Planetary nebula chemical abundances: Z-distribution and connection with the central star masses

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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Chemical Abundances of the Planetary Nebula IC 4634 and Its Central Star

The Astrophysical Journal ◽

10.1086/307903 ◽

1999 ◽

Vol 525 (1) ◽

pp. 294-304 ◽

Cited By ~ 17

Author(s):

Siek Hyung ◽

Lawrence H. Aller ◽

Walter A. Feibelman

Keyword(s):

Planetary Nebula ◽

Central Star ◽

Chemical Abundances

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3D photoionization models: the bipolar PN IC 4406

Symposium - International Astronomical Union ◽

10.1017/s0074180900130529 ◽

1997 ◽

Vol 180 ◽

pp. 231-231

Author(s):

R. Gruenwald ◽

S. M. Viegas ◽

D. Broguière

Keyword(s):

Planetary Nebula ◽

Three Dimensional ◽

Chemical Properties ◽

Diffuse Radiation ◽

Central Star ◽

Type I ◽

Chemical Abundances ◽

Line Intensities ◽

Physical Conditions ◽

Self Consistent

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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Detailed studies of IPHAS sources - I. The disrupted late bipolar IPHASX J193718.6+202102

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3270 ◽

2020 ◽

Author(s):

L Sabin ◽

M A Guerrero ◽

S Zavala ◽

J A Toalá ◽

G Ramos-Larios ◽

...

Keyword(s):

Planetary Nebula ◽

Dust Emission ◽

Central Star ◽

Physical Structure ◽

High Resolution Spectroscopy ◽

Type Ii ◽

Chemical Abundances ◽

Deep Imaging ◽

Bipolar Type ◽

Pn Morphology

Abstract We present a detailed analysis of the new planetary nebula (PN) IPHASX J193718.6+202102 using deep imaging and intermediate- and high resolution spectroscopy that are interpreted through morpho-kinematic and photoionisation modelling. The physical structure of the nebula consists of a fragmented torus and an extremely faint orthogonal bipolar outflow, contrary to the pinched waist PN morphology suggested by its optical image. Our kinematic analysis indicates that the torus is expanding at 25±5 km s−1 and is gradually breaking up. At an estimated distance of 7.1$_{-0.3}^{+0.8}$ kpc, the corresponding kinematic age of ∼26000 years is consistent with a faint and disintegrating PN. The intermediate-resolution spectra reveal an excited PN with chemical abundances typical of Type II PNe. Based on the latter we also estimate an initial mass for the progenitor in the range 2–3 M⊙ and a central star (CSPN) mass MCSPN ∼0.61 M⊙. The Spitzer MIPS 24 μm emission that closely follows the fragmented torus could be attributed to the emission of [O iv] at 25.9 μm rather than to dust emission. All the results coherently point towards an evolved moderately massive bipolar Type II PN on the brink of dissolving into the interstellar medium.

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Planetary Nebula Evolution Traced by Distance-Independent Parameters

Symposium - International Astronomical Union ◽

10.1017/s0074180900172134 ◽

1993 ◽

Vol 155 ◽

pp. 480-480

Author(s):

C.Y. Zhang ◽

S. Kwok

Keyword(s):

Physical Properties ◽

Mass Distribution ◽

Planetary Nebula ◽

Strong Support ◽

Planetary Nebulae ◽

Central Star ◽

Evolution Model ◽

The Core ◽

Independent Parameters ◽

Central Stars

Making use of the results from recent infrared and radio surveys of planetary nebulae, we have selected 431 nebulae to form a sample where a number of distance-independent parameters (e.g., Tb, Td, I60μm and IRE) can be constructed. In addition, we also made use of other distance-independent parameters ne and T∗ where recent measurements are available. We have investigated the relationships among these parameters in the context of a coupled evolution model of the nebula and the central star. We find that most of the observed data in fact lie within the area covered by the model tracks, therefore lending strong support to the correctness of the model. Most interestingly, we find that the evolutionary tracks for nebulae with central stars of different core masses can be separated in a Tb-T∗ plane. This implies that the core masses and ages of the central stars can be determined completely independent of distance assumptions. The core masses and ages have been obtained for 302 central stars with previously determined central-star temperatures. We find that the mass distribution of the central stars strongly peaks at 0.6 M⊙, with 66% of the sample having masses <0.64 MM⊙. The luminosities of the central stars are then derived from their positions in the HR diagram according to their core masses and central star temperatures. If this method of mass (and luminosity) determination turns out to be accurate, we can bypass the extremely unreliable estimates for distances, and will be able to derive other physical properties of planetary nebulae.

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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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SAO 244567 (HEN1357): A Post-Agb Star which has turned into a Planetary Nebula within the last 20 years

Highlights of Astronomy ◽

10.1017/s1539299600021092 ◽

1998 ◽

Vol 11 (1) ◽

pp. 358-358

Author(s):

M. Parthasarathy

Keyword(s):

Planetary Nebula ◽

Far Infrared ◽

Central Star ◽

Terminal Velocity ◽

Galactic Latitude ◽

Iras Source ◽

High Galactic Latitude ◽

Alpha Emission ◽

Early Type Star ◽

Emission Strength

SAO 244567 (Henl357) (IRAS 17119-5926) is a high galactic latitude (1 = 331°, b = −12°) early type star, originally classified as a B or A type H-alpha emission line star by Henize (1976). It is an IRAS source with far infrared colours similar to planetary nebulae. The IUE ultraviolet spectra obtained during the last eight years show that the central star is rapidly evolving. It is found that the central star of this young PN has faded by a factor of 3 within the last seven eight years. The terminal velocity of the stellar wind has decreased from −3500 km/sec in 1988 to almost zero in 1994. In 1988 the C IV (1550A) line which was a P-Cygni profile with strong absorption component had almost vanished by 1994. The CIII] 1909A emission strength increased markedly within 4 years from 1988 to 1992. The optical spectra obtained since 1990 shows very clearly only the nebular spectrum which is very similar to that of low excitation planetary nebula. The optical spectrum of SAO 244567 obtained in 1971 shows that it was a post-AGB B 1 or B2 supergiant at that time. This result shows that SAO 244567 has turned into a planetary nebula within the last 20 years. Recently Bobrowsky (1994) obtained narrowband optically resolved images in both H-beta and [OIII] 5007A with the HST planetary camera which revealed a well resolved nebula of size 2 seconds of arc. In this paper we discuss the recent new results.

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New models for the rapid evolution of the central star of the Stingray Nebula

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab890 ◽

2021 ◽

Author(s):

T M Lawlor

Keyword(s):

Mass Loss ◽

Stellar Evolution ◽

Planetary Nebula ◽

Rapid Evolution ◽

Central Star ◽

Asymptotic Giant Branch ◽

Initial Mass ◽

Thermal Pulse ◽

The Past ◽

New Models

Abstract We present stellar evolution calculations from the Asymptotic Giant Branch (AGB) to the Planetary Nebula (PN) phase for models of initial mass 1.2 M⊙ and 2.0 M⊙ that experience a Late Thermal Pulse (LTP), a helium shell flash that occurs following the AGB and causes a rapid looping evolution between the AGB and PN phase. We use these models to make comparisons to the central star of the Stingray Nebula, V839 Ara (SAO 244567). The central star has been observed to be rapidly evolving (heating) over the last 50 to 60 years and rapidly dimming over the past 20–30 years. It has been reported to belong to the youngest known planetary nebula, now rapidly fading in brightness. In this paper we show that the observed timescales, sudden dimming, and increasing Log(g), can all be explained by LTP models of a specific variety. We provide a possible explanation for the nebular ionization, the 1980’s sudden mass loss episode, the sudden decline in mass loss, and the nebular recombination and fading.

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Chemical Enrichment and Central Star Properties

Symposium - International Astronomical Union ◽

10.1017/s0074180900172468 ◽

1993 ◽

Vol 155 ◽

pp. 572-572

Author(s):

C.Y. Zhang

Keyword(s):

Planetary Nebulae ◽

Central Star ◽

Agb Stars ◽

Physical Processes ◽

Chemical Abundances ◽

Core Mass ◽

Chemical Enrichment ◽

The Core ◽

Stellar Temperature ◽

Independent Parameters

We have selected a sample of planetary nebulae, for which the core masses are determined using distance-independent parameters (Zhang and Kwok 1992). The chemical abundances of He, N, O, and C are taken from the literature for them. Relationships of the ratios of He/H, N/O, and C/O with various stellar parameters of planetary nebulae (PN), such as the core mass, the mass of the core plus the ionized nebular gas, the stellar age and temperature, are examined. It is found that the N/O increases with increasing mass, while the C/O first increases and then decreases with the core mass. No strong correlation seems to exist between the He/H and the core mass. A correlation of the N/O and He/H with the stellar temperature exists. The current dredge-up theory for the progenitor AGB stars cannot satisfactorily account for these patterns of chemical enrichment in PN. Furthermore, the correlations of the N/O and He/H with the stellar age and temperature indicate that besides the dredge-ups in the RG and AGB stages, physical processes that happen in the planetary nebula stage may also play a role in forming the observed patterns of chemical enrichment in the planetary nebulae.

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