulae, III. The Shaping of Lobes by post-AGB Winds
• H${}_2$ emission in the low-ionisation structures of the Planetary Nebulae NGC 7009 and NGC 6543
• 3-D modelling of the collimated bipolar outflows of compact planetary nebulae with WR-type central stars
• Rings and arcs around evolved stars. II. The Carbon Star AFGL 3068 and the Planetary Nebulae NGC 6543, NGC 7009 and NGC 7027
• IFU spectroscopy of Southern Planetary Nebulae V: Low-ionization structures
• Fast, low-ionization emission regions of the planetary nebula M2-42
• Knots in the outer shells of the planetary nebulae IC 2553 and NGC 5882
• Are He and N Abundances in Type I PNe as High as Empirically Derived?
• Distance mapping applied to four well-known planetary nebulae and a nova shell
• Spectroscopy of southern Galactic disk planetary nebulae. Notes on chemical composition and emission-line stars
• Spectroscopic Analysis Tool for intEgraL fieLd unIt daTacubEs (satellite): Case studies of NGC 7009 and NGC 6778 with MUSE
• Pushing the limits: detecting H2 emission from faint bipolar planetary nebulae in the IPHAS sample
• The kinematical behaviour of ORLs and CELs in Galactic PNe
• Chemistry and physical properties of the born-again planetary nebula HuBi 1
• The case of NGC 6302: The impact of shocks in the derivation of Nitrogen abundances

Cited by in corpus (7)

• Low-ionization structures in planetary nebulae -- III. The statistical analysis of physico-chemical parameters and excitation mechanisms
• Detection of the [C I] $\lambda$8727 emission line. Low-ionization structures in NGC 7009
• Long and short term variability of the possible nascent planetary nebula IRAS 22568+6141: A late thermal pulse?
• H${}_2$ molecular gas in the old planetary nebula NGC 3587
• Andromeda's tenuous veil: A likely Milky Way nebula projected toward M31
• Low-ionization structures in planetary nebulae -- IV. The molecular hydrogen counterpart
• [Fe II] 1.644$\mu$m imaging survey of planetary nebulae with low-ionisation structures