3D photoionization models: the bipolar PN IC 4406

A three-dimensional (3D) self-consistent photoionization code is developed in order to build more realistic models for asymmetrical and/or inhomogeneous photoionized nebulae. With these models the assumption of spherical or plane-parallel symmetry can be dropped and models with various geometries can be treated. The gaseous region is divided into numberous cubic cells, and the physical conditions in each cell are obtained taking into account the effect of the other cells in the optical depth and their contribution into the diffuse radiation. A model for IC 4406, which is a typical example of bipolar planetary nebula is presented. The model assumes a torus of dense material around the central star, as suggested in the literature. Its presence is confirmed by the model, in particular by the shape of the theoretical Hα + [NII] isophotal map. The chemical abundances required to explain the observed line intensities indicate that the chemical properties of this bipolar nebula are not characteristic of type I planetaries. A detailed paper will be published in Ap.J. (FAPESP, CNPq)

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Twenty years of observations of PM 1-188: Its chemical abundances and extraordinary kinematics

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab517 ◽

2021 ◽

Author(s):

Miriam Peña ◽

Liliana Hernández-Martínez ◽

Francisco Ruiz-Escobedo

Keyword(s):

Chemical Composition ◽

Planetary Nebula ◽

Central Star ◽

Emission Lines ◽

Type I ◽

Chemical Abundances ◽

Line Intensities ◽

Physical Conditions ◽

The Past ◽

Spectrophotometric Data

Abstract The analysis of 20 years of spectrophotometric data of the double shell planetary nebula PM 1-188 is presented, aiming to determine the time evolution of the emission lines and the physical conditions of the nebula, as a consequence of the systematic fading of its [WC 10] central star whose brightness has declined by about 10 mag in the past 40 years. Our main results include that the [O iii], [O ii], [N ii] line intensities are increasing with time in the inner nebula as a consequence of an increase in electron temperature from 11 000 K in 2005 to more than 14 000 K in 2018, due to shocks. The intensity of the same lines are decreasing in the outer nebula, due to a decrease in temperature, from 13 000 K to 7000 K, in the same period. The chemical composition of the inner and outer shells was derived and they are similar. Both nebulae present subsolar O, S and Ar abundances, while they are He, N and Ne rich. For the outer nebula the values are 12+log He/H = 11.13 ± 0.05, 12+log O/H = 8.04 ± 0.04, 12+log N/H = 7.87 ± 0.06, 12+log S/H = 7.18 ± 0.10 and 12+log Ar = 5.33 ± 0.16. The O, S and Ar abundances are several times lower than the average values found in disc non-Type I PNe, and are reminiscent of some halo PNe. From high resolution spectra, an outflow in the N-S direction was found in the inner zone. Position-velocity diagrams show that the outflow expands at velocities in the −150 to 100 km s−1 range, and both shells have expansion velocities of about 40 km s−1.

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Mapping the physical and chemical properties of the planetary nebula NGC 3242

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312011866 ◽

2011 ◽

Vol 7 (S283) ◽

pp. 448-449

Author(s):

Hektor Monteiro ◽

Denise Gonçalves ◽

Marcelo Leal-Ferreira ◽

Romano Corradi ◽

Sebastian Sánchez

Keyword(s):

Planetary Nebula ◽

Three Dimensional ◽

Chemical Properties ◽

Small Scale ◽

Chemical Abundances ◽

Electronic Density ◽

Spatially Resolved ◽

Integral Field Spectroscopy ◽

Main Components ◽

Physical And Chemical

AbstractWe present optical integral field spectroscopy analysis of the main components, with the exception of the halo, as well as of the detected small-scale structures of the planetary nebulae NGC 3242. The observations were obtained with the VIMOS instrument attached to VLT-UT3. Spatially resolved maps of the electronic density (Ne), temperatures (Te) and chemical abundances, i.e., in a pixel to pixel fashion of the small and large-scales structures of this planetary nebula are determined in this work. These diagnostic and abundance maps represent important constraints for future detailed three dimensional photoionization modeling of the nebula, as well as providing important information on biases introduced by traditional slit observations.

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

Publications of the Astronomical Society of Australia ◽

10.1017/pasa.2017.30 ◽

2017 ◽

Vol 34 ◽

Cited By ~ 8

Author(s):

A. Ali ◽

M. A. Dopita

Keyword(s):

Emission Line ◽

Planetary Nebulae ◽

Central Star ◽

Chemical Compositions ◽

Physical Analysis ◽

Type I ◽

High Excitation ◽

Chemical Abundances ◽

Physical Conditions ◽

Integral Field Spectroscopy

AbstractIn this fifth 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 ionisation 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 is of Type IIb/III. The observations unveil the presence of well-defined low-ionisation structures or ‘knots’ in all objects. The diagnostic diagrams reveal that the excitation mechanism of these knots is probably by photoionisation 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-ionisation 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 characterise its central star as a weak-emission line star type are in fact of nebular origin.

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A 3D view of the planetary nebula NGC 40

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312011854 ◽

2011 ◽

Vol 7 (S283) ◽

pp. 446-447

Author(s):

Hektor Monteiro ◽

Diego Falceta-Gonçalves

Keyword(s):

Planetary Nebula ◽

Three Dimensional ◽

Central Star ◽

Low Mass Stars ◽

Line Intensities ◽

Fitting Procedure ◽

Modeling Process ◽

Low Mass ◽

Hydrodynamical Simulations ◽

Physical And Chemical

AbstractWe present the results of a study of the planetary nebula NGC 40 with the use of the 3-D photoionization code Mocassin constrained by observational data of different types. The modeling process allows us to derive the three-dimensional nebular structure, physical and chemical characteristics and ionizing star parameters of the object by simultaneously fitting the integrated line intensities, the temperature map, density map, and the observed morphologies in different emission lines. For this particular case we combined hydrodynamical simulations with the photoionization scheme in order to obtain a self-consistent distribution of density and velocity of the nebular material. Finally, using theoretical evolutionary tracks of intermediate and low mass stars, we estimate the mass and age of the central star of NGC 40 as being 0.57 M⊙ and 5810 yr, respectively. The distance obtained from the fitting procedure was 1150 ± 170 pc.

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The Evolution of the Planetary Nebulae in the Magellanic Clouds and the Galactic Bulge

Symposium - International Astronomical Union ◽

10.1017/s0074180900172031 ◽

1993 ◽

Vol 155 ◽

pp. 433-441 ◽

Cited By ~ 3

Author(s):

M.A. Dopita

Keyword(s):

Strong Evidence ◽

Central Star ◽

Magellanic Clouds ◽

Expansion Velocity ◽

Type I ◽

Chemical Abundances ◽

Helium Burning ◽

The Third ◽

Self Consistent ◽

Central Stars

From self-consistent photoionisation modelling of 147 Magellanic Cloud PN, we have constructed the H-R Diagram for the central stars, and have derived both the chemical abundances and the nebular parameters. We find that the central stars have core masses generally between 0.55 and 0.7 M⊙, and find strong evidence to support the model that they leave the AGB as helium-burning stars following the final shell flash. Type I PN have more massive cores, up to near the Schwartzschild limit, and show clear evidence for the Third dredge-up episode. From HST images, younger PN are very compact. The expansion velocity of the nebula is closely correlated with the position of the central star on the H-R Diagram.

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Exploring the differences of integrated and spatially resolved analysis using integral field unit data: the case of Abell 14

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa383 ◽

2020 ◽

Vol 493 (2) ◽

pp. 2238-2252 ◽

Cited By ~ 3

Author(s):

Stavros Akras ◽

Hektor Monteiro ◽

Isabel Aleman ◽

Marcos A F Farias ◽

Daniel May ◽

...

Keyword(s):

Emission Line ◽

Planetary Nebula ◽

Three Dimensional ◽

Position Angle ◽

Type I ◽

Ionization State ◽

Chemical Abundances ◽

Combining Data ◽

Field Unit ◽

Integral Field

ABSTRACT We present a new approach to study planetary nebulae using integral field spectroscopy. VLT@VIMOS datacube of the planetary nebula Abell 14 is analysed in three different ways by extracting: (i) the integrated spectrum, (ii) one-dimensional simulated long-slit spectra for different position angles, and (iii) spaxel-by-spaxel spectra. These data are used to build emission-line diagnostic diagrams and explore the ionization structure and excitation mechanisms combining data from one- and three-dimensional photoionization models. The integrated and 1D simulated spectra are suitable for developing diagnostic diagrams, while the spaxel spectra can lead to misinterpretation of the observations. We find that the emission-line ratios of Abell 14 are consistent with UV photoionised emission; however, there are some pieces of evidence of an additional thermal mechanism. The chemical abundances confirm its previous classification as a Type I planetary nebula, without spatial variation. We find, though, variation in the ionization correction factors as a function of the slit’s position angle. The star at the geometric centre of Abell 14 has an A5 spectral type with an effective temperature of Teff = 7909 ± 135 K and surface gravity log(g) = 1.4 ± 0.1 cm s−2. Hence, this star cannot be responsible for the ionization state of the nebula. Gaia parallaxes of this star yield distances between 3.6 and 4.5 kpc in good agreement with the distance derived from a three-dimensional photoionization modelling of Abell 14, indicating the presence of a binary system at the centre of the planetary nebula.

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The Remarkable Evolution of the Post-Agb Star FG SGE

Highlights of Astronomy ◽

10.1017/s1539299600021134 ◽

1998 ◽

Vol 11 (1) ◽

pp. 363-363

Author(s):

Johanna Jurcsik ◽

Benjamin Montesinos

Keyword(s):

Time Scales ◽

Effective Temperature ◽

Planetary Nebula ◽

Planetary Nebulae ◽

Central Star ◽

Evolutionary Models ◽

Single Star ◽

Line Intensities ◽

Evolutionary Changes ◽

Evolutionary Studies

FG Sagittae is one of the most important key objects of post-AGB stellar evolutionary studies. As a consequence of a final helium shell flash, this unique variable has shown real evolutionary changes on human time scales during this century. The observational history was reviewed in comparison with predictions from evolutionary models. The central star of the old planetary nebula (Hel-5) evolved from left to right in the HR diagram, going in just hundred years from the hot region of exciting sources of planetary nebulae to the cool red supergiant domain just before our eyes becoming a newly-born post-AGB star. The effective temperature of the star was around 50,000 K at the beginning of this century, and the last estimates in the late 1980s give 5,000-6,500 K. Recent spectroscopic observations obtained by Ingemar Lundström show definite changes in the nebular line intensities. This fact undoubtedly rules out the possibility that, instead of FG Sge, a hidden hot object would be the true central star of the nebula. Consequently, the observed evolutionary changes are connected with the evolution of a single star.

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When nature tries to trick us

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833693 ◽

2018 ◽

Vol 619 ◽

pp. A84 ◽

Cited By ~ 6

Author(s):

Henri M. J. Boffin ◽

David Jones ◽

Roger Wesson ◽

Yuri Beletsky ◽

Brent Miszalski ◽

...

Keyword(s):

Planetary Nebula ◽

Binary Star ◽

Central Star ◽

Equal Mass ◽

Type I ◽

Eclipsing Binary ◽

Common Envelope ◽

Bright Object ◽

F Stars ◽

Central Stars

Bipolar planetary nebulae (PNe) are thought to result from binary star interactions and, indeed, tens of binary central stars of PNe have been found, in particular using photometric time-series that allow for the detection of post-common envelope systems. Using photometry at the NTT in La Silla we have studied the bright object close to the centre of PN M 3-2 and found it to be an eclipsing binary with an orbital period of 1.88 days. However, the components of the binary appear to be two A or F stars, of almost equal mass, and are therefore too cold to be the source of ionisation of the nebula. Using deep images of the central star obtained in good seeing conditions, we confirm a previous result that the central star is more likely much fainter, located 2″ away from the bright star. The eclipsing binary is thus a chance alignment on top of the planetary nebula. We also studied the nebular abundance and confirm it to be a Type I PN.

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